Replacing flat roof

[john306]

My tandem garage roof looks like it will be in need of replacement in the next year or two.
It's got felt on it at the moment with chippings, no leaks, splits or flaps, looks decent ish, it just looks a bit tired and the overhangs into gutters are crumbling in places.
I've no idea what condition the boarding is in as i can't see it as from inside its been plasterboarded, but assume its ok as I've said,no leaks.
The garage is 11.5m x 3m, two thirds joined to side of house, one third free standing.
I was considering EPDM, but how good does the surface have to be to fit it?
If I rip up the felt, and it leaves the boards in a right mess, what would my options be, considering I wouldn't have any boards to hand to replace immediately, and I'd rather not pay out £100s that I might not need?
Thanks for ant info, or alternatives.

 

[foxhole]

Ripped my flat roof off which left a mess , just over boarded with 12mm ply which left nice smooth surface for Epdm.

 

[john306]

Ripped my flat roof off which left a mess , just over boarded with 12mm ply which left nice smooth surface for Epdm.

Oh OK, that might be an option. It would save the hassle of ripping all the old ones off.
Thanks

 

[Bosswhite]

Just overboard it .

 

[^woody^]

Your option is to rip the felt off in the summer when there will be several days of no rain, and assess the deck, and then buy what you need.

 

[john306]

Your option is to rip the felt off in the summer when there will be several days of no rain, and assess the deck, and then buy what you need.

Thanks, looks like the best option.
But how good a surface does EPDM require, if the felt was torched on I'd expect it to be a mess, but I'm unsure what it is?

 

[Makie]

Thanks, looks like the best option.
But how good a surface does EPDM require, if the felt was torched on I'd expect it to be a mess, but I'm unsure what it is?

Plywood is your best option as it is the smoothest finish

 

[Vinty]

EPDM rubber membrane is easier to install than torch on felt.
Firestone ltd are the world's biggest manufacturer of EPDM.
They have a list of approved contractors if you don't want to do the work yourself.
If you want to DIY they have a technical department bloke who will give advice on quantity and installation,
Firestone UK used to have place in Cheshire ,I had to do the contractors course there years ago.

 

[^woody^]

Strip the felt and see what the deck is like. If you can get any lumps off and are left with a smooth-ish surface and no blown or raised board edges etc, then you are good to go. Otherwise, fix a new layer on top - potentially 6mm ply would do, or go up to 9mm.

Also check the current fall and for any ponding. If need be, sort that out at the same time.

 

[john306]

Strip the felt and see what the deck is like. If you can get any lumps off and are left with a smooth-ish surface and no blown or raised board edges etc, then you are good to go. Otherwise, fix a new layer on top - potentially 6mm ply would do, or go up to 9mm.

Also check the current fall and for any ponding. If need be, sort that out at the same time.

Many thanks, that's probably the way I'll go.
Fall is good and no ponding.
I'd thought I'd need minimum 12mm ply/OSB, can I really get away with just 6mm? Better for me if I can as it's cheaper.

 

[^woody^]

Many thanks, that's probably the way I'll go.
Fall is good and no ponding.
I'd thought I'd need minimum 12mm ply/OSB, can I really get away with just 6mm? Better for me if I can as it's cheaper.

If the existing deck is sound, then you are only overlaying to get a decent flat surface so you can go with a thinner board. Just ensure that you still fix it down adequately (every 150mm), and stagger the boards to that the joints are not in line with the existing deck.