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zmt 02-16-2010 07:04 PM

Flat roof repair/replacement questions
Hi everyone, (long post ahead)

first of all, I'm just going to go out on a limb and guess that my situation is unique, but I'm looking for any help I can get.

I've got a house that I purchased about a year ago that has a flat roof. well, flat roofs actually. The hosue has been described as a "european second empire" style house with a mansard roof, but I would guess most people would just call it "weird." Here's a picture so that people can get an idea of what I'm dealing with.

The lower levels of the house (including the garage) appear to have an SBS modified bitumen roofing on the flat sections, and the tallest, 2nd story roof looks like it has some sort of built up roofing. The house originally had cedar shake shingles on the vertical portions that we had replaced with decking and conventional shingles.

When we bought the house we knew that the flat roof sections' days were numbered but were able to get the house for cheap enough for it not to matter. Since buying the house we've had to patch a couple of sections near the flashing on the flat portion of the roof that have leaked (we think from where the roofers damaged the seal while installing the shingles), and have some leaking in the garage.

I guess my big question is, what should I do with the roof now? I'm looking for options, and hopefully going to try and settle on an solution with good cost-benefit and ROI aspects. I think my big options are to either redo the flat sections with any one of a myriad of systems (BUR, modified bit, EPDM, PUF, etc) or to try and get a plan drawn up for adding a pitch to the roof. I'd love to hear from some professionals on what they think would be the best course of action.
Is something like a peel and stick modified bit roof something that a non-professional like myself could tackle? Are they any good?
Would a spray foam roof be better here in Texas and do they actually work as advertised?
Does the weird shape of the house make pitching the individual sections cost prohibitive? Anyone have ballpark figures on pitching a roof that looks anything like mine?

I've been thinking about all of these things for a long time and haven't really come across information that's applicable to my specific situation because there are so few flat roofed houses down here, and even fewer that look like mine!

Thanks everyone for taking the time to read all of this, and I'd appreciate any and all information you guys have that you think would work, including any other places where it might be handy to post this kind of question.

Cliff's notes: Have weird house with flat roof (see picture), dunno whether to replace with another flat roof or spend money to pitch it, dunno how much it would cost.

Grumpy 02-17-2010 08:53 AM

Where you are located and your budget will determine your next step in the roofing. If you are looking to get a quick 10 years out of the house and flip it, then I would suggest an elastomeric roof restoration over the existing. It's cheap and when done properly will buy you some time. If you are looking to stay in the house I would suggest a single ply roofing system. Where you are loacted will partially determine what kind of single ply.

As far as spray foam goes, it is highly specialized. Most of the guys I know doing spray foam don't do residential, only commercial. ALL of the spray foam I have seen has been a failure due to installation error. I'm not an advocate for nor against spray foam. Like ALL flat roofing systems it will leak if not done properly.

If you were in my area, Chicago, I would be suggesting either a white TPO or PVC. White is good due to the reflectivity, epdm would not be my choice because it's black and I would think in texas you'd want to reflect the heat. I also prefer the heat welded seams on a thermoplastic roof (tpo and pvc are thermoplastic) vs the taped or adhesive seams on a thermoset (epdm is thermoset). PVC has a more proven track record than TPO, while TPO is cheaper. In addition, replacing all of the edge metal would be a must no matter what roofing system you chose (other than a restoration). Also now is the time to consider roofing insulation... again how much and what kind is determined on your location. I really don't know the texas recommended standards. What about a tear off? That depends on how many layers you have and if you think there is any bad wood beneath the roof.

The addition of a pitch to the roof is easily done one of two ways. Tapered insulation, or if you think you have alot of bad wood, just build a pitch into the framing structure. On a building of your size, the costs would be a wash either way IMO. If you're looking for faster, easier and more insulation value, go with the tapered. Reframing the structure may leave it exposed. However with a TPO or PVC, puddles are not warranty exclusions so unless you have puddles more than 1" deep I wouldn't worry about it. Puddles 1/2" deep which evaporate within 48 hours are totally acceptably by nearly every material manufacturer. It's almost impossible to have a flat roof without some sort of puddle.

Here is a write up about commonly asked flat roofing questions which I wrote to help my customers make educated decisions. If you have any specific questions, I'll be happy to answer.

As for this mansard style roof being unique, it's not. I have worked on several and am in the process specifying the best solution to one very similiar project in Lake Forest, IL. It's a nice house you have, treat it right.

Grumpy 02-17-2010 08:54 AM

You may want to contact Rayburn roofing. I am not sure if he does residential, but I know commercial flat work is his specialty and I know he's somewhere there in Texas.

zmt 02-17-2010 11:28 AM

Thanks for all the help grumpy, I really appreciate it. Here's my brain dump after reading your post, sorry if it's a bit disorganized.

I forgot to mention TPO as an option, but it was something I've looked into. With most of the people I talked to it was one of the more expensive solutions, but if I can get a lot more longevity out of it I would definitely take it into consideration. What is maintenance like on a TPO/PVC roof? Is it something a fairly handy homeowner could keep up with?

Is there any way to really know the condition of the wood underneath the roofing material without actually removing it? I bought the house as a foreclosure and have only been there a year (the house also sat vacant for about 9 months while I tried to buy it, long story) so I'm not sure about the history. There really isn't evidence of water infiltration inside the house other than the garage, but I doubt that speaks to what's going on up on the roof itself.

re: replacing the edge material. I would love to do that, the stuff that's up there now has seen better days and wasn't treated well by the roofers that put up the shingles. I think it was a galvanized aluminum, any idea if it's possible to get it in colors? The roofers that did the shingles decided to spray paint it and well...

I was planning on putting some additional insulation in the void between the roof and ceiling if at all possible, but I guess that would require a teardown. Any idea if spray foam insulation can be applied from the outside-in, so to speak? All the applications I've ever seen go from the interior -> exterior.

When I talked about pitching the roof before, I actually meant building a pitch (2/12 at least) with trusses/framing and shingling that. I'm not sure how tying it into the existing shingled roof would work, but that's why I'm asking questions! :) Any experience with something like that, or anecdotes about why I should/shouldn't? I've heard from both real estate people as well as roofers/construction people that replacing the flat roof with a pitched one (I guess it would technically make it a gambrel at that point?) would be the "perfect world" solution, but I don't even know where to start going about getting ballpark figures for that sort of thing.

I live in the DFW area, know anyone there you'd recommend talking to?

ok, I think that's about it! :surrender:

AaronB 02-23-2010 11:24 AM

Yes, Spray foam is a viable roofing system, as long as your applicator knows what he is doing.

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