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Estimated cost to install insulation1500'underEPDM


rommell2
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I'm buying a house with an 8 year old flat rubber roof in Reno, NV that has drainage problems. There is standing water for days after storms with a few water stains on the inside. Old or new I don't know. The rubber has been laid over a hot mop roof but is only attached on the edges so the newer rubber is not connected to the under lying older roof. It springs around when you walk on it.

I had a routine physical inspection and the inspector suggested an expert come and take a look. Problem is, there doesn't seem to be any in Reno. This roof is unique to the area.

Any ideas regarding the roof and more importantly, any inspectors in the area?

Thanks in advance

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Hi,

Try to find out the brand name of the product and call the manufacturer. If you can't determine the name, google 'rubber roof' and then contact Firestone and one or two other rubber roofing product manufacturers, ask to speak with their technical assistance department head and then ask for the name of the best flat roof guru in your area.

I did that once many years ago and two different manufacturers knew one guy's name right off the top of their heads and said he was without-a-doubt the best flat-roofed guy in my area. I took their advice, called the guy and you know what? They were right. They guy was a guru and I referred every difficult flat roof issue that I couldn't adequately investigate/comment on to him for years until he retired.

But I digress. My point is (I have trouble staying on point - adult A.D.D. and all) that these guys know who they sell their products to and they know who they get questions from and the quality of those questions allow them to determine whether the guy calling is a turkey or really knows his stuff. I think they'll be a better source for you than we will.

ONE TEAM - ONE FIGHT!!!

Mike

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Originally posted by rommell2

I'm buying a house with an 8 year old flat rubber roof in Reno, NV that has drainage problems.

What do you mean by a "rubber roof"? Is it EPDM, PVC, modified bitumen, or what? I've found that people call all sorts of things "rubber roofs." The specific material makes a huge difference.

There is standing water for days after storms with a few water stains on the inside. Old or new I don't know.

How much standing water? How many days? While the rule of thumb is that water shouldn't sit there more than 48 hours after it stops raining, some modern membrane products are perfectly happy sitting under water. Some of them are actually pool liner material that's been morphed into roofing material. Once again, it's critical to know exactly what type of material you've got.

As for the stains, someone needs to figure out whether they're old or new. Did your inspector have a moisture meter? Is there any documentation that they existed before the "rubber" roof was installed?

The rubber has been laid over a hot mop roof but is only attached on the edges so the newer rubber is not connected to the under lying older roof. It springs around when you walk on it.

That's normal and proper for some products, wrong for others.

I had a routine physical inspection and the inspector suggested an expert come and take a look. Problem is, there doesn't seem to be any in Reno. This roof is unique to the area.

I can pretty much guarantee that's not true. Reno has miles of flat roofs. There must be an expert out there. Call your inspector back and ask him to help you with the foot work.

Any ideas regarding the roof and more importantly, any inspectors in the area?

Thanks in advance

Post pictures.

- Jim Katen, Oregon

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Thanks for the information. The roof is EPDM with glued seams, the water had been on the roof for 4 days. Sounds like sloped insulation applied under the roof material might help with sloping and drainage...yes?

Any ideas on approx. cost to do this and add an overflow? I can't get anyone out there for 2 weeks and I have to make a decision on this house sooner.

Thanks!!

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How many square feet? 1500? The title of the post suggests you want to install insulation 1500' under the EPDM; did you mean 1500 sf?

Understand, there's no way to lift the existing roof, install tapered foam, then replace the same material. At least, no one I know does it that way. By the time you're done messing around, it's easier & cheaper to install new material.

Basically, you're looking @ an entirely new roofing system. Strip it, laser to get the foam layout, fabricate, install foam, install membrane.

Around here (Chicago) that'd be about a $20,000 job, but without pic's that is a complete WAG. Don't make your investment decision on my WAG.

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I just saw a quote in Phoenix for $12K to tear off a 25 y.o gravel roof and apply a foam roof on a 1100 sf home. They quoted $8,600 to do rolled comp.

I did a few EPDM's back in the day, but that was in Connecticut over 10 years ago, so it won't do you much good.

You can do a foam application that can even out some ponding issues, so that may be an option.

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Hi,

There's an article in this month's Journal of Light Construction about spray-foam re-roofing. I don't think water remaining on an EPDM roof for 4 days will do it a lot of harm. It is, after all, solid rubber.

I'd be more concerned with what all that water might be doing to the structure. You never did answer Jim Katen's question about how much water is remaining on the roof. According to a nifty chart I have here, a gallon of water contains 231 cubic inches and weighs 8.33 lbs. A 10' by 10' by 1" deep pond that varies in depth from zero to 1" deep in the center contains 62.34 gallons and weighs .26 of a ton at 520lbs or about 5.2lbs per square foot. A 20' by 20' by 1" deep pond will weigh 1.04 tons (2080) lbs. but the weight per square foot will be the same. Isn't most roof framing designed for a 10 psf dead load plus a 20 psf live load? If so, the weight of a little bit of water ponding on it isn't going to be the issue unless the water can degrade the cover. With a modbit or a built-up it would be a bad thing, but would it really hurt an EPDM or a PVC roof?

OT - OF!!!

M.

P.S.

Sorry, can't post the chart. It's all faded and worn and it was a poor copy of a copy in the first place.

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Well,

How deep are they? As I've stated above, a 10 by 10 area would only add another 5.2lbs per square foot and most roofs are designed for a dead load of 10 plus 20, so the weight would not be an issue with a pond 10 by 10 by 1" - at least that's my understanding of it.

Of course, remember that I'm a math idjit, so I could have this all upside down and backwards. I posed the question hoping to get the smarter guys to come on here and examine it.

ONE TEAM - ONE FIGHT!!!

Mike

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Does it freeze in Reno? IOW, would the pond freeze up?

And, I'm not aware of any roofing mfg. that approves their material for ponding, including EPDM's. I could be wrong, but that's the premise I operate on; no mfg. approves ponding, i.e., water hanging around for more than a couple days.

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There's other issues beyond weight of ponding water.

Will the warranty be voided if it is not sloped ¼ in. per ft (typically required by the manufacturers and codes)?

Do you have West Nile virus carryin' mosquitos out there that will plant billions of eggs on the roof?

Do you want a 230 sq. ft. bird bath on top of your home attracting winged critters with puncture capable claws and beaks?

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$12,000 to $20,000.*

Naturally, concealed defects are not within the scope of this estimate. We'll talk.

*Estimates provided for repairs are based on a limited visual inspection. The actual costs to correct problems may be more or less depending upon a more detailed professional analysis.

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Originally posted by rommell2

Thanks for the information. The roof is EPDM with glued seams, the water had been on the roof for 4 days. Sounds like sloped insulation applied under the roof material might help with sloping and drainage...yes?

Yes, tapered insulation will eliminate the ponding. Unfortunately, it's too late for that. You've either got to accept the roof as it is or replace it. Personally, I wouldn't trust ponding water on an EPDM seam.

Any ideas on approx. cost to do this and add an overflow? I can't get anyone out there for 2 weeks and I have to make a decision on this house sooner.

Thanks!!

Around here, $20K would be high. I don't know about Reno. Prices for this kind of thing tend to vary by region.

If I had to cover a flat roof on a budget, I'd be looking at a torch-down modified bitumen membrane with a white granule cover. If I had money to burn, I'd be looking at a PVC membrane - my favorite is Durolast.

I'm not a big fan of EPDM.

- Jim Katen, Oregon

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Re: ponding:

Some manufactures of CPA (copolymer alloy) membranes warrantee installations against leakage (though not mechanical damage resulting from such causes as deck failure) even if long-term ponding is present.

As Kurt notes, in freezing climates you have an additional set of issues.

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Just a FPN....

I look at >200 flat roofs a year, installed in all manner of doofus setups. I gotta agree w/Katen that granulated mod bit is really something wonderful.

If you do it right, or even close to right, it works. Period. And, it's "alterable", IOW, if you have to go into it for some reason, years down the road, you can, w/no problem. It's real handy when the remodeling job you undertake has a roof penetration; just cut it open, do what you gotta do, weld in new stuff, and forget about it. Don't want to even begin to mess w/EPDM.

The guys that like EPDM the most are the guy's that install it. Personally, I wouldn't ever use it. Ever.

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