How to cut & fit insulation between rafters. PIR board install between rafters. DIY fit insulation!!
Vložit
- čas přidán 28. 10. 2021
- In this video I show you as a DIYer how to cut and fit PIR (insulation) board between rafters. I show you the tools, the products and methods I use to carry out this task and provide a few tips along the way.
For the tools used in this video click here:
Makita LXT 18V Impact Driver & Drill plus batteries (Twin pack)- amzn.to/2txC1Rn
Makita LXT 18v 5Ah Li-ion batteries - amzn.to/3mAMMbU
Hand saw - amzn.to/38QudtA
Stanley knife twin pack - amzn.to/37gkfSh
Stanley spirit level - amzn.to/37jCbMX
Pencils - amzn.to/32BclRk
Stanley 8m measuring tape - amzn.to/37XWzBu
Stanley Fatmax folding jab saw - amzn.to/3epVpTj
Draper 9 piece hole saw kit - amzn.to/2GVU5ry
Expanding foam gun - amzn.to/3ifW5xX
For the products used in this video click here:
Wood screws - amzn.to/39Zfn45
Face Mask - amzn.to/3nIsZaO
Expanding foam - amzn.to/3kNSAk2
Aluminium tape - amzn.to/3ibTNji
Insulation board - amzn.to/3m4VArH
SUBSCRIBE - you can subscribe to my channel here: / pousearoundthehouse
For my loft conversion videos click here - • DIY loft conversion
The Amazon links above are affiliate links. As an Amazon associate I earn from qualifying purchases.
For more DIY, HOW TO, HOUSEHOLD TIPS and PRODUCT REVIEW please subscribe to POUSE around the HOUSE.
Thanks for watching!
#PIRboard #fitinsulationboard #fitPIRboard #DIYinsulation - Jak na to + styl
Awesome. Simply awesome. Thank you. Didn't realize a wood saw would do the trick to cut the board down to size.
Excellent stuff Pouse. Another no nonsense tutorial. Well done. 👍🏻
Thanks for the feedback 👍
Great stuff fella. Thank you.
Nice one Pouse, also good to see you making good use of your paintball kit too @00.29 ;). Keep up the good videos, love them
Thanks 👍
Great work as always mate.
Thanks for the feedback 👍
Really good mate. Cheers
Great stuff.
Muito bom parabéns 👏🏼👏🏼👏🏼
thankyou so much this has helped me loads, cheers
Glad to help.
Very cool and helpful video. Thx. Mate
Glad to help 👍
Great idea using screws to maintain the air gap spacing. I wonder if one could 3d print a few spacers and screw them in to help align the boards. Will try this on my garage pitched roof.
Top videos as usual
Thanks for watching Martin 👍
Great video, thanks for that
No problem.
Excellent tips. We are hoping to insulate our loft conversion during the Christmas holidays. We got gapotape for the Garden room roof between the oak beams but we are putting superquilt around the loft so no need for the gapotape up there. Keep up the good work. 👍
Best of luck with your project 👍
Amazing thank you 🙏🏼
No problem
So what I find works well is to intentionally undersize the cuts (by 5mm or so each side). Then jam it in with packers, and fill the gaps up completely with foam. As the foam expands it will 'glue' the board in, making it absolutely rock solid while also eliminating every potential gap. Then you just remove the packers and fill those holes too.
Basically like a budget, messier version of gapotape.
Thanks for the tips 👍
thanks this is helpful. Was looking for info on the air gap and yes confirmed at about 8:44 in your video. you have 25 mm which is about 1 inch. I'm going a bit more bc I'm in a very hot climate with humidity - want to give it that much more breathing room
This is a lot of work.
Would it suffice if you had tile vents to contribute to airflow? Wanting to put insulation between rafters, roof has breathable membrane. Any advice appreciated
Does the hole you cut for the downlighter allow warm air to escape? Do you foam around the downlighter? Thanks. Great video.
If the depth of the ceiling joist is 100mm do I need to use 100mm thick board or 50mm to allow for airflow between the membrame and board? Thanks.
So u go right up to the rigde how the air flow get to the other side of the ridge or does the air flow come up from the eves to the ridge and back down
Hi I used cardboard in each panel it stpoz draft through the luvers just used a staple gun then I ues a 12volt dash board heater on a timer so it's on for 15 min then turns of to save battery and also car alarm I've got two huts with flashing light on both huts my door is side of hut cut out into dorma roof so to walk in with out bang head on roof. You can do loads with huts
how do you insulate with wool on a pitched roof?
What is the done thing in terms of vapour barriering on a cold roof? Im struggleing to find out.
100%'d that job :>
Great video, very useful. I’m about to do a bathroom ceiling in PIR and set down lights into it, which is what I think your hole sawed holes are for too? 👍👍
Yes they are for the downlights. Best of luck and thanks for watching!
POLYSTYRENE vs celetex which one to use ?
What I don't quite understand about leaving an air gap is that if air is comming in vents through the soffit and going up to the ridge board where does it vent out, air will stop moving if it's not vented at the other end, and if you have roof vents you would need one between each roof joist on both sides of the roof.
This was exactly my concern as well!! Does every rafter pair need to be vented? My roof only have about 6-8 vents on each side where the roof meets the ceiling, no ridge vents. And how can you provide air flow on the other side of the roof if the PIR boards are tightly pushed to the ridge? This is my main question after watching tones od videos on CZcams and doing my research. Can anyone shed some light? How the rafters without vents can provide air flow when they are closed with PIR boards?
Doesn’t it vent out on the other side soffit? So comes in one side, goes up and then back down the other side and out?
Nice work, I am doing the similar project, how much insulation materials used for this project?
Excellent tips, just about to start my project.
How much space between the eaves and insulation do I need for airflow please? as the eaves are currently covered
Hi Norman, with old bitumen felt you'd usually be required to leave 50mm air gap from the eaves all the way to the ridge. To achieve the airflow you need either soffit vents or fascia vents which allow the required air flow.. You can see me install fascia vents in one of my loft conversion videos here which may help - czcams.com/video/TtS4oEyQptY/video.html
Another your great video, I will do it in next spring year on my looft , but I have a problem on my loft with dampness, I need to imrove a ventylation.. but how to do properly if you instaling kingspan everywere?
Windows is the obvious solution. I have velux windows which can be left on a trickle vent which is fully waterproof but allows small airflow in/out of the roof space. If you're not using the loft space then just insulate the floor with a mineral wool and get some ventilation in the roof space by either using polystyrene wedges between you layers of bitumen felt allowing air in, or you can use soffit or fascia vents to allow air in also. If you take a look at my loft conversion vids you can see where I used fascia vents for airflow over the top if the insulation, however this will ventilate an entire loft space if you just insulate the floor leaving the rafters clear. Hope that makes sense. Best of luck 👍
Very useful video - thanks! One question, do you also tape the join between the PIR and the rafters? Or just the joins between the PIR boards themselves - and if so, why?
I tend to tape just joins between pir to join them together, but I fill all gaps with foam if required. Because I was overboarding (see my other video) there's a continuous layer of insulation across all rafters. But if you want to tape to rafters you can. Best of luck!
@@POUSEaroundtheHOUSE Thanks for the prompt reply 😁 I will also be over boarding with 50mm PIR (as you are) and plan to tape all seams on this. After this I will be plasterboarding, what size screws would you recommend, 100mm plasterboard screws? - if I can find th
Can you foam the seams?
I’m having my loft floor raised and boarded soon then I will do the rafters me self ,there is felt back of tiles ,can I put the boards in like your doing leaving a gap like you have or do I need to replace the felt that’s there at the mo ,thanks
Old felt requires 50mm air gap between it and insulation. Hope that helps.
Hello I just have a question if you could please answer…
I’m looking to knock a wall down to make my downstairs bathroom a little bigger so my bathroom is joined with my W.C however my W.C has only a single skin wall.
Can I apply the same method for this with 100mm PIR and also the real question I need answering is: do I leave an air gap or do I butt the stud wall right up against the brick wall?
Hope you can answer thank you 🙏🏼
If you mean a single skin wall to the outside, then best practice would be to do a stud wall with an air gap of at least 50mm, but on the outer most side of your timbers, cover with a breathable membrane, then infill the studs with insulation. You should really put a vent in the outside brick wall to allow ventilation behind the stud timbers and membrane. You can then plasterboard the inside of the stud timbers. That's along the lines of how garage conversions are done and means you should avoid any damp issues. If you want to cut corners you could but it up to your wall but your're likely to get damp problems and condensation in time. Hope that helps.
So useful. At the bottom end of the rafters, can I stop where the top of the wall is? I'm insulating a garage conversion and wil be using 100mm celotex with 50mm gap above for eaves vents to ridge. Do I also need to tape the end of the insulation board that's exposed to the eaves?
No need to tape the ends although you can if you want. Yes you can stop where the wall is. I pushed mine as far as it would go whilst remaining flush with the underside of the rafter. You'll find it will hit the wall just before the cavity that way. If you have cavity wall insulation, then might be worth it meeting with that so you have no bridge between the two ensuring the interior wall and roof is all insulated. Hope that helps. Thanks for watching.
U tube - Insulation Cutting Jig. The RIC jig. The fastest,easiest way to cut pir boards. NO DUST. Now available to cut up to 150mm boards.
I have a question, should there be a gap between the insulation board and the roof tile to stop condensation and a gap at the bottom? thanks
Yes, you need airflow always
is there any ventilation between the insulation and the roof wooden cover?
No need for foam.
Nice video. My loft doesn't have breather felt, Would these instructions be ok. Thanks
You'd have to check with your building control officer but they would usually wany 50mm air gap for that with facia or soffit vents at the eves of the roof to allow enough air flow. Hope that helps.
Ah ha ! Now I see you leave the air gap between the felt / membrane and the outer foil skin !
TCA Hi, I have been looking at your vidio PIR between rafters. Great & easy to follow. In my 1939 3 bed semi I only have 75mm depth of rafter to felt. In your opinion could I use 50mm pir board, leaving 25mm air gap. I dont want to add extra timber to face of rafters,to accomadate thicker pir as this makes the job larger & also adds more weight. I would appreciate your thoughts.
If you're not doing it to modern building control standards then you could use a thinner board yes. If you have the old bitumous felt then the satandard is to leave a 50mm airgap. I left 25mm gap but I also installed a modern breathable membrane and fascia vents allowing air circulation above the insulation. So you may get away with it but you want to avoid condensation building up above. Hope that helps. Thanks for watching.
Hi mate - in my older bungalow loft the sarking has started the perish. I've thought about doing this PIR board for a while. If I could repair the sarking with a breathable patch and then put the PIR boards in - would you then still keep the insulation above the ceiling? So you'd effectively had loft floor insulation, the loft itself, then the PIR board in front of the breathable sarking membrane and tiles.
Alright pal, great videos. I know this is 2 years ago so comments are probably dead but worth a go. I bought a victorian terrace and just found problem after problem. Feeling overwhelming to be honest. But starting to insulate the loft. So couple questions... Do these boards cover the amount government say you need. Also i have a vent in my roof i think is for ventilation, would you just board around it to keep airflow? Thanks
You have to have suitable ventilation when insulating like this. But you need ventilation over the top of the boards either with roof vents or in my case I used fascia vents. This stops condensation under your roof felt. The insulation should really seal the room so you then need internal ventilation via a window that can be left on the trickle vent of a velux on the catch. As for insulation, mine was done as part of a loft conversion so it had to meet a certain standard but if your not making a 'proper' habital room then you don't need to meet those standards but it can only be called a storage room rather than a proper bedroom. Here's a link to my loft conversion playlist - czcams.com/play/PL2-FHRIF3qm-skuIrOxfivCGhoE0v8g2n.html. Take a look through the vids (44 so far!) as I cover vents, insulation, velux windows etc throughout. Best of luck.
Do you install insulation FLUSH with roof joists or push in enough to allow space for foam?
Flush if you can. I only add foam where the cuts are slightly out. There is a tape you can use now which expands onto your foam allowing you to cut board a touch smaller. It's called gapo tape. Hope that helps. Thanks for watching.
I live in an old house (tile and horse hair stuff!) in the loft there is no membrane just straight to tiles. do i need to leave a gap to the tile or can i just go up straight to tile with the board? thanks
You still need to leave a gap to allow air flow which will remove any condensation that forms under the tiles. If you don't you will end up with damp problems. Hope that helps.
Pouse should you not leave a 50mm airflow between felt and insulation for airflow? We are in progress of planning this we have dropped all internal ceilings on 1st floor and will be having a vaulted ceiling. All specs and kingspan are saying 50mm airflow? Good video 👍🏼
Always check with your building control officer as things change and ultimately they have tge last say. But 50mm is the recommendation when you have bitumen roof felt. I replaced mine with tyvec supro breathable membrane (plus tge use of fascia vents) so I was allowed to reduce the gap but it depends on what your local officer allows. Best of luck with the conversion. 👍
Great video buddy.
If you're not using the loft space for anything other than storage, can you use this and mineral wool insulation as a double effect, or will it be bad for condensation? (Just had a brand new roof fitted with breathable membrane)
If you fill between rafters you still need a void for air circulation above the insulation and some fascia or soffit vents at the eves. You can get different mineral type insulation that can be used in the rafters but you'd have to just check the spec is suitable for your needs. Once insulated you would need some ventilation in the room like velux windows for example. Hope that helps. Thanks for watching 👍
Hi Pouse, I'm currently insulating my loft and above the bathroom there's quite a lot of condensation for obvious reasons. Do you have any suggestions on what insulation to use at floor level in the loft above the bathroom? Thanks in advance,
Do you mean a vapour barrier at floor level in loft above the bathroom? Would that not simply cause condensation to form in the rafters just above the loft ceiling and rot them? Instead, should you not ensure that no moisture rises through the bathroom ceiling.... but maybe I am missing something here..
@@wotcherfaz At floor level yes but not a barrier more a vapour control layer. I read that you should put breathable insulation above bathrooms but can't seem to find one. The bathroom is on the list of things to do and when I get to it it'll be done properly but at the minute I'm insulting the loft and want to do it right. Any help would be appreciated. Thanks
@@alexanderparnell ok, i guess the important thing to remember is that if moist warm air from bathroom goes up and hits that vapour control layer, if that vapour control layer is warm under and cold above, then partway through it the warm air is likely to deposit water condensation _in_ the vapour control layer -- so that layer probly ought to be thin and non-absorbent, else it could get wet and heavy over time... instead you want to make sure any warm air stays under the layer, and that it's warm there, or that it goes through quick and is removed by ventilation above. Just basic thoughts from me... hope it helps.
@@wotcherfaz thanks for the advice.
Hi. How much room do you need to leave between roof tiles and new insulation board? Cheers James.
50mm if it's old bitumous felt but you can go down to as little as 25mm with a fully breathable membrane. to check with your local building control if in doubt. Thanks for watching.
what do you do when a breatable membrane isnt fitted?, i just want to insulate the roof to keep as much heat as possible in the house, many thanks
You need to leave 50mm gap between insulation and felt, then add ventilation, fascia vents or soffit vents will do this but you need enough to stop condensation build up. Hope that helps.
So just to be clear, the PIR is pushed between the rafters with the outer foil skin in contact with the roofing felt / slaters felt ?
Then the requirement is for an air gap between the inner foil skin ?
No, the gap is between upper side of board and roofing felt, and ventilation is required at soffit or fascias. I used fascia vents. If you watch my other video, I apply insulation over that board on the inside of the room to cover timber rafters as well. Hope that makes sense. Thanks for watching.
Im looking to create a ceiling in my garage with a pitched roof and rafters overhead.
My plan is to wedge this stuff overhead, then screw 5mm plywood under it. If I'm hearing this right, are you saying I should lay the boards up to 50mm higher than the plywood boards, or is the airgap not relevant as I'm not mounting anything against the roof?
FYI, it's to keep the garage cooler in summer as I'm putting a treadmill and aircon in it. It's like a furnace on a hot day
No. The airgap needs to be above the insulation, between the insulation board and tge roof membrane / felt. It's to stop condensation forming above. You also need some way of getting good airflow by using vents. I used fascia vents. If you go to my loft conversion playlists, there's a video of me fitting the vents so it all makes sense. Hope that helps.
@POUSEaroundtheHOUSE I thought that's what you meant but wanted to check. The insulation will all be directly above the new ceiling with a fairly large space above it as the roof is pitched 4 ways into a pyramid shape. There's something onto that would allow airflow as well. As in, it's not air tight
DO you have to leave space for air flow between roof and insulation?
Yes, 50mm is standard, which may be reduced with a good breathable membrane. You can check with building control. You need vents at the fascia or soffits to allow the air to flow in also. You can watch me fit fascia vents in one of my loft conversion videos here - czcams.com/video/TtS4oEyQptY/video.html. Hope that helps.
Robin clevett is the guy to watch to fit this stuff.
Yes I love Robin, he's very good, not DIY like me. That said he's usually working with new rafters. My roof is 130 years old and not one rafter was straight or evenly spaced so sometimes jigs and guides don't help. Thanks for watching 👍
maybe try Gapotape ?
Hi, great video. We have just had our 100 year old slate tiles relaid, membrane and new batons. We want to celotex to insulate, how much gap between membrane and cellotex?
Where is your eye protection while spraying the foam above your head? Once while spraying the attachment to the foam bottle exploded for me. Luckily I had safety glasses.
For the roof. Shiny side toward the heat, non shiny side towards the cooler room
It's shiny on both sides! In fact, I'm not sure PIR board is even made with one shiny side.
@@POUSEaroundtheHOUSE ... It can be faced on either side or none,,, depending on the purpose of use intent claimed of the manufacture. All good ;)
Just mentioning to have a faced side towards the roof, the heat side, is all.
What do you think of GapoTape?
I've never used it but it seems like a good solution. Thanks for watching.
Was going to ask the same question.
Gapotape seems good but at approx £2 pm it’s a bit pricey so I’m looking at all options.
Just wondering if a quick bead of expanding foam prior to pir sheat so it expands onto the sheat and perfect seal, I would expect but no experience for proof of concept yet
Too expensive and time consuming preparation for what it does. BUT…. It is good at what it does. If we all start using it, hopefully with ‘economy of scale’, the price might come down.
watch Robin Clevett insulation video. guy's a genius
Is that kind of insulation one-sided, or is the the same both sides?
Foil backed both sides, can go in either way. It's called PIR board. Hope that helps. Thanks for watching.
@@POUSEaroundtheHOUSE I wondered about this, because the boards have printed on one side "This side down"... I'm guessing this means it reflects heat (infra red radiation) better on one side... but not sure what 'down' means (because sometimes these boards are used to insulate against a cold floor, not in an attic). What do you think Pouse? BTW love your down to earth style.
Sorry forgot to say I carnt put velux window in solar panels on roof
I’m pretty sure you’re supposed to “foam glue” all the sides. Definitely between the raft and panel
Are you really sure? Thanks for watching 👍
can you do our house please?
No time to finish my own projects!!
What next going on this pir?
More PIR, then plasterboard. See here for how to fit insulation over rafters - czcams.com/video/HGy4hNV7tAA/video.html
@@POUSEaroundtheHOUSE drywall directly screwes to pir board?
Why don't you cut the insulation 1cm narrower on each side and then foam the gap and voila' compleetly tight without exact messuring???? Thats how i did and a perfect result! No leak anywhere and our house stays warm!
Problem with that is you can't guarantee the depth of the foam. So it may not go as deep as your insulation or it could do the opposite and expand into the air void behind which would not only bridge the gap between insulation and roofing membrane (which is bad) but would block the airflow between the two which is essential to avoid condensation and damp above the insulation. Hope that helps, thanks for watching 👍
@@POUSEaroundtheHOUSE Thanks! No problem cause my board had tongue on 2sides so i just had to "glue" them together and foam the sides. They were 12 cm(5 inches) thick so i had to foam 2 times. This was how the manufactor recommended to do. No snow is melting on the roof like it does on many other house around ours. Been there for 19 years and counting. 😎
Nice Video......BUT for a better insulation.......NO insulation between ........ but UNDER the rafters !!!
I did both. You can watch my other video here - czcams.com/video/HGy4hNV7tAA/video.html
Look like you're about to do a joint mission with the sas, hair suspiciously looking thicker years on from your early videos 🤔 you should watch some American diy videos and remake them in your style for us brits i feel like i learn easier hearing from a brit plus you would be able to translate into imperial measurements and translate the names of tools, materials and equipment into our lingo.
I wish my hair was thicker! This footage was filmed over 2 years ago when doing my loft so maybe that explains it?! Thanks for watching 👍
Gapotape
Sorry, but this is utter bollocks. There is simply **no way** you (or anyone else) can get an accurate enough cut to prevent air moving around any given section of insulation. Thus, 80% of your expense and effort is completely *wasted*.
The *only* truly effective method of using rigid insulation in this scenario is to undersize it and seal it in place with a *full depth* application of expanding foam.