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Author: Subject: EPDM roofing and cold vs. warm roof.
James

posted on 22/7/21 at 12:29 PM Reply With Quote
EPDM roofing and cold vs. warm roof.

Greetings,

I have a number of leaks in a felt-roofed small flat roof extention.

It's been leaking for quite a while but I've been irresponsible and left it and now things have started to go mouldy!

It's about 1.8m x 4m rectangular apart from where a corner is missing where it joins the corner of the main house. So it's ' h' shaped essentially.


I've been recommended using EPDM roofing and I'm thinking of converting it from cold roof to warm roof at the same time.

I suspect joists have rotted and they've certainly been hacked about a lot for cables/piping (plus a guttering valley was cut into the joists- also leaking) so I think I'll remove the lot and start again and add furings(sp?) to give it some slope.


I know you can buy EPDM kits with all the trims and everything. There's loads of companies, any you'd particularly recommend?


Am I mad to be converting cold to warm roof? If I have to replace my joists anyway (or at least make significant repairs to what I have) it seems fairly easy to convert- I already have most of the selotex at least!

Any advice greatfully received- thank you!

James





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David Jenkins

posted on 22/7/21 at 12:36 PM Reply With Quote
I can't comment too much on what you're planning to do, but my shed roof started to leak and I decided to get rubber roofing from here (lots of useful info as well):

https://www.rubberroofingdirect.co.uk/

Next job is to fit it! Weather's much too hot to do this atm, so I'll wait for an overcast but dry day.





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SteveWalker

posted on 22/7/21 at 12:43 PM Reply With Quote
For a flat roof, EPDM seems to be good and they quote long life, but don't rule out fibreglass.

I fibreglassed our 6m x 2.5m flat roof over 20 years ago. Buying it all from Glasplies in Southport.

We have had one leak since then, but that turned out to be getting under the edge of the fibreglass, underneath the tiles of the pitched roof and was resolved with an extra piece of flashing.

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nick205

posted on 22/7/21 at 12:44 PM Reply With Quote
IMHO if you've got to strip it back and replace rotten joists then I see it as worth converting from cold to warm roof. It'll make a noticeable improvement to the inside space all year round. Warmer (less heat loss/lower heating costs) in the colder months and cooler in the warmer months.

Around 15 years ago we added a glass roof conservatory to the back of our house. Nice to have the additional space, but freezing in the winter and boiling in the summer. A couple of years ago we had it re-roofed with a tiled system + Velux windows. Effectively changing it from a cold to warm roof. It's transformed it - usable all year round now and a pleasant place to be.

Can't advise on EPDM - never used/fitted it myself. It does seem recommended though.

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johnH20

posted on 22/7/21 at 03:22 PM Reply With Quote
I have just done my bike shed in EPDM. Very easy process and supposedly lasts for ages. Just as well because I had to replace the old bitumin roof every 3 or 4 years.
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tegwin

posted on 22/7/21 at 03:44 PM Reply With Quote
James,

I just replaced the roof on a double garage using epdm. Built up as a warm roof. I canít see sense in doing it any other way.

It had an asbestos roof with basically no timber work left.

Put up new rafters, an osb deck, 100mm of Kingspan, another osb layer and then the epdm and finished with all the trim pieces.

A few gotchas along the way but worth it. The last epdm roof I did was cold and suffered from condensation inside as air was getting into the insulation.



Donít underestimate the weight of the epdm. It was a mission getting an 80kg roll of material 2.5m up onto the roof!
Happy to email you a load of photos of my build If that helps.

[Edited on 22/7/21 by tegwin]





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loggyboy

posted on 22/7/21 at 04:04 PM Reply With Quote
reroofed my large shed in EPDM last year after felt lasted less than a year and even when laid well it leaked due to being a shallow pitched pent shed.
Still looks good, was easy to lay and trim. Warm roof is better IMO, the venting of a cold roof is rarely adequate especially a flat one.





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James

posted on 22/7/21 at 05:09 PM Reply With Quote
quote:
Originally posted by tegwin
James,

I just replaced the roof on a double garage using epdm. Built up as a warm roof. I canít see sense in doing it any other way.

It had an asbestos roof with basically no timber work left.

Put up new rafters, an osb deck, 100mm of Kingspan, another osb layer and then the epdm and finished with all the trim pieces.

A few gotchas along the way but worth it. The last epdm roof I did was cold and suffered from condensation inside as air was getting into the insulation.



Donít underestimate the weight of the epdm. It was a mission getting an 80kg roll of material 2.5m up onto the roof!
Happy to email you a load of photos of my build If that helps.

[Edited on 22/7/21 by tegwin]



Did you use a vapour barrier anywhere in that? Does it go between the rafters and the OSB?

What did you do over the ends of the rafters- fit a fascia board to them? Does it end up very tall with rafters, OSB, kinspan etc to cover?


You mention condensation. Do you need to fit vents or anything anywhere?

How did you get a slope? Firrings?

Thank you!





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"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights." - Muhammad Ali

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tegwin

posted on 22/7/21 at 05:50 PM Reply With Quote
Slope was built into the top of the wall. I then bolted a timber bearer into the top of the wall as it was a bit crumbly.

Rafters screwed into wall bearer. And add noggins.
Screw down osb to rafters
Plastic vapour barrier across whole lot.
Then kingspan on
Kingspan between joist ends. I added extra noggins inside as well.
Then top osb secured with ressessed cupped screws
Glue down epdm
Fascia boards on
Finish epdm edge with the correct trim strips.

trick is to get enough timber in to the ends of the rafters so you can nail your fascia boards and trim pieces to.

Yes height added is quite a bit but not really noticeable once itís up.

Gain in headroom is fantastic as the insulation is above the deck.

I mentioned condensation as the last epdm roof I did was a cold roof with insulation pressed onto the spaces between rafters afterwards. Looked shit and leaked warm air onto the bottom of the cold deck.

U2u me an email address and il send you some photos if that helps





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James

posted on 23/7/21 at 08:19 PM Reply With Quote
quote:
Originally posted by tegwin
Slope was built into the top of the wall. I then bolted a timber bearer into the top of the wall as it was a bit crumbly.

Rafters screwed into wall bearer. And add noggins.
Screw down osb to rafters
Plastic vapour barrier across whole lot.
Then kingspan on
Kingspan between joist ends. I added extra noggins inside as well.
Then top osb secured with ressessed cupped screws
Glue down epdm
Fascia boards on
Finish epdm edge with the correct trim strips.

trick is to get enough timber in to the ends of the rafters so you can nail your fascia boards and trim pieces to.

Yes height added is quite a bit but not really noticeable once itís up.

Gain in headroom is fantastic as the insulation is above the deck.

I mentioned condensation as the last epdm roof I did was a cold roof with insulation pressed onto the spaces between rafters afterwards. Looked poo and leaked warm air onto the bottom of the cold deck.

U2u me an email address and il send you some photos if that helps



That's great mate- thank you!





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"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights." - Muhammad Ali

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James

posted on 23/7/21 at 08:20 PM Reply With Quote
Thank you for all the advice folks.

Going to book a couple of days off week after next and give it a go then! What's the worst that can happen? The roof leaks!


Cheers,
James





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"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights." - Muhammad Ali

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David Jenkins

posted on 23/7/21 at 09:35 PM Reply With Quote
I put EPDM on my shed roof today (2.5m x 2.8m) and it really wasn't too hard - a fair amount of physical effort, but not excessive. Getting the old roofing felt took more time than putting the new stuff on. The rubber sheet was VERY heavy to lift onto the roof though.

The water-based glue is bleedin' sticky, and gets everywhere! I kept finding my hands getting stuck to stepladders, the outside of my gloves, everything! And the paint roller I used is no longer fit for purpose...





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nick205

posted on 24/7/21 at 04:33 PM Reply With Quote
Be sure to post some photos of the job.
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smart51

posted on 18/8/21 at 02:19 PM Reply With Quote
I used rubber roofing direct and was pleased with their service. Beware though. A big roll of the stuff is heavy!

When we had our loft conversion done, the company wanted to do a felt roof. I insisted on EPDM. The boss was hesitant as his roofer was a traditionalist who more or less would only do slate or felt. The boss and one other guy went on an EPDM course and came back as an evangelist saying they would only ever do EPDM from then on. I think the instructor welting it with a sledge hammer until the plywood it was glued to broke but leaving no scar on the rubber is what did it for him.

We had a warm roof done, but only to maximise headroom. Birds on the roof are loud. I don't know if a cold roof gives more noise insulation.

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