Gus Potter
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Everything posted by Gus Potter
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SketchUp fantasy Garage. Drawings for building control
Gus Potter replied to Russdl's topic in Garages & Workshops
Thank you, much appreciated. Gus- 27 replies
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- detached garage
- structural engineer
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LPAs playing around with 'validation' timescales?
Gus Potter replied to Alan Ambrose's topic in Planning Permission
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
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Agree. I have a list of builders that I am ok.. ish to recommend. None however are perfect.. mind you neither am I!
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Concrete screws for cladding batons ?
Gus Potter replied to Firsttimer's topic in Insulated Concrete Formwork (ICF)
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.
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LPAs playing around with 'validation' timescales?
Gus Potter replied to Alan Ambrose's topic in Planning Permission
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.
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Great post. These things let folk see what a site looks like, gives them ideas.. food for thought. Well done!
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Flat renovation starting: payment schedule and contract?
Gus Potter replied to lb00's topic in Costing & Estimating
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.
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Drainage pipe depth. Minimum 600mm or is that unnnecessary?
Gus Potter replied to saveasteading's topic in Boffin's Corner
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! -
Concrete screws for cladding batons ?
Gus Potter replied to Firsttimer's topic in Insulated Concrete Formwork (ICF)
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. -
Concrete screws for cladding batons ?
Gus Potter replied to Firsttimer's topic in Insulated Concrete Formwork (ICF)
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. -
How to find the right type of foundation engineer?
Gus Potter replied to Great_scot_selfbuild's topic in Foundations
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.
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How to find the right type of foundation engineer?
Gus Potter replied to Great_scot_selfbuild's topic in Foundations
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.
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It will be scary if it's not properly restrained against not least movement in the direction of the ridgeline... in fact likely dangerous. John you have a number of pivot points (like rocker bearings) and due to the nature of steel fabrication and behaviour it will tend to buckle sideways due to the vertical load. I can see where you are coming from ( gables taking out the wind load I assume) but it is very important that this arrangement of steel has solid restraint against moving in the direction of the ridge and also perpendicular to the ridge. Please check your SE drawings and make sure you follow them religiously.. don't let the builder / steel fabricator go off and do their own thing. Do this before you load up the roof further. If in doubt get some temporary bracing in.
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13k sqft self build in Hertfordshire
Gus Potter replied to LadybuilderLOL's topic in Insulated Concrete Formwork (ICF)
Hiya and thanks for posting on BH. I've had a quick look at what you propose. With my SE hat on.. because it it so big you probably have loads of stiff structural floors / roof deck.. unless there is a massive atrium. This can be an economic form of construction. The size tends to lean towards standard commercial building construction.. nothing new and you should get competetive prices for a project of this scale.. it's basically office construction that is fitted out as a house with enhanced U values, heating / cooling systems etc. Looks great to me! Keep posting. -
Light refurb/renovation & building regs
Gus Potter replied to Roger440's topic in Building Regulations
Good advice. Lets see some detail, a drawing or two. Look at it another way.. there are plenty BCO's that will be happy to help you with this, make suggestions. In my day job I often have open and frank discussions with BCO's.. we don't fall out.. we chew the fat and talk about how we can meet each others technical requirements and do a good job. -
Steel spine staircase
Gus Potter replied to crispy_wafer's topic in General Self Build & DIY Discussion
Less than 3.0k is achievable for say the steel work with one winder. The biggy is the finishes.. solid oak treads and glass. If you are a fan of LVL (basically thick ply wood) and want a contemporary look.. like Ikea say but bespoke then you can save loads on the treads and afford to make the odd mistake if doing DIY! . The glass ballustrade.. you can't compromise on that as it is for structural safety first and foremost. To finish though folks.. as I've said before build / design into your structure strong fixing points if you want a stair like this. Tell your SE early you want this! -
Light refurb/renovation & building regs
Gus Potter replied to Roger440's topic in Building Regulations
Here are a few of my thoughts for you to mull over... I'll do my best to explain. In my day job I often take on these kinds of projects, an old house that needs a bit of an upgrade. I've got one on my books at the moment, circa 1915 house with solid wall, little insulation. Out the back is essentially an out house that I'm turning into a utilty area / shower room and internally knocking out some walls to make it open plan. Now that needs BC approval as I'm extending the floor area, carrying out structural alterations and increasing the insulation envelope. To make this work it's not possible to get enough insulation into the out house to meet the U values so to compensate I'm upgrading parts of the old house. But you are not doing this! The last bit of text was to hopefully let you see how we compensate elsewhere. I'm based in Scotland but the English regs are similar ( know the Scottish regs but don't do bedtime reading of the English regs / nuances.. but I do projects in England if they are of interest to me ) if they were not then we would be totally stuck when we refurbish / upgrade old buildings. It is often impossible to upgrade an old building to make each wall / floor / roof element for example comply with the latest regs. This excercise is about doing what we can (in so far as reasonably practicable) and all the UK regs allow for this in some form or another. For you it seems that you are not extending the insulation envelope or floor area. Thus my starting point would be to go back to the regs and see what needs BC approval. I think you'll find that a lot of the things you are doing (if any) don't require formal approval.. but in the regs there is a bit that says even if you don't need formal approval they still need to be compliant with the regs in terms of say workmanship, durability and safety ( the bit that worries you about the law? ). In terms of upgrading they don't say that anything you do must meet modern U value regs for example. Look for the phrase "in so far as reasonably practicable". This means that you can carry out upgrading work even if you don't meet the target U values. But in doing so you still need to comply with the regs.. for example.. you don't compromise the structural integrity of the house.. introduce a condensation risk, a fire hazzard and so on. If you want you can possibly regularise it by way of BC permission.. but they may turn round and say to you.. nothing to do with us so long as what you are doing is still compliant with the regs, British Standards and so on. I would go back and read the regs carefully and you may well find that you can upgrade your house the way you want if you apply common sense and do a bit of research. Hope this helps a bit. -
Steel spine staircase
Gus Potter replied to crispy_wafer's topic in General Self Build & DIY Discussion
Just be aware.. structural steel can be a bit " industrial" looking. What a lot of these photos don't show is the welds and what it looks like from underneath. Structural steel is not as straight as you think and fabricators will work to standard tolerances.. tread mounting plates distort for example which can lead disappointment if you want a high end look on the cheep. These things can look great but they do need an understanding about fabrication costs.. for the different levels of quality and how the treads marry up and fit to the steel. For me my job is to explain the different nuances to Clients. Yes get a local fabricator cheep but make sure your tread / glass / tension wire / balluster design can cope with what the fabricator can reasonably be expected to deliver. For all.. SE wise these things are too hard in principle to design. Box sections are favoured as they can resist the twisting effects better than say an I beam. But if you want something like this it's best to let your SE know at an early stage of the design so they can build in strong points of support at the top and bottom of the stairs. There are lots of folk on BH that have asked questions too late in the day about connections at the top of the bottom of the stair that have to resist twisting (torsion) effects.. which can be quite onerous in terms the top and bottom connection design. Also you need to think about newal posts.. stiff points for mounting glass and tension wires for example. It's not diificult or horribly costly if you plan early.
