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-   -   preparing coated roof for recoating (http://www.diychatroom.com/f9/preparing-coated-roof-recoating-102211/)

GeneS 04-20-2011 05:27 PM

preparing coated roof for recoating
 
I am preparing my roof for re-coating. I have lots of old bubbles in the current coating. I have cut around the larger bubbles and plan to use roof sealer with fabric to cover the scar. Should I also do the same with small ( l to 2 inch) bubbles. Can I just put the new coating over the small bubbles without using sealer and cloth.
Please help me!!!
GeneS

Grumpy 04-20-2011 07:38 PM

You should first power wash the roof to remove anything that may be loose. I would do that before any patching or cutting as the power washer will do alot of cutting for you.

GeneS 04-21-2011 03:55 PM

Preparing coated roof for re-coating
 
Thanks Grumpy for the info. I did power wash the roof. What I really wanted to know is how to take care of the bubbles in the existing coating. I have small ones and some tht are 3 to 4" and a inch high. I have the patching material and want to know how large they should be to require patching.
Awaiting your reply,
GeneS

Grumpy 04-21-2011 07:42 PM

My guess was if you had already power washed I wouldn't expect there to be any more bubbles. Perhaps you need to wash it again on a higher PSI or move the tip closer. Don't be shy.

Scrape or cut all the old bubbles off, wipe down the exposed metal with a detergent cleaner, usually recommended or provided by the manufacturer.

Before you apply the new coating make sure the existing coating will stick. This is done by performing a test patch. To perform a test patch you coat a small area a few square inches and imbed some polyester fabric into the new coating. Give it a day or two to seal. Then peel it off, it will peel off. If on the back of the peel you see the new coating, great, it'll stick. If on the back of the peel you see the old coating. That's bad, it won't stick for long. You need to wash some more or contact the manufacturer of the product you intend to us for recomendations.

1985gt 04-21-2011 09:19 PM

Are the bubbles just in the coating? What type of roof is this. Power washing should have removed any bubbles in coating on a metal roof it kind of sounds like a asphalt roof and they are blisters.

GeneS 04-22-2011 04:51 PM

Preparing coated roof for re-coating
 
The roof is an asphalt base. When I remove a blister there is a black tar underneath. After my last coating job, about 5 years ago, I seemed to have gotten many more blisters. Since I covered white on white I would have assumed the color under the removed blister would be white, no, it is black tar. Do I need to cover the large removed blister area with a coat of sealer, than imbed the cloth and put another coat of sealer on top? Do I just put the finish coat over the smaller blisters and not worry about sealing them? By the way I live in southern Arizona, temps 75 t0 80 in the winter, 90 to 105 in the summer. Very dry in winter, high humidity mid July to mid Sept. I believe I coated the roof about this time of the year, March or April.
Thanks for any help.
GeneS

1985gt 04-23-2011 01:24 AM

Alot of the times the blisters are caused by moisture that has been traped. Could be new moisture could have been around and working its way up. If you cut the blisters becarefull not to cut all the way down. Just the top layer that is blistering. I would patch it with a mastic and membrane or mastic and a modified patch first. Then coat the whole thing. What kind of coating are you using?

GeneS 04-23-2011 09:54 AM

Preparing coated roof for re-coating
 
I am going to use Black Jack Ultra roof 1000. It is a siliconized elastometric coating. I don't think I mentioned in my earlier postings that it is a flat roof with slight pitch for drainage. The pitch is about 1" in 2 ft.. It does drain well.

1985gt 04-24-2011 12:01 AM

Might look at the data sheets and around the site to find out if they have any recomendations about fixing blisters first. Might even have a 1-800 number to call to see what they say.


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