Badly fitted insulation between joists and thermal imaging

I’m a carpenter and currently constructing my partners gym. All timber construction.
Using the tape you have mentioned. Much prefer this method, it is time consuming but a better job.
Couple of things to mentions:

I do have a crown roof construction which adds to the overall outlay.

Cost. The tape cost as much as the pir insulation for the whole build.

Once you have a system going it can be quite quick to install tape.

All in all this method will have to become the norm as we evolve in the construction industry I just hope the tape price will come down.

I like to leave a gap around big enough to get my foam gun in and then it's easy to fill with foam,

Although it reduces the size of the room I always use 25mm of insulation board - cross boarding to finish off!

You simply lay a thin layer of PIR over the joists that acts as a vapour barrier and also reduces thermal bridging even more.

Use rockwool and will fit easy and nice. Then a vapor breathable barrier and is done.

In your experience do you think this could lead to damp patches showing in the plaster . (Condensation? )

Just spray foam the whole thing? No gaps.

Incredibly interesting and helpful ! Thank you so much !

Ventilation...air quality....damp

In Finland we leave the foam insulation about 15 mm smaller on each side than the cavity and then fill the gap with flexible gun foam. That way we can ensure the gaps are filled entirely and no places for heat loss or air movement are left.

We usually also add another continous layer of pir-foam on the inside (normally 30-50mm). This layer acts as vapour barrier, insulation and thermal break all at the same time.

I’ve had nightmares fitting this stuff when the joinery isn’t correct and the measurements are all over, in my opinion it’s rubbish stuff a better way would be sprayed insulation like a foam filler with an insulated plasterboard over the top.

Sprayfoam is the answer, so much more reliable IMO

how can you expect good results with single 100mm insulation🤯🤔madness

where are you buying your foam from? they're tucking you up mate. insta stick is only £13 from your builders merchant

You will never get a perfect fit if you try cutting your foam to exact size. I always, purposely cut my foam around 70 mil. short and less wide. This leaves a gap of 35 mil. on all sides. The 35 mil. is a perfect size to properly fill with spay foam. I am sorry if I am being rude, but you don't know how to spray very well. When the gap is big enough, you can stick the nozzle of the spray gun deep enough to get to the other side of the gap...fill it to 50 to 60 % full (depending on the product..read the instructions) usually, a second pass is barely necessary.... cut off the excess.

I'm rebuilding my old 1880s house and am using Rockwool/Rocksilk everywhere with a membrane. Cut it 1/2" - 1" bigger than the gap and it makes a nice tight fit and fills up any wonkiness in the battens.

Nice video thanks I didn't know this

Thank you for the advice, having recently done a hot roof myself ( also tested with thermal imaging) i wondered what they would be looking for. This video explained it perfectly.

I have heard good things about flexible wood fibre board insulation. Being flexible, may massively reduce this problem.

Excellent information. Thanks.

Hi, we moved into a bungalow that has no cavity wall insulation and the pointing is very bad. I wondered what your opinion on the best solution to insulate, renew the pointing then insulation in the cavity or external wall insulation?.
Many thanks 👍

With no stud being perfectly straight and cutting PIR perfectly also unlikely, surely rockwool is a better option for in between studs? PIR is a better insulator but the draughty gaps it leaves negate any benefit in my opinion. Plus it’s a lot more plastic for some poor sod to deal with later down the line

The amount of heat loss is negligible and so is the cost it’s not going to alter anyone’s life making an issue from nothing .

When i lived at home we had single glazed wooden windows, no central heating, no insulation in the loft or walls and just an open fire in the front room . But i never remember feeling cold or my parents complaining about being cold. Have we just become to soft?

When I was looking into PIR foam panels being placed in a wooden frame like that, the Kingspan website said that it didn't actually meet any standards until you placed a PIR backed plasterboard across in the other direction, and from there I guess you would plaster/skim it and paint it making it a complete solution?

Stuff carpet offcuts of different thickness or fiberglass insulation in the slots

It's not your shadow in thermal imaging. It's a reflection.

I'm glad I live in Mosselbay (+-400km north of Cape town,indian ocean side) where it's mild and never even snow thus ⁰ insolation anywhere😂😅

Why not use wool batts in the studwork then insulated platerboard over that?

The harder and more costly they make it becomes an incentive to do nothing.

EXACTLY the issues in our loft converstion - built by the builder who owned the place before us, but apparently didn't think insulation needed to fit edge to edge. Big gaps around the celotex, freezing air blowing though roof space so if it's freezing outside, the interior of the plasterboard is about 12C even with the heating on. The downlighters of course have NO insualtion above, so would be frozen if they weren't conducting heat out of the room so effectively. Cold roofs are a bloody stupid idea, since they're all installed so poorly. 😤🤷‍♂️

Have you seen that insulation burn? We will be pulling all that stuff out in a few years and putting in Glass fibre.

Hhhmmmm
Interesting.
Nice energy production tangle you have there.
It's a shame IPCC was just so Maggy had another weapon against the coal unions.
This could have all been avoided!
Chasing one's tail with all this! 😉😁

👍

I don't need any insulation, I cant even afford to keep my home cold these days!

Well it’s better f all 😂 right

Interesting thank you. Would you say with those poorly (but typically) fitted bits of PIR that it's better to leave a ~1cm gap round the edge so you can ensure the expanding foam runs all the way from front to back?

Cost benefit calcs are the way to equate the efficiency of the extra work. This does mean shoddy work can be accepted and good fitting timber and insulation first round is a must. Now have a country full of incompetant and unprofessional builders and thats my experiance. I am not a builder but I am an mech engineer having used many diff builders. Roofers, id say 80% are pretty poor. This has led to some court cases. WhatbI also find is even getting detailed quotes of the work is near impossible and many just refusse to detail standards used and material/labour separate. The point here is hos is a home owner supposed to ensure high standards when the industry is just so bad.

Actis hybris instead of that celotex every day of the week.

£200 of tape. The tape is like £6 for 45m 😂

I'm doing a timber frame annex right now and am putting 65mm in the studwork and then later 65mm insulated plaster board inside. Do I need to be foam taping the studwork insulation considering there will be a second continuous layer?

Finding people with the skills to diagnose poorly insulated warm roof constructions seems to be almost impossible. I have an extension which is very cold and I'd love to be able to find someone who can tell me what can be done about it - I just can't find anyone!

I think we are getting a bit hung up on making things 100% air tight ect, it's the stuff of night mares, just do the very best you can otherwise you will never sleep worrying about heat escaping through pin holes youv'e missed and life's to short for that.

Like it very good info

Quick question if I may, I have a dormer with cheeks of 150mm so builder is using 150mm insulation between timber. Should I have more insulation over the top as well? He wants to use just plasterboard over

There's the debate on air gap versus no air gap - is there a consensus on this are you aware ? In my case i'm talking about insulating the floor from below with 100mm PIR against tongue and groove flooring. Thanks

so its ok to having 25mm kingspan between battens. the a vapour barrier on top. and then insulated plasterboard on top of that?