Nice work fellas. And yes, insulating is tedious ! Although I haven't used it, there is a games-changing product out called:- Gap-o-Tape, it's a soft foam strip with a sticky back:- • Cut your PIR 10mm short • Stick it to the 4 x sides of the PIR • Insert into the wall Down side is the cost. Looks good though
This video has been a great help. I am just about to undertake insulating two porches and a loft conversion, I didn’t know that you could get low profile downlights, so this has been a great help. Also seeing how you still insulated and vapour barrier around the lights, thanks for taking the time to make this video 👍
I love those light boxes. I have just built a house for my son and can concur insulating between rafters with ridged insulation is the worst job of the whole build. Wish I bought the Festool insulation cutter
Thank you Mr R, we really appreciate your comment. We constantly wonder if we are going about things the right way so comments like yours are great to receive.
Why does nobody use actis hybris? Am insulating my loft conversion at the moment, no mess and you just squash it a bit for downlights. The big holes can take a fair bit of squashing until you start to compromise R val. Downside is it’s a bit nuanced for cutting/fitting but once you get you head round it, it’s a joy!
Not a big fan of PIR. Sometimes it's the only thing you can use to get the required U values, but the fact that it's almost exclusively used these days in all situations just feels like the result of a big marketing campaign. It has great thermal values, but it's near impossible to install without any possible gaps or bridges, it's a pretty big fire risk with the sheer mass of it that goes in, and it's awful for sound proofing too. Keep hearing about people disappointed with the thousands they've spend on insulation only to be woken up by seagulls walking around on their flat roof. Rockwool can solve most of those problems, and supposedly if you use it in conjunction with multifoil you can get great U values, but because it's not "the norm" few people have enough confidence to try it on a big project.
Well said, I totally agree. The vapour barrier is such a misunderstood, under used and important aspect of the insulation process and a properly fitted one and easily bring down the amount of insulation needed. PIR for a cold roof is a must though, I don't think it's possible to rock wool a roof that's made of 7x2 timbers and not guarantee that it won't get pushed up in places and sit on the underside.of the top OSB. But the walls definitely can have rockwool in my opinion and a high quality vapour barrier. If you follow this link ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Pm5MS1U-60U.html and check our videos on the garden room you'll see that we used rockwool and vapour barrier on the entire project and I'll stand by it's thermal efficiencies. Cheers for your comment mate.
@@mrabuilders6723 I have used Rockwool on a pitched roof before. We had the extension built with deep timbers so that I could get 140mm in. When I told the builder what my insulation plan was he was aghast and asked whether I'd spoken to the inspector. What people don't realise is there are lots of ways to skin a cat and the inspector will just tell builders the easy way to achieve code but if you can present the figures on paper (using manufacturers figures) they will usually allow it. I had battens and multifoil over the underside of the Rockwool. The flexi edge batts were much easier to fit in the spaces.
Quick question, my house was built in the 1880s. There are no trusses as such. The roof sits on 50 x 50 timbers supported by 200 x 100 oak purlins with a similar sized oak ridge Beam supported with a vertical 100 x 100 at the centre. I am about to start fitting PIR into the gaps to insulate the roof do i need to leave a 50 mm air gap behind the kingspan. If so I can fix new 50 x 50 to the existing timber.
Nice work - did you see Robin Clevett’s video on cutting and installing PIR. He goes to the trouble of knocking up internal and external jigs for the angled cuts and promotes ‘gappotape’ as the best way to achieve the performance standard?
Hi Norman I have seen that but he’s got the time, money and the sponsors to do it all how he does it. I like his videos and it would be nice to complete jobs that way. We will be using gapotape on our future installs because it’s in the regs now. Thanks for watching
@@mrabuilders6723 Thank you for taking the time to answer. I like Robin’s work and his approach, he is in the upper centile in all respects - except height.😉
Thanks for the vid, good to see such comprehensive documenting of your job. I'm confused about building regs, though: don't the new regs mean you had to use foam tape around the edge of the PIR boards?
Hello FunkyMunkey, that's a great question. Although the amendments to part L are now in place, we've got an exemption because the work started before the cut off date in June (the 15th I think?) so the changes will affect us on the next job. Saying that, what the addition of a foam tape will do to enhance the thermal performance when we take so much care as it is, I don't know. Taping the joints to create a vapour barrier, or installing a vapour barrier is key for thermal value and extremely cheaper than foam taping the edges...but I'm not in charge of these kind of things...!
@@mrabuilders6723 thanks for the reply. I understand the principle of what they trying to achieve, but to mandate a product which it seems is only currently offered by one company and at a great cost seems illogical
Exactly. It's going to be interesting to see how strict the building inspectors are going to be with it on domestic jobs. Fingers crossed the attitude will be a sensible one...time will tell!
As the internal stud walls were in place before you started the insulating, is the usual thing to just butt the 25mm over-rafter insulation up against the top plates?
What thickness do you use with the new regs? Need to check with BC but I'm looking at 100mm between rafters and 40mm kooltherm over the top. Bit more costly for the kooltherm but space is tight in the retrofit
Hello Craig, hope you're well mate. To be honest I need to gen up on the new regs as I haven't done a job under them yet. Even the one that we're on now is under the old regs. The rule of thumb that the building inspector told us is that you need to increase the insulation by 25%. Obviously meaning that were you would have normally put 100mm in that now needs to be 125mm. Now how you do that can be open to interpretation and will need discussing with your building inspector because I'm theory you still have the full filled 100mm and have an insulating plasterboard internally, or if a certain U value needs to be achieved maybe they would let you put more insulation in one part of a build where there's room and less in another tight spot. Lofts are going to throw up all sorts of issues I fear and I think that jobs will have to be assessed on a case by case basis. Sorry not to have been more helpful. Hope all goes well for you mate, let us know what they say.
@@mrabuilders6723 Hi mate thanks for the reply! I've done the U value calculations and it's only just within the 0.16 needed. It seems mental to me having it this strict on retrofits, my rafters are only 70-80mm so need extending to start with lol and I can't lose too much space. Luckily my tiles have no membrane underneath so no air gap is required but I will be leaving 10-20mm anyway just to be safe.
@@mrabuilders6723 he ended up saying I was fine with 100mm between the rafters and 25mm PIR underneath. That doesn’t hit 0.16 U value when I do the calculations but I’m not going to argue 😂
Hi a little off topic but I was wondering if you could help. I'm starting to renovate my loft for a basic play/storage room. I have 100mm deep timbers/rafters. Cost wise I can't afford pir foil backed insulation so was thinking rockwool or cavity batts. My main question is do you still need the 50mm air gap between the roof tiles and the insulation if its the more breathable cavity batts? I'd like to use the full 100mm depth for insulation. hope you can give some constructive advice, cheers
Peter, I'm not a builder but have done work with Rockwool before. I needed 140mm of Rockwool batts plus a multifoil layer to achieve the existing (at the 2014 regs). So you can see, you'll need a hefty depth now to achieve the new requirements.
I had to comment regarding the electrical wiring. Why did the electrician tack the clips to the OSB boards. He should of cut a spade bit through the ceiling joints. To run the cables through. A i know what you are thinking right now so my method is better because if the roof ever fails then someone else and the OSB boards are rotten then when they pull up the boards to change them then they will pull the mains wire's with it. Just a thought good job all in all kind regards David
Just an observation. The cut out won’t be a perfect fit if it isn’t a perfect square because you are installing it in reverse as u can see you struggle on the video 😀
Hello Paul, yeah to avoid the reverse situation you need to cut the bottom 25mm off and move it up, not the top bit and flip it over. Sorry mate, should have made that a bit clearer.
Morning TheeThee, hope you're well. As far as I'm aware the jury is still out on spray insulation, not sure though. It definitely won't work if you're trying to achieve a cold roof.