Gus Potter

What a great piece of advice from @Alan Ambrose Now the next question is how do you find the right SE / Architect / Designer. I'm an SE / Architectural designer, to be honest I started out as a local builder, went to uni.. learnt about SE stuff. When I look back my education gave me the tools to teach myself.. and that changed my life.

Much appreciated. Your post is a mine of infomation. So that is a big thanks from me!

Hope this helps a bit.. but when we want to create a void above the wall head level the forces in the roof members change a lot . The following is very simplistic but intended to give folks an insight into some of the things we design for and hopefully give you all some ideas. Below is a standard fink truss. This fink truss is triagulated, very economic an importantly the loads at the supports are downwards.. and upwards when you get wind uplift. A lot of roofs can be "uplifted".. Below is what we call a raised tie truss. Here we have an extended leg. The ceiling tie and wall support create a lever arm... like having a long spanner to take off a wheel nut on your car. This type of truss depending on the length between the ceiling tie and the wall support causes other forces / sideways movement which can grow exponentially with a small increase in length. An important one is that this kind of truss can push the wall outwards (sideways movement).. so you often need to have "special" sliding truss clips at the wall head or a very strong wall.. and if you have a very strong wall then there are other options! Now the above truss generates some nasty forces at the connection between the ceiling tie and the sloping rafter. Timber connections can be quite weak and they are hard to design economically / buildability wise once you reach a tipping point.. which can be quite early on.. this can be a hard lesson for a Graduate Engineer / self builder. Below is a scissor truss Here you can see that the sloping ceiling tie stops the forces that want to spread the walls outwards as the bottom of the scissor is conneceted to the wall head. Often when we design timber roofs one of the problems is not the size of the timber but having enough timber to make the connections work ok. If you have an old house with a traditionally cut roof you'll see that the ceiling ties and soldiers (the short upright bits) are 1/3 to 1/4 checked. Below is a screenshot of one of my drawings that shows this. The dark green bit is the rafter, light green the soldier/ ceiling tie framing in. But there are only three nails! The one shown here is later detailed as having only 3 no 90x 3.1 mm dia Passlode ring shank galv nails. The three nails are there just to hold the soldier in place when there is say snow / access and roof self weight on the roof. The check in the timber allows for direct bearing.. timber to timber contact... much "stronger" than a few nails! Also we need to watch out for nail spacing and edge distance.. to many nails / to close to the timber edge and we weaken the timber so folks bear that in mind. The three nails are enough to hold the connection together when the wind is trying to suck the roof outwards. To sum up. Timber roof design is a bit of an art.. but hope the above gives some insight into what it is all about. The key thing is that often its the connections that govern the design rather than raw timber size. A good starting point is to go into some old buildings/ terraced houses and see how the roof is put together. @ProDave If you want to chew the fat then would be delighted to hear from you, mind you I'll want to pick your brains too so no free lunch!

To provide a bit of context to become an Architect takes about 7 - 8 years, a degree coupled with professional development and on the job training. As an SE / Designer I agree with your Architect. Your Architect is giving you good advice. If BC pick this up they may ask. But at the end of the day do you want a safe house or not? BC are not there to make sure your house is structrally safe or be SE's. There may be some way to strengthen the roof in a cost effective way to make it compliant.. don't despair.

Ok have you sounded this out with the SE and buildings Engineer? They may be as equally frustrated as you are. If they are willing to support you then one of the two can often have a quite word with the Architect on your behalf (you keep it at arms length) along the lines of.. we don't want to make a big thing of this but what about if we certify our bit.. and you do your bit... by way of the Architect's certificate.. otherwise the Client may instruct us to look more closely at your work and delivery.. and we don't really want that to happen as we are all busy! If an agreement is made in principle then any oustanding fee element can often be "made to go away" Your Architect's certificate is often separate from the JCT.. and that will depend on what kind of JCT contract you have entered into.

I did the structural and foundation design for @Russdl, just call him Russ. It was a great journey for me as a designer. At the outset Russ kind of knew that he wanted to use Geocell and he had good valid reasons for this, had researched widely and already has one self build at least under his belt. Key factors; the ground conditions, the shape of the structure (odd shape) drainage, boundary proximity, site access, muck away cost, the odd planning constraint and cost awareness. In summary this lead to a flat raft type foundation with masonry walls, EWI and cold formed steel roof joists supporting a warm flat roof. Russ build most of this himself and put in a lot of hard work sourcing and fine tuning the installation, his door insulated solution is remarkably good, I'm going to pinch some of this final (on site understanding) threshold detail off him! Ok the Goecell. Russ and I chewed the fat for a while. Me with my SE hat on, him with his practical hat and attention to detail. At the end of the day we ended up with a flat slab on the Geocell.. it is really simple. No edge thickening. His slab is pretty big so I added extra anticrack reinforcement near the doors and funny corners. The objective was to do the slab in one pour and avoid day / control joints as they would then translate up into the super structure.. and cause problems with the masonry design. Folks there is no free lunch and that is why all parts of the design need to be coordinated. What you do at foundation level can have a cost implication later on. At my end one trick was to use standard reinforcing mesh site bent at the ends to give the reinforcement anchorage. I selected the slab thickness to make it a structural slab (a raft) and no more. For the tecky.. my starting point was to have 0.13% of rebar which turns it into a structural slab (cf a ground bearing slab).. if you make the slab thicker is needs more rebar to comply with the minimum % for it to qualify as a structural (raft) slab.. I aimed for the thinnest slab.. and from memory this was driven by how flat you can get the Goecell and having enough of a bend on the reinforcing mesh to anchor it. Now the Goecell. It has a good bearing capacity cf a crappy CLAY soil. We know how the slab will impart the loads. We also know we just needed to provide enough compaction to consolidate the material.. no compacting it to death as this is counter productive. In summary, can be a bit hard to get your head around but you kind of need to lay Geocell in layers and give it a "shoogle" and not actually whack it to death. Russ is posting some of my drawings which I'm pleased about. I hope this helps give folk on BH some ideas / inspiration. Just remember that Russ' job is bespoke so just use them as a bit of food for thought. For old / historic buildings it is a pretty breathable matrix.. Historic England I think have a bit on this, lime floors floors and so on. In summary this sort of stuff floats my boat in terms of how as an SE /designer you make the best out of this type of product in a cost effective manner .. if the opportunity presents!

Thank you, much appreciated. Gus

Hope you are sure of your ground here @DevilDamo! Lets see how it pans out, every day is a skool day.

Yes do that first and then just monitor the house to see house is still moving about between the winter and summer.. expect this in an old house. Attached is an old document I refer to that gives guidance on subsidance / settlement. Read this and hopefully it will allow you to relax! Start with pages 5 and 7! BRE Digest 251 Assessment of damage in low-rise buildings.pdf

Agree. I have a list of builders that I am ok.. ish to recommend. None however are perfect.. mind you neither am I!

Nick (fixings) they won't commit to. This is not part of their design liability. This is completely understandable, they are just giving a representative example. Fixings are rated in two not least general ways. One is the exposure rating.. your C4 wet dry.. near the sea (salt air for example) the other is strength. The ICF folk can't be expected to recommend fixings for all the different combinations of insulation and wall cladding. For all. Most structural fixings these days are based on the Eurocode design and have what is call a European Technical Approval (ETC). Hilti et al have a link on their web site to which states how their fixings are tested and in what environment they are appropriate for. These are hard reading and difficult to navigate if you are not familiar with the terms and notation. Your easy way around this is to treat the fixings like a dowel supporting a flying shelf. The compressive strength of the insulation can be neglected for the most part. The higher the compressive strength of your insulation the lower the thermal resistance.. think of insulation like cells in the body.. the cell walls are more conductive. A higher strength insulation needs more and smaller cell walls. Now maybe you don't need millions of fixings? .. which technically could introduce repeating thermal bridges. Can you design the cladding like a curtain wall / rain screen panel where the panels are supported at the bottom ( carries the weight) and the top fixings just stop it pealing off in the wind? Maybe look at this in a different way?

Feel for you! Sometimes there is a way of recourse. Let's not focus on the cost to start with. Rather, look at the workmanship, the advice you were given by the builder and what could be reasonably expected by you as a domestic Client when you employ a builder. I often use the same basis of arguement when I do Claims against big builders / the NHBC etc. Roughly under the consumer protection act you are covered as you are domestic Client. The easy way to explain this is that anyone who comes to work on your house has a duty of care. Also if they carry out defective work then this could compromise the structural integrity of the building! Now that may explain why I'm writing.. as my main day job is as an SE. Often it does not take me too long to make a convincing argument and this often circumvents all the aggro about cost ect. OK.. taking this forward a bit. There is a Bristish standard series called.. Now the courts will take the view that you as a domestic customer ( industrial / commerial ones are generally left to fend for themselves) should reasonably expect that any workmanship should comply with the above, caveat... in so far as reasonably practicable. This leaves an avenue open for folk that are doing renovations on historic and old houses as a case in point. Proving that you have been over charge is much more difficult. It sounds like your builder is a chancer and thus won't be affilated with any trade associations for example. Did you pay any of this in cash? Mull this over. But let's just say you didn't for now. To prove you've been heavily over charged will probably entail a bit of professional advice. Here is some for free. If you can find something that the builder has charged you for.. could be work they never did or used thinner lead ( the workmanship is covered above) for example then that is fraud! .. you can use other words but it's the same... a rip off. Often in a dispute with builders I'll lead them down a path where they drop themselves in a hole! I then point out.. never mind you workmanship.. here is where I've caught you thieving from my Client as you have charged them for something you never installed. You then go back and link what should have been installed to comply with the above standards. You catch them both ways. Then if you catch them doing something dangerous SE wise, threaten staturtory breach of the HSE regs and all sorts. A good example here is where the roof can be comromised by additional moisture content that impacts on the structural integrity. The timbers in the roof wil have been designed for a certain level of moisture content.. more moisture causes extra deflection / timber creep and so on.They may have compromised the ventilation to the roof.. as structural issue! Once you go to town.. you see? There may be some milaege in this for you. But make sure you get all you ducks in a row before you level any accusations. A lot of what I say above is an example of how you can put together a case. Don't panic but please monitor your roof for some of the things I mention. This may help you bring them back to the table to fix things. Don't lay it on too thick at the start.. give them enough rope to hang themselves on. At the end of the day they may walk away but at least you'll know you did your best. It's not your fault you are having a hard time.

This is a great point. I've experienced this where the planners have used this as a delaying tactic. They then go off and use their own terms. I've said NO.. your change of description could cause my Client difficulty when they come to sell. This is a legally binding process that not just involves you the planners so get a grip! The application must be treated as valid.. the submitted drawings clearly show what is intended as does all the other documentation which is compliant with the recognised submission format. The portal is not in it's self part of the true legal process.. you could send in paper drawings for example.. and just say I am submittting an application for a new house.. here are the drawings.

Get a few tie straps in there to stop it lifting up in the wind. Make sure you get a good gutter detail to keep the rain away from the base as best you can.

Great post. These things let folk see what a site looks like, gives them ideas.. food for thought. Well done!

Be careful here and make sure non of the work requires BC permission. Drainage can be tricky.. are you messing with the fire protection / sound proofing between the flats or having to notch joists for example which are often commonly owned. Best to check as this can come back later to bite you. Your builder will probably run a mile if you mention a full on JCT contract on small works like this.. also these tend to need a professional to administer = cost. But avoid that you run more risk. Keep researching on the T & C's ! If you want to spend say £50 quid or a bit less you can get a copy of the minor works contract (RIBA can work) which may suit you. It's old hat but Which magazine has some legacy wording that may help you navigate this. Your builder seems to be front end loading this.. much will depend on what each staged payment means in terms of the amount of work effectively, competantly and compliantly has been carried out.

Hi CaptainDram. Are you thinking about a plot in Scotland? If so plenty folk up here that can chip in with advice. Good advice.

I doubt that you've been doing it wrong! Aye and no.. depends on where it is and the loads on ground.. vehicle traffic or garden load for example. Yes I think so. Is this the kind of thing you are thinking about? Passed by Scottish BC... more than once. The main BS is BS EN 752.. the head code I'll not post it here for copywrite reasons. A good heads up is to look at the old Scottish regs. The detail below is based on these. I'll try and dig it out but a lot of the recent regs are silent on this.. they just refer you to the Eurocodes!

Just for you @steamy! Below is a knocked up (it's not prefect but hopefully gives you the jist) idealised model of some of the forces in the fixings. In real life they behave in a much more complex manner. Maths wise its pretty easy to solve this, quadratic equation or if lazy just use the goal seek function in excel. Now intially I would apply a lot of safety factors.. mostly to do with the local crushing of the masonry at the outside edge.. then wind them back by saying.. if I use a few more I can handle a few failures.. which is basically what a lot of builders do.. chuck in a few more if in doubt. For all the easy way if you are buying a lot of fixings is to contact say Hilti / Fischer et al and ask for advice. They may (and often do) send out a rep.. to do a few load tests on site.. On something that is a bit out the norm I would take a fag packet approach (idealised model) as above so I don't end up with too much egg on my face = being wildly wrong and also as a second qualitative check in case the rep gets it wrong.. which is sensible.

You probably did this many times.. so will know what your doing. To jog your memory they are Halfen channels or similar.

Technically.. on paper maybe.. but you have such a mix of materials that it would just be a guess and probably too conservative. The way to design it is to assume the fixing is acting like a short cantilever out from the wall.. like a dowel supporting say a flying shelf in you kitchen. You then add the wind load sucking the cladding off the wall which adds tension to the fixing.

Hiya. Hope this helps. Bit of theory first and a few general comments. Excuse the spelling and grammer please! A gabion wall is fundamentally the same as what we would call a gravity retaining wall. Its weight does most of the work to stop it moving. The difference is that gabion walls move about a lot more and often they are designed for a 20 -25 year life span rather than a 50 year life span which houses are designed for to meet mortgage requirements.. Now for all. If you truck about you'll see many more developments by big house builders where they have big high gaboin walls to retain gardens, the houses themselves are set back. Can you smell a rat? The thing to take away from this is that gabions have a time and a place and much is to do with how much they move and their seviceable life.. before serious maintenance. Ok how do we design a gabion wall.. 1/ We need to know what it is holding back. @Great_scot_selfbuild it's your driveway. Now if its gravel then I would say.. how much do you want to spend.. do you mind if the gabions moves a bit and you need to level out the drive every 5 years? If you say I'm ok with that then I know I don't need to worry to much about movement (serviceability). I also need to know how long you expect it to last! The building regs can be a moot point here in terms of movement.. the regs aim to make sure it will still be safe! To design a gabion wall we often apply the same principles as we would use for a concrete or brick gravity retaining wall. Rule 1.. we need to make sure it does not tip over. Often walls have drainage behind but behind the drainage layer we also have a bit of sideways soil pressure. The drainage can avoid hydrostastic water pressure and having a "funny" effect on the soil. Rule 2.. there needs to be enough of a key and friction load at the bottom of the gabions to stop them just sliding sideways. For all types of gravity retaining wall design we allow for a surchage load ( a load applied to the top of the ground) of roughly 1000kg per square meter on the drive way in this case.. thems the rules folks! Drianage or not this surchage load causes a sideways thrust on the wall. Rule 3 / This is a biggy.. we need to watch put for a global failure (often called a slip circle) where the whole wall, driveway and soil above up the slope just takes off and moves down the slope. This can be a catastorphic failure and very dangerous. Some times to mitigate we need to drain the soil much further up the slope.. even then we are taking a risk. If you have challenging topography then I would need to know what is happening further up the hill. You may need to extend the scope of any site investigation. Now most SE's should have a grasp of these basics. But its your vegitation, could be trees an local topography that needs nuancing. I see you are using a Fittleworth stone gabion fill and probably you SE will just design these gabions as having no intelocking effect.. so the design will be standard. Theoretically the design can be realtively easy.. but for economic design.. that requires you to to identify what you expect and balance that with how much you want to spend on ground investigation. To sum up.. I've given you a few tips. Have a chat with some SE's and say.. I've read this and that, here is what I would like to do and what do you suggest would be a good balance between soil investigation and practical common sense design? Once you can get a handle on what your expectations are in terms of long term perfomance of the gaboin wall then most SE's will be able to handle that kind of design. What they will do is make sure is does not fail dangerously and if it moves about a bit, then you now know that .. and everyone is happy.

Redo the pointing in the brickwork above so the water is shed out the ways and see if that helps.

Gabions can look great. You can creat a structural butress in them if you want to design an Arctitectural seating area for example.. The quality of construction matters. cheep infill and badly placed = less perfomance.. time taken to lay the stone.. like a dry stone wall can increase the service life. You can use decorative stone on the outside.. grow plants on them and so on. Great habitat for wildlife too once they age a bit. The structural design concept is a little different in that you expect them to move about quite a lot unlike say a concrete retaining wall which can't move quite as much.. well you hope not!. These things move which makes them flexible and forgiving and so long as you recognise that you are off to a good start. The presence of the trees makes the design more fun! I think some of the keys to this are: 1/ You need good ground information.. soil properties, water tables and hydraulic gradients etc. 2/ A good detailed topographical survey so you can see just how much you need to retain, the slope of the ground and the location and type of trees / vegitation. 3/ A good idea from you as the Client about how you want to finish the driveway and how often you anticipate maintaining it. The retained soil may move about so if you have a tarmac drive it may crack. 4/ Available drainage paths for draining the soil.. but then you need to watch what happens to the trees if you take their water source away or make them compete harder for water. You can do a lot to help yourself here (as you are doing) by trying to get your head around the things we need to know and importantly why.. to enable a design that meets your expectations economically and also in terms of later maintenance. If you can gather some of this info then it will help you find the right SE for you.

If I've drained a rad or messed about with the UFH I tend to top up with a splash of inhibitor. I have a mixed system.. part UF and part rads. Luckily I have a towel rail in a first floor bathroom that is a magnet for an air pocket. I unscrew the half inch cap on the top of the rad and just pour in some inhibitor before repressurising / opening up the flow and return valves.