chaikwa

Anyone here familiar with flat roofs that are covered by a rubber membrane? We have had several leaks that are getting more pronounced as the years go by. Someone was in the building a couple of days ago and was commenting on these leaks and said that he thought the roof could be covered with that silver colored, brush-on type mobile home roof coating. I'd never heard of using that stuff on a rubber roof but I have used it on its' intended application with good results. If this is true, it would certainly save me a lot of money that I don't have. I've tried regular roof tar/sealant stuff on this roof and it won't even stick to the rubber when I apply it. When I go to lay it on with a putty knife it just peels up behind the putty knife, rolling right off the rubber.

Any other suggestions would be appreciated as well. This building is over 130 feet long and 45 feet wide, so a new roof just ain't gonna happen!

Adaminak

I think the problem you're having with the sealant is because the rubber has oxidized and the sealant is just pulling the oxidation off. Can you hit the trouble spots with a bit of sandpaper to get to fresh rubber and then try the tar? The mobile-home roof repair is basically roof sealant with an aluminum additive to reflect sunlight and reduce heat soak.

annabelle

I have installed 1000's of square feet of Firestone and other rubber membrane roofs for Ma Bell....now AT&T. Patch it like you would a bike tube...forget the roof tar.....it will destroy the membrane.....best get a pro with the correct material.

Bark

I had to use VM&P Naphtha thinner to clean a rubber roof before I could get anything to stick to it. It was about 50 bucks for 5 gal.
Maybe you could buy a small can and experiment with it.

Wow, a roof that big is gonna cost no matter what you do.

annabelle

Make sure that what ever you decide to coat the roof with is compatible with the rubber membrane......petroleum based products will eat up rubber. I have never seen the product you are referring to used as a roof sealant on a commercial rubber roof.

BC847

^^This.

It's been my experience that, barring mechanical damage, the field rubber (that out in the middle) isn't a problem. Most leaks are where someone made a splice be it to the field rubber or the HVAC curbs, pipe witch-hats, or walls, etc.

That being said, by default suspect any existing seams. A lot of times, one can simply press around a suspect seam and see water squirt out.

- If you find an existing seam has failed, pull it apart and clean all the loose glue and stuff from it. Allow it all to dry thoroughly.
- Clean the rubber very well 6 to 8 inches around the hole (both surfaces). To the point of mechanically abrading it.
- Use a quality rubber compatible contact-adhesive. Apply as per the recommended instruction to both surfaces. Allow both surfaces to dry tack-free (5 minutes?).
- Without allowing the surfaces to touch, position the stuff where you want it to be, then bring them into contact with one another (you can't have them touch, then pull apart to reposition).
- Starting from the center of the repair, firmly roll out to the edges so as to ensure a good bond.

**UNDERSTAND: The above does not make the splice water-proof. The above is only the mechanical bond.

- Now go around all the seams with a rubber compatible caulking to make it water-proof. The applied caulking should feather-out toward both sides of the bead.

Applying asphalt based roofing compounds to a rubber roof is like trying to teach a pig to sing. You only waste your time and annoy the pig. Same results using silicone based caulks, etc.

annabelle

Does your roof have ballast on it or is it bare? You may want to consider walk mats to access mechanical units so that you aren't walking directly on the membrane.

chaikwa

If I could find someone around here that would entertain the idea of REPAIRING, I'd do just that. Everyone I call said they won't repair, only replace the whole roof.

This roof is FULL of seams. About every ten feet width ways, about 40 length ways. And they NAILED it to the plywood underneath, so it could be seams or nails leaking. Or both.

What would be a compatible caulking? I've been told this is probably an 'EPDM' or EDPM' roofing rubber material. (I forget which is the proper abbreviation).

Thanks all, 'preciate all the help!

chaikwa

Missed your latest post while I was posting a reply.

It is bare. 2X12 framing with 5/8" plywood overlay, with the rubber on top of it. No roof units of any kind up there.

I forgot to mention that it looks like they sealed the seams with something white in color. And it was spread with a brush because you can see the brush marks in it.

annabelle

Sounds like the white paint was an attempt to fix leaking. I have always seen the seams lapped about 6" using the glue BC847 speaks of and rolled smooth.......never had a need for any need for seem type caulking to alleviate leakage. The only way I have seen leaks at a seam fixed is a thorough cleaning of the seam about 12" across. then a 8-10 piece of rubber adhered over the seam and rolled smooth......but Bell had some fairly rigorous procedures they made you follow......of course they have millions of dollars of equipment under their roofs.

dodgeguy71

Chaikwa,

I have to agree with Adaminak and annabelle. Been on many a roof welding pipe and seen them up there installing or patching it and they have a special glue for it. The contractor on the job was up repairing some and had a 5 gallon bucket of glue and some rubber. He'd cut off a piece, brush on some glue and stick it to it.

Blake Clark

http://www.koolseal.com/product_fami...ly=rubber_roof

BC847

Blake, that's good stuff but not for EDPM rubber roofing (it is formulated with an EDPM component however).

FYI for folks, EDPM -> http://en.wikipedia.org/wiki/EPDM_rubber

The EDPM roofs typically are either loosely layed and basically held in place by loose river-rock ballast. Or, are completely adhered to the roof structure and lay fully exposed with no ballast. There's pros and cons to both.

@ chaikwa. The typical roll of EDPM is 10' in width. As such, you'll commonly see it installed as you do.

You say it's nailed down. Where? In the field-seams or in the field-rubber itself? Is the field-rubber glued to the roof structure or is it floating on the structure?

Blake Clark

Thanks Dave

We have used it on all different kinds of roofs and it said it was good for rubber. Didnt know Scott had weird rubber.....

chaikwa

Looks to be nailed on each rafter on 16" centers.

Don't even GO there!