Flat roof suggestions

My house (built in '54) has an addition (approx. '65), that has a flat roof. It's about 12'x15'. Currently, it's got a steel roof, consisting of ~18"x24" panels, welded together. I have no idea how old it is, but it has many pinholes in it, and leaks. In a half-assed attempt to curb water's intrusion into my dwelling, I slathered it with some rubberized coating (only marginally better quality than the screen door boat stuff).

It's lasted a year or so, but now it's time to come up with a more permanent solution. What's a GRMer to do?

Is the flat surface surrounded by parapets or do the edges drop off?

If you are parapet, TPO roofs are about the best I know. They are a little more, but last well. If you are dropping off, I would need to know more about your slope. Maybe you could spray foam it, but around here the spray foam has become a four letter word. Leaks are very hard to find, and there are many to find and short life in the hot sun.

Rolled rubber roofing material might be your best bet.

The problem with anything you spread on the roof is that UV radiation breaks everything down. That's why you see gravel on flat roofs so often, rock doesn't break down and pretty much everything else does.

I assume appearance isn't particularly important, a heavy roofing tar might buy you a few more years. As small as that area is a 5 gallon bucket will give you a thick coating. Look for UV resistance.

I should add, this is a first-floor room of a two-story house, that's on the north side, so it gets little, if any sun.

Also, there is access to it from the room above, making it balcony-like. So, something durable enough to walk/put chairs on would be beneficial.

In reply to former520:

I'm not an architect. What's a parapet? The edges just drop off, like the panels are folded over, if that helps you get an idea.

In reply to KyAllroad:

Should I tear off the existing metal roof, or just lay the rolled rubber over it?

In reply to RealMiniParker:

You need a flat surface for rubber, so whatever option provides that would be best. Also, there are different categories of rubber. On our building, which is really 2 adjoined buildings, we put a rubber roof on the 2-story side, but then a different material on the 3-story side...it's more of a rubber-like membrane, is white vs. black so it helps keep it cooler, and is almost twice as thick. For each of our ~1750 sq-ft roofs the price difference was about a grand between the two. So yours should be marginally more expensive. Also, anything on a flat roof can cause leaks, so you may want to consider a raised deck over the top, or to stop using it as a balcony/deck.

You might look into Hydro-Stop. I used it on a low slope addition on my previous house.

How flat is flat? If you put a level on it, would it read level, or are we dealing with something more like a 3 to 5 degree slope?

If somebody actually made the thing flat, how much trouble would it be to raise up the end near the house and get something with a bit of a slope?

We use rubber on our 9x9ish flat roof between the garage and the house. My parents put a new one on when they moved in, and about 25 years later we got another one with newer better materials. Holds up fine year round, and even supports me when I need to clean the gutters or trim trees behind the house.

On the north side, you want a 60 mil unreinforced or 45 mil reinforced EPDM (rubber) roof. If the metal is solidly attached, I would leave it and install a 1/2" recover board with fasteners directly through it to the framing or sheathing below. Then install a metal roof edge trim and fully adhere the EPDM over everything, with a strip of EPDM flashing all the way around the edges.

On that small a size, you can do it yourself, but I'd consider getting a pro in.

Nothing is going to take traffic well. You can get heavy EPDM walkway pads and basically adhere them over the whole roof. But the best bet would be to build a wood deck that spans over the membrane without touching it more than absolutely necessary.

This is my business although I do it for almost exclusively Commercial clients. EPDM is the way to go (in your case). Thermal plastic's are good and have there place but if you need to fix anything home depot carry product to make repairs. Sika Sarnafil (PVC) or any of the TPO manufactures are not available at the local big box hardware stores and unless you are a certified contractor you can not purchase it from the MFGR or there distributors.

If you are worried about foot traffic or damage from something I strongly recommend the Sky Paver system that Firestone sells. Install this over a drainage mat and the roof is virtually bullet proof. This is over kill for your needs but it is a great system.

As for EPDM use the seam tapes not the splice adhesive or better yet install it so there are not field seams (get a piece from a 20 foot wide roll if you can find a roofer that would sell it to you. If you have to have a seam make sure it is lapped with the flow of water and never allow a seam to fall in an area where there is any kind of stagnant water. Use cured EPDM membrane for flashing and only use the semi cured or uncured EPDM when absolutely necessary. Strip in any seams and base wall flashing seams with a 2nd layer of the self adhering flashing (Firestone PS40-20)

Take the time and spend the little bit of extra $$$ and have proper edge metal (gravel stop) installed with continuous hook strips that are fully crimped in place. .032 alu with a kynar or hylar finish. I like Atas as they give a 20 year finish warranty. Stainless steel would be better as would copper or Lead coated copper but these area all $$$$. Your roof is so small this cost should be negligible. All flashing should be a minimum of 8" in high at walls or other penetrations.

I could go on but these are some of the things that come to mind. I have made a very good living from poorly installed roofs. You would not believe the things I see. Oh and I could write a book about the things I have found on roofs.

dean1484 wrote: Oh and I could write a book about the things I have found on roofs.

I think you should at least start a thread about it Dean!

The following assumes your roof has at least a 2% slope (1/4" per foot). If it doesn't, add decking amd furring to the reroof project requirements.

I'm not a fan of single ply roofs, because they're one ply. One cut and you are chasing that leak.

EPDM seams require an adhesive seal. Those work but eventually they fail. TPO or PVC single ply membrane seams, on the other hand, can be hot air welded, which I personally believe is favorable to adhesive seams.

Cover the new membrane with a 2nd "sacrificial" loose sheet of the same membrane to resist rubbing from foot traffic, and then lay down ballast pavers like Dean suggested.

Now might be the time to add rigid insulation also if you need it.

Be sure to check with the membrane manufacturer about asphalt compatibility, if your roof above happens to be shingles. Some single ply membranes degrade in the presence of asphalts.

Thanks for the advice, guys.

Losing the balcony-ness of it wouldn't break my heart. I don't use it for that any how, as it is - mostly going out there to clear snow and the gutters.

RealMiniParker wrote: In reply to former520: I'm not an architect. What's a parapet? The edges just drop off, like the panels are folded over, if that helps you get an idea.

Then you don't have a parapet. A parapet is a wall around the edge of the roof. Basically the walls are higher than the roof.

I am disappointed. Not one mention of plasti dip or spray on bedliner so far.

In reply to curtis73:

Nope. I got none of that. I also learned what it was, while reading up on flat roof membrane coverings.

OHSCrifle wrote: The following assumes your roof has at least a 2% slope (1/4" per foot). If it doesn't, add decking amd furring to the reroof project requirements.

Per the IBC Only required on new construction here in MA. Existing slope (no matter how low) as long as it drains and you don't get ponding (3/4" of water after 24 hours) is acceptable. There are also provisions for dealing with low base flashing hight but if any of this comes in to play then there are design considerations for augmenting the membrane roofing system.

OHSCrifle wrote: I'm not a fan of single ply roofs, because they're one ply. One cut and you are chasing that leak.

True but there are only ackers of it installed very day. IF you are having issues with cuts then you are not managing the roof access properly or the service people need to be spoken to it is funny once you back charge an HVAC contractor for the couple of square of roofing that there tec got wet because the damaged the roof they all of a sudden get alot better about things. If you are getting cuts in the roof with out any one up there then the roof was not a good design choice for that installation application (probably a cold process BUR system of some sort should be considered) but they have there own list of issues.

OHSCrifle wrote: EPDM seams require an adhesive seal. Those work but eventually they fail. TPO or PVC single ply membrane seams, on the other hand, can be hot air welded, which I personally believe is favorable to adhesive seams.

Yes and no. The new technology is seam tapes (been around 15 years or so). The old glued seams with splice adhesive were just stupid as the adhesive was susceptible to degradation when exposed to water. The seam tapes do not suffer this mality. I always use the 30 year seaming spec that requires stripping in the seams with PS4020 (or equal) even if it is a 10 or 20 year warranty. Cheap insurance that the roof will last. The reputation of the original seam technology using splice adhesive and lap sealants and inseam sealants just does not apply to the "new" seaming that uses seam tapes. In his case that roof is so small it should not have any field fabricated seams anyway. Installing it with a sam would just be poor installation practice by the installer (again how I have made lots of $$$$)

OHSCrifle wrote: Cover the new membrane with a 2nd "sacrificial" loose sheet of the same membrane to resist rubbing from foot traffic, and then lay down ballast paver like Dean suggested.

I strongly recommend that you eliminate roof traffic if possible. It is a roof not a patio after all. If you do this then it is imperative that you don't have any field seams. I would recommend using a drainage pat between the paver and the EPDM it will alow water to get off the roof from under the pafers easier.

OHSCrifle wrote: Now might be the time to add rigid insulation also if you need it.

Code may dictate this anyway. Depends on if the area under it is conditioned, depends on if it is internally insulated. depends if you are leaving the old roof in place. This is spelled out in the code. And then there is the applicability of the stretch code. It is never bad to add insulation but with the IBC energy code you need to be aware of a lot more than just R value. Things like the need for a vapor retarder and depending on the specific roof assembly if there is an effective vapor barrior in place is it above or below the condensate point in the new assembly will then dictate the need for more insulation or possibly the need to remove the effective vapor barrier and installing a new one in the proper location in relation to the added insulation.

OHSCrifle wrote: Be sure to check with the membrane manufacturer about asphalt compatibility, if your roof above happens to be shingles. Some single ply membranes degrade in the presence of asphalts.

EPDM this is not really a problem. I have standard details I could give you to keep things separate. You don't want direct contact for an extended period of time and there are standard details to deal with this. Hacing a single roof up slope from a EPDM roof is a non issue. On the other hand EPDM does not play well with animal fats of any kind. Vents from kitchen stoves or fryers or grills are always something you have to be careful with on an EPDM roof. PVC on the other hand does not play well with asphalt. It will suck the plasticize-rs out of it very quickly and cause the PVC to breakdown and get very brittle and crack.

Good stuff Dean! I only mentioned foot traffic on the roof because he said it was a porch (though rarely used).

ncjay wrote: I am disappointed. Not one mention of plasti dip or spray on bedliner so far.

Is it ok to get any of the roofing sealants/adhesives on your hootus? If, no when, it happens what is the best way to get it off?

Good thread. I have a small porch that forms part of the roof of my sunroom/screened porch below. It has some sort of black rubbery looking surface and is covered with some outdoor carpet. It leaks when it rains really hard and I have been reluctant to try to fix it. It is a job that I think I will farm out to a roofer instead of tackling myself.

People put astro turf over epdm roofs and then have parties. High healed shoes are bad.

The local home improvement store has EPDM in sheets large enough to my roof without a seam. I grabbed their installation guide and whatnot, and did some reading. Doesn't look too dangerous, for a GRMer.

That sounds good. You can do it. Just don't leave a substrate that'll punch holes from below, and terminate every edge knowing that water moves very reliably by gravity and can also be pushed around by the wind. So lap the joints and terminations with all that in mind and you should be able to pull it off.

For flat roofs, I prefer the 60 Impala.