Water resistant Chipboard for EPDM Flat Roof

[bennyboy1]

Our builders who have converted our garage want to use water resistant chipboard to go under the EPDM. Any thoughts on this? I have heard this isn't a suitable material, although the building inspector seems to think it is OK. If it makes any difference, the chipboard is being laid on top of celotex boards which is laid onto of the old felt.

 

[catlad]

I would not recommend doing it that way or using those boards as they have no structural integrity unlike OSB3 which is the normal thing to use. Cost cutting is the only reason you would use chipboard they are half the price.

 

[geraldthehamster]

You'd do a lot better to keep this one topic in one thread, rather than splitting it into 3 so far...

Don't take our word for it. See the following links, for suitable decking materials:

http://www.justliners.com/roofingintall&faq.htm

"Can I install EPDM membrane directly over an existing roof? You can install EPDM membrane over an existing roof only if a new layer of 5/8" plywood, 5/8" OSB board or polyisocyanurate board with a fiberglass backing is used as a barrier to protect the EPDM."

http://www.rubber4roofs.co.uk/epdm-warm-deck-roof-design

"Roof Deck - Minumum 18mm ply or OSB3 deck."

http://www.permaroof.co.uk/rubber-roof-faqs

"Which substrates can I adhere the membrane to? Either OSB3 sterling board or plywood timber, but smooth concrete and tissue-faced insulation boards are also suitable."

Chipboard is a poor material for floors, let alone roofs.

Cheers
Richard

 

[noseall]

Chipboard is so low end I'm surprised pro builders even consider it.

 

[bennyboy1]

You'd do a lot better to keep this one topic in one thread, rather than splitting it into 3 so far...

Don't take our word for it. See the following links, for suitable decking materials:

http://www.justliners.com/roofingintall&faq.htm

"Can I install EPDM membrane directly over an existing roof? You can install EPDM membrane over an existing roof only if a new layer of 5/8" plywood, 5/8" OSB board or polyisocyanurate board with a fiberglass backing is used as a barrier to protect the EPDM."

http://www.rubber4roofs.co.uk/epdm-warm-deck-roof-design

"Roof Deck - Minumum 18mm ply or OSB3 deck."

http://www.permaroof.co.uk/rubber-roof-faqs

"Which substrates can I adhere the membrane to? Either OSB3 sterling board or plywood timber, but smooth concrete and tissue-faced insulation boards are also suitable."

Chipboard is a poor material for floors, let alone roofs.

Cheers
Richard

Thanks Richard, that is really useful, I think I'm going to have to insist that our builders use ply or OSB3. Is one better than the other? Also one of the points in the first link mentions that EPDM should not be bonded to felt. Our roof joins onto our neighbour's roof which is felt, so the EPDM will come into contact with it, when they join it. I was wondering where the two materials overlap whether another material could be placed in between them to stop them coming into contact, or another method, what do you think?

 

[geraldthehamster]

Thanks Richard, that is really useful, I think I'm going to have to insist that our builders use ply or OSB3. Is one better than the other? Also one of the points in the first link mentions that EPDM should not be bonded to felt. Our roof joins onto our neighbour's roof which is felt, so the EPDM will come into contact with it, when they join it. I was wondering where the two materials overlap whether another material could be placed in between them to stop them coming into contact, or another method, what do you think?

I don't know which is better, but either is acceptable. I used OSB.

I had the same situation where my flat EPDM roof abutted a sloping felted roof. I used flashing tape from the new deck onto the adjacent felt, then finished the EPDM on top of the flashing tape. This avoided the EPDM coming into contact with bituminous substances that might degrade it. You can also get metal edging strips to secure the edge of the EPDM, though I just glued the edge down with contact adhesive. But I'm a DIYer, and not a builder or a roofer.

I suggest you read some of the installation guides and watch some of the videos on the suppliers' websites, and on youtube, to get an idea of how it's done.

Cheers
Richard

 

[gregers]

Chipboard is so low end I'm surprised pro builders even consider it.

probably there wanting to earn as much out of lo spec materials on the job.
really made me laff that did.CHIPBOARD THEY SURE.??

 

[bennyboy1]

Chipboard is so low end I'm surprised pro builders even consider it.

probably there wanting to earn as much out of lo spec materials on the job.
really made me laff that did.CHIPBOARD THEY SURE.??

Yep. Have a look at this photo.

 

[gregers]

so no glue,what happens when the boards move?

 

[bennyboy1]

the boards are screwed down.

 

[geraldthehamster]

The horror, the horror.

Those boards are designed for interior flooring, and they're not hot at that. They are NOT SUITABLE as a roof covering.

Makes me wonder how well the rest of the job was done. Do you have any photos of the EPDM installation?

Cheers
Richard

 

[bennyboy1]

Mate the rest of the roof job was a disaster, we've had roofers out who have been shocked at how poor the job is. I don't have any other pics of them doing it. Thankfully our builders have admitted fault and are going to replace, however we're not exactly chuffed on them redoing as our confidence in them is 0% at the moment. Ideally we would go elsewhere and get it done by someone else, but that's going to cost us about £3000, a lot I know, but it needs to be repitched as no drop was created when it was built by them first time. We still owe our builders about £2000 but unfortunately unless we give them another chance at redoing we don't think we will be able to hold that money back and request more to cover the cost of going elsewhere in the eye's of the law as the builders have offered to redo. However if they screw up again then I think we are in a much stronger position to sue them for the full cost of getting it done elsewhere.

 

[geraldthehamster]

I think you're required under consumer legislation to give them the chance to put it right. Though from what you say it seems this isn't a certainty I don't supposed they've admitted fault in using interior flooring as the roof deck?

At least you're in a stronger position if you haven't paid them all the money. I wouldn 't be tempted to pay any more until the job has been done properly, with the correct materials, and to a satisfactory standard. If this hasn't happened after one more attempt, I'd get them off the job tout suite and not pay another penny.

 

[gregers]

think it may pay for you to employ a roofing surveyor and have him/her inspect at each stage of the REDO.
get the cowboys to agree to pay for this as a sweetener to get there hands on the retainer also stops them from cutting corners,coz we all know they will try to.
that way you will feel better that each stage has been done to a decent standard.

 

[JoinerAndy]

I have seen a local company do multiple flat rubber roofs using moisture resistant chipboard and they are positive it's the best material to use. They have never had an issue with it and this is also on the Scottish northern coast so extreme weather conditions are normal here ‍. I guess the main advantage of rubber is it's impenetrable so there should never be any moisture affecting the chipboards strength. They said one major plus point is you get a much smoother surface to bond to and less chance of noticing any joints.

Il be doing a project myself soon on my own house and I am still unsure what to use.

my own personal issues with the moisture chipboard would be 'will the adhesive get a lasting stick to the chipboard' given it has a moisture resistant coating?

Apart from that theres not much difference in strength between that and osb.