Any roofing experts here? Can I please pick your brains....

[OscarG]

I've spent last few weeks using various products attempting to patch up my parents leaking garage roof (my workshop!). They've got this awful corrugated bitumen stuff nailed direct to the joists.

The roof is approx 5m x 3m. It's not quite a flat roof, there is a slight incline. It's slightly complicated that one side of it joins on to their neighbour's garage who also has the same rubbish corrugated bitumen stuff.

We got a quote from a very respected roofer to fit new roof: fit 3/4" plywood boards on joists, 3 layers of felt, top layer being that mineral backed Torch-on stuff. Total: £2400 inc VAT.

I have 2 questions for the experienced roofers here:

1) Does that quote for £2400 seem excessively high to you?

2) Is this a hard job to do yourself?!

I figure I could get 15 sq m of 18mm thick plywood for about £200 from Wickes, no problem fitting that myself. It's the felt bit I'm unsure of. I saw this stuff on youTube where they glue a one-piece membrane of rubber onto plywood, no underlay or blowtorch required.

https://www.youtube.com/watch?v=dnw5soR ... e=youtu.be

Cost for a 5mx3m roof is about £400.

Do you think that rubber stuff might be any good?

Any advice appreciated!

 

[Kev]

Not an expert in this but have fitted a rubber roof to a 5 x 3 metre gym I built in my garden about 18 months ago. It was a measured kit (that's to say I gave the company the dimensions and they sent everything you need for that size). Mine was also fitted straight to plywood. I have to say I am very impressed with it. Just follow the instructions and very straight forward. I fitted mine on a warm day which would recommend as a) it advised laying out out and letting the sun get on it for a bit ( from memory helped remove any creases that could have occurred during delivery) and b) the roof doers need to be very dry so a dry patch makes sure no moisture underneath. I am guessing it took me about half a day in total, including fitting the external trims that came with it etc. As I say only been down 18 months but so far have had no problems at all and seem to have held up well.

In terms of felt, sure you can do this yourself but personally would leave to professionals. Have seen this done on jobs and working on and more to it than you think. Also if it leaks I would want it to be someone else's problem to fix! But as I say this is just my opinion.

Hope this helps.

 

[Hornbeam]

Single ply membranes work very well. For your size of roof, you can do that with a single piece. Be aware that there are a number of different types and qualities.
!8mm weatherproof OSM or ply will form a good substrate. The key point in installation is how you detail around the corners edges and onto any abutting wall

 

[OscarG]

Not an expert in this but have fitted a rubber roof to a 5 x 3 metre gym I built in my garden about 18 months ago. It was a measured kit (that's to say I gave the company the dimensions and they sent everything you need for that size). Mine was also fitted straight to plywood. I have to say I am very impressed with it. Just follow the instructions and very straight forward. I fitted mine on a warm day which would recommend as a) it advised laying out out and letting the sun get on it for a bit ( from memory helped remove any creases that could have occurred during delivery) and b) the roof doers need to be very dry so a dry patch makes sure no moisture underneath. I am guessing it took me about half a day in total, including fitting the external trims that came with it etc. As I say only been down 18 months but so far have had no problems at all and seem to have held up well.

Thanks for your message!

Can I ask which company you used for your rubber roof?

I assume the rubber is going to be brutally heavy to lift up on to a roof?!

 

[MikeG.]

EPDM is one of those star products which is transforming life for architects. I use it all the time. I never do a flat roof with anything else, and it works on balconies and in box gutters too. Absolutely brilliant fit-and-forget product which should assign torched on felt to the same place in history as whale bone corsets. It's also a simple DIY product. Any half-competent DIYer can do a simple roof in EPDM (provided they can get safe access). It's also way cheaper than torch-on felt (and fibreglass). Don't consider anything using else.

 

[OscarG]

Thanks Mike

My dad's a little concerned about it's durability, is it pretty good at resisting UV light/melting on a rare sunny day?

 

[Brandlin]

I don't have experience of EDPM as a roofing material. However EDPM is the preferred material for pond liners. Most come with a 25 to 40 year life guarantee and cope with the rigours of frozen ponds, hot sunny days on the exposed edges and general wear and tear of getting in the pond to clean it. I've had mine installed for 19 years without any problems at all.

 

[MikeG.]

Thanks Mike

My dad's a little concerned about it's durability, is it pretty good at resisting UV light/melting on a rare sunny day?

It's UV resistant, and will last 60 years or more. Seriously, you won't get a longer-lasting roof finish for your situation. It's great bonus is that it is flexible, which means that expansion and contraction with changing temperature doesn't wreck it (like it wrecks felt, fibreglass, and so on). We only have 60 years as a figure because that's how long they've been using it in Europe. IN twenty years time, I bet they'll be saying it lasts 80 years.

 

[HappyHacker]

Having constructed a few flat roofs and repaired quite a few as well I would keep away from three layers of felt applied cold or torched on. The price does not seem unreasonable but I don't know what your local prices are like. The EDPM stuff is great, I had it applied professionally about 10 years ago to three flat roofs on my house/garage and no problems at all. It has become a DIY solution now with but as has been said it is quite heavy so make sure you can get it onto the roof.

I have also used the black corrugated stuff (Ondulene) and it is great if used properly. For flatish roofs it needs boarding underneath or lots of support as it tends to sag otherwise.

Installing the boarding yourself is easy just make sure the board you use can support your weight between the joist spacing. Also the boarding and EDPM will probably be heavier than the existing stuff so make sure the joists are adequate.

 

[Woody2Shoes]

+1 for EPDM if properly designed and detailed. It's easy buy what you need online and there are various sites/YT videos to learn methods for applying it.
Another, slightly cheaper, alternative might be galvanised corrugated steel sheet as a direct replacement for the onduline sheet (which always rots eventually, even if laid at a decent pitch angle - any moss/lichen encourages dampness/ponding which accelerates decay) - with steel, I'd ensure a vapour check barrier on the warm side of any insulation (now might be a good time to consider some insulation perhaps) and bituminous paint on the upper surface plus care with detailing of fixings and round the edges.

Cheers, W2S

 

[Kev]

'Can I ask which company you used for your rubber roof?

I assume the rubber is going to be brutally heavy to lift up on to a roof?!'

The company was called rubber4roofs.

The Rubber is no that heavy, manged to lift it myself. Once its up on the roof you unfold and leave to rest then roll it back and adhere a section of a roof at a time so quite straight forward.

 

[OscarG]

Many thanks for all your replies, hugely appreciated.

I'm now convinced a rubber roof on ply is the way to go. As soon as the weather improves, I'll put some rubber on!

 

[MikeG.]

It doesn't have to be ply. Use some 18mm OSB and save even more money.

 

[RobinBHM]

I use rubber4roofs, they have always sent out my order next day if ordered by 2.00pm.

Their site has pdf downloads and videos which is very helpful.

One key thing is to get your rubber laid out flat, ideally in sunshine to relax out the creases, if you dont you will struggle to avoid bubbles.

 

[Beau]

It doesn't have to be ply. Use some 18mm OSB and save even more money.

No expert on roofing matters and really rate OSB but only potential problem I can see with OSB in this instance is if it does get wet (maybe from condensation) it can swell far more than ply. This could leave a step putting uneven presure on the roofing membrane.

No expert but just a thought.

 

[Harbo]

I used 18mm OSB from TP and EPDM from Rubber4roofs.
Very easy to lay, get some disposable rollers for applying the adhesives.
Watch a few UTube videos.

Rod

 

[defsdoor]

The Rubber is no that heavy, manged to lift it myself. Once its up on the roof you unfold and leave to rest then roll it back and adhere a section of a roof at a time so quite straight forward.

I used the rubber4roofs thickest option on a 6m*5m roof and 2 of us could barely lift it

I had to fashion a slope and a trolley (with self applying brakes!) and pulled it up bit by bit.

This picture tells only half the story - the slope was too steep for the rubber (I'd had no problem sliding OSB up) and had to raise the bottom on to a table to reduce the include

I'd recommend rubber - it's pretty simple to install. Just don't do it on a blazing hot day - the glue went off quicker than I could roll out the rubber so it's not perfect.

You can't tell though unless you get up on it -

 

[OscarG]

Your roof looks great! Thanks for tip regarding temperature.

I was talking to a rep from permaroof.co.uk they told me their rubber roofs are about 1.4kg per sq m so I can see why your one (twice the area of mine!) could be a test. They were really helpful but seen quite a few posts here with great results using rubber4roofs so despite feeling a bit guilty I'll probably go with them.

I'm very jealous if that lovely big space is going to be your workshop!

 

[defsdoor]

I'm very jealous if that lovely big space is going to be your workshop!

It is - and it's very nearly done Just a plaster skim and SWA to run down to it. Oh and I need to source some thin light panels.

 

[OscarG]

One thing I forgot to ask. The ply used underneath the rubber, is ordinary structural play ok to use? It doesn't need to be that more expensive marine ply does it?