How to properly install Insulation to a pitched roof

[@therabman_5606]

The amount of damp/mould jobs I have been to because insulation hasn’t been installed correctly is crazy! top video as always robin 👍🏻

[@ukconstruction]

Thanks 👍

[@davidbruce5377]

I've seen moulding buildings too. If you seal off the exterior with rigid foam - that means your building must dry from the inside. In colder NA climates, you can't dry to the inside because the inside walls are poly rolled. Rockwool on the exterior is my go to.

[@415volts]

My neighbour about 6 years ago insulated his loft with polystyrene balls - every time we have have strong winds there are hundreds of the f**kers blown all over our backgarden.... I now have a magpie digging up my lawn every day to find them like it's a game. Good vid on how to do it properly. Thx

[@skiiddy]

😂😂😂

[@therabman_5606]

@@415volts 😂, there’s a few estates I used to work in had them in the cavity everytime you replaced windows or the front or back door frames they would blow all over the street when you’d rip the old ones out! They are a nightmare.

[@markrainford1219]

Ventilated soffits and polystyrene balls don't mix. 😆

[@gr0wler147]

Lord if only all contractors were like you

[@stevetillman6921]

Such excellent detailing and precision. We had our extension roof retiled recently. When it was done first time the electrician had pushed all the insulation away from his inserted ceiling lights to avoid overheating them. So we had massive cold spots. Unfortunately it’s still not perfect.

[@stewartmcardle8149]

Tha's (you're) working to your own specific system Robin....frugal, common sense ecological way of working! Hats off to you. PS..who said the subject of maths wasn't practical 😂

[@mergrew0110]

As a customer, your videos give a good reason for why these jobs aren’t cheap. Assuming of course the contractor is reliable. This is the part of the iceberg you don’t see, once it’s all finished all this detail is hidden. For us customers so much is riding on trust. Sadly, not all contractors are equal. I watched a crew do a loft conversion on a neighbor’s house, every time the gaffer left site the laborers downed tools, out came the phones and they lit up. Being up on the scaffolding they were able to see when the gaffer returned and, without fail, pretended to be working!

[@briantwigley]

Brilliant work as always. It’s great to see someone taking the dust so seriously. And cutting down on waste. Rarely seen, well done

[@ukconstruction]

Thank you Brian

[@paulfinnonjoinery]

ive been on jobs where theres been that many gaps in the pir it may aswell not have been there. Last insulation job i used pir on was a floor on an extension at a friends house. i bought the festool saw and it was such a worthwile buy.. I didnt use gapotape on it but id spent a bit time making sure every single bay was the same size so i could batch cut it all and i ended up with hardly any waste at all and each piece was a really nice sliding fit. Id be watching a few of your videos again if i had a roof to do there is a lot to learn to do this sort of job properly and not waste the customers money

[@DIYLONDON]

Another day at school, except I watched from an airport lounge heading home ! A part of my ground floor extension is always cold, freezing! I have to reveal soon, maybe poor insulation, I’ll be definitely using your method of cutting rob! ❤cheers for another great lesson 👍

[@nickdemetriades335]

Robin- great to meet you at the screwfix live event yesterday. Thanks for your time and sharing some stories too on how you started out. Take care

[@ukconstruction]

Hi Nick, it was good meeting you too, thanks for coming to my stage chat with Clive Holland!!

[@over-engineered]

I doubt there are many people in the building trade with patience enough to do what you do!

[@northeastcorals]

I'd say zero in my area, I'm always a nosey parker when I see building works going on & I've never seen it done to a standard I'd be happy with hence why I do everything my self. To be fair if a builder has to add around 4k to his price just for the extra man hours alone required to do the PIR properly (plus the use of Gapotape or copious amounts of foam etc) I bet most customers would opt for a cheaper builders quote, especially up here in the north vs more affluent areas.

[@simonthompson15]

Thanks for amazing video. What do you do if you have a cable running down the middle, how much of a gap around the cable is required to stop It from potentially over heating

[@SD43]

Robin will be on the Top Table at the Gap O Tape Christmas Doo🤞

[@richardgatehouse1520]

Great video Robin, just insulating a loft conversion so an interesting watch.Hope the angle attachment for the Festool comes good

[@ukconstruction]

You and me both!

[@ewanbruce7026]

Intrigued by the amount of framing timber (?) behind you on the end wall while you're talking at the 21 minute point. Looks like up to 5 pieces of timber thick at some points! Is that in preparation for a window opening? Great, informative video as ever. I have just finished doing my loft room - with many compound angles and scarcely a common spacing!! First and last time 🤣

[@moomastico]

Hi robin great video as always. Have you ever worked with wood fibre insulation ? It’s a dream to work with compared to pir or rock wool and it’s a green option. It doesn’t quite have the same insulation value as pir but it manages moisture better. It looks like they’re building a factory to produce it in the uk now and kingspan has just bought out one of the major producers ( steico ). I’d be really interested to see how you approached a job using that stuff anyway 👍🏻

[@tlangdon12]

Wood fibre insulation has some particular advantages over foam products, such as its breathability and thermal mass, that make it especially suitable for installing between joists, studs and rafters, but it isn't a good an insulation as the best foam products, so for insulation on top of the rafters on warm roofs, foam products will remain the best choice.

[@moomastico]

@@tlangdon12 good points mr Langdon I think that there is more to insulation than just it’s U value however. Given that we’re moving into extremes of temperature wood fibre helps keep buildings cooler in summer and is a carbon store rather than producing carbon during production.

[@jonfenwick6200]

I've used it. I used it over some cork based plaster applied prior, but it's Another tricky material to get used to cutting. I used a hand saw in the end. But great stuff to work with.

[@marcustait79]

@@moomasticoit’s seldom discussed that PIR performance deteriorates over time too as the material offgasses. Woodfibre remains inert

[@NickLaslett]

@@marcustait79 This is meant to be built into spec, so the U-value quoted is the performance after off-gas, but I am a little sceptical. I’d also read that if PIR gets wet its performance is degraded permanently, not sure if this is true.

[@ramhomes9074]

Great video robin, buy yourself the blue tooth on/off switch for the festool hoover. Thank me later!!

[@riptiz]

I’m not a builder but I’ve used gapotape, only problem is if the trusses aren’t parallel. I did a bedroom ceiling for my stepson and his mate put the electrical cable low down and it’s difficult to get the gapotape in those circumstances.

[@JurassicJungle]

We had this on our build with a drift of as much as 2cm along the lenght of a board, we were able to cut the sheets to fit with Gapotape but it ws harder work than it needed to be. We also saw that issue with a few cables so made sure we fitted them higher, a lot less risk of a screw finding them later that way.

[@riptiz]

@@JurassicJungle unfortunately I was following someone else so I had to make do, I also had a steel beam at the top of the gable to insulate for cold bridging. Cables were a nightmare.

[@bdizzle7633]

Amazing work robin no one can say different.. if I priced my Lofty’s allowing to do all this I fear I’d never get any jobs it’s bad enough being undercut and moaned at as it is.!!!

[@ukconstruction]

I hear you!! Yes especially in the domestic Loft Conversion market there is stiff competition and some of the work I see from viewers that send me footage and images of poor and dangerous workmanship is chronic!!! What you could do is this... Explain to future clients that you are happy to deliver a "typical standard Loft Conversion" but then you could offer a better built and insulated shell as an up-sell, I find when my clients are given the choice they are most likely to go for a more superior job

[@bdizzle7633]

@@ukconstruction that’s a great point robin Thankyou for taking the time to offer advice.👍🏻

[@garyhollywell2112]

Brilliant Robin as ever thank you

[@allanbeckett1537]

Awesome video. Insulation badly installed causes all sorts of damp and cold bridging problems. Would you use mineral wool over PIR?

[@dougieranger]

Looking forward to seeing what 3D printing can do to help you Robin. There’s a channel called CAV Joinery and he designs lots of 3D printed objects to help with his kitchen projects. 👍🏼

[@riptiz]

What membrane do you recommend over the Celotex if at all?

[@zakkychan123]

Another great video Robin! Would you still need to aluminum foil tape over two boards butted against eachother that have already been gapotaped to form a continuous air tight layer from below? I'm seeing the £ skyrocketing!

[@scotland2256]

I’ll buy that jig mate and insulation saw if you get a decent one set up 100% I spend most of my waking life installing pir board/kingspan. Never bothered with an insulation saw though as they only cut square which is no use for me

[@scotland2256]

Fantastic work btw 👍

[@donderjager4770]

Good vid as always Robin. Was wondering how you determine the angles in the valley? They are spot on. Is it some simple math or is the setting up trial and error?

[@keithwiddows2391]

450mm centers on the rafters. Is that you specifying to the truss manufacturer to get maximum use from sheets of pir or have you adjusted those to that dimension off your own back so to speak? Nice clean work

[@ukconstruction]

That is what we specify to get the best fro the PIR as you say, also we use a 2.7m plasterboard

[@Stewart_Bell]

I am curious about the techniques you're using here Robin. The jigs and guides appear to be less elaborate than those you used on the big build. I'm wondering if this is plenty good enough whereas previous was overkill, or perhaps this is something 'prototypey' for the saw base development. I will say that the cuts certainly do look spot on despite being rather more freehand. What a great tool too.

[@ukconstruction]

Hi Stewart, we had a lot more repeat sized cuts on the Big Build so the flat table jigs worked a treat, I always have used smaller devices fitted to the ISC240 base and the free hand cutting is spot on, the large riving knife on the tool helps too!!

[@LukeLarder-n1w]

Hi robin i have a similar self build, i am considering purchasing the isc240 festool, in your experience is this the best tool on the market or have you had any success with any other tools,it is a job i have been putting off

[@bikerchrisukk]

Start as you mean to go and get the awkward cuts out the way first eh Robin 👍

[@ukconstruction]

First rule!!!

[@danthechippie4439]

Hi Robin, thank you for posting that video. Can I ask in regards to the outside installation, do you fix directly onto the rafters or do you put a membrane on first? Also how do you fix the installation to the rafter or do you simply screw through the batton _ through the installation and into the rafter? Thank you

[@ukconstruction]

Hi Dan check out my KZbin channel for the warm roof video that I have recently posted and its all on there, hope it helps mate

[@danthechippie4439]

Will do Robin, thank you

[@nigel8247]

Where’s Ed?having his tool belt removed? Great content as usual..

[@Bouche88]

Just curious, In a standard warm flat roof there would be an air/vapour barrier beneath the insulation adhered to the deck, in this instance is the foil from the insulation providing this control layer? Also, thanks for all the informative videos I reckon the editing takes ages but it is truly appreciated

[@tlangdon12]

No, in a warm flat roof, the vapour barrier is needed because the weatherproof layer of the flat roof is bonded to the structure such that there is a very significant risk of any water vapour that passes from inside the building to the insulation layer getting trapped there - it can't get out through the weatherproof layer. In a warm pitched roof the insulation isn't covered by a completely weatherproof layer, it is covered by counterbattens and battens that provide a vapour-open layer beneath the final covering (tiles/slates).

[@ukconstruction]

top of my class!!!

[@jonfenwick6200]

I have all the confidence in you mate, so I know the outcome of this scenario, but...... I'd really love to see you do exactly this job, but in a really old , wonky house... A 49 degree cut is lovely, but I work in all the above mentioned houses, and as I'm sure you know, 49 degree cuts are there in any given roof structure, but so are every other degree in the same roof! Haha. Anyway, Any helpful tips on doing this kind of thing where the whole house is £ucked , would be really really helpful pal. Cheers. Love this video but the way. Jon

[@ukconstruction]

Hi Jon, There is a technique that I adopt for out of parallel roof rafters etc, next time I do it I will shoot a video!!

[@brianbostock1698]

Planned to perfection, as usual. clever idea on the saw.

[@leeedwards3783]

Very neat.

[@martinclemmensen8071]

You are officially Britons best carpenter, if not the worlds. Your quality is above regulations and above all others. Your attention to detail is astonishing. Love your work. Love your channel. I got introduced to you through Skill Builder channel 4-5 years ago and i have followed you since. Say hi to Roger.

[@ukconstruction]

Thats really Kind, I will say hi to Roger for you, there are many many amazing carpenters and joiners around and I know quite a few, I am just fortunate to have a platform to share knowledge such as KZbin!!

[@andrewmacdonald1897]

Britain's best carpenter

[@martinclemmensen8071]

@@andrewmacdonald1897 Are you commenting on my language capabilities?

[@andrewmacdonald1897]

​No, just being a knob......sorry😂😂

[@theetheeyog9878]

Out of curiosity since you have a warm roof why don't you spray forum with closed cell on the inside

[@Sjf542]

With the way Gappotape expands, does it not create soft rounded edges to the corners of the PIR sheets? Specifically the transition between the long edge and the short edge of the PIR. Doesn’t this prevent the sheet from getting tight into each corner?

[@ukconstruction]

You can run the tape over the corner by the thickness of itself to mitigate against this

[@Sjf542]

@@ukconstruction thanks Robin, makes sense. Thought there’d be a way, just couldn’t visualise it in my head!

[@eddjordan2399]

do you ever worry about pir off gasing?

[@JurassicJungle]

Great job Robin, I so wish more trades worked like you. I have recently removed all of the insulation my builder installed and refitted it again using the Festool saw and Gapotape as i didn't tell him I wanted a Rolls Royce job, what we got was not even Skoda. None of the timber spacings were the same and they drifted so much from one end to the other over 3.5m it was very hard work. I see you only have one dust extractor as we did, I think it justifies having a second one on site to clean the cuts after they are cut. We struggled with PIR boards being very curved, is there a way to get around that? Also at what point would you add a VCL?

[@bobjit252]

Would you be prepared to pay the prices though

[@JurassicJungle]

@@bobjit252 With hindsight it would be good to have the choice, we struggled to get builders to even want to quote for our project and it came down to a choice of 2. One of them messed up the quote so badly that we had no confidence at all in what was included and the other one seemed OK and had good references. It has taken a great deal of time and cost to correct and finish works so I think it would have been much better to have worked with a higher quality builder in the first place.

[@bobjit252]

@@JurassicJungle that’s nice to hear , it’s a shame that there isn’t more like you , on the plus side to you tube these guys who make the time to do these videos they really do deserve there recognition

[@michaelsteele9782]

Well this job for Jones brother 😮.36 years Robbie long time ago .recall ur first car a ford Capri 😮

[@ukconstruction]

Hi Michael!!!! yep Gold mark 2 Capri!!!! How you doing???

[@michaelsteele9782]

Ok house prices have got through the roof in Oz and a loft conversion would take off .

[@elendil354]

If that tape is aluminium, wont that create very efficient heat transfer at every edge? Perhaps its so thin that the combined surface area of cold bridges is still small. But It just seems that 1-2 cm strips of firm mineral wool at the edges might be better?

[@northeastcorals]

Interesting question.

[@ukconstruction]

The mineral wool may just roll up as you try to fit a closely fitting panel of insulation to the rafters, not sure about the heat transfer through the tape??

[@elendil354]

@@ukconstruction Probably the PIR is so efficient that any additional bridge created by the aluminium is more than made up for. It just seems to go against first principles to have metal spanning the entire insulation distance from hottest to coldest side.

[@Hundredthldiot]

What's the total list price of the tape used on this job?

[@Swwils]

@@Hundredthldiot £2,800

[@northeastcorals]

@@stewartstewartstewart You reckon? Last time I looked the stuff was around £2 per metre, so if it's still the same priced be amazed if it came in under a grand for a complicated roof like that with dormers etc. I remember pricing up the stuff for my little simple up & over cottage roof & it was well over £500, which was as much as the actual 150mm PIR boards that I was fitting.

[@liamleech6844]

@@stewartstewartstewartmore like a few thousand

[@bobjit252]

This is the problem , general public watches these you tube celebrities and expects the same job done in there extensions etc but doesn’t want to pay the ridiculous prices for the tapes etc

[@northeastcorals]

@@liamleech6844 Thats what I was guestimating, especially if they use it in the vertical walls as well

[@yolomc2]

this roof is too beautiful to be hidden y'all , is it possible to just put timber over the PIR and leave it as it is ?

[@NoItAllLiveStreams]

We use super foils now, Easier to install no waste & better R value

[@declandoolin4356]

Declan Doolan from westmeath ireland It's good idea bring to construction site

[@deejay-su7uf]

I moved to the tropics to eliminate these expensive problems.

[@RichieRich845]

👍

[@stevenwest3555]

Like and share

[@tombeever6309]

Will the UK ever move towards woodfibre insulation? Way better for the enviroment and its vapour permeable

[@gordonmackenzie4512]

Regulations are not UK wide. Maybe you are thinking of England 🏴󠁧󠁢󠁥󠁮󠁧󠁿 ? From January 2025 Scotland will be full “ Passive House “ regulations. I always note on these videos that English roofs are not solid and strong. In Scotland they must, by law, be sheeted in ply or OSB prior to felt or membrane, then counter and tile baton. This has always been the case, due to 2 feet snow load regulations.

[@ukconstruction]

Possibly.... It will be price driven in the main.. Also the build up required to meet regs can also be a problem

[@davidallinson7837]

Where's ed gone

[@S-Theo]

your RC logo is out of proportion . The letter C is too thin in comparison to R

[@markrainford1219]

Hate the job. Joinery skills definitely required to do it properly+efficiently.

[@ukconstruction]

Yes Mark agree about Joinery skills needed!!

[@Lyonscarpentry]

£400 jigsaw without a base that bevels…

[@tlangdon12]

Robin's attachment will have a ready market with all the early adopters of the Festool ISC 240.

[@Lyonscarpentry]

@@tlangdon12 you’d expect it to bevel on its own, not buy another jig for it

[@tlangdon12]

@@Lyonscarpentry It will when Festool figure it out.

[@danielmurphy1034]

I’ve done a roof like this , without the tape but with the Festool saw. I work on my own a lot and this is just soul destroying in terms of labour involved. To be fair we used 150 mm thick between rafters with cold roof situation. In future I’d avoid 150 as it’s much more difficult to work with. I’m hoping I never have to use it again, definitely interested in alternative insulation system for this type of roof.

[@danielmurphy1034]

Thanks for the nice tips and tricks , I hope I never have to use them , maybe I need an apprentice 😂

[@Anglo-Saxon4231]

The Makita 250mm circular runs on the track saw guide rails and bevels. Just saying. Does 100mm insulation and timber. Way better than that over priced festool turkey carver.

[@ukconstruction]

Does the Makita saw cut that deep???? I have tried the 250mm XGT it was 95mm at 90 degrees and 70mm at 45 degrees, and on the rail its 6mm less, this would mean finishing by hand??

[@samuelmellars7855]

For added depth there are some attachments that turn circular saws into chainsaw hybrid abominations However, I don't know what brands have that option, or if it only exists as a third-party retrofit job.