Gus Potter

It looks like this is, on reflection, just an infill roof, like a small canopy that is constrained by substantial walls either side. Are we over thinking this? Vertical loads could be roof access, at a push, maybe snow dump coming off the higher roof. But the canopy looks like it has a good slope. I would go back and look at what is Architecturally pleasing, like your proposed joints earlier.

To add a bit. If you use traditional dowels, pegs then there is an old trick that was used in Scotland. We have lots of solid stone walls lined with lathe and plaster on studs on the inside. Timber wedges were driven into the stone work mortar beds. Then they were cut flush using a string line and the studs fixed to them. That is how they got the wall plumb etc. The spelling differs, as a traditional craft, but they are commonly called Dooks. But the secret was that they would dry the Dook's often near a fire thus they had a really low moisture content. Once they were driven into the wall they expanded. A traditional wall never gets below this moisture content and thus the Dooks always hold tight. You can use the same principle if you want to peg / dowel the way you are thinking. The dowels will need to be tapered as standard, but to get them really tight dry them out in an oven first. You could of course use a modern structural glue, but that may be cheating?

Are the posts just there to carry vertical load or is the beam and column acting to resist sideways sway.

But you have just posted one photo! You should know if you want folk to invest their time to help you then you need full inside, outside photos along with a good location of the property. Is it in Fife Scotland on highly mobile soils for example. Is it sitting over a tube line in London, is there vibration from a nearby road etc. Come on, you should know better than to just post so limited info. You have been on BH long enough to know better.

The unfortunate reality is that from time to time companies cease trading during the course of your job. We need to be pragmatic and say. Let's first understand the design intent, where the forces go and then seek an equivalent solution, it happens a lot! To interpret @Square Feet question a little further. If you are a self builder then you need to seek out designers that will explain to you what is normal industry standard liability that they will take on and what is not. Often designers are not as transparent as you may wish. I'm just up front about where my liability starts and ends. Each project is different, particularly on self builds. If a Client wants more cover then I'll phone up my broker and say, how much is it going to be to extend cover, then leave it up to the Client to decide what they want to do, pay the extra or not. One great example here is that one of the warranty providers asked me for contaminated land insurance. Now the fee for a contaminated land design may be less than 1.0k, but the clean up costs could be hundreds of thousands. There is no way I or my insurer's can take on this liability for such a small fee, it's just bonkers!

Don't cry and don’t apologise for a long read, you want to see what some of myself and others write when we get keen! As a bit of background I also design rafts, ground bearing slabs and everything in between. I share some of the stuff I do on BH, but also want to see what my competitors are up to. I've had a look at AFT's design details and I can see that they know their stuff, some of their designs are very elegant. Olaf is mentioned. He strikes me as being a very knowledgeable Engineer with excellent creative skills based on first principle design. If you are short on your modules then you can improvise. There are a few key steps to this. 1. When you improvise you have to be very careful you don't change the load path down through the insulation for example. The diagram below is probably more complex than yours. The hatch below the slab shows XPS insulation, the bit up the sides is PIR insulation. The key bit is that I'm stepping the XPS so the load transfer from the concrete goes down to the hardcore below in direct bearing at 45 degrees. The extra rebar you see and the square links are due to the fact that this raft is supporting point loads from an oak frame, and the raft rests on some engineered fill I've designed. The external plinth course, only extends some 5 - 6 courses above ground level and is deliberately decoupled from the main structural frame, partly for thermal performance for example. Now if you can get your head round this then you are well on you way to being able to sort the problem yourself. 2/ Next is to understand what insulation you could use to improvise. You want to get this off the shelf. Insulation is primarily specified with a certain compressive strength at 10% compression. EPS is very squashy, even though it seems initially it has the same strength as other insulations. If it squashes too much before carrying the load then it will compromise the structure, too much deflection for example, which will crack your concrete. Don't get caught out, check to see the insulation you use to fix this is not more squashy than AFD insulation specified. Post the AFD detail you have and let us all have a look. My gut feeling is that there is a simple and justifiable fix available to you without any drama. Keep your head up!

Title problems can sometimes be fixed with negotiation? By all means get in touch with me, you can find me easily on the internet or DM me. But in the round my preference would be for you to share as much info on BH as you can, to benefit other members. I without doubt don't know everything! I enjoy learning from others on BH. Stick with BH for now.

I appreciate what you are saying. A common complaint on BH is about SE's over engineering founds or say BC coming out and saying they need to be much deeper. For all. SE's don't deliberately over engineer your founds, if they did it would be a lack of duty of care not least. They have to balance what information is available against the risk. Often the reference point is say the NHBC regs, maybe BC regs. These in lots of cases can be very conservative. Often a Client has spent little time or money on even understanding the ground, the trees (species and height not least), looked at the local and wider topography, possible perched water table, the topography and where ground water may be flowing form and to. @Bonner if you are serious about buying a site that may have "issues" then you need to find a good SE that can help you. I have commercial Client's that keep me on a "retainer". They can phone me up for a 30 min chat for free, it usually ends up much more as we touch base, ask about family and so on, then get back to business, it's good fun. If I need to chip in and commit in writing then I charge a fee, which they are happy to pay as they appreciate the value I bring. Over time I teach them and they can progress under their own steam.. it might seem to the cynical I'm doing myself out of work.. but the more successful they are, the other parts of the design come my way. Now in terms of trees. The key thing is to learn about how they grow, different root depths, types of roots and how they influence the soil depending on soil type. Next is to understand ground water and typical soil profiles in the areas where you may wish to buy a plot. @Bonner Here is a play. Sometime it's best not to be discrete when pitching for a plot! If the plot is a bit blighted you figure out you own solution, don't tell anyone. Put you own value on it but publicise potential issues so your competition backs off! It also brings the seller to the table to spell out what challenges the plot presents. If they are that nosey and raking about about on BH then it's fair game? OK how does that apply to a first time self builder wanting to buy a plot. In the current market there are fewer plots with "clean hands", the ones available often command a premium. The ones with mucky hands are often avoided by developers, but they present a great opportunity to self build. They go a a lower price, but if you don't want to loose you shirt then you need to find say an SE like me or really know your onions. Your best bet is probably not me !, try and find someone local first. You need to find a local SE or a designer that really knows their stuff. Now the fee is going to be more, but a good designer will make sure they wash their face fee wise and will steer you towards the right price to pay for the plot.

You don't need to. For all: The following assumes you are not in the building trade, have all the advantages that that brings. It's intended to appeal to folk on a budget, possibly first time self builders that are willing to learn and invest time. As I've said before, in the old days self building was a great money spinner even if you were a complete idiot. Property prices were achieving a year on year 10% at a minimum increase in value. Thus on a two year build the land just alone would increase in value. The game is changed now. For a while it worked where you could go to a TF company, say Scot frame etc, AFD foundation design were doing a lot of really great stuff, Tanners Structural Design were chipping in etc. for example and others for "work packages" and it still stacked up, the profit was less for the novice self builder but still worth a go. You still got a return from "managing the project" One of the main problems I see at the moment is not just the regulatory stuff (Planning and BC), it's actually the idea that you can put different work packages together without dealing with the interfaces, where the hidden cost lies. We could describe this as "day works", expensive! The "work package" providers are now taking too much cream, there is little left for the self builder, and the risk remains the same. Designers are certainly not helping. Few if any take the time to help you coordinate, some of this is bad practice, but also, there is tendency for folk to think good designers are like washing machine engineers, we are not here to fix your washing machine. In the round all the cream is taken out the project before you get a shout. One fundamental key to a good self build is to not pay too much for the land. A while ago you could buy a nice flat grass plot, easy services and so on. But these now are less attractive as they command a high price. What is attractive is a cracking site, great views, but brown field. In other words maybe a bit contaminated, hard to service for example. if you crack that nut you can get it cheep. The big developers are not interested, your local builder with say 10 men is not interested as they will have to pay for professional advice, they look for the easy route. This puts you in a pretty good negotiating position if you can identify what's wrong with the site and explain to the seller, this is is a good offer I'm making, and here is why. Now just say you could get a 100k plot for 70k by explaining to the seller, you are selling a pig in poke. To do that you need to just bring forward the professional fee advice. It's not going to cost you the full whack, an advisor may give you this advice for under £1.0k. My own view is that it's now time to go back and consider old school stuff, say getting local ground workers in to do the founds, joiners to stick build the TF, slaters for the roof. You buy the materials, you then own them, eases cash flow. I think this can deliver a good bit of profit! In summary I do think self build can be profitable, we just need to go back to old school stuff and the basic laws of business. But adapt with a view to say modular construction. @Square Feet has some thoughts on this in fruition.

Possibly not! Have you commissioned and run your UFH for a few weeks? If I was working for the flooring contractor I would be aware that the underlying structure also has to condition, move about a bit, it's not just the screed. They are just getting paid to lay the floor? But maybe being sensible. If something goes wrong then think about it from their end, put yourself in their shoes and work back from there. They could be faced with a massive hassle trying to prove movement is also related to the structure and not their fault. To be blunt, the suppliers of flooring and the installers have so many caveats, not least min and max floor temperatures, which are hard to achieve when you have congestion of UFH pipes. Sometimes you have to make your best guess. Anticipate where movement will occur in your particular self build and lay the flooring accordingly. To make things a bit harder, it's often the summer that modern highly insulated TF house expands as the UFH heating has been off, particularly if on say a concrete slab, this is counter intuitive!

The soils are just above the plasticity A line, not much to worry about. Lots of rafts get designed with an L shaped building, we design joints for this and make sure the super structure can cope with anticipated movement. The allowable bearing pressure is good at 115 kPa, a standard benchmark of 100kPa is a good comfortable reference point. Where does the water table sit? You probably need to post the full SI for the best feedback, there will other stuff buried in it that you may not have the experience to be able recognise it's importance.

You did, no offence intended! I layed in a bit as AI is more dangerous than not if you try and get it to do SE stuff.

Great post, very informative!

Now by now you should know that there is no way any of us that can take a punt on this. Post your geotech info, a site plan etc. You know the rules, the more info you provide the better quality response you'll get.

Reading a lot of these posts it's pretty clear that that many on BH don't have a high opinion of folk like me who design as a day job. I can see many professionals have lost their compass and are not delivering value for money and are not that good at running a business, hence the poor service delivery. I've been in the construction industry for over 40 years, 20 spent as a contractor running my own business' , did my own self build, really pretty much all by myself on the tools ( took me three years) then off to uni to be an Engineer, now for the last ten years I wear two hats as an Engineer and Architectural designer. Thus have a fairly rounded view of the in and outs of this. I can say that in the last 20 years there has been a race to the bottom, not just from designers, but also say the timber frame suppliers, ground works designers ( UFH and rafts etc) and designers who think that if they curtail their design brief, caveat it a lot the money is going to flow. But in the long term it doesn’t, as often the key to good business is repeat business, recommendation, even in the short term cutting you brief down often leads to problems, queries, design mistakes that just eat into your profit and leads to potential claims or Clients rightfully withholding money. Ok, lets look at some financials. The bottom line for a new self builder ( not someone who works in the trade with contacts) is the tendency to split each element into work packages, say foundations, timber frame and roof ect. Each package supplier takes the cream out of the job, leaving nothing for the self builder. Then you have planning and BC regs on top not least, that all adds to the cost. I work on a lot of projects where I'm involved holistically. I work very closely with the Client, not just as a designer but also do hand holding and participate in all of the design. Now to be blunt. Say for a self build the design fee is £10k. An experienced chippy ( joiner may cost you £250 a day, a labourer £150 as day, total 2.0k per week. All I have to do to wash my face is to save you a few weeks, just on the labour alone and I have well and truly washed my face! The pendulum is swinging back where folk are clocking that we need to "go back to the old days", but now you need someone like me who can cope with the modern code requirements for example, and the modern way of doing business., much less trust and more hard arse stuff. I get this kind of business where folk are happy to pay me a bit more as I can guide them, hold their hand and most importantly we all have fun, we do whacky designs that you only get to do on self builds! We also tend to avoid " work packages where we can, say from MBC et al and keep the cream to ourselves. This also often helps cash flow and gives the Client more control on day to day site activity. Now in the round if you want to make some money then try and find a designer like me that is local to you, with good contacts.