How to Install GRP on Flat Roofing (Fibreglass)

We get the OSB and vapour barrier on the warm deck ready for the GRP roof.
Thanks to the guys at Gee GRP: www.gee-grpfib...
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GRP Fibreglass Roofing
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[@ashleyrowe2681]

Regarding the advice on what the roofers want, i always leave the finishing bits for them to tell me what they want, ie over hang to gutter, whether they want anything around the roof lantern etc etc. Each roof finish and installer likes a few different things............as long as we get the required guarantee all is well. Great vid

[@wbroofing0151]

I've never done or seen a grp roof done without using trims

[@northeastcorals]

Yeh & I'd presume the bit at 5:27 where they are applying the top coat to the glass on the vertical brick wall, it'll need a flashing trim putting into the wall afterwards?

[@stuartweatherburn8809]

@@northeastcorals 100% it will

[@davebatman847]

This hurts my eyes, i would say this is a substandard grp installation, wet laying straight onto brick, were they primed with g4 prior? Also the the grp trims should have been used at wall abutments , there needs to be a 25 mm gap with the boards for expansion and contraction. If the subbies just butted 8x4 sheets together then thats wrong also, 3mm expansion gap and joints taped with grp bandage which i didnt see had been installed, just looks like they screwed the boards on and went straight down with the csm. I wont say anything about the finish. This isnt how i would have installed this roof because it isnt correct in my experience or personal preference. With grp 90 % is in the preparation, glassing is the easy part

[@RobNorman08]

Clearly knowledgeable comment! , couldn't agree more with what you said, spot on.

[@somalia5019]

New subscribed from Somalia

[@SunnyLotay]

Why has a consolidating roller not been used on the laminate, all GRP’s use one to take the air bubbles out and consolidate the matting Into the resin.

[@samtemple3182]

This Video should be taken down. It’s not very helpful for customers or guys wanting to learn GRP systems. They haven’t used fibre glass trims. The internal and external corners will definitely crack. They have applied it directly to brick without PU adhesive or a primer. Absolute bodge job! Also tongue and groove osb3 boards should always be used…

[@thomassheridan4252]

Very surprised with you ,all your work is off an extremely high quality, these lads not even close.they did not bandage joints or use tape before .should be 2 to 3 millimetre gap between 8 x 4 sheets never ever butted whole roof will expand and crack and sound like a dripping tap.they only rolled over fiberglass never used a consolidation roller will be air underneath topcoat.no proper trims used cheap and shoddy job very very surprised 😮

[@SkillBuilder]

To be fair the GRP guys were recommended by a local buildng firm who use them all the time. You kind of assume they know their stuff. If it leaks we will not keep it secret.

[@buildingperfectiongrouty8767]

I agree with the points made but I rarely scrim the joints first especially over t and g. 600g matting is more than enough. And a decent topcoat

[@thomassheridan4252]

@@SkillBuilder I love all your videos from day one great work and can see the pride you take ,I wasn't implying about your end of the job👍

[@thomassheridan4252]

@@buildingperfectiongrouty8767 agreed no need over t and g this was osb3 8x 4 .

[@buildingperfectiongrouty8767]

Granted. I saw that. As long as the boards are joining above a joist and well noggingd then id be happy to cover it. Iv never like the look of the scrim showing through the final coat. I always avoid scrim if possible. But obviously if you want it installed to the book then scrim is required to please the manufacturer

[@tk2097]

No expansion gaps between the butt joints!!! 😂 ok! Please go back in 18months to show us all of the puckered joints, most flat roof work I'm doing now is replacing these grp roofs

[@SkillBuilder]

We will keep you posted. The boards are free on two edges for expansion

[@tk2097]

🤞 it's all fine, in my experience a little 10mm gap all the way around is the way to go, especially with GRP as it has no strength on that direction, I've seen these crack many times around puckered joints.

[@andyeveritt9003]

i replace so many as well trouble is all the cowboy roofers can get a roller and knife then can become a flat roofer with fibreglass or buy a gas torch and be a torch on felt roofer

[@MrKanga1231]

Unfortunately OSB3 isn't waterproof as the roofing manufacturers would have you believe. It is a stable board in as much as it doesn't expand in linear direction. If it gets wet it will expand to double its width. I'm sorry to say I think you will have problems on a massive scale with this roof in 4 to 5 years time. The installers did not use the preformed trims as a manufacturer would recommend. At any point there is a differential in movement such an angle, internal or external corners a preformed trim is essential as it will give a degree of flexibility. Generally a 450gm mat is used sometimes 600gm for flat roofing, this will certainly crack if bonded to boards on a 90 degree internal or external corner. Because you have made such a good job of the vapour barrier, it will hold the water under the boards and no one will know the roof is leaking until the whole roof has failed.

[@thomassheridan4252]

Correct excellence observation.

[@andyeveritt9003]

there are so many people who dont know how to use this fibreglass roofing properly the cowboy roofers look at a video buy a roller and knife and there away i rip so many of these off . so any one wanting a fibreglass roof needs to find someone like yourself who knows

[@bruce-le-smith]

love this concept, the 'marine grade' osb, fibreglass, and roll on plastic "paint" look smart. essentially building a light boat hull instead of a traditional roof. I'm sure you could always add more layers and flashing, but when we moved into our place I gave our old 1990s vinyl deck material (over 1970s plywood) a short new lease on life using some of that roll on rubber paint and even that alone was enough. our deck is over the garage and we live in a rainforest, and I haven't seen a spot of water on the plywood between the joists in the garage in 5 years. honestly the humidity inside the garage is probably a bigger risk than the rain on the deck. And I've definitely seen old boats round these parts that are not as well sealed as this Orangery and they're still still floating in the bloody ocean. As long as the owners are good about cleaning and touch ups this should be fine, it's not like they're trying to fly this thing to mars or something.

[@joshuamatheron1]

That’s a good size roof. I personally would’ve put a few expansion joints in it. Also looks a lot cleaner using the appropriate trims. Trims take time so I see why they’re not always used but make for a nicer end result. As long as it doesn’t leak, who cares.

[@SkillBuilder]

The jury is out on this one. More videos to come before this is put to bed

[@stephenadams9767]

well well why hay you glassed on to the brickwork ? that will delaminate. fact just give it time, also why are you not using paddle rollers, they save you time and money, You look like a DIY when it comes to fiberglass, not that im a expert but learn by my mistakes just doing you you boys are doing in this video, sorry for criticising

[@SkillBuilder]

Hi Stephen We had contractors in for this one and this is the way they do it. Judging by the comments it is not the conventional way. If the GRP comes away from the brickwork it still form an upstand and the flashing will prevent water going down the back.

[@stephenadams9767]

@@SkillBuilder understand roger but a crap way trying to glass to brickwork, what i do is buy premade upstand cut them to length then cut that in to the mortar joint glue that to the brickwork, then the lead flashing over the top of that, that way nothing will fail As for paddle rollers i remember my first job glassing it was like a 2 year old done the job, and a mate said what the F is that crap, he gave me a paddle roller never seen one before, and i was glassing like a pro in no time, also another tip always have one man mixing the resin, that way you have it to hand when you need it, and no mess, on a good note i have used your videos for tips many a time, at the age of 60 i still like to learn from anyone even young kids can pass knowledge on,

[@MrFlatroofer]

That is not a warm roof.

[@AJ-ds5gf]

There are so many videos on youtube from manufactures who supply GRP. The youtube channel "fixmyroof" has a great tutorial on it and the manufactures "cure it" have a great series too. It's not something you need a specialist for because it's literally no more complicated then applying a bit of paint on the wall. It looks like these guys didn't leave a 3mm expansion gap between the boards, nor did they tape those expansion joints and I'm sure they didn't use a ribbed metal roller over the resin to remove air pockets and ensure an even coverage of the resin on the laminate.

[@bruce-le-smith]

ribbed metal roller would be good for sure

[@AJ-ds5gf]

@@bruce-le-smith it definitely has other uses... 😉

[@benclarkson4205]

Having done three GRP roofs I wouldn’t for a second butt square edges boards. Any unsupported joints when stood on in the future is a crack risk!! Do that at your own risk!

[@darrenharlow8947]

GRP is not for this country it is to wet.that roof was done wrong 1.no bandaged joints of boards 2. no trim detailing around all up stands including that box gutter and i would of liked to see were the rain water outlet was, and to see how they did that,also when you put your vapour barrier down and taped all those joints so moister can not escape how did you fix the insulation down and the osb over that i would think you used a machanical fixing so you would pierce the vcl hundreds of times and making all the sealing of vcl pointless in my opinion

[@Brown969]

You're right about the GRP faults. I use Alutrix 600 as a VCL and asked the manufacturers the same question about fixings. They said that the VCL is self-sealing and that I should not install and remove screws, that once a screw goes in, it stays in. How do you get around the VCL issue?

[@darrenharlow8947]

@@Brown969 it depends on the specification some times just general visqeen so how would you seal that you can't really

[@Brown969]

@@darrenharlow8947 good point. the visqeen is way cheaper than the Alutrix, but does have its limitations. If you come up with something better I want to be first to buy stock!! 😉

[@alandowling4348]

No wall fillets? First coat not sanded? Experts??? No chance!

[@ericfroment4065]

Didn't know you can fiberglass bricks???

[@freddiepartridge5563]

I did one in my extension and I’m so gutted I did, they’re too noisy with creaking and cracking when it’s gets hot and cold

[@lewishunt5615]

im a felter so not a fibre glass specialist how ever using no trims? Going straight on the brick work? Problem with grp is how often it cracks due to expansion, the grp is going to be most vunerable on the upstands or bends so i only lay the actually matting on the flat generally but each to owns I suppose

[@SkillBuilder]

I think you are right and we will fix it

[@DesperateDan3231]

Looks good. We had some mock lead roles added to ours. They screwed some big wooden dowels (broom handles) on to the OSB then fibre glassed over them. Looks good. They said they also allow for more expansion across the roof and will potentially extend the life of the roof.

[@joinertanner]

Ya you can buy the preformed trim that looks like rolled lead 3 different sizes it's the cure it brand I use.

[@burwoodbuild]

Surprised to see a lack of trims used! GRP is fantastic stuff… some great videos on KZbin by “cureit” that cover every eventuality of GRP. 👍🏻😁

[@SkillBuilder]

Great suggestion!

[@Brian18741]

Never saw a painted fibre glass roof like that, I thought they were going to put edpm or something on top of it!

[@stevet2603]

It’s actually a grey resin and part of the fibreglass process rather than just decorative!

[@Brian18741]

@@stevet2603 nice one thanks 👍

[@dansmith7829]

This video doesn't do what it says on the tin, all time filler about the wood used and nothing about laying fibreglass.

[@SkillBuilder]

you should watch it backwards

[@MrB3ngy]

No expansion/tilt fillet trim against the main house or brick parapet? No primer on the brickwork, didn’t see a paddle roller either? You sure they knew what they was doing…??

[@esquireeventrade4838]

What is the grey product that they are rolling onto the roof?

[@DesperateDan3231]

The finish touch is a liquid rubber. It provides an additional layer of protection, smooths the surface and gives it a colour

[@bluevanmani]

@@DesperateDan3231 it’s not rubber it’s for top coat

[@garyengland5326]

It's called flowcoat. It's basically gelcoat with a wax additive so it cures to a non tacky state. You can get it in any colour you want.

[@jacklee8247]

No trims no bandages and no wall fillet trim with flashing. Think you had the cowboys in mate.

[@xxwookey]

Now when should you use EPDM (or PVC) membrane roof vs a fibreglass one? They both work well and are a great deal better than traditional felt. EPDM is a lot nicer for the chaps who have to put it down - not sure that breathing resin fumes every day is all that good for you. EPDM accommodates (much) more movement. Fibreglass is a lot more robust to people walking on it. I don't actually know which has the lower carbon footprint, but I suspect it's the membrane. Personally I prefer the membranes.

[@danielbernhardt5632]

Haha just before your talking head I was going to ask why you didn’t use the t&g OSB3. As I’ve always put that down for fibreglass. Like you say it’s the manufacturers recommendation

[@davidelliott5843]

I built rolling tool cabinets and drawers from OSB. Mostly. The bits done with plywood spit and delaminated. That’s just mechanical loads. No damp or weather whatsoever.

[@alikayani9878]

Just wondering, has the industry fallen out of love with proper 3 layer mineral felt and marine ply?

[@SkillBuilder]

Yes.

[@noskills9577]

Plywood quality is absolutely down the toilet and has been for quite a while

[@xxwookey]

Yes. Just about everything else is better.

[@kletops46]

With you Roger on the T&G debate... Every little helps, as they say.

[@gongatots4115]

I've seen at least 4 failed grp roofs replaced with edpm. I've not seen a failed edpm roof yet. All failures imo were the use of incorect boards.

[@SkillBuilder]

I like EPDM, the only trouble is that it smells on a hot day.

[@SBIGDTSM]

Actually, my edpm has failed, the sticky corners I got around my lantern upstand have all let go within 18 months, not impressed at all, it obviously couldn’t cope with welsh winters at a 1000ft. I’m pulling the lot off in the next month and doing it again, with what I don’t know yet.

[@xxwookey]

@@SBIGDTSM Interesting. First time I've heard that. Was it glued rather than welded (sounds like it from your description)?

[@SBIGDTSM]

xxwookey self adhesive corner patches that get supplied with the kit.

[@garvielloken3929]

😎

[@sproggyjoe1]

Every job I have been back to fix over the last 6 months are fibreglass roofs stick with the pvc membrane glued down fleece backed or macanicaly fixed and you can't go wrong

[@xxwookey]

They can be very good (there is a 37-year old one next door here that looks to be in good nick), but I think it's significantly easier to get the membranes right.

[@timcharlton7423]

I Roger when are we going to see the last job James done as you was going to up date us to see the finish job

[@trevcam6892]

I did a GRP job on my own garage flat roof some years ago (at least 6) with the aid of my wife. Bloody hard work but we did a good job and it worked and has never leaked. When my kitchen extension flat roof needed doing I paid a roofer to do it. By that time I was 80 years old and my wife couldn't climb ladders any more. I reckon the two roofs will outlast us both and then it's the kids problem.

[@LabRat6619]

Make a grp casket if you wanna ease the funeral costs ha ha. Only kidding, respect to you.

[@bruce-le-smith]

love it! yeah wet soil movement or critters in the framing will probably be an issue before that roof is, there's always something to chase and someone trying to charge you 10x too much for performance you don't actually need

[@susanhogan1350]

There's want one word about what was used in the roof?????

[@hughwilliams8062]

Hi Roger some advice needed hope you can help, I have been told you can't lay a fibreglass roof over bitumen coated OSB board, so if you lay 3mm hardboard over the top and staple it down will you be able to fibreglass over the hardboard (smooth or the other side up thanks, will really appreciate your advice.

[@SkillBuilder]

Hi Hugh I would use OSB rather than hardboard. The hardboard will buckle

[@hughwilliams8062]

@@SkillBuilder Hi Roger would the hardboard buckle on top of the OSB stapled down

[@DerekTJ]

As regards OSB vs ply, if I was to floor my (suspended floor) hallway, with engineer floor to finish, which would you recommend? The original floorboards have been up and down many times and aren't great, and I want to put pir board in between the joists. So yeah, osb or ply, and what thickness?

[@northeastcorals]

I take it the new boards will just be mechanically fixed or floating? If so I've had to do this on a few floors & would recommend ply if it's not to much more expensive than OSB although OSB should be OK as well. I used 12mm, you could maybe get away with 9mm depending on the state of the old floor etc but personally I'd go for 12mm or thicker (as long as you have enough height to fit it in).

[@briangreen6321]

With a flat roof with upstand like that, how do you go about shedding the water from the high side of the upstand? Does it not need some fall to make it run either side and then down to the gutter?

[@SkillBuilder]

It is done with the furring pieces Watch the previous episode

[@swiftgames5382]

Looks good but get those knee pads on 😁.

[@baraklazza1595]

TnG not needed if you put noggings inbetween sheet join to catch edge of sheets

[@baraklazza1595]

screwed of at 150mm cntrs

[@allanstephenson3083]

Have you ever had anything to do with Dempsey Dyer Ltd, hardwood doors or windows?

[@SkillBuilder]

No, is it something we should look at?

[@billysmart24830732]

Another good video. I am with you, I used tongue and groove OSB on my extension. Far less risk of a screw failing and a corner popping up. it is also so easy to miss the joist and I seriously doubt someone on an hourly rate is going to have the same adherence to standards as the homeowner doing it themselves.

[@nhojnhoj6767]

Hello Roger. Off topic, but what boiler do you have installed in your house?

[@SkillBuilder]

I now have a Baxi. I have had a Worcester, Trisave, Viesmann over the years.

[@buildingperfectiongrouty8767]

Iv done a lot of grp . Looks like a good job. You hit all the points 👉. One thing I did find out over the years is that drying wet patches with a tourch only drys the top layer and can still delaminate further down the line. I honestly think grp is in the top 3 flat roof Coverings out there. But completely dry osb is a must.

[@SkillBuilder]

Good comment

[@superiorbeing95]

B&Q had the T&G OSB last time i were there, seems like a good system, wondering what UV does to it over time.

[@SkillBuilder]

The U.V doesn't reach it.

[@endalynch6877]

FIBERGLASS OVER BRICKS??

[@joejoey316]

Just wondering why no one use neepads? Great content BTW!!

[@SkillBuilder]

Good question!

[@michaelplays2449]

Great video Roger , thanks !!!!!!!!

[@FiscalWoofer]

Super work Roger! Thank you!!

[@roydodd4694]

❤❤it 😊😊

[@bobbydelcavallo7181]

Brilliant 🥳🥳🥳

[@noskills9577]

Selco used to sell the T&G osb boards - ordered a few pallets off them a couple of years ago.

[@ricos1497]

Should have kept them, they'd be worth a fortune now!

[@SkillBuilder]

They still sell it but Selco is not everywhere. They go for heavily populated areas

[@noskills9577]

@@SkillBuilder fair enough

[@michaelreardon8573]

I always say the best system is the one the installers are most experienced/comfortable with. But saying that I do prefer EPDM for flat roofing

[@ianarmitage3518]

Very tidy

[@Chanesmyname]

Very nice!

[@krisgair5863]

I would never of known there even was a water resistant osb on the market 😮, would it be the right thing for an outdoor build like a work shop?,

[@krisgair5863]

I meant for the walls also

[@SkillBuilder]

yes it is a good bet

[@worldadventureman]

Like everything these days, the truth is in the wording. "resistant" not water proof. It will withstand some water but not over a period. So when you say for an outdoor building, do you mean as a sheathing? and then painting? Probably not the best and not worth it, it's not cheap. It's also not necessary for walls, as walls drain water, but roofs and floors pool water so needs something to resist water should it get in contact.

[@Tom_Hadler]

@@worldadventureman yeah ply for roofs I reckon.

[@xxwookey]

@@Tom_Hadler OSB3 is better than plywood unless you pay at least twice as much for the finest grade ply. OSB3 is very good stuff.

[@livingladolcevita7318]

Did you ever get an ev van Roger?

[@SkillBuilder]

No, I am too poor

[@livingladolcevita7318]

@@SkillBuilder 🤣

[@stevendavanna]

First comment, love the Channel. Would really appreciate a like 🖤🖤

[@paul756uk2]

❤️👍

[@qatarislamictv24]

Hello sir i need your nambar

[@gwilko6452]

I give it 1 year before it leaks. Professional flat roofing companys stay clear of grp. Single ply membrane all the way

[@noname-un4cu]

What is single ply materials mate

[@johnconnor9106]

Edpm is crap

[@davidbuckley620]

By the way, I do watch the videos you have done in the past and for the most they do check out, just make sure that your facts are sound and not like the air source heat pump vid that you had to back track on.... Kind regards Dave

[@SkillBuilder]

Tell me what I have back tracked on. The air source heat pump video was a criticism of the government scheme to squander millions of pounds of tax payers money on technology that will not be suitable for many of the homes it is installed in. This is already being acted out and we will have many examples of these failures in future videos.

[@buildingperfectiongrouty8767]

Rodger. Don't explain yourself. Your advice is always good 👍. Some people are too quick to find falt with your content. You cover a wide range of building techniques and products and I think you always give a very fair judgement of your findings. Your opinion is very helpful and reliable. Id like to see how well Buckley comes across

[@xxwookey]

@@buildingperfectiongrouty8767 His advice is generally very good, but he does sometimes talk ranty bollocks, and that heat pump vid was a good example.

[@buildingperfectiongrouty8767]

Obviously. Rodger is definitely not the answer to all building problems or solutions. One thing he is is honest, and yeah he might be grabbing a few quid for his troubles but nobody is forcing anyone to watch any of the vids

[@andreashessler838]

​@@xxwookey No it wasn't! The vast majority of that rant was pretty spot on regards them being unsuitable without huge additional home improvement expense. In most cases, insulation alone would be sufficient without these things.. This was backed up with a follow-up interview with the engineer from Worcester Bosch. I have no problem with people installing things like heat pumps, but I do have a problem when they expect poor people to pay for them through taxation subsides.

[@davidbuckley620]

Ah your talking utter bollocks mate, when ur putting resigning any roof area it doesn't matter what your substrate is, it could be made out of cheese if you insisted

[@SkillBuilder]

Are you sure it is me talking bollocks. I can't make any sense of your comment. Friday night comment

[@buildingperfectiongrouty8767]

As long as the cheese was made from cows that have be fed osb all their lives. Grp (resigning) don't like any type of moisture during the curing stage. But obviously you knew that being the master roofer you are

[@SteveAndAlexBuild]

Great job , love seen the fibre glass method and the resitrix method now . Both excellent 👌🏼 🧱👍🏽