SBMS

Thanks - are these recommended/needed (with the polystyrene insulation in middle) if we are doing beads? Or is the polystyrene on the product image just an example?

Thanks -the pool has very marginal chemical levels as it has a uv and sand filter so may only need small chemical treatment. I was more concerned with the humidity level affecting the bricks… I guess if it does become an issue I could tile over the bricks??

We’re building brick and block with a 200mm cavity. EPS beads blown in. Our engineer specified (notionally) a one piece lintel. Builder has had lintel company let us down and now those lintels are a couple of weeks out. Floor Is ready to go on so he is suggesting we do steel split lintels. Is there anything anyone would advise as to why not to go this direction?

Anyone?

Also architects always specify expensive kingspan at 0.019. They specified 150mm 0.019 boards for our flat roof - super expensive. Two layers of 90mm were thermally equivalent and less than half the price!

If you have the benefit of a new build then why constrain yourself to such a small cavity width? I would absolutely widen the cavity to 200mm and pump EPS beads in. 0.15 u value and anything more was diminishing returns (brick tie expense, wider trench blocks etc). With the floor we settled at 180mm PIR (two layers of 90mm) which gives 0.1 U value. Again anything more is diminishing returns and that was the sweet spot when we did the calcs for UFH heat loss.

We are looking at an in ground, indoor swim spa. It has a roller cover so will be covered 95% of the time. 8mx3m in a 10mx5m room. Two of the walls are pretty much glazing and the other 10m wall we are thinking of doing the internal skin in face brick and then just leaving it exposed as a feature. It’s a cavity wall with outer brick, 200mm beads and then inner brick. we will manage the humidity in this room using mvhr, but it will naturally be more humid than normal. Would it be advisable to seal the bricks internally, can they be left as is? My simple brain says ‘well bricks outside are left exposed’ but not at the humidity levels experienced here. Anything to consider with the mortar or anything over many years?

Did you do a pressure drop calculation for your 25m run? Or was it less risky with a smaller ASHP?

What’s your actual rafter depth and then we can help advise?

We are looking at the vaillant aerotherm 12kw so that sounds useful re the pump - is its internal pump powerful enough to push 25m?

Stupid question (I know little of plumbing) but if a secondary pump were needed can it live at the end of the 25m run, in the plant room? Or does it need to be next to the ASHP?

Thanks all 👍

Does this pump typically exist in the heat pump (outside) or in the loft?

Currently planning on ASHP positioning relative to plant room. Plant room is on top floor (room in roof) and, by my calculation, it's going to be a 25m run from the outdoor unit, to the cylinder, controller and plumbing etc. All of this 25m is inside the house/thermal envelope (just an annoying, complex route, and it's got to get from ground level to 6m to attic floor)... Is this going to be a problem?

Looks great @GK22 - it seems your design ethos carried through into the build. Did you hit your 2k per sqm target for build cost?

Think you need/would recommend a cavity tray in the parapet across the cavity.

How about UFH upstairs?

100%.

We were given conditional approval that requires further information prior to the construction of that element (specifically it states relevant structural calculations from roof engineer prior to roof construction..) LABC also specifies conditional approval is a ‘thing’. Am I getting my wires crossed?

For anyone interested, I can now answer my own question and the answer is no, in my instance it’s not worth it! Had costs from our contractor to incorporate a basement (we are doing a swim spa pool so much of this space would be taken up by that anyway.). Difference between just sinking the indoor swim spa and making the full extension a basement is circa £50k. Considering only 7m x 4m of that is useable space we are going to go back to plan A to sink the pool and keep the rest at ground level.

Our private BC is happy for us to defer certain elements until the end. So things like MVHR calcs to meet ventilation regs etc are deferred. Even some calcs for floors were deferred to the flooring engineer for later, and we are cracking on.

And when there’s an issue with the materials or they’re not on site and your builder has 5 brickies ready to lay… that’s £1000 gone. We are open book with builder. He sent across everything - labour, materials and then his %. But critically I could see what he was paying for blocks etc. some volumes were low so I didn’t bother looking but I found a couple of materials in volume - such as blocks that I could Source slightly cheaper. Sent the cheaper prices to him and his merchant matched them all. So I don’t think there’s a massive incentive for builder to get better price on materials if it’s open book. But it does mean you can get better price and the builder pays for it and manages it so no VAT to cover. Best of both worlds?

Thanks @JohnMo. Wonder if its cheaper to insulate the external walls with 200mm of EPS (bigger hole, bit of labour), or internally with 200mm PIR...

Exploring a mad idea to extend what was going to be just a 1.5m hole for an indoor swim spa, to an actual basement with a cinema room.. Am trying to work out what insulation to use. I am thinking of 100mm PIR stuck to the walls. 300mm waterproof concrete walls. Is there a U Value calculator that'll approximate this, taking into account that the walls are underground? I used ecotherm IWI calculator and with 215mm block walls and 92mm insulated Plasterboard is around 0.23.. Would this be much improved with another 85mm of concrete wall, and by virtue of being underground?

I did yes, we were put in touch with a local installer. Where are you based?