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Old 06-10-2013, 12:10 PM   #1
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Flat Roof Repair Advice


Hi,

I have a flat roof on a brick twin. It has a good grade to it to shed the water. In general it is in good condition and there are no leaks. The house is 100 years old. I've been there since 2000 and had the roof coated every few years. The past few years, the silver sealer has been flaking off. I notified the roofer and they came and recoated it in the past 6 months or so. It has continued to flake off. So I got up there over the weekend to evaluate the situation. There is a huge old oak tree with many branches over my roof. I love the tree because it keeps my house very cool. What I found was that the roof was coated with slimy stuff, probably growing a little of something from the shade and water. Where the water pooled at all the flaking was much worse. So I power washed the roof and used a little bleach to kill the slimy growth, and power washed several times to rinse after leaving the bleach sit for a little while. My theory is that the roofers coated over slimy stuff and that is the reason for it not adhering. Now I have a nice clean surface that is not slippery or slimy at all. In many areas the coating is completely off and the rubber sheeting is exposed. It is slightly dried out but soft to the fingernail and seems to me like a sealer should stick fine to it now, but before I seal it, I wanted to get some advice.

Is there a better, more adhesive something I can lay down before the standard silver sealer that will make it adhere better?

Also, there are low spots in my roof in certain areas. Again, there are absolutely no leaks but the low spots hold water too long and are causing stuff to grow and rot. I'm not going to spend the money at this point to replace the entire roof and fix the low spots the right way, it's just not in the budget, this is going to be DIY. But I'd like to do the best job I can with my budget and have it last as long as possible. I know that means doing things that a roofer would not do, and would not leave in that condition and be liable for. I am not asking for how it would be done professionally because I know the answer - tear down and replace. What other ways would there be to bring up the level in some areas and inch or so to keep the water running off and eliminate the pools in certain areas? I was thinking of buying a roll of rubber roofing sheeting and layering it in, then coating it with black muck roofing cement, then sealing it with the silver sealer. My roof beams are huge and strong and there is absolutely no issue with weight - it could hold a truck.

I just want to shed water and make this thing last a couple of more years and not have all the flaking.

Thanks for the help

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Old 06-10-2013, 12:25 PM   #2
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Flat Roof Repair Advice


You said that the "rubber" is exposed in areas where the silver coating has flaked off, leaving me to believe that you have a membrane type roof. Likely to be EPDM. If that is the case, then it needs to be coated with a product compatible with EPDM, not an asphalt based product. Overlaying the surface with another membrane will not solve drainage issues. If it dries off within 24 hours after the last rainfall, then drainage is not really a particular issue anyway. Drainage planes on flat roofs are created by tapered insulation systems under the membrane or by building slope into the deck. You absolutely do NOT want to apply an overlay to a rubber roof and then muck it in with an asphalt mastic. EPDM and asphalt are not compatible. The oils in the asphalt can attack the rubber. Most aluminized coatings are meant to be applied over metal or asphalt based roofing systems, not EPDM. There are reflective coatings meant for EPDM. Make sure you are using the correct one. And that is making the assumption that it is in fact EPDM. There are other membrane sytems. Each being different.

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Old 06-10-2013, 12:47 PM   #3
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Flat Roof Repair Advice


OK, thanks I get that. I will try to figure out what I have for layers or take a picture to figure out what I have. Thanks!
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Old 06-10-2013, 12:49 PM   #4
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Two options.

This is if you have a asphalt roof with silver alumacoating. From your description that is what it is.

1. Clean off roof like you did, allow to dry for 48 hours with no moisture getting on the roof. Prime the low spots with asphalt primer. Allow to fully flash off. Coat the entire roof with Fibered Alumacoating enjoy until ponding water damages coating again.

2. Install 1/2 coverboard and EPDM. Trim off with new edge metal ect. Do not use any asphalt based products at all on EPDM as they will damage it.

Take a picture and post it up. If it is an asphalt roof, you could also fill the low spot in emulsion or other ways. But the question is why is is ponding? is the roof sagging? is the insulation under compressing because of moisture in the system?
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Old 06-10-2013, 01:42 PM   #5
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Flat Roof Repair Advice


You have some contradictions in your post. First you say you have good slope, then you say you have areas that pond water.

Post a couple of pictures of what you have, so we don't mislead you.
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Old 06-10-2013, 01:58 PM   #6
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I just meant that the roof has a good slope in general, over all. I'll get some pictures.

I have always had some big pools at the bottom of the roof - not sure how it got compressed, probably years of water sitting on there. It's been that way for the 13 years I've lived there and no leaks or issues inside so I just keep limping it along...just trying to stay ahead of things to try to avoid a big bill I can't pay right now and keep the water out any way possible.
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Old 06-10-2013, 02:13 PM   #7
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Flat Roof Repair Advice


Quote:
Originally Posted by braddgood View Post
I just meant that the roof has a good slope in general, over all. I'll get some pictures.

I have always had some big pools at the bottom of the roof - not sure how it got compressed, probably years of water sitting on there. It's been that way for the 13 years I've lived there and no leaks or issues inside so I just keep limping it along...just trying to stay ahead of things to try to avoid a big bill I can't pay right now and keep the water out any way possible.
That generally happens when the installer does not use tapered edge at the drip edge to increase the slope there. The roof is installed, then drip edge metal is nailed on, then the flange of the drip edge is stripped in with flashing cement and fabric, or a couple of plies in hot. This results in a built up mound just before the gutter. Metal moves at a different rate than aliphatic materials, so Invariably the joints at the tie in fail. Somebody then comes in and coats the tie in with more flashing cement again, and again etc etc.

If your insulation has become compressed it is probably wet, and turned to mush.

Hose down your roof, then send pictures.
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Old 06-10-2013, 03:49 PM   #8
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Flat Roof Repair Advice


Here you can see the pools at the bottom of the roof....and the redirect someone previous installed to get some of the water to go to one side instead of all in the middle - I can see why they did that.

It just got done pouring rain so this is the worst it gets.

Also, in the close up you can see the black material and a scratch I made with my fingernail.

From what I've heard so far I think I want to use a bit of insulation and then cover it, seal and coat. Need help understanding where to get all the materials and what exactly they are.

Thanks







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Old 06-10-2013, 06:17 PM   #9
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Thank you for the good pictures. You have several issues that should be addressed in the future when you re-roof:

1. The chimney has been gooped up over the years. I would completely remove this and install a metalbestos chimney when you re-roof.

2. Whoever put the diverter in knew very little about roofing. It should come out when you reroof. It may have been a half axed means of trying to pull up the joists below.

3. You have deflection in the joists from the drip edge running forward about 10 feet. Again I would address the joists when you re-roof.

For now, you should:

1. Pressure wash all of the loose crap and coating off the roof.
2. Prime the roof with a light cut back coat of ASTM D-41 Asphalt Primer. Let dry.
3. Coat the roof with two coats of Non AB fibered aluminum roof coating with a 3/4 inch Nap roller. Stir aluminum coating continuously.

It is probable that you have quite a few roofs in place now, you most definitely do not want to put another one over what you have. You may even have a standing seam metal roof under there, a couple of roofs down.

Addendum: I just looked at the close up you posted of the surface of the roof. It appears to me that you have an APP torch applied modified bitumen membrane in place that was coated with aluminum. The striations in the surface of the membrane are indicative of this type of membrane being installed in cold weather when the membrane has been left out in the cold. I have also found this in some of the really poorly formulated Modified sheets that have gone belly up and are out of business. It is important that you keep this roof well coated with a fibered coating to prevent leaks.

I don't think you have too many more years left in this roof, before complete removal to the deck will be required.
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Last edited by jagans; 06-10-2013 at 06:47 PM.
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Old 06-11-2013, 01:05 PM   #10
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Flat Roof Repair Advice


To update my post,


Yeah don't put another layer on. It likely does have a lot of layers.

I would how ever use fibered alumacoating. Not sure what Jagans has against it

There was one APP sheet 20 or so years ago that no coating, or anything would stick to, I don't recall the name but I know the company is no longer in business.
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Old 06-11-2013, 04:55 PM   #11
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In all my years I've never really understood the exact reasons why we never use fibered. It's just one of those things that that's what we were taught and that's the way it's always been. Only reasonable explanation I give is that it's just a coating. Fibered or non-fibered accomplish the same thing. UV protection for the roof system. Since they are doing the exact same thing and it is cheaper and much easier to apply, the non-fibered has always been the way to go. You don't gain any added benefit from fibered.
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Old 06-11-2013, 05:11 PM   #12
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Quote:
Originally Posted by OldNBroken View Post
In all my years I've never really understood the exact reasons why we never use fibered. It's just one of those things that that's what we were taught and that's the way it's always been. Only reasonable explanation I give is that it's just a coating. Fibered or non-fibered accomplish the same thing. UV protection for the roof system. Since they are doing the exact same thing and it is cheaper and much easier to apply, the non-fibered has always been the way to go. You don't gain any added benefit from fibered.

From my experience the fibered holds together better in ponding areas, and also in transitions.

The main thing is to prime the bad areas IMO.

But yes in this case if your looking for a couple of years, go none fibered. as it is cheaper.
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Old 06-11-2013, 05:18 PM   #13
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Quote:
Originally Posted by 1985gt View Post
To update my post,


Yeah don't put another layer on. It likely does have a lot of layers.

I would how ever use fibered alumacoating. Not sure what Jagans has against it

There was one APP sheet 20 or so years ago that no coating, or anything would stick to, I don't recall the name but I know the company is no longer in business.
Go back and read my post. I did recommend the use two coats of fibered aluminum in this case, just not asbestos fibers. Believe it or not, AB fibered is still available, and really is the best, at least it was the last time I checked. On this particular project the fibered may have a bit more crack bridging ability than the non fibered.

Karnak has always made pretty good stuff, as well as Bulldog, but the best aluminum coating I have ever used is the stuff sold by Tim Barrett (an old friend, and a very old name in the roofing industry) They use it to coat their Ram-Tough membrane. Its expensive, but it lasts twice as long as the others.
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Old 06-12-2013, 08:41 AM   #14
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Thanks all for the replies, keep them coming. I am learning a lot and considering all of the options.

Can your friend Tim Barrett sell just the coating? I am considering using only the best of everything for this repair. If it buys me twice as long that is worth it to me for sure. And I don't want any flaking after this so I'm going with two coats for sure...the best primer (need recommendations), and then two coats of the best fiber coating...this sounds good to me at this point from listening to everything. Would two coats of primer be better than one or worse?

I am even close enough to Millington, NJ that I could drive there after work to pick it up from Barrett but my guess is that they have some closer to me near Philadelphia somewhere with someone that does their work in this area.

Also, what is the ideal weather to apply these coats in? What temperature and how long sunshine is ideal before rain? I was thinking of washing it in the evening, brooming off the water then letting it dry for a full day, then applying the next morning just after the sun hits it around 9AM and making sure it's not going to rain the rest of the day...so two full days of sunshine, one before and one after. I think this is important to my situation given the existing flaking and the mostly shaded roof.

Now that I've gotten into this I'm thinking I'm going to do this repair the best way possible to last as long as possible. So far I'm thinking materials are only adding up to a few hundred dollars if I'm correct, so if I can spend a thousand or even two and make it last a few more years I may want to do that.

But it also depends on what I'm going to do with the space up there...and this is one of the reasons I am delaying the full replacement. In a few years I might decide to put a deck on the back part of the roof and a small box of a room on the middle of the roof, with a spiral staircase up to it...no plumbing, no HVAC, just a basic structure with huge windows and screens - only screens during the warm months, and possibly a green roof on top of the room...the room will be my office, hangout and place away from the family noise. And I should have the funds for it in a year or two, maybe three.

So I may be talking to Barrett roofing at that point. Looks like they do great green roofing stuff. Thanks for that recommendation...and they are close to me which is good.
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Old 06-12-2013, 09:00 AM   #15
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Anybody can buy it, but there is really no sense for you to apply a high end coating to that roof. A coating is not a roof. I used the coating in question, Ultra Silver, on a mop applied SEBS roof with polyester felts that was a 220 foot high right on the Atlantic ocean. The roof was in the configuration of a V with the open end facing west. There were exceptional problems with blowoff of 4 previous roofs in 17 years, so I did not want to use gravel ballast for UV protection. I used two coats of the Ultra SIlver. I went back there in 2002 10 years after it was installed, thinking it would need a re-coat and the silver coating still looked new.

I would recommend that you use a white Acrylic elastomeric coating like Firestones acrylitop, but I am not sure about adhesion to a roof that has been previously coated with Aluminum. I think your best bet is to do what we said in a prior post. Prime with a light coating of D-41 primer that has been cut with a solvent like mineral spirits, let it dry, then apply two coats of fibered aluminum like Karnak 97 or the like. Again, check with Malarkey out where you are, they probably have a good coating. VOC is probably going to be a problem in CA though.

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Last edited by jagans; 06-12-2013 at 09:28 AM.
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