Gus Potter

Good, just make sure that you can vibrate the concrete ok and get the pour sequencing right. Go back and just check the design with you SE, in case there is an annotation error.. it happens.

Fair enough if you take the slab in isolation.. but often these things require a holistic approach. As a designer folk often ask me.. why is your raft slab thicker.. I've seen some slabs at 100mm thick internally.. and I say because that little extra thickness allows me to shed load into it which makes the other parts of your design cheeper. Why have you got the extra complexity in my attic conversion.. often because it lets you get the stair to fit and complies with BC regs We are renovating a historic building so we can't apply standard rules and need to design from first principles this is the way to go I say.

Post your design drawings if you want and see if folk on BH can put some reasonable cost numbers / suggestions to this. In terms of pricing raft slabs ideally we want to split out any excavation and back filling cost from the slab and then further split out the insulation cost.

Hello Bob. I've not been tracking this thread much and have been busy with the day job. I'm assuming you are in Scotland? A few comments as best I can which may relate to your build. I've made a few assumptions, correct me if I'm wrong. To get your building warrant I think you got your pal to do the drawings (call these the Architectural Drawings) and for the structural design you went the SER route and got an SER certificate from an SE? As an aside there is another route which I use and that is to submit structural calculations to BC who then get their in house Engineers to check. It's not true that you must have an SER registered Engineer to do self builds in Scotland. Either way the process in Scotland is much more rigerous than often in England and the warranty providers often do not recognise this.. particularly if you have a case handler that knows little about the diffrent ways the Scottish system works. What can often work is to educate and lead them through the process.. you can instill confidence that you know what you are doing. The warranty folk are trying to do is to limit the worst of their exposure. After a while on Buildhub you get to see the folk who want to do things properly and at the other end there are those that cut every corner under the sun and bend the rules. Now Protek call you up and ask if there is a Principle Designer. Under my PI cover I have an element that allows me to act as PD, but always within the limit of my compentence. My insurers ask what experience I have and to wrap the PD bit up they say ok.. Gus we will cover you so long as you excercise reasonable skill and care. If you run about and do daft things we will not pick up the tab. Now the same ethos applies all the way down the food chain to the self builder. But the remit of a PD does not extend to ensuring what is shown on the drawings is actually built properly on site! Now @Amateur bob the same rules apply to you and you can use them in principle I think to solve the problem you have. 1/ You have a building warrant. 2/ You have a structural design. 3/ You need to be able to demonstrate that you have built everything in accordance with the drawings. How do you do that in Scotland? Well when you get a building warrant in Scotland there is a bit called the Construction Notification Plan (CNNP). This means that you have to notify BC where you are at and they often come out to inspect. @Kelvin may be able to offer some help here as will @saveasteading. If you educate your insurance case handler on the Scottish process then that may be enough to get you over the line. You can also add loads of photos to show you are being dilligent and following the design drawings, employing where you can competent builders and so on. To get a completion certificate in Scotland you often need,if going down the SER route, a thing called a form Q. You can get the warrant to start the work but the SER Engineer needs to see all the design calcs from everyone that has a hand in the design. A good example is calculations for roof trusses which are not available at the start of the job. If all this info is not forthcoming at the end of the job and gets the SER approval then no completion certificate from BC... and then you are totally stuffed. This is where I gain an advantage over the SER route in that I'm doing all the calculation work up front most of the time. @Amateur bobOn no account offer up the below until push comes to absolute shove! as it will cost you money. I think you can navigate this ok without getting into a bind. You are not the first Scottish selfbuilder that has encountered this issue so take heart from that. But say that does not work and it goes nuclear! One option is.. You could call me for example. I would intially ask for all the design information and site photographs, spend say a day reviewing that. I would then come to site and look about.. ask you to walk me through how you have got to where you are, listen lots and then ask you lots of questions! I would then provide a evidence based report on what I have observed and whether what I have visually seen complies with the design drawings. This would be based on my 20 years experience as a building contractor / my 20 years design experience and all that gets backed up with my PI cover. Now say I find something that is not in compliance with the drawings? Will BC see this also, maybe, but at the end of the day you want a safe house. I'll have a look at any non compliance and see if what you have done is still ok in my view.. say it is a structural thing. Now to get your completion certificate under the Scottish regs the BC officer may say.. hey you have deviated from the SER design certificate and it's now invalid. What I do is to work out if it still is ok, maybe do a drawing or two and some calcs, phone up the SER Engineer, have a chat and resolve any issues. The same rules apply if say you have deviated in term of DPC, weathering details and insulation details.. call this Architectural things. Bob. There is a fee attached to this and I would be looking at what you signed up for and see if you can get your premium back and go with a different insurer. For all on BH. As an SE I carry professional indemnity insurance. My insurer's look at my experience and competancy. The fine print says ok.. Gus we will insure you provided you don't take on designs that are outwith your competency or try and manipulate the terms and conditions of you insurance contract.. in other words.. don't be an idiot and expect us to pick up the tab. What they absolutely do is to insure me if I make a genuine mistake or get pelted by other folk that have made mistakes and try and pin the blame on me.. which is quite common in the construction industry. @Amateur bob This could be a way of solving your problem at the extreme end, try and avoid by educating Protek.

Shape code 51 is this Table 2 says this And there lies your problem. I suspect your SE has made a bollocks of this link / beam design. 10mm links with only B = 90 mm? even if in terms of buildability and cost.

I'm cack handed, good at the maths but not good at spelling and grammer. I'm going to try and distill but add a bit to my last (long and admittably long rambling post with less ramble).. Seriously folks. @Saul.. you buy a house in good faith, you see something that worries you, do some research and kind of know you are right.. then you get fobbed off, you get over that and then you encounter the delay, deny and defend tactic. This is standard industry procedure. Now as I've said I do a bit of claims work 95% probono . I've represented Architect's that have got sued and domestic clients.. I've only been in court once and won hands down! It's not that I'm a fair weather SE it's because I know how to approach a problem and "change the conversation" if need be. Also, If you ask me to fight on you behalf and think you are swinging the lead.. I'll turn your brief down. The pragmatic objective is to not go to court but get a good settlement. In @Saul case the opponents have much to lose. If they don't settle then their insurance premiums will go though the roof, they could end up featuring in the daily mail or getting a black mark from the HSE. Now even if there are a few houses with the same problem then in the grand scheme of things it's not a big financial problem for say the NHBC.. they have huge resources and "lay off" in the insurance market for example. It sounds brutal but that is how the industry works. @SaulYou must absolutely must get your head around this for your own sanity. Now what about @Saul issue. This will be dealt with at maybe middle management level. One of the secrets is to make it easy for them to just pay out. Everyone has a boss. What you seek to to is to find a few things that are very difficult to contradict. Often you see folks in dispute about cracks in the walls. But that may or may not be structurally unsafe.. the insurer / builder will say " general shrinkage" we told you that in the fine print when you bought the house. As an SE it is very hard for me to argue this case as it's subjective. The Eurocodes make it even harder to argue this case which we call serviceability.. the Eurocodes almost allow the builders to pick their own crack and shrinkage widths.. as an SE I'm often on a hiding to nothing trying to argue this as the NHBC et all chuck professor x and y at me. But as soon as I talk (in an evidenced based way) about the strength of say beams and how they rely on not having too much movement of the walls the Professors point to their fine print and back off! At that point the game is nearly over. I don't discredit the Profs reports I just point out their limitations and how they are invalid to the context of the arguement... by simply asking a few targeted questions. Also I find that some same Professors have had a hand in writing the design codes.. where they stress the importance of say beam bearings, wall ties and building stability systems. @Saul may have been povided with a report.. but you need to know enough to know what it says and means.. but basically look at who paid for it! To understand the meaning you need someone like me! There is no way on this good earth that a laywer will know this.. unless they have a dual qualification.. laywer and SE! Now again @Saul says there is a report that ok's to have a weak mortar. I'll bet that said report is highly qualified. Yes, it may be written by an expert, I'm not challenging that.. what I'm saying is you need to look at everything else that relies on the mortar being of sufficient strength and durability in terms of fire and damp proof protection. You can get this information by phoning up the manufactures. and talking to their experts. At the end of the day they can be quite helpfull. They don't want their name tarnished either! Just imaginge the daily mail saying.. 40 houses need to come down because of wall ties.. when in fact it was shite mortar! Summary : My own view on what I have read on BH is that @saul has a good case.. but to get the best out of it Saul needs to control and lead the laywer.. if not then the case could be potentailly lost or pay badly, the house blighted., and the personal stress and damage to health is just not worth it. I've had a case where the developer has just bought the house back, paid a healthy compensation and you need to sign an NDA. @Saul don't rule this out as an option. I made this work by pelting them so heavily on the cost of HSE compliance, structural safety that a deal was done. The Client wanted an element of "punishment" for what the developer had put them through. That came as part of the deal.

All good stuff Alan. For me as an SE and the thing that keeps me awake at night is the thought of designing something that falls down and hurts or kills folk. If I did that then there are many examples of SE's that never work again. Persoanlly I would find it a hard thing to live with, I hope it never happens. I've seen fatalities on site. In that context sometime I see folk on BH doing stupid things structurally or things that I can see are going to cause problems with say BC compliance. But this is social media and you all wear big boy pants. Good advice.

This is pragmatism and actually very clever.

Hello Saul Sorry to hear you are having a hard time. Here are a few comments. They are just general but may help you, even if just to rule out. Often ruling things out let's you focus. I do a bit of Claims work now and again, not a lot as I would rather be having fun designing stuff. I'm off the day job so excuse the spelling, grammer and hope you get the jist of my comments! When you get sight of a professional report you must read the caveats and scope of the brief. But as a lay person you will still struggle to understand what these actually mean. This type of report is carefully crafted. You have a lot riding on this and so do the insurers etc. Ok I see you have gone a bit legal.. part of the torture these folk put you through. I was interested when you discussed about the diffferent views on the mortar compressive strength. There was professional who: Now that is almost / true in some context.. An example. Say you have a building that is made out of quality Bath Limestone. The beds are just there to keep the weather out and allow the stone to move so we don't get movement cracks...and shed some of the local stress in the stone. Anyway.. You are in dispute, your text and posts exhibit an often observed pattern from my end. You may be feeling that you are getting stuck as you are focusing on the mortar. Now there are lawyers and so on thta add to the confusion. I often feel this is a standard appoarch by say Contractors / Insurers. From their end it's about numbers, size and frequency of claims. Let me paint you a picture: Let's say you find an SE that is a crusty bugger and who does everything based on evidence, knows how the game is played. Let's also say that this SE knows how to inform your Lawyer, who may be young and wants to learn / win and pocket a bit of cash. For me as an SE part of my claims work is to provide the tools to allow the laywer to fight the case. I always go back to basic design principles and most laywers can make hay with that. You write to your opponent and ask to see the original design calculations for the house and if there are any "as built drawings" Now 99% of the time these will not be provided. No calcs / drawings you now have opened the door! Saul you are focusing on mortar strength, say durability, a professional report is introduced about 1:10.5 mortar mix. Your opposition is tying you in knots, taking up your time, causing you stress, potentially blighting the value of your house. This is standard fair and practice when you go up against developers and say the NHBC.. especially when there may be more than one house at risk. What can you do: Ok you are feeling that you are fighting a big wall. BUT it's an old expression.. just change the conversation!.. it's an old addage from I think 1960's marketing.. but still true to this day! Go around the wall! I do claims work now and again.. I don't take on a Claim unless I think I have a decent chance of winning. The NHBC et all have huge resources.. the trick is to find a way round their firewall. I focus on structural safety / fire safety and how all the other ements of the building rely or not on the wall and mortare for example. You can quickly turn the tables on them and rack up their costs! Importantly you can highlight structural safety issues which puts the shiters up them. They have to address this quick as you might report them to the HSE. You are concerend about say the mortar falling out over time.. I'm concerned as an SE about the current structural safety! To fix this the NHBC often need to fix the structural safety aspect which fixes the thing we started argueing about in the first place which is the mortar strength..there are different ways to skin a cat! Well as a home owner you can write, I'm just touching on a few examples here.. but in my day job I go to town! I'll go into any beam bearings on soft mortar, durability.. the whole lot. Once I get going with my SE design safety hat on it can be free for all. In my experience most insurers just throw in the towel.. but you must educate your Lawyer and a good SE for example will do that. Some question you may ask as a lay person: 1/ I know the roof sits on the walls and puts vertical load on the walls does this report (1:10 etc) take the behavoir i=of the buildingninto account. I would love to see copy of said report for interest. 2/ I know the wind blows on the roof and to stop it moving sideways or upwards it needs to be tied to the walls. I know that the regs require the masonry to be of a certain standard so the vertical and as equally important the sideways wind loads are transferred to the walls all the way down to the foundations. 3/ The floors tie into the walls and for these to work the walls need to comply with the assumptions in the floor design. 4/ The wall ties as recommended rely on a certain strength of mortar bed.. if my mortar is not strong enough then that invalidates the wall tie design. 5/ Fire protection. Now I can see the mortar is falling out on the outside. If it is happening on the inside then the fire pretection in the cavity may be compromised? How do you know it's not? 6/ Bridging of DPC's and wall ties in the cavity.. is the mortar falling out causing bridging? 7/ I have windows and doors.. my supplier needs to verify that the walls they are fixing into to comply with the standards. I've just touched in laymans terms on some questions you may want to ask. Gus (that's me) What I do from time to time is to phone up the technical department of say the wall tie manufacturer and say I'm in a bit of a bind what do you think unoffically ? Is this defensable or do you think I'm right? Remember folks that from time to time I may defend a builder? To close: To win this I think you need to change the conversation.. focus on structural safety and how the weak mortar has invalidated the rest of the design. Try and rack up the cost and time to defend for your opponent. At some point they will come to the table and want to negotiate. That is a story for another day.

I agree with you. there are a lot of conspiricy theories.. but I'm inclined towards looking at what I know. The fire protection got blasted off the steel.. it got hot, failed, which cuased the building to collapse. The planes impacted on more than one floor. Where the plane hit was at the height where there was a lot of dead load from above. Once that dead load started moving the dynamic effects were multiplied. You only need to lose say 1.0 or 2.0 metres of column fire protection over a number of columns to promote what we call disproportionate collapse. I still find it personally uncomfortable to distill and write about it in this way when so many people lost their lives. No is a hotpoint and looks good! I'm in awe of the Space X Engineering team. Stainless steel is a wonderfull material.. it's ductile, forgiving but comes at a cost. I love what Space X is doing.. they have the best Engineers.. we British used to be like that! For me it's about how the marry up the best young talent with old school testing engineers.

xxx for you! Yes you are right.. I can't think of a time when you have been wrong! wish I could., just kidding. For low rise domestic design we try and limit the SE fee. At foundation formation level (the depth of the hole we dig) we dig a bit of soil out and put some concrete back in. But then we often make the founds wider for buildability and call it a day. Good point. We as SE's have a term called load sharing and load spread..,. similar to electrical diversity when sizing a supply or consumer unit. The piano and Eltons "charisma" gets spread about by the time it reaches the founds. While we do calculations some of these are based on a best guess and experience. The soil under the founds is variaible , best guess. If we are blessed with say 4 Eltons on a floor then that is where the safety factors come in. Anyway Elton does not stay more than a few hours which will not impact on the long term settlement.

I'm dabbling with a bit of AI off the back of some of the help and suggestions I've got from folk on BH. Thanks all. I've found it usefull in that it acts as a prompt. My own problem (I have more than one) is that I've been in the construction industry for some 40 years.. I forget stuff while at the same time I'm still on a learning curve. As new stuff (like what BH members are doing) crops up I'm working out.. how do I design this, where can I use first principle design and so on while sticking to the ethos of say the building and structural design regs. What I have learnt so far.. is to treat AI like tabloid news.. with a large pinch of salt. About 20 years ago I first got involved in producing cold formed steel SE calculations for the biggest supplier of cold formed portal framed buildings in the UK, it was great fun and they supported me in my SE training.. In some ways they were not actually a steel company but a software company that manufactured and sold steel buildings. Their big market was actually in Australia (huge mining companies and so on).. the UK was a bolt on with R&D, engineering tech from the uni I went to. l got to work with computer programmers all over the world, still dabble a bit when I get the chance. What I've learnt about software development is that you have to fly by the seat of your pants. If you want to get software perfect with no bugs then by the time you do that the market has moved on.. and you will lose all your investment money! Matt. I think the construction industry is going to have to embrace AI in terms of some design, the paperwork, call it that for simplicity. I supsect you may be wanting to go at 100 miles an hour (160 kph).. but if you have time go back and read the Sir John Egan, published in 1998. Matt can you explain what you do do in laymans terms and what you seek to achieve?

This is a good point. On normal low rise houses we may go to site and dig a few trial pits and find CLAY soil. We can do some tests on the soil (or just look at and mould it in our hand) and based on that information we can calculate how much load we can put on the soil before it fails, like just totally gives up the ghost big time. We don't want that to happen so we may say let's put a factor of safety of 2.0 on that. An example would be.. say we calculate that we can put thirty tonnes (about 300 kilo Newtons kN) per square metre on the ground before it totally fails. Puttinga factor of safety on that of 2.0 and that gives us a number of say 15 tonnes a square metre. But CLAY soils settle over time. The next calculation is for settlement. In the UK for normal low rise housing we often limit this to 25mm over 50 years. This gives us another load that the ground can carry without settling excessively. We pick the lower of the two numbers.. and often you'll see on you SE drawings what is referred to as say.. "this design is based on an allowable soil bearing capacity of 100 - 150 kN/m squared which is about 10-15 tonnes. When we have a SAND soil ( I capitalise as the use of upper case denotes the dominant component of the soil) we carry out a similar calculation but are very keen to know about the level of the ground water and where it might be in the future as this can half the strength of a SAND soil. Ben. The biggest number on your drawings is 12.5 /5.0 unfactored load. Now take that as is and add the dead (the weight of things) and live load (people, snow, roof access and so on) together which give 12.5 + 5.0 = 17.5 kN per metre run of wall. Now say that sits on a simple strip concrete foundation with a bit of A142 mesh to stop it cracking too much. Also say that your soil can carry an allowable bearing pressure of 100 kN per metre squared. Let's see how wide the foundation needs to be to carry that load. 17.5 kN per metre run / 100 kN/ m squared capacity= 175mm! But that is the theory.. Incedentally if any of you have renovated old Victorian houses you may find internal walls that are just sitting on bricks laid sideways on a bed of lime mortar on the soil. So while the number above look crazy it's not actually in old money. Anyway back to your build Ben. You can't reasonably dig or fit a wall onto a found that narrow. When we go to set things out for a DIY self build found.. we may be not get the marking that straight. If your builder / you get a local hire JCB they often pitch up on site with a 600mm and 450mm wide bucket and a blade bucket for scraping the ground and tidying things up.. Thus on a house like yours I would say can we just do the narrower internal wall founds with the 450 bucket, the external walls with a 600 bucket. Make all the foundations 200 mm thick. Alan is spot on, this happens! In the UK we still use a combination of the British Standards and the Eurocodes. These codes have different factors of safety and we combine the loads in different ways depending on which code we are designing to. By providing the unfactored loads we allow the different suppliers / package designer more scope. That drives down cost.

Good point, as aways. Steel is an elastic material, like all materials. In the UK we don't suffer from particularly low temperatures, but in some cases where we have structural steelwork that is exposed to low temperatures we select a steel grade that is more ductile (less brittle). Going in the other direction when we heat it up it starts loosing "strength" that give designers concern at just over 300 deg C. @saveasteading is correct about the oven There is some softening of the steel at 250 deg but it is for all intents negligeable. . Below is a typical fire curve for steel from the SCI. Simplistically when we design steel for fire we may pick the 550 degree curve. Work out the loads on the building during a fire. When we do this we don't assume the building is fully loaded in the same way as when we are designing for day to day use. Fire is what we call an accidental load case and we reduce the factors of safety and the loads to reflect that this is an accident. If we did not do this then building cost would often be prohibitive. Fire protection is about providing a protective layer of material that insulates the steel in one way or another. Or for example you can use say sprinkler systems that reduce the heat and duration of a fire. Fire is a terrible thing. What we aim to do is to provide warning of a fire first. Smoke and heat alarms say and this lets people exit the building. We aim to provide them a safe route to do so. Here we may see reference in the regs to escape windows and the like on a single story house, we avoid having a room off a room with no escape window for example. On a three storey house we often want to have a protected stairwell or a sprinkler system with an enhance fire detection system. Once buildings get taller (often 3 habitable floors or more for domestic use) we need to think even more about people that may be trapped. Here we want to further protect the floors, walls, the structure and so on to provide a safe shelter space until the fire brigade can effect a rescue. During and after the rescue we need to protect the structure so it does not collapse on the fire brigade or set light to any surrounding buildings.. and that is where the other structural aspect of fire design comes into play. Often if your house is well away from other buildings the fire brigade (if sure no one is left inside) will fight the fire from a safe distance.. or if in doubt just let it burn. I take Nick's point.. but at the end of the day it's often the insurer that has to pick up the tab. The more you can limit the extent of the fire damage the less they often need to underwrite and that is reflected in the premium.

Yes I agree. In simplistic terms there is chemically "locked in water" in the plaster board. The heat transfer is slowed as the plasterboard "soaks up the heat" as it is forced to change chemically. But.. often the fixings are the vulnerable point. An easy way of getting your head round this is to go to the BC standards. They talk about fire "resistance" and fire "integrity" The resistance bit is to do with a material transferring heat. The integrity is about making sure that the fixings and the things the fixings go into remain ok.. as if they fail then boards say fail also. The regs combine intergrity with resistance to give you the overall number. In summary though. Say you are completely new to this. I would explain that steel starts to lose its strength when it gets hot.. that can start at temperatures similar to when your oven is at full whack.. say 250C.. this lets the home owner get a feel for what we are talking about in terms of how quickly steel can loose strength when it gets hot. What we need to do is insulate it so it does not get hot. Then we look at the different ways of doing this. @saveasteading and others have pointed out the different ways we can go about keeping the steel cool.

This is a tricky question. Time? The internet allows you to work in some places in the world as I've done for a long time. USA is a no, AU is ok... for now. We have large cavities due to say blown cellulose insulation. Thank you for the compliment, I like to have a chat as you know! Seriously though.. It's a very good question. I'll mull it over and try and come up with a coherent, reasoned and justifyable answer for folk to discuss.. I'm learning too folks about wide cavities, how they behave and how you insulate and so on! It not just the cavity width.. its the way the roof loads are transferred to the walls that is often changing, the way the floor joists / floors are connected in to avoid cold bridging is changing and on top of that we need to get it buildable, the works sequenced and cost effective. One of the things is that a lot of the masonry design codes are based on; calculation, partly emprical (call that Grandads rights) and partly based on test results. As soon as you go off "piste" in terms of the design codes you often need to go back to first principle design and that can be conservative and too conservative can add a lot of cost.

Hi @ETC there use to be a bloke called @the_r_sole who was a right down to earth Architect and massively experienced that gave up his time to contribute to BH. He really knew his stuff.. a bit like you. You can find his posts in two ways.. on google and with a BH search.. hard to find. Try and look them out. His writing style probably is similar to yours, no nonsence. I have my own informal style of writing / shite spelling ( story for another day).. it's ok to be different and give Clients a different offer. @ETC I'm chatty on BH, (just sharing my knowledge) when I pitch for a design brief.. I seem to win briefs.. but when I deal with industrial or hard nosed folk I can play that game too. I do now and again Claims work.. my head does not zip up the back. My style then is a different animal... but I'm confident in my ability... my style sets me apart from the competition. Even when I do claims and just day to day jobs. Over the years I've learnt my design craft.. but also try and improve the way I can communicate what are often complex design issues into simple concepts that a lay person can get their head around while enabling them to make informed financial descisions. @ETC that in my view thatv is the mark of a good professioal. I think the mods on BH are ok and if you get a bit of business, it's ok provided you don't take the pish. Now and again someone from BH engages me, often these are folk that are really stuck, bad builder. and so on. About two years ago I commented on a post about bad blocks from Ireland.. got a email couple of days ago.. can you help. That is the thing I love about the BH community folk will come back to you for help. My basic qualification is in Civil Enginnering and that key word is Civil.. we work for the public. For all I'm proud of that and will never forget my civic duty. @saveasteading has expanded on this civic duty. It's like being a doctor.. we have a duty not to harm, you as Client are lower down the list even thought you are paying the bill! The sole put his heart into BH but basically got hounded off BH as there were too many twats that thought they knew better, they thought all Architects were arseholes. So going back a bit and not picking anyone out in particular..I'm just saying remember when the sole was doing his best. @nod @MikeSharp01 and the rest of the mods. On the other hand @ETC what about using your own name like I do? I would like to see you tighten up many of you comments, you can't have your cake an eat it? For me I read what you write and think.. mmm here is a smart arse.. It would be good if you went on to reason out your comments so the lay person on BH can undestand.. that is what I try and do.. give it a go!

No, you need to go back to the SE AND the Architect or the person who made the drawings and ask why there is a high bond DPC. If you decide to swap DPC's then you are exposing yourself to a big risk. You could also be acting in a dangerous way. If BC come out and find you have swapped out materials then you could be in big trouble. Re read my post. Be safe and ask the question.. it costs nothing. It's OK to ask "silly questions".. what is stupid is not to ask the question at all. I think you are mixing up the different types of NHBC guidance. We used to make cavity trays etc out of DPC (folding it and so on to make a tray) and before that heavy duty bituminous felt. .. but modern brickies are crap at it.. at it so the NHBC are leaning towards factory made trays. The High bond Zedex is more associated with the structural performance of the walls and that is why I'm doing my best to encourage you to just ask question.

For me, in my last life, as a local building contractor I learnt to have a look at who was making the most profit. Business is a learning curve. You get subbies in.. say ICF.. tie them into a contract, learn and if it looks profitable then cut them out. There are no friends in the desert. Profit is sanity, turnover vanity.. especially if you are carrying risk for someone else's turnover that is leveriging that... you can end up being a useful idiot. Not just in the way that the finances work but as soon as they get enough well completed jobs they will ditch the local guy. The pressure to do this will come from above.. the folk that are making the ICF insulation. Now a case in point. Advanced Foudation Technology have got accreditation for their own product. This requires a serious amount of investment. I know about this kind of stuff as I've been involved in developing cold formed steel buildings and the raft foundations they sit on, be these insulated or not. I'll leave it at that for now other than to say I may have been into this for a long time... and spent a lot of time learning about what is cost effective or not.. I've made a few mistakes but that comes with the innovative process. The building trade is brutal. I work for contractors as an SE at times, we trade blows. Sometimes they say to me.. hey Gus I can get an SE for a few hundered less. I say go on then, give them a go on a few jobs.. I'll not get offended.. too old for that. Sometimes they come back..once they realise that others designs are not buildable.. but the ones that don't are probably cutting corners and being unsafe. Yes they will get away with it for a time but God or the tax man will catch up with them. For all I've touched on this before.. insulated rafts are not new. ICF is just permenant insulated shutering. I have serious doubts about the economics of this as there are just not enough contractors about to make it a competetive market. By all means if you want to go ICF, have the funds and it floats you boat then go for it. As a designer / SE advising a young couple with a few beans to rub together then I would look at other options rather than ICF, even if to rule them out. There are folk doing ICF in the North of Scotland.. great until you have an on site issue not least! These type of folk tend to have a large contingency fund.. but if you are a nurse on an average wage it's bollocks. But see in terms of getting paid as a contractor and on time .. the nurse is probably your best bet provided you do what you say you are going to do as as a contractor. If you are a building contractor reading this then don't feel unconfortable about making a profit. Many people work for the NHS like my wife. . some of the contractor profit allows them to go on holiday.. in the public service this comes with the job. But for all.. see when your builder is off on holiday they still need to keep the wheels running..

I'll take that as a feather in my cap if you don't mind?

Hi all. This fire protection thing crops up often on BH. I'm going to pick out some of the folk that often chip in on fire design. Now you could be a designer, a contractor or just someone that has done a lot of self builds. What you see is a lot of is folk saying we did this and that. But if you are a newcomer to the self build or internal alteration / extension market then unless you all then go onto say why you did what you did / or do then it gets even more confusing? I've just copied a bit of an extract from posts. There is nothing wrong in the above or right. It's a best guess on limited info on a building forum. @nod you do this stuff as a day job.. time to step up to the plate design / theory wise? Now there are a lot of folk here commenting as above. What would possibly be more helpful is to say.. we had to do this because of this type of design. I use my own name. I write stuff., over time I've been a member I've said some daft stuff, BH members and the MODS have cut me a lot of slack. yes this is a place where as an SE you can shoot the breeze if off duty. BH is also a place where you can make mistakes and folk will forgive. So in that context folk surely you can go the extra mile and say.. here is why we think we did what we did. in terms of fire protection. In summary, folks who comment on fire protection often. We should be stepping up to the plate and saying.. this might work and here is why. We kind of owe that to new members?

@BTC Builder Well done you for spotting this and asking the question. Honestly I can't commend you enough. You have probably saved the SE's arse and most importantly made the folk / the public safe by asking this question. This is a bit long winded.. take what I discuss below and make hay! I'm going to try in laymans terms to offer up an explanation. For all, often when we design a masonry wall it often has downwards load that is a bit off the centre of gravity of the wall. There is sideways load from the wind. Sometimes these may be a masonry wall round a school playground.. big red flags! When we use plastic DPC's and membranes these break the small tensile strength in the wall that is required when we do the bending / stability critical safety check. This bending force in the wall arises when we take wind, and off centre grqvity loadings into account. Now many young SE's are under pressure in the work place. There is a small switch in most software that lets you select the type of DPC. A high bond Zedex is a highly specialised DPC that has not least a sanded surface top and bottom which replicates the way a mortar bed behaves. Thus in the software it appears as a continuous wall. Now technically I can design walls this way.. but first and foremost I would put a massive warning box on my drawings to say this is a critical element.. the contractor will often say to me.. Gus you are asking too much and I'm going to pass this high extra cost (the extra labour / brickie skill level required) onto your Client and I'll leave it up to you to justify this added cost element. As a designer I am responsible for not just the SE sums but also the buildability.. as per new regs on Principle Designers etc.. @BTC Builder That is why you don't find this product as an off the shelf item any more. For you if you agree to install it you have to follow the instructions. It takes time and care.. and that will eat into your profit. If you have signed a contract to install and your bollocks are up to the post then you might want to find a way to do a deal. If I was say acting for you then I would look at the radon barrier position.. there is a chance the SE has shot themselves in the foot! The may have changed the setting in the software and forgotten about the radon barrier which breaks the bond in the wall. In this day and age we avoid using DPC's that are able to act like the masonry bed as say Zedex.. it's just too risky. There are school walls falling down all over the place and compromised designs where SE's just don't have a clue about the costs on small self builds or extensions. Nod.. I know you have a pile of experience but this is something that is not bedtime reading.. you have to be a bit of an anal twat like me to pick up on this stuff.. but on the other hand we all need to realise that every day is a school day.. and the older we get the more we realise how much we don't know. And I'm saying to you.. I admire what you do but you don't know it all as I .. and small things like this if missed can be dangerous! as in using high bond DPC's can be very dangerous.. I know a lot about this to be blunt and that is why I'll have to sing @BTC Builder builders praises again. @ETC We get to a certain age where we are good enough at business to put the bread on the table. Then when we all put out heads together we have fun in designing particularly odd stuff which personally floats my boat, make a bit of profit, get to truck about and get invited socially into the things we have hand in desgining. Shite job eh?

Hi bob. Hope this lift your spirits a bit. Firstly 99.99% of designers don't set out to do a bad job. Your friend has probably gone the extra mile with the details so there is probably some value in that. Also, if you have issues during the build your friend may become your best friend (if not already) as they will often be "on tap" so to speak and that, even in itself, could easily offset any money you have paid. In the UK (in terms of the building regs) it boils down to your design being undertaken by someone who is competent. In Bob's case his friend is probably highly competent. They can demonstrate this by producing drawings to a high standard, producing drawing details that identify critical parts of the design [could be structural (SE stuff) or weathering details (Architect stuff)] that lets someone who is checking the design see that there is competency in play. The crux of the matter is how warranty providers take a view on the risk they are underwriting. Yes, I think your SE will get you sorted.. see below... if you can hang in with my submission and observations.. To make headway here I go back go back first.... excuse the spelling and grammer folks.. please. I wear two hats. My main hat is the SE hat, the other is my Architectural Designers hat. My professional indemnity insurance premium (if I try and split it out) as an SE is about 4 - 5 times more than when I have my Architectural designers hat on. Each year, to renew my PI insurance, I have to fill in a form that splits up the design work I do into various categories, one of these is "Architectural" design. Now most SE's will allocate a percentage value to this more than zero, it might be only 1% but that covers you in case you inadvertantly stray into say @ETC's world. In my case the % is more but I'm not going to tell you what that is. In summary @Amateur bob this means that the SE may be able to say..ok.. I'll tack it all together and take the Architectural design liability on... with a few standard caveats. If you (bob) came to me out of the blue as the SE / Designer I would say ok.. lets have a look at what your warranty provider is asking for and is it reasonable. I would want to know a bit about you also. We would have a chat.. you want me to cover the design under my insurance. I might say, I'll cover you and our contract is between us only.. can you live with that, you may say yes and, that gets recorded. If it turns out later that you sold the house on promptly and I get some random chancer sending me notification of claim, then in the first instance I'll tell you to take a hike. If you want to do this selling on (developing) then you need a collateral warranty and that comes at a cost, its often not a crippling amount but what I don't want is some hard arsed chancer with a tame laywer running up my clock to get a few quid out of me. In other words if you want your pals SE to consider you then you need full transparency. Now for all. One of the privileges of being an SE is that the warranty providers know that we carry lots of insurance. If things go wrong then we are often the first target, they go for the low hanging fruit. Often other folk.. your contractor might have gone bust.. SE's and Architect's can be the last folk standing so we get the blame for everything. The easy way as others have said is to think about this in terms of gambling and bookmakers. Bookmakers and warranty providers will often lay off the risk... but they need the business. They can lay off the risk to the self builder and make conditions.. but then too many and the self builder will go elsewhere. There are plenty folk that do their own drawings.. or get drawings from sub contractors. For me I provide to my Clients a copy of my professional indemnity insurance on request. If the warranty provider asks for detail I can provide a bit of that also.. enough to show that my insurer's are actually covering the things I have designed. For example.. it's not worth my while designing swimming pools.. I have no cover for that. When I was younger I designed stuff for the Nuclear Industry.. but my employer held the cover..the premiums were I understand large.. but not as large as you think..say 50% more! story for another day. What I won't and are not allowed to do by my insurer to do is to provide you with chapter and verse of the forms I fill in each year. This has no bearing.. it's a private commercial transaction between me, my company and insurer. The warranty providers know the rules so don't let them try and pull the wool over your eyes. Ok to finish on a high note @Amateur bob I have a friend and colleague who was an outstanding award winning Architect but has got to an age where he wants to still keep his hand in.. but just wants to spend more time with his grand kids. To keep up his Architect's registration is a lot of work. I've done his SE designs for a long time. We are starting to change the way we work together where I take on more of the day to day tasks, take on more liability under my PI cover.. BC compliance etc. But he is still competant and see if I get stuck I'm straight on the phone for advice! If you have BC permission and sign off but no other designer that can take help lay off the warranty provider's liability then just send them the cv of your pal, state what the SE has done and what they cover and ask for a quotation. At least that gives you a benchmark. You'll be getting "the computer says no" treatment maybe.. but insurers are there to make money.. like bookmakers.. if there is a bargin to be struck they will do it!

Correct from Ian. In the title box you need to say the drawing is this paper size if electronic submission. The planners are yanking your chain to kick the can down the road. You kind of need to suck it up and move on.

Ok what I do is this. I issue a pdf drawing with a scale bar. I put a numerical dimension on the drawing. This means that you can check to see if the scale bar matches with the drawing dimension. That verifies the drawing dimensions no matter how you print it on paper or look at it in pdf format if you are working from home as planner. I suspect your planner is kicking the can down the road and that is why I put on my site plan a reference dimension that they can check the scale bar against to head them off at the pass. But I round off the dimension to 100mm.. so I'll say 6.1m approx. Now the main reason for the rounding.. it is to do with the legal site boundary. I need to be really careful not to establish the legal site boundary by default as I could expose my Client to a property boundary risk.