ASHP & triple glazing

[Richard77]

Did you insulate the floor Joeboy?

[Joeboy]

Did you insulate the floor Joeboy?

Not fully yet, I've got a man who will fit under there in the original part of the home later in the year. The extended sections (3 of) are all done though. All the rest of the original house has been floored over the top of chipboard but will be better for an underfloor overhaul. Not sure what to use, its a bit tight under there and wouldn't want to inflict earthwool on him?

[Richard77]

I will keep an eye on what you decide to do and what the results are. An awful lot of heat is lost through the floor apparently, isn't it about 15-20%?

I've got 2 rooms on the ground floor that are suspended and everywhere else is concrete. God knows why. It was going to be one of the "easier" things to tackle. I was just thinking at least 100mm pir in-between the joists (battens or netting to keep in place) and bobs ya uncle.

It will be interesting to see what you come up with.

[Joeboy]

I will keep an eye on what you decide to do and what the results are. An awful lot of heat is lost through the floor apparently, isn't it about 15-20%?

I've got 2 rooms on the ground floor that are suspended and everywhere else is concrete. God knows why. It was going to be one of the "easier" things to tackle. I was just thinking at least 100mm pir in-between the joists (battens or netting to keep in place) and bobs ya uncle.

It will be interesting to see what you come up with.

On the big lounge when building it we did suspended net pockets between the floor joists and filled them with 100mm earthwool

[NoraBatty]

We turned our heating off on monday as had hit that its not worth it time of year. The house was fine and comfortable until yesterday when temperatures dipped again. Its back on again this morning as it was 15C downhere yhismorning though the upstaits is still 19C. So 2-3days for the fabric to cool down.

I still havent finished the underfloor insulation. Going to get the saw out again in a few minutes and cut up some more lengths of PIR ready to tape tonight.
I am gapotaping the PIR. Its a memory foam and alunimium tape that allows a friction fit between the joists so no additional support is needed. You cut the boards about 1cm smaller than needed, and the tape takes up the airtight sealing and fixture role.
Its quite expensive for what it is, then you have the PIR ontop (seconds and co) and you could probably make your own diy version of the tape, but it is excellent stuff and the fitting of it is so much easier than battens and foaming etc.
Its the actual getting under there, measuring and fitting that is holding the project up, because my dodgy neck and shoulders just reject the idea of doing it without severe punishment afterwards.

I looked around for someone to do it for us, and no one was prepared to do the PIR, or how i want it done.
Everyone wanted to do the rockwool and netting thing.
We had that in our last house and it made a massive difference instantly, but there were areas left not as insulated as possible, due to the nature of how its retro fitted under the floor. And the winters down south are significantly warmer than up here, hence the PIR decision.

The best way for rockwool to be fitted is with floor lifted up, a continuous VCL layed over the joists to drape down into the gap, and rockwool filling the gap that way, with no way for draughts or windwashing to occur.

It is definately worth doing in rockwool and netting, but the PIR will give the better result.
I think the rockwool would also be easier for an installer tbh as joists dont have to be measured so exact, and rockwool flexes to go in holes, which is especially helpful if your subfloor is shallow.

Ask your installer what he is prepared to do, and what he isnt. Unless you want to diy, you may be stuck with what someone will do rather than what you want.

[Richard77]

We turned our heating off on monday as had hit that its not worth it time of year. The house was fine and comfortable until yesterday when temperatures dipped again. Its back on again this morning as it was 15C downhere yhismorning though the upstaits is still 19C. So 2-3days for the fabric to cool down.

I still havent finished the underfloor insulation. Going to get the saw out again in a few minutes and cut up some more lengths of PIR ready to tape tonight.
I am gapotaping the PIR. Its a memory foam and alunimium tape that allows a friction fit between the joists so no additional support is needed. You cut the boards about 1cm smaller than needed, and the tape takes up the airtight sealing and fixture role.
Its quite expensive for what it is, then you have the PIR ontop (seconds and co) and you could probably make your own diy version of the tape, but it is excellent stuff and the fitting of it is so much easier than battens and foaming etc.
Its the actual getting under there, measuring and fitting that is holding the project up, because my dodgy neck and shoulders just reject the idea of doing it without severe punishment afterwards.

I looked around for someone to do it for us, and no one was prepared to do the PIR, or how i want it done.
Everyone wanted to do the rockwool and netting thing.
We had that in our last house and it made a massive difference instantly, but there were areas left not as insulated as possible, due to the nature of how its retro fitted under the floor. And the winters down south are significantly warmer than up here, hence the PIR decision.

The best way for rockwool to be fitted is with floor lifted up, a continuous VCL layed over the joists to drape down into the gap, and rockwool filling the gap that way, with no way for draughts or windwashing to occur.

It is definately worth doing in rockwool and netting, but the PIR will give the better result.
I think the rockwool would also be easier for an installer tbh as joists dont have to be measured so exact, and rockwool flexes to go in holes, which is especially helpful if your subfloor is shallow.

Ask your installer what he is prepared to do, and what he isnt. Unless you want to diy, you may be stuck with what someone will do rather than what you want.

I've seen that gapotape NoraBatty, it looks a really good product and achieves a nice airtight seal. I assumed it still needed some way of keeping it in place though, especially if underfoot and would eventually work it's way out of the joists after a while due to gravity and the traffic above it?

[NoraBatty]

I've seen that gapotape NoraBatty, it looks a really good product and achieves a nice airtight seal. I assumed it still needed some way of keeping it in place though, especially if underfoot and would eventually work it's way out of the joists after a while due to gravity and the traffic above it?

Not that i have found no.
The friction fit is obviously as good as you make it, and with taking off 1cm from the width, ive found it is very tight. Ive been pushing it into place as best as possble by hand, then standing up under the floor and pushing on it to make sure it is hard against the floorboards with my shoulders. My arms dont go above my head very well due to various issues, so i lack the strength needed to do it just with my arms.
Its not moved at all, and very unlikely to do so without being prised out. You could batten under if you wanted to be doubly sure, but its onenof those you have to see it to get it things.
You would instantly know if the friction fit was not tight enough.

We sourced 90mm PIR cheaply.
Our joists are 150mm thick. If using PIR you are supposed to leave 25mm of joist exposed to let it breathe.
I looked at various pricings, as initially did want to go 125mm thick, but we went with what was on offer and cheapest at the time.
We ordered in the 90-100mm range and we just eneded up with the 90mm, again wouod have prefered the 100mm, but you get what you are given when buying in a thickness range.
Quite a step down from my ideal of 125mm, but the boards are practically perfect bar a couple of ripples in the metallic paper, and it will come in under £1200 in total to do the whole underfloor myself.
It cost us £1000 12 years ago for rockwool and netting to be fitted for us. So i all that a bargain.

We can always net and hang rockwool undet the PIR to add an extra insulative value, but i dont think its neccessary. Even doubling the 90mm wouldnt add that much in gains compared to the first 90mm.

[Ronski]

Interesting info NoraBatty, we've solid floors mostly uninsulated, but my brother has got wooden floors and been buying up cheap lots of celotex off eBay, he was wondering what method to use to seal around the edges and get a nice fit, although he's probably too tight for Gapotape, but it seems ideal, so passed the info on.

[NoraBatty]

Interesting info NoraBatty, we've solid floors mostly uninsulated, but my brother has got wooden floors and been buying up cheap lots of celotex off eBay, he was wondering what method to use to seal around the edges and get a nice fit, although he's probably too tight for Gapotape, but it seems ideal, so passed the info on.

You can buy some memory foam strips and some alu tape and do it yourself cheaper i am sure.
The benefit of the gapotape is thst the tape is quite heavily reinforced and harder to tear when fitting it.
Im sure reinforced alu tapes are out there but ive not come across them. The think tapes tear so easily in comparison.

We have used a 50mm sheet with gapotape around the edges to seal against our front door in winter with amazing results, much better than a heavier curtain.
This summer i will be changing that and making some removeable grp storm doors that will be filled with it, to do the same thing but from the outside

Many people try to friction fit the PIR between the joists as best as possible with precise cuts and then foam in between the gaps, whilst battening to hold it all up. It is what i was planning to do, reluctantly, until i discovered gapotape.
It takes more prep to measure, cut and tape over the edges, but that is all done above ground in somewhat comfort.
The actual install conversely is a lot faster, easier, and cleaner than cutting to fit in situ and getting inevitably covered in foam.

We are blessed with a 3-4.5ft "crawl space" here, but can only get a maximum length of 1.2m down the hatch, which means you have to use more tape than if you had longer sections so that you have a nice seal when teo ends are butted up together.
The shallower the crawl space, the more expensive it would work out to be tape wise due to the small chunks you wouod have to feed down there.

[Ronski]

Thanks, he's got no crawl space, but then he hasn't any fixed floor covering, and all floorboards are easily removed, the bigger problem would be moving stuff out the way with somewhere to put it.