How Many Coats Of Elastomeric Coating Do We Need? - Roofing/Siding - DIY Home Improvement | DIYChatroom

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Old 09-29-2010, 11:22 AM   #1
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How many coats of elastomeric coating do we need?

I am on the board of a condo association, and we are getting ready to do maintenance of our flat foam roofs which were last serviced ten years ago. We have gone out for bids, and three contractors bid showing two coats of foam, each a gallon and a half per sq ft. One contractor whose bid is significantly lower than the others, bid just one coating. When we asked him why, this was his response. My question is, is what he says true? Means lots of money to us but we want the roofs done properly. Many thanks for any advice.

With regard to the coating, the foamed sections of the roof DO NOT need two coats of elastomeric coating and for a contractor to suggest would lead me to beleive that either he does not understand the basic reason for re-coating the polyurethane foam roof or he is trying to perform work that does not need to be done. When a polyurethane foam roof is installed we apply one base coat of elastomeric coating and then we apply one coat of Top coat elastomeric coating. After five year or so the UV rays of the sun break down th top layer and it needs to be replaced by a a new layer of Top cat. I inspected each and every roof and i found no reason to warrant applying two coats of elastomeric coating. your base coat is in perfect condition. The areas that we repair will have two coats orf coating.


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Old 09-29-2010, 01:35 PM   #2
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you already seem to know what you want and you're basicly answering your own question my friend.


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Old 09-29-2010, 01:41 PM   #3
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Mr, Williams

Thank you very much for your reply. I think I was not clear in my message. The second paragraph is what the contractor said to us, and I was hoping to get comments on whether what he said makes sense to an experienced roofer.

Thanks in advance for your further input!
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Old 09-29-2010, 03:23 PM   #4
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I'm not ultra familiar with foam roofs, although I do install a fair bit of elastomeric roofing products. What I do know about foam roofs is that the elastomeric IS the waterproofing, not the foam. Therefore it is imperative that what ever be installed be installed absolutely water proof.

HOWEVER I have some questions for you. What type of elastomeric is to be installed? Acrylic, Urethane, SEBS, Silicon, Urea? I ask this because each will have their own application rates and methods. For example, a polyurea would not need two coats for sure.

I also ask how many gallons per square would be applied and to what dy mill thickness would the product be applied?

My suggestion would be to contact the manufacturer directly. Having said that I took the liberty to check into ER Systems and read their specification for you.

A. Base Coat
1. Base Coat of the selected chemistry (urethane, acrylic or silicone) shall be applied to foam repair areas the same day the
foam is applied.
2. Sufficient Base Coating must be applied to the repaired areas to provide a smooth transition to the original coating.
Application is typically 32 wet mils minimum and tied into the original coating for 3-4" beyond the repair.
3. Primer shall be applied to the original coating if the adhesion test dictates the need.
4. Base Coat (urethane, acrylic or silicone) is then applied to the entire roof at a minimum of 16 wet mils to provide a
minimum of 10 dry mils of protection at all points.
Keep in mind that any other manufacturer may have a different specification, so this specification is meaningless unless the product to be used is ER Systems. This is why you shoudl contact the manufacturer in question and ask them yourself.

You may learn a little more about roof coatings at my website, although there is no information about spray foam... Roof Coatings
The information found in this post is not to be considered legal advice. The author of this post takes no responsibility for any losses that occur. Use at your own risk.
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Old 09-29-2010, 11:30 PM   #5
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What he is telling you does have some merit as far as the base-coat's function. Whether it is correct on your particular project I cannot tell. The average coverage the others stated is also about right (1.5-2 gal per layer per 100sf) Ours is always calc'd at 2gal/sq
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Old 10-08-2010, 01:47 PM   #6
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Hello, I am a manufacture of Polyurethane foam and coatings for commerical roofing. It is impossable to answer your question based of the info you supplied, but here goes. The number of coat's put down is not what you need to know. What you need to know is the following.
1. How many Dry mils is the contractor putting down.
2. How many mils are currently in place.
3. How many mils is he spraying over new foam (if any).
4. What is the warranty that you are requiring? I.E. 10,15,20 - System or material only
Once you have the above info than you can decide which is the best qoute to go with. My company is based out of Wisconsin and would be happy to work with you on deciding which is the best option.


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