# Low slope Rubber roofing ?



## Dave in Pa (Oct 10, 2009)

I did a job a few years back with rubber roofing, backer, adheasive, etc. as per specs. all went fine! Now my question, is it possible, FOR MY OWN PLACE, no customer invloved. I want to use the left over material, but want to keep the cost down, CHEAP! 
Can I glue the rubber down to OSB or should I put the backer down? What if I put a 1/4" ply underlay down for a better bond/smoother? 
Has anyone done this before with good results? Like to go on the osb if possible. Trying to keep the cost down, just a storage area!
I do know, that if I do this for myself, the guy doing the warranty work on it will be slow! LOL
Thanks, Dave


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## OldNBroken (Feb 8, 2008)

As long as it's fully adhered it can be done and is actually allowed. My issue with it is the few I have had to go on and repair is slivers poking through the membrane. I'm against it and would not do it but that's just me. 

Recovery board is not very expensive and, in my opinion, just gives you a better roof.


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## ohiohomedoctor (Dec 26, 2010)

While I have never done this it may work to paint or skim coat the osb prior to rubber installation. This would help prevent the above mentioned from occurring. I would think that you would want to spend the extra few dollars and make it right. :thumbsup:


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## OldNBroken (Feb 8, 2008)

ohiohomedoctor said:


> While I have never done this it may work to paint or skim coat the osb prior to rubber installation. This would help prevent the above mentioned from occurring. I would think that you would want to spend the extra few dollars and make it right. :thumbsup:


except then you are adhering to the paint. weak link


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## oldfrt (Oct 10, 2007)

For the few extra dollars and peace of mind I'd do as Renegade suggested and
use an approved underlay.Painting OSB would only create a weak link between 
the substrate and the decking.
Any possibility of a chemical reaction with a painted surface should be avoided.
Years ago I worked for a company that had their roofer glue directly to fire rated
plywood.They did this on an entire prison complex.A few years down the line,the 
roofs failed, and repair costs were estimated at $10million.
Guess who went out of business?


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## LCG (May 30, 2011)

You can do whatever you want. I can guarantee you it will pull itself apart from the OSB in 4-7 years.

Reason:

Last January we were called to do a job walk to "repair" the roof on a 60+sq commercial building. This was a modular kit building on a permanent foundation. I was around when they installed this structure but never went on the roof as it was not my project. The roofing contractor they hired installed an fully adhered EPDM membrane directly over OSB. This membrane had completely pulled it self from the parapet walls, the feild had pulled itself from the OSB. UGLY. The building was 4 years old. They paid me over 30K for a new PVC layover. 

I cannot tell you how many times I have seen this happen. It's dissapointing because a propely instaled EPDM will last. Problem is it can be bought over the counter and is rarely installed correctly.

Spend a few more dollars. Do it right!

Besides, if my stuff came apart on my own home my wife would never let me hear the end of it. Relentless.


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## red_cedar (Mar 30, 2005)

LCG said:


> You can do whatever you want. I can guarantee you it will pull itself apart from the OSB in 4-7 years.
> 
> Reason:
> 
> ...


What would be the dynamics occurring, to have the fully adhered epdm pull itself away from OSB and not mechanically attached surface to high density fiber board that is pretty easy to pull epdm away from?


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## LCG (May 30, 2011)

red_cedar said:


> What would be the dynamics occurring, to have the fully adhered epdm pull itself away from OSB and not mechanically attached surface to high density fiber board that is pretty easy to pull epdm away from?


For the same reason that fiber cement siding holds paint 3X's longer than wood. For the same reason floor or wall tile is glued to a cement backer rather than OSB or sheetrock. You are taking one element out of the equation. Yes, the sheet can pull itself from fiber board. However, the fiber board doesn't pull away from itself. Every Epdm sheet that I have seen pulled up from OSB, the OSB is still attached to the underside of the sheet. 

I have never seen a PVC spec'd for a fully adhered system to be directly applied to OSB nor have I ever seen an EPDM spec'd for direct adhesion to an OSB base. Yes I know the manufacturer says it's ok. It isn't. We have so much expansion and contraction in Wyoming that EPDM doesn't seem to hold up as well. It does OK but it's not PVC.

I have however seen EPDM adhered over OSB that "has" lasted 15 years. I know, against everything I just stated. I haven't seen EPDM pull from a primed dens deck or secure rock. I am just stating my experience. Again, EPDM is usually installed impropely anyway. 

I suppose for a your shed roof it really isn't a big deal. I just have PolyIso, Dens, Secure Rock, and 60mil IB laying around so doing it right is just a given. 

Don't be shy on the glue!


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## linderman (Mar 26, 2012)

I too strongly suggest you use a wood fiber recover board for best results.

OSB and plywood dont take the heat very well which occurs from the black surface of epdm in the summer months; basically it bakes the wood sheathing.

also no matter how diligent you are, there are bound to be some nails or screw heads that will work up and puncture the membrane in the future.

always remember one thing when working on a tight budget; if you cant afford to do the job right, how will you afford to *do it again*?


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## 1985gt (Dec 10, 2010)

We have done a number of them over plywood or OSB. I'm like a lot of others and can not say I'm a huge fan of doing it this way. I would put atleast a fiberboard done. It won't add much at all t the cost.


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## Dave in Pa (Oct 10, 2009)

I am agreeing with you all! I didn't know, thought it was worth a try, maybe? BUT I will spend the money, to insure a good job, for twice does cost more than twice with labor! Even free labor! Beer factor involved! Thanks, for the help guys! 

dave


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## roofny (Mar 18, 2010)

The manufacturers allow OSB. I have not seen any issues with it and actually thought it made for a tighter system. But I could be wrong.


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## LCG (May 30, 2011)

roofny said:


> The manufacturers allow OSB. I have not seen any issues with it and actually thought it made for a tighter system. But I could be wrong.


I ate breakfast with the Carlisle rep today and drilled him on this. Installing over OSB is acceptable. We all know this. I did finally get it out of him that they prefered a primed dens deck. My only issue is OSB is easily saturated and expands with minimal condensation. 

Honestly i'm not a big EPDM guy. I prefer PVC. I would take an EPDM over TPO anyday. Man, I really need to post the report I read on a TPO study in Vegas. UGLY. Can anyone say SCREEN DOOR...


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## OldNBroken (Feb 8, 2008)

LCG said:


> I would take an EPDM over TPO anyday. Man, I really need to post the report I read on a TPO study in Vegas. UGLY. Can anyone say SCREEN DOOR...


Oh I've known that for years. It's getting it's true reputation more and more every day.


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## smalpierre (Jan 19, 2011)

Renegade said:


> Oh I've known that for years. It's getting it's true reputation more and more every day.


I've seen good and bad EPDM. The thin stuff doesn't hold up. It tents at pitch changes, and I'm not a big fan of glued seams - that being said, I've seen the thick stuff hold up really well over time on flats, with little tenting at flashings and curbs.

TPO I'm not sold on, but the seams are heat welded, and there are no plasticizers to migrate out like there are with PVC.

There is no perfect system, but my bet is on PVC for longevity over EPDM or TPO. I'll spec PVC over either any day.


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## smalpierre (Jan 19, 2011)

For your original question - if you've already got leftovers from a job that will cover and glue it, why not spend a little money on recover board and do it right? Sounds like a cheap way to do it right to me!


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## theflynner (Jul 10, 2007)

*OSB + Rubber*

No problem - actually recommended !

When Firestone started issuing 30-year warranty systems, they required OSB board to be the substrate for their roof membrane. They required this because they felt is was the best surface to adhere rubber. They only changed to allowing iso or other boards after they conducted enough testing. (The main concern was delamination of the iso facer). 

John in MN


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