Garden Room Flat Roof in EPDM

[vinty]

Just got a reply from a big US roofing firm in response to my question above regarding EPDM:

"EPDM can be installed as a mechanically attached, fully adhered, wind vented or a ballasted system. Mechanical attachment is the easiest and usually the most cost effective option."

Anyone know how this works, where I can find info on it, or who does it in the UK?

When we did the Firestone contractors course they had a place in Cheshire ,if it is still there you should be able to get all you need.
A simple roof like yours shouldn't require mechanical fixing.

 

[efunc]

You would be better stripping of the existing membrane,and recovering it with a single sheet ,you could do it in less than a day.
Mechanical fixing is usually for large industrial roofs.the reason panels are used is because the sheets of EPDM have maximum width they then have to be joined with seam tapes.

Thanks for the reply Vinty, very informative. Yes, you're right, I probably will just strip it off. The disadvantages were that it would probably leave a lot of messy residues and the resulting new roof will be uneven and slightly compromised because of it. The advantage of leaving it on were also that I thought it would be a shame to remove it because it would add a secondary line of defence under the new covering - the more the merrier I thought. Afterall, there's nothing wrong with it other than having poorly executed seams and rear flashing which would be fine under a new covering. But off it'll come I guess. Thanks for your advice.

 

[efunc]

BTW Vinty, what do you make of that other video where they're bonding the Firestone directly onto what looks like 100mm insulation board? Is that possible of kingspan or celotex for example?

 

[Notch7]

Thank you, that confirms what I suspected. Someone did say they could do a single layer of SBS Torch-on for £540, but that sounds like a total bodge job. If, on the other hand, the base layer were nailed on over the top of my current EPDM and another 2 done on top I would be quite interested in this as it would save me having to rip up the EPDM or over board it! Is that how it works if I do it properly? Also any idea of the approx weight per m2 if I do a 3 layer torch-on? It sounds like it could get heavy; much more so than EPDM anyway.

Felt needs a 1 in 40 fall to overcome ponding due to the seams.

 

[efunc]

Felt needs a 1 in 40 fall to overcome ponding due to the seams.

OK, thanks. That's it decided then. It needs to be a single layer EPDM then. The only thing I need to investigate further is if it's possible to overlay an PIR insulation layer and bond onto that.

 

[Notch7]

OK, thanks. That's it decided then. It needs to be a single layer EPDM then. The only thing I need to investigate further is if it's possible to overlay an PIR insulation layer and bond onto that.

Im not sure thats wise, you can get insulation with a ply face bonded to it, for a warm roof though.

http://www.insulation-online.com/kingspan-thermaroof-tr31-ply-wood-bonded-flat-roof-board.html

 

[efunc]

Thanks, that's very interesting and it's the sort of product I want to look into and possibly use. However, frustratingly, I called Celotex about their similar Crown-bond boards and the lady there said they don't do that product at the moment, and in any case you can't bond EPDM directly to it, which is not what their website implys. And additionally the Firestone video I posted earlier shows them doing exactly that in their installation.

 

[efunc]

Ooo.. this looks even better: Kingspan Thermataper® LPC/FM tapered roofing system

 

[efunc]

Well, after some investigation I discovered that EPDM can indeed be bonded directly to insulation boards, and that there are various tapered boards available for over boarding existing roofs and enabling a single-ply membrane to be bonded on or mechanically fixed.

This would address several of my problems in one solution:

- Enabling me to replace the terrible existing EPDM roof, yet allowing me to still retain this underneath the replacement for additional protection
- Negating the need for heavy 18mm OSB over boards
- Creating a 1:60 or 1:80 fall where there is currently no pitch to the roof
- Creating a warm roof

The Firestone technical support said "the Firestone EPDM membrane could be fully adhered to a PIR insulation board with coated glass tissue facers. This would initially be mechanically attached through the existing waterproofing to the structural deck, using appropriate fasteners and insulation plates.” Their video also shows it being bonded on to foil-backed PIR boards too.

There seem to be a number of other examples out there, but here are some I found:

https://www.building-innovation.co.uk/products/pir-insulation-solutions/inno-bond-inno-bond-tapered
https://www.bauder.co.uk/roof-syste...-insulation-boards/tapered-pir-for-roof-falls
https://www.jablite.co.uk/application/jablite-flat-roof-tapered-insulation/
https://gradientuk.com/applications/single-ply-membranes/
ROCKWOOL, HARDROCK, Multi-Fix (DD) www.rockwool.co.uk
https://www.achfoam.com/Insulation/RoofInsulation/Tapered-Roof-Insulation.aspx

So anyone here have any experience of doing this, or know anyone who could do it?

And also, if I'm adding a layer of insulation above my current roof decking, do I still need to install vents in my soffit, like with a cold roof?

Thanks