Iceverge

@JohnMo what did you use in the end?

Sorry I missed your reply. Here's one from another thread I drew up for a timber frame. Nope. PIR doesn't fare particularly well in these circumstances. EPS is best.

Kingspan are playing tricks here. You have a ventilated cavity in both cases so bricks or weatherboard will make no difference to the U value in reality. They are simply there to keep the rain off the timber frame and maybe in the case of brick to add a little to the structural stability. Looking at their product which i assume is 140mm kooltherm between the studs and 40mm over the top just maybe scrapes a U value of 0.155 ish. Are you committed to their system?

Paint it with some dilute PVA.

I wonder would wet UFH buried in the slab and a layer of electric underfloor heating just under the tiles for the summer be a worthwhile system just to de chill your feet. We don't have any heater in our bathroom but being in the bath with the air temp at 20deg can feel chilly when your skin is wet. I did put a cheapo fan heater in the shower room and it can get the room up to nearly 30 deg very quickly but it's a bit noisy. Maybe an IR heater just to warm your skin briefly when in the nip would be more pleasant. There doesn't seem to be any need to actually heat the room otherwise. @Nickfromwales I'm sure will have chapter and verse.

I would preferably something like this for a pitched roof. Much less wasteful of labour and material and cheaper by my calcs too. Better for airtightness and windtightness and heat protection also if done properly.

If you look for Walltite and Isothane closed cell foam there'll be some documentation. It's about 5 times the price of bonded EPS beads hence its rare use but it is an option.

Hard to say without knowing airtightness levels. Form factor (external surface area Vs floor area) is important too. Also glazing levels. Even the best windows normally only achieve a total u value of about 1.0 by the time you take into account thermal bridging due to install so even if they're the best windows they'll still be 6 times worse than your wall. If you have lots of windows...... HOWEVER. ......big houses have better airtightness scores and better form factor scores. Assuming you have MVHR I would think that 20w/m2 would be an adequate heat load for sizing the ASHP and 30w/m²/annum would cover the heating demand. So 508m2*20w ~ 10kW ASHP minimum. Add bit for DHW and mum maybe. Lets use gas first of all. And 508m2 X 30w/m2/annum ~ 15000kWh @10p/unit of gas =£1500 plus 1000kWh=£100 per person per year for DHW. With 5 occupants you would spend £2000. OR ASHP @ a COP of 4 for heating all done on a TOU( time of use) tarrif at say 15p/KwH would be €562/year. DHW at a COP of 2.5 half day rate half E7 or similar would be ~£500. Total ~£1100 per year. Your mileage may vary depending on the cost of your utilities. In any case install UFH capable of using a low temperature input buried in the slab so you can bank heat on an ASHP using TOU at a later date if you go with gas initially.

It can be done, it's only about 6 mixers. However..... I'd probably go for a volumetric mix or 1m³ delivered. It won't cost much more and it'll be a far more consistent pour. Concrete is heavy enough work without shovelling 2.5t of ballet and cement into a mixer on top of barrowing it in and shovelling it out too. No need if you're tidy with a hand float after the pour. No Yes. Yes. I would put. Hardcore. A minimal amount really say 50mm just to level the existing ground. The subsoil will be plenty stable under an existing house. EPS insulation direct onto the ground.( If nothing else it's far easier to cart in than hardcore) Say 100mm. DPM, lap it well up the walls and tack it there. It can be cut back later. 100mm of concrete. You could probably reduce this to 75mm with some fibers in the mix to reduce digging and mixing.

EWI on PIR wouldn't be a normal detail. EPS is better for this. I think you're better off ditching the strip foundation and just making an insulated slab from EPS.

What is it about solar thermal and solid fuel heated water. Completely outdated, expensive, require too much maintenance but none the less my inner schoolboy really likes the idea of playing with them.

That's very cold. You'll be suffering from damp and very high humidity. 18deg is probably better IMO.

That sounds fine. It'll give you a U value of about 0.22.

I wouldn't bother. We did both and the one without is much better. Less bubbles etc. I think this is mainly due to the thermal coupling of LVT and concrete with underlay.

What are the layers on the outside of the lightweight concrete block and the soleplate?

Put a couple of these on it, take regular pics of it and save it to the cloud. Delay rendering until all movement has stopped.

I wouldn't worry about that. How long since it has been built?

Your issue is differential settlement. You can tackle this by either having a very consistent strength of substrate to your foundation or else having a strong foundation that will ensure the whole structure sinks/moves evenly and prevents cracking. You are going for the first solution. Thinking out loud here. As a idea you could hammer some timber pegs to the point of refusal under the paving slabs and then trim them level with the hardcore. They would act as mini piles. Otherwise consider 2 layers of paving slabs with the joints crossed. Probably overkill. 99% sure if you build bricks straight onto the hardcore it would stay put.

A sketch would be valuable here. Avoiding PIR between the rafters is best. How much roof thickness do you have to play with. U-Value is only one component of a house buildup. Don't forget airtightness, windtightness, decrement delay, fire performance, longevity, noise protection, material availability, cost, thermal bypass and condensation risk.

@nod What's taking the weight of the door? Is it resting on the outer leaf?

Top marks for the demo. Everyone's house should be knocked down and rebuild IMO.

How much of this regulation is based on data rather than hunches? Our kids just fine a suitable box/chair to climb up on what ever height they fancy. Having higher window sills make zero difference in our case other than increase the fall risk back into the room when they invariably find their way up on the sill.

Good Closed cell foam to top up the cavity. It'll do a cracker job of improving your airtightness too. Blow in another 300mm of cellulose. It'll help with airtighess much more than mineral wool, you'll get better coverage around roof timbers etc and it involves none of the human suffering. Consider good quality uPVC. Better performance and less cost. Think about ventilation. Depending on access a central MVHR would be ideal but dMVHR/DCV/MEV/PIV would all work.

Stop any chance of the EPS floating if the concrete was too watery and to protect the perimeter strip and DPM during screening. Also if you use PIR isn't there a risk of the aluminium foil reacting with the cement and making bubbles in the concreting? Thought it was best practice but more than happy to be corrected. Less components is always better than more! We didn't use one by the way.

Points to note 1. I've moved the Radon membrane between the two layers of EPS and forgone the Sand binding as the EPS will protect the membrane. You could then use 150mm X 2 of Floor insulation then which will give you a U value of about 0.11. 2. I've put a French Drain at the perimeter which is always a good idea to keep the bottom of the walls dry and prevent splashing. 3. The cavity insulation extends well below the floor insulation. This will ensure any mortor droppings don't fill the cavity and create a thermal bridge here. 4. The PIR upstand is "pinned" in place by the floor insulation. Otherwise it comes loose during the floor pour. 5. Let the slip membrane extends well beyond the internal leaf during the pour and trim it back later. It'll protect the Radon membrane and the PIR upstand during screeding. 6. I've included the block sizes to allow for normal cavity tie spacings.