Joist Problem While Installing Celotex Insulation - Underfloor Insulation Part 2 - 24V03

[@ALifeOfStew]

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[@MT-zn6tc]

We did this on a 125sqm bungalow. Fortunately we could lift the 8' x 4' plywood floorboards but it was still a pita to do. Coupled with that, like you said, each space isn't perfectly square. We used 100mm Celotex (cut from both sides with a circular saw as we couldn't stretch to the miniature chainsaw/rail that Festool sell). We also used Tyvek breathable housewrap stapled between the joists underneath and lobbed load of surplus glass fibre under there too. The Tyvek was there to further reduce wind wash. It took us months and we hated it, but we are enjoying the benefits now with lower bills and wet underfloor heating. I'd never do it again though. A builder said he would have concrete it all up to the right level, put the appropriate moisture barriers and insulation in place and cut all the joists out. About a weeks work instead of the months of dust, grit and DIY that we did.

[@ALifeOfStew]

Sounds a lot of blood sweat and tears but like us the benefits make it all worthwhile Concrete cost would of been high I suspect dependant on void depth

[@MT-zn6tc]

@@ALifeOfStew agree the cost of the concrete might be relatively high (44cu m) but the time compared to the months of work, we would have easily saved that in interest and mortage on where we were living until the house was ready. On hindsight, moving the project forward by 2-3 months would have been a much greater time and cost saver compared to the few hundred quid of concrete.

[@ALifeOfStew]

@ true as you say it’s all about the different drivers I guess

[@LifeistooshortCK]

That is going to make a huge difference come winter. It will be interesting to see if your bills go down

[@ALifeOfStew]

Interestingly the odd time we have had the heating on since I completed had shown the room retaining the heat - it’s never ever done that plus a change in noise and makes the sound more solid and dense Thanks for watching and commenting

[@josephthompson4363]

I've done similar jobs to this over the years, found it much easier to remove about 10 feet of floor boards at a time. Using a proper floor board lifter, remove nails as you go along, fit rails then insulate. Refit floor boards by screwing them down. Screws help stop floorboard squeak.

[@ALifeOfStew]

Yep it’s a good project - in the cold snap recently the difference in the warmth of the lounge was unbelievable I did use plenty of screws in putting down the boards - not seen a floorboard lifter sounds good though

[@MikeandTriciaOotnAboot]

Cracking job Stew👍

[@ALifeOfStew]

Thanks - made a difference with heat retention and sound proofing already

[@iancharles7596]

Superb job Stew.

[@ALifeOfStew]

Many thanks! It’s already making a difference with heat retention but also has made a noticeable reduction in noise

[@Mobile-pd1uc]

Great job. I could only imagine how much someone would charge to do this and then break the odd floorboard.

[@ALifeOfStew]

Yep a labour of love but I have to say this week with the cold weather the lounge has never been so warm so it’s really paid off

[@andyblake1849]

Nice job 👏

[@ALifeOfStew]

Thanks for watching

[@FergusNCasey]

Fair play Stew. Looks a great job.

[@ALifeOfStew]

Thanks 👍 it’s making a difference in heat retention and sound dampening

[@mattiafrancesco]

This looks great! Any tips for those wanting to do a similar project? Would you do anything different?

[@ALifeOfStew]

Regarding the underfloor insulation if you have space under the cavity you could install rolls with strapping across the joists to hold in place - that would be a quicker job and reduce the floorboard removal but it depends on the void and how the joists run. Soft roll will fill the edges easier than cellotex

[@johnarmstrong4015]

Sorry Stew, had to stop watching, brought back too many memories, I was a joiner in another life before retirement. keep up the good work. ATB

[@ALifeOfStew]

Sorry about that - I’m just bumbling amateur on this one

[@clivewilliams3661]

Or course the tongues add to the integrity of the floor boarding. They make the boarding act in unison and distribute the loads over several boards. Without tongues you will need thicker boards for the same performance and you will get differential movement that may show as a board pattern in floor finishes, even with underlay. You could put the full 100mm of insulation as this can rest on galv metal angles, either door frame cramps, bent strapping sections or roofing cleats nailed to the joist with galv nails the supports need not be continuous and set at say 450mm ctrs will be better than a timber strip that would need to be pressure impregnated to minimise rot. All the floor boards should have been taken up to allow the insulation to be slotted in. The issue with this installation is that no vapour barrier was put over the insulation to prevent interstitial condensation forming in the joists that will eventually rot the joists as they were not treated on their original installation, relying on the ventilation all around the joist to ensure that it stayed dry. Because Celotex has an integral foil vapour barrier, all that would have been necessary would have been to tape over the top of the joists and onto the Celotex board on each side with aluminium tape as well as taping any joints between boards. A much simpler way would have been to use multifoil insulation as it provides all that is necessary for insulation and vapour barrier as well as leaving enough of the joist to ensure that it is well ventilated.

[@ALifeOfStew]

Thanks for your comment - unfortunately the video I watched that i followed did not raise these concerns but at least this comment is there for others to read so thank you - I guess I am where I am where I am now and will have to address any issues as they arise Thanks for watching

[@didevilliers1238]

What a job - well done Stew 🤮

[@ALifeOfStew]

Thank you for watching - we have already seen benefits in heat retention

[@didevilliers1238]

Oops don't know where the emoticon came from - sorry 😢

[@ALifeOfStew]

@@didevilliers1238 lol I didn’t notice - I suffer badly from finger trouble and autocorrect lol