Flat roofs

[Wolf Kiessling]

That posting the other day re the gutter ice formation on that flat roof got me to thinking about a problem I may/or may not have. My rent house has a garage with a flat roof. It is covered with rolled roofing (don't know what grade) and sealed with, I suppose, tar. I have had this house for seven years and the roof never leaked except one time. This is why I say I may/or may not have a problem.

About five years ago we got hit by an ice storm. We got doused with freezing rain and then everything was covered with ice. We had many broken trees, power lines down, etc. Anyway, during this ice storm, the garage roof leaked like a sieve. After the situation cleared up, I figured the roof must have buckled or something and consequently developed a leak. I inspected the roof and found no problems whatsoever. As mentioned, this has not happened again. This tells me there is no leak, opening, fissure, crack or other kind of opening in the roofing material.

Would someone have any idea what happened here? Any remedy to keep this from happening again if/when we get another ice storm?

Does anyone here have an answer to this possible dilemma? Thanks.....

[Ernie Nyvall]

Wolf, the ice sitting on the roof started melting underneath first. With this type of roof, the water had no where to go and found some cracks you can't see. The tar they probably used up there will get hard in the winter and get hair line cracks. Then in the summer they may close up a bit. Ice sitting on a roof acts completely different than rain so it is very possible for it to leak with the ice and not during a rain.

I don't know that the tar used on big building flat roofs is any different, but that that comes in a bucket is the worst thing to patch a roof with. I used to repair a lot of roofs behind someone who had patched shingles or roll roofing with this stuff.

The best thing to do since there is probably not the support for a real flat roof covering, is to put a pitch on it with shingles and forget about it. Otherwise, you might get some of that liquid tar and paint it on each year until it gets so heavy you have to tear the roof off and start again. New roll roofing done right might get you 5 years depending on how flat and how much the outside temp ranges from summer to winter.

It's possible there is something new to put over the tar, but I haven't done that stuff in a while and wouldn't know.

Best of luck,

Ernie

[Jim Dunn]

Wolf, here in the midwest I think for a roof, make that not a builder so I'm not sure at all, you want atleast a 4 in 12 pitch. This makes the water run off before it gets a big chance to freeze. Also the pitch angle is so high that, with roofing shingles anyway, the water under the ice can't climb up high enough to get around the nail holes kwhich is realy the only hole in the roofing material.

[Wolf Kiessling]

My gosh, the solution sounds really problematic. Since it is a rent house, I may just have to let it go and hope like heck we don't have any ice storms for a while. If we do get hit, just let the renter gripe about it :-)))))

I was just thinking, though, about 20 years ago, or so, seems to me there used to be some stuff that was sprayed on a roof. If memory serves, it was maybe a foam and usually white. Is that stuff any good, is it still in use. I don't think I've seen it around for years. Would that work on a flat roof? I even thought about a rubber roof like you see on many RV's but I don't think they're all that good. I had one on one of my RV's and, again if memory serves, I think I had some problems with that. So many questions, so few answers........

[Bill Lewis]

Wolf,
HGTV, "Dream House" show is following the construction of a modern style house in the Boulder CO area that has a flat roof. They used a spray roof system that sounds like what you remember. They stated that it is typically used for commercial applications. I can also attest to that as I have also seen it used on a flat roof where I work. You may be able to find more information about this roofing system from the HGTV (http://www.hgtv.com/hgtv/shows_drh) website