gavztheouch

I reckon there is a good business in pouring and finishing these slabs. I agree, most of the local insulated slabs near me have had errors, some big some just niggles. Usually it was sun contractors not giving a dam.

Thanks @JohnMo great advice

I’m about to start my isoquick insulated foundation it’s 250mm thick insulation and 250mm concrete. Four layers of a393 insulation. Just looking for advice on laying the pipes. Should I pressurise them before the pour. If so air, water or antifreeze. It will be exposed to cold weather over the winter so if water I would need to drain down which might be tricky. should the pipes be connected to the manifold before pour or after. I have seen both ways on in picture on this forum. Some pipes come pressured from the supplier with end caps. My mesh is 200mm spacings on the bars this would suggest 200mm centres on the pipes. I have a low heat demand I’m hoping this will be ok. Not worried if it is not as efficient as it could be. The last point is the pipe diameter, as I have a large number of mesh layers (4) the build it could get tricky and any overlap or misfit will push the top layer of mesh higher, in turn encroaching on the 40mm of cover concrete. If I run a smaller diameter pipe as 12mm instead of 16mm I would gain some more space but the volume of water would be much less I think.

Thanks for your post @Gone West That does indeed sound like the nightmare scenario. Did you replace all the isoquick insulation? are you happy with the isoquick system now? I’m thinking about pouring the slab anytime after next week maybe. This includes some cold months. I’ll prob need to wait until it is dry which normally means it will be cold. To get better weather I would need to wait until March at least. Has anyone poured concrete slabs like this in cold weather. Did you take any precautions?

My internorm and dako windows quotes have dropped slightly, since February this year. Cortizo aluminum windows have doubled in price since February. Just got a quote from enersign they are also double the price I initially received but this was 3 years ago.

The French drain will go into the river forth. Because I’m close to the river I shouldn’t be causing any flooding Issues other than raising the height of the river forth itself. I don’t know if that’s an issue. Do people build houses without French drains? If so what are the alternatives. My dads house about 200-300 years old goes not have drainage like this. My 1930 flat does not have a French drain. It might have a gravel drain. The 110mm soil pipes need a 90 bend to pop up through the slab. I assume I don’t need a slow bend here and a normal 90 rest bend will be ok here? A slow bend will increase the depth of the pipe a lot more. A rest bend needs about 300mm to go from horizontal to vertical. It needs to be vertical before going through the Iso quick slab.

Click on picture for higher resolution, Trying to work out my soli pipe runs, the architect has run them like shown in the pic, reduces the number of inspection chambers but means running a lot more pipe under the slab. For repairability in the future would it make sense to bring all the 110mm soil pipes straight out of the slab, it would mean more inspection chambers as there would be a lot more changes of direction. I especially don't like the run on the left side of the house that picks up the three soil pipes, one from upstairs, toilet and bathroom. What would you do?

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I have been getting cheaper quotes recently even the internorm window quote went down since February. Still isn't enough to make building attractive yet, but I reckon you could design a simple house that performs well for a reasonably cost. My house is way to complex for me to build myself and that is what is costing me, wish I had stuck to my guns and built a single story house that is designed to be easier to build.

Hi I am planning on using arotherm plus 5kw Ashp. Thinking about using Rauthermex Duo or similar to pipe water into building. Not sure what size I should use or how to even figure it out. What I've done so far is look at the connection size of the 5kw model, which is 1 1/4, so 32mm, but the 12kw model with a higher flow rate also uses the 32mm connection so its possible the 5kw does not need a 32mm connection and the 25mm will be fine. The 25mm is slightly cheaper and has a better heat lose value. There would also be less water sitting inside the pipe getting cold between cycles which in a low energy house where it might cycle a lot on and off throughout the day this could be significant.

No big reasons, the architect had used a few different companies and this was their preferred system. Personally I like the fact they had been around for a while and also the egg crate mechanism and dovetail joints on the blocks is pretty cool to lock all the insulation together. Yes having machines and shed storage space is blessing and a privilege. We dug a few trial pits. The engineer reckons there is at least 1m to 1.5m of stiff clay before it starts to get jelly like. For the foundations we need to strip back only the top soil which is about 150mm plus only 50mm of clay for a total depth of 200mm. Into this pit we fill back in 100mm of Type 3 with 50mm of angular gravel. This means the bed for the foundation is only 50mm below the existing ground level. The isoquick is 250mm of insulation and 250mm of concrete so 500mm in total meaning the top of the slab will be 450mm above the ground. The house is going to be sitting quite high in the field so Im going to have to blend the soil/garden heights with the rest of the field so it doesn't look weird. Good to be high out of the ground though.

Isoquick insulation arrived today.

Amazing delivery price maybe some of the shipping is built into their prices.

First job was building a road down the side of the farm sheds for access of heavy traffic. Tractor’s long term, concrete Lorries in the short term.

About to start my isoquick foundation about 110m2. My soil is sticky clay, the top layer of clay about 1.5 meters is quite stiff then it turns to a watery jelly consistency. The plan is to keep the foundations shallow to bear down on the stiff clay. The isoquick should be arriving this week. I was hoping to get the slab finished before the end of October but the more I research the more work I find and details/levels to be found for the underground pipe work/ septic tank and rebar. It’s going to be a challenge I think. If I can get close to the end of October I’ll be happy, it would be helpful to not be pouring concrete in very cold weather.

I put together a test shopping basket on the Latzel website about £2000 of tapes and membranes. The delivery charge was only 25 euro. Is this similar to what other have been charged? Seems too cheap?

Good to know. Our architects own house is a polished slab like this they have done a few others. I will ask them what they have done themselves for the collective knowledge bank. I would hope having a lot of mesh in the slab should help matters

Hi Mark did you end up using control joints ie cuts in the slab. I’m going to do my slab soon. It’s 250mm thick with 4 layers or A393 mesh. Underfloor heating tied to mesh.

Any tips for negotiating prices?

Would love to know the rational for anyone buying a plot right now and building a house using builder at say £2500m^2 Trouble is interest rates look set to stay high. Job security is prob falling. If your self employed there may be less work. Building materials are in some cases double what they were 2-3 years ago. It’s a bit of a mess. The only way out is for wages to catch up with the price of building but that could take years or never happen if material prices keep rising. It’s possible self build to current standard may never be achieved again in the county by the same number and type of people that did it in the past. I guess solution would be to build drastically smaller and plot values to fall a lot ie 90% My grandad built a house in the village. Build cost was something like £5000 but the plot was £100. We could see something like this happening.

I’m planning on doing heated structural slab it’s about 7m by 15m 250mm deep in an isoquick foundation system. Did you guys have to put control joints ie shallow cuts in the slab to prevent cracking in unwanted places?

Thanks nod, yes most items seem to have come down. Not enough to offset higher interest rates though. Could be a Mexican standoff for years until wages/savings catch up.

It’s been a while since I got a quote for our windows. About a year ago they where about 40% higher than they were in 2020. I couldn’t really see why this was the case as wood and energy have come down from there crazy peaks. Anyway I was wondering if higher interest rates have helped soften window prices, anyone noticing any drops?

In hindsight low interest rates created bubbles in property and stocks at a time when things were quite stable ie 2010-2020. Now we have wars, supply shocks and climate change (transition is expensive) it’s a hell of a time to return rates to normal. Im 38 was going to build a house a few years ago. Unfortunately I have been saving for years and built up £200k that money is prob only worth £100k today in terms of building rates per m2. That’s a big hit to take, wish I’d bought a house pre covid at least my money would have somewhat held its value. If house prices fall close to where they were in 2019 I’ll prob buy and knock the self build on the head, for now at least.

Well interest rates have gone higher and will possibly go higher and stay higher for longer than I imagined. Now even more confused about what to do. Apart from farming wood and osb I don’t see a lot if any reductions in material costs. Labour rates are still sky high and material prices are not reflecting the underlying fall in commodity prices or rise in interest rates. All in all, I feel it’s becoming harder or more expensive to build a house but cheaper to buy a house (assuming you don’t need a mortgage)