Warm roof insulation fixings explained
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- Опубліковано 29 лис 2017
- Warm roof insulation fixings explained.
Insulation fixings for flat roofs have evolved over the years to where we are today, about four years ago glueing down the insulation started to take off, mainly because of two things. The cost of the fixings and the fact that we could not get fixings the correct length.
This video shows some of the problems we have with glueing down flat roof insulation. I show you the new thermally broken fixings for warm flat roofs we now prefer to use.
Mechanically fixing down the insulation to a flat roof is now our preferred method. Flat roof insulation is becoming more and more an issue with badly installed vapour barriers and badly installed insulation. If the insulation on your flat roof is not fun and fixed into position correctly cold bridging could occur and internal sweating may take place. We are seeing more and more poorly installed warm and cold flat roofs and the cost of putting right the bad workmanship is expensive. Trying to vent a new flat roof that hasn't been vented correctly is very difficult and normally we have to strip the roof completely and start again.
very very informative
Hi Steve. Love the videos. About to begin a roof myself but has a couple of questions. What spacing would you use for the fixings in your video ? How much expansion would you allow for in the bottom and upper deck? Thanks in advance
Amazing info! Need a roofer!
Great video. Many thanks for that. Hadn't appreciated about the bounce issue.
Glad it helped
Hi Steve, thanks for such informative videos. I am in the process of constructing a warm roof with only a relatively small thickness of insulation. The fastfix company you mention have suggested that I use their pressure plates instead of the plastic tubes. Will it be all right to put the rubber membrane over these plates? Working down I assume the roof build up to be .....EPDM membrane/ Pressure plates and screws into top layer of OSB / PIR insulation / vapour barrier/ bottom layer of OSB / roofing joists. Does that make sense? Thank once again
Hi Steve, really useful video. I'm replacing a badly constructed Warm roof Pitched Shingle Roof on a log cabin with EPDM. Had to strip back all the layers of the roof including the insulation which was soaked. The insulation will be 50mm with 9mm OSB, would you still use the fixings suggested. The Rubber4roof fixings look to long - Any advice greatfully rec'd.
Hi Steve, Once again very helpful video on warm roof fixings.
I am planning to upgrade my existing flat roof to warm roof . The current roof looks like its cold roof. It has particle board with felt on the top with insulation between joists. My question is that if the particle boards are good then can I just use it as bottom decking (instead of stripping it off)? I am not sure how hard its going to strip off the particle boards from the joist.
Alternarively Is it advisable to put 11mm OSB on top of particle board? So it will be Particle Board (existing) > 11 mm OSB board > VCL > insulation > 18mm OSB board > EPDM. Does it looks ok?
We’ll explained thanks Steve
Great video and thanks for explaining these as I didn’t know these fixings existing. I think this has solved a dilemma I have for an upcoming DIY summerhouse build!
I get them from fix fast .co UK hop that helps
@@SteveRoofer HI Steve great video what size tube washers and screws do you use in this video? I am also using 120mm insulation
Great video, very clear and useful! For a pitched warm roof with height restrictions, should we insulate between the rafters, then a continuous layer of insulation over the rafters, followed by osb using the blue fixings, before finishing with breathable felt and rubberised slate? I dont think you need osb beneath standard composite slate, because you screw batten over the insulation. We basically need a light weight roof and seal edges to prevent rodents getting in. Appreciate your advice. Cheers!
hi steve/everyone - im just putting my first Warm flat roof on lots of question sorry - do you use the alternatives to celo Travis are offering xtratherm ? the roofer im looking at using is talking about 3 layer felt - so im thinking 18mm OSB fixed with 75mm round head galv, insulation (xtratherm 125mm), 18mm wbp ply, alutrix 600, then 3 layer felt - what are your thoughts please ?
What is the best fixing for a warm roof grp to fasten the two boards and the insulation down securely
Does it matter if the screw come through the bottom OSB layer and not hit a joist? Many thanks
Would filling the holes in the thermal fixings be advantageous?. Giving better insulation levels. Perhaps fire some spray foam in them or pushing some rockwool in there. I mean after the screws have fixed it all down
Hi Steve, great videos, they're really helpful when trying to understand the warm roof construction methods. I bought the thermally broken fixings and noticed you have them on top of the OSB above the insulation. I'm planning on having a GRP finish on top of this, would you say it's ok to apply this straight onto the plastic fixings, or would there need to be any prep work, sanding etc? Thanks in advance.
I don't know as I don't do GRP Glass fibre roofs. All I ever do is take up GRP roofs after a year or so as they are not that good for flat roofs so my advice would be DONT USE GRP. All roofers I know are now stopping using it only DIYs and builders who do their own roofs are still using it. The time of GRO rooting has been and has gone. It was a very small existence for it but we will be living with the problems for some years to come.
Hi Steve great videos really helping with my choices for our warm roof , is it reccomened to use a T&G bottom deck or would we be ok with a 11mm osb bottom deck, 120mm Insulation then 18mm T&G top deck, I take it you just need to pilot the top deck to allow the fixing to pass through, or could we lose the top deck and fix the edpm direct to the insulation as seen this in other installs? thanks Trev
yes you can use 11mm bottom deck as its only supporting the VCL however 19mm T+G is better and better to get the screws to go into from above or you will have to hit the joists yes pilot hole the fixings
Hi Steve. What vapour membrane are you using underneath? Does the membrane maintain its functionality despite screwing through it?
Would you then fill the plastic tube with expanding foam??
When you screw the layers down, how do you preserve the integrity of the vapour barrier. Also what do you seal the vapour barrier with to a wall. Thanks in advance.
If you use the vapour barrier we use alutrix 600 Self seals when screwed through. It's also sticky back so providing the wall is smooth and no dust it will stick directly to it or you can prime it we don't use much primer as we use mechanical fixings to screw down choice is yours
Hi, how many screws per sheet of insulation would you use? I'm doing a flat roof soon with Resitrix, 130mm insulation and Alutrix. The architect doesn't want another layer of plywood on top on the insulation before the Resitrix. Thank you.
Steve, thanks for your informative videos. With the thermally insulated fixings as shown in the video (on top of the OSB), is it ok to apply EPDM over the top even with the slight bump of the top of the fixing? Thanks in advance!
Yes it is it actually doesn't look that bad but I like this method much better than putting a timber deck over the top of the installation and then trying to scrape down the reason I like it is because you've got no wood in the build up you've got vapour barrier then insulation then your roofing material nothing to go wrong
@@SteveRoofer so the warm roof would be composed of a decking board (osb), vapour barrier, PIR insulation screwed through to the joists using the thermally broken fixings then the epdm? Will that be strong enough to walk on? I can see my heel going through and puncturing the rubber. I've just got planning permission for my 2.7m high garden room so I am watching your videos with interest.
What do you do if its a concrete base?
Hi Steve. Fantastic help and videos. Im building a play house for my daughter, but I can't seem to find these fixings. Would you advise where these are available please?
I get my fixings from www.fixfast.com/surefast-product-selector, however, rubber4roofs.co.uk and SIG also supply some although I think not as good as the ones I use from fixfast
Steve Roofer Thank you very much for your reply and help.
Hi - Great video thanks. Does it not matter the screws puncture the vapour barrier?
I read in another post that if you apply a self adhesive vapour barrier to the bottom layer of osb, then it should be self sealing, and seal itself around the screw
Hi Steve, very informative video. I would like to send you a photo of my flat roof installed a couple of years ago. the builders did not use the blue fixings for the screws. When frosty, the cold bridging is evident through the screw fixings. Is this something to live with or is it going to be a problem further down the line? let me know many thanks
Yes please send the photos regarding the fixings. However, you can't change them now. Will it be a problem? Possibly I see thermal bridging through fixings all the time when it's frosty. If they've used a standard screw then the interstitial condensation. This is the moisture that can form around the screw, can rot the screw away quite quickly. All fixings for flat roofs should be specially treated for external use, and unfortunately, most screws or nails used do not come up to the correct standard
Really great info!! Thanks.
By the way is mineral felt still the best option for flat roofs? The weather is a bit treacherous up here in the north....
I've got nothing against mineral felt the new high tensile mineral felt is really good. You just need to make sure like everything that the person installing it knows what they are doing and then you will not have a problem for a long time with Felt.
are sips panels any good instead of this method? I know they are more expensive
Hi Steve
Thanks for the great informative videos.
Just wondering what product you use when you do stick down the insulation or boards...?
So many products out there
Thanks
I use firmly broken fixings I don't use glue anymore as this can fail
@@SteveRoofer thank steve
But I have a slight 5 degree pitch so I was asking as I was planning on using a little foam stick to hold the insulation on the vapour barrier before i fix the tip deck down with broken fixings
Thanks
Great video - have you any concerns on the long screws penetrating the vapour barrier - does that not render the vapour barrier useless & porous… I only ask as I just saw it done on my own house last week 😅
No, if you get the roof airtight with the vapour barrier by the time you put the screws through it, the leakage is so minimal that it's just not a problem
Hi Steve. Do you need to mechanical fix through all the layers below the EPDM. I will be putting ply then Vcl, glued to insulation. The osb glued to insulation. On top of the osb it will be Epdm. Do I need to screw, nail or can it be left?
We always fix with thermally broken fixings we get from fixfast .com
@@SteveRoofer thanks Steve. Your videos have been really helpful. We really appreciate it👍
Hi Steve I decided that my warm roof is going to finish too high so going for a cold roof instead. I've got to the vapour barrier stage self adhesive with a coat of primer over 18mm OSB. Could I lay 11mm OSB over the top of this or will it trap moisture? Thanks
you dont use sticky back Air Vapour Control Layer (AVCL) on a cold roof you use plastic on the underside of the joists
Hi Steve. I can see you thave screwed throught the vapour barrier. Doesn't that defeat the whole purpose of having it in the first place? Or are you going to say that the number of punctures has minimal effect?
In the next week or maybe two I will be doing a video showing you how to fit the vapour barrier correctly because your point is very valid and although everybody fixes through it and then that does downgrade it it's not the correct way of doing it
Hi Steve, is it necessary to have the lower deck under the Insulation for a smaller project? I've built a small garden Room with no requirement for roof access, and I have achieved a warm roof my laying the PIR direct onto the joists below, and then laying a sheet of OSB on the top, followed by a glue down EPDM membrane. Is this an adequate system? Do I need an additional vapour barrier below the joists? Many thanks
You have one Air Vapour Control Layer (AVCL) in a roof or a wall and thats just under the warm side of any insulation.
@@SteveRoofer Hi Steve, in an instance where the PIR, deck and covering have already been mostly installed (not too late to fix), is it possible to retrofit the AVCL under the joists, wrapping the AVCL around the warm roof (PIR, Deck) on the exterior, and refixing the covering down ontop of the AVCL?
Didn’t know when I started but I’m worried moisture may migrate between the foil faced insulation sheets if AVCL isn’t used in addition
Many thanks
Hi Steve. Im thinking of going 11mm OSB deck -- alutrix 600 -- 100mm pir -- 120mm pir -- 18mm OSB -- EPDM. If using the thermally broken screws wont they stick up slightly, making the sticking of the EPDM down tricky and each fixing visible through the EPDM. Is there a sollution to this?
No the fixings don't really show through the EPDM they certainly don't make any difference to fixing it we get ours from fix fast.com
@@SteveRoofer thanks. That's very helpful
hi, if you install a Vapour Barrier covering on to the existing roof joist covering such as 18mm weatherproof ply, then install the 100mm insulation ad fix using the tubular fixing at say 300mm spacings, could you then install 18mm osb3 over and screw using say 200mm galvanised fixing and still prevent thermal bridging. the reason for using tubular fixing is to ensure the roof covering such as grp or EPDM does not mould over the tubular fixing and thus achieve a clean flat surface appearance.
No as the metal fixing will have one end in the cold and one end in the warm thus thermally bridging. But I like your the way you are thinking about this we use OSB3 T+G over the top and the tops of the fixings show. We are thinking of trying to countersink the top a bit to stop this. however it may prove to much work for something that only you and I notice!
Many thanks for you prompt reply, I have been looking for warm deck roof fixing and saw long stainless steel twisted nails from Twist Fix claiming to reduce cold bridging by 80%. Do you think there's any truth in this?
Metal conducts more than plastic
Chandresh Varsani stainless steel doesn’t transfer heat very well at all
Hi Steve, are you still available to quote for flat roofs? I tried to call
Thanks for the video Steve, like many ill be using EPDM over the top deck and am slightly concerned over the bump these washers will show through the EPDM.
Would you recommend using something like a Fortsner bit to make a shallow countersink hole in the top deck OSB so the fixfast washer will sit flush?
No as they hards show
Hi Steve, would you just glue epdm down over the insulation tube washers shown in this video?
When doing a warm flat roof I like to screw down the insolation because I can trust that better then I can trust glue the problem with glueing down insolation over the top of silver-based vapour control is making sure that it sticks. If it doesn't steak then you have a problem so in my experience whenever possible always screw down
I have some of these tube washers coming along with the insulation and osb. My worry is that the EPDM maybe not lay flat and adhere properly to the tube washers? They will protrude just a little from the osb?
@@marksparrow474 That's not a problem. we dent to use the thermally broken fixing from fixfast with the big head as the edges of the top feather down to nothing leaving a nice hump
@@SteveRoofer excellent thanks for the reply! I'll screw it all down like you have shown in the video and then glue the epdm down on top.
Thanks again
Is it worth putting a bit of low expanding foam into the fixing on top of the screw? Seems to be a void that could be insulated?
You could do no harm in it however it's a such a small misdemeanour compared with some of the massive problems we see
@@SteveRoofer Maybe there is a business opportunity selling tube fixings with screws and pir inserts to be marketed as fully thermal fixings :-D
maybe
What I found that manufacturers advise 12 fixings per 2.4/1.2m sheet and depth of stress plate around 15-20mm less than total roof buildup and screw penetration into wood 30-40mm. For 150mm + 18mm osb buildup I need 145-150mm stress plate (plastic part) and 70-80mm screws...
I think a sensible approach is what's needed. This is why we use plastic fittings more than metal plates and metal screws so there is no thermal loss. Also we put in as many fixings as we think necessary. We always double up when we go around the edges to stop wind uplift.
Problem is when u screw the boreds down on too the insulation in to the joist ur pitting holes in to the vapour barrier suppose theres no way round it tho really
is the final board needed? can i add just the final covering over the insulation?
No, it's not necessary it just means that it's a little bit softer on the top. Personally I like that because there is no timber in the upper structure and therefore nothing to go wrong or to rot.
@@SteveRoofer im a bit afraid of damaging poliurerane boards when walking on top of the epdm by the pressure of the poliurerane boards over the wood boards
Steve, i presume screwing through the vapour barrier isnt an issue here as its going into rafters?
No just make suer the Air Vapour Control Layer (AVCL) is taped and sealed on all edges and air tight as posable
Hi Steve, what spacing do you use for these fixings? Is 9 or 11mm OSB ok for the top deck layer. I have used 18 on the bottom. Cheers.
18 mill T+G for the top and 300mm to edges 400 to 500 in the middle
@@SteveRoofer is t+g essential or or just ideal? Tough to get hold of where I am. Cheers.
@@tigergor I think is essential as it holds the edges to gether if you dot have T+G then yu will get movement at the joints
The warm deck roof construction on our new extension will consist of:
Upper Deck (18mm Ply)
120mm Kingspan
Vapour Barrier (resitrix alutrix 600)
Sub/Lower Deck (18mm Ply)
Joists
Plasterboard
We were going to these plastic tube fixings in the same way as in this video.
I'm wondering if we can use these plastic tube fixes if we are using torch on felt for the final roof covering. Is there a way to protect them from melting under the heat? Will they be fine just as they are or is there something we could cover them with to protect them whilst the felt is being applied?
One other concern is the gap these tube fixes leave within the insulation once inserted and screwed down. Should we fill that gap with something to prevent condensation building up, if so, what can we use for that?
If I use metal fixings that won't leave any gap, is thermall bridging something to worry about, especially if the fixes are only applied to the joists and not the lower/sub deck which is plywood?
Thanks
I don't know about the heat but I think it will be OK just go quickly over them. as regards the hole they leave its absolutely minimal
That’s great if you want to pierce 500 holes in the vapour control layer you’ve just spent a day installing. 🤷♂️
He uses a self adhesive vapour barrier called alutrix 600.
Once you screw through it, it seals round the fixing .
It’s expensive stuff but really good .
No it doesn’t . I use it and it also causes a cold bridge.
@@paulnewell5329how
Great video Steve. I'm looking to install a warm roof above felt using long fixings similar to the blue one you show in the video. I'm planning on laying EPDM onto of the OSB and I assume you end up with little 'domes' at each of the fixings or is there a way to countersink them to avoid that?
they are so small you won't notice them just go over them with the EPDM if you cant find a photo of me doining it on the net then email me and I will send one to you info@londonflatroofing.co.uk
Hi Steve, great informative vids, I'm doing a place for myself which is a bit unusual as I'm matching an existing barn on the land and will end up with a corrugated sheet finish on a mono pitched roof, Before I get an architect I'm thinking about how to do the roof, After watching your channel I'm thinking a warm roof like this, once OSB is on, then breathable membrane and the corrugated sheets on, can I ask you for your thoughts on this please?
First I find that the info from architects is not always reliable I'm on my second project this year that the architect has admitted getting wrong and are paying towards putting thing wright. So my advise is research as best you can. Sounds to me that you are nearly at the level of an industrial type roof so a SIPS panel with the tin roof already attached may be the way to go. Most of the suppliers of these things have already worked out that the products work together unlike the architect that think they work together.
@@SteveRoofer Thanks for quick reply Steve, yes I had considered a SIPS , only I couldn't find one which would match the barns corrugated sheet finish , that's why i was thinking of doing it the way I suggested , thanks for advice on Architect, I'll keep researching , thanks for your time
@@MultiNonserviamconstructs out of SIPS panels then suspend corrugated sheeting over making sure you venting top and bottom. An excellent method as you keep the first attack of the cold out in the winter and also keep the heat out in the summer, Sun heats the panels, air under moves up and out excellent
if you have the time this guy is total on the ball about this ua-cam.com/video/rkfAcWpOYAA/v-deo.html im not sure if this is the best of his videos but there are two or three that really explain the problems you may have they are long but well worth watching
@@SteveRoofer Cheers Steve, great advice as usual, really appreciate it, I'll check out them vids, thanks again