Do it yourself re-coating of a foam roof

I thought that Eichler owners who have SPF roofs (sprayed polyurethane foam) might be interested in hearing how a do-it-yourselfer re-coated their own roof for about $650 in supplies, as opposed to paying a roofing company $6,000 to do it.

My SPF roof was installed in 2001 by a company that is no longer in business. At the time, they told me that it should be re-coated in 8 to 10 years. When the re-coating is done properly and regularly, SPF roofs can last indefinitely (which is one of the reasons why I chose that type of roof over tar & gravel, torched bitumen, or the sealed fabric "Duro-Last" type). During the past 8 years I have had to apply sealant to a number of low spots on the flat roof side of the house because the original top coat was cracking where there was standing water, but that's easy to do. However, I was disappointed to see that some of the cracking started just three years after the roof was installed. This lead me to question the quality of the application and/or the materials used.

The coating used on SPF roof is an "elastomeric" coating that is like a thin, rubberized paint. It protects the foam surface from UV degradation and physical abrasion (SPF is waterproof but like any material it will gradually break down when exposed to sun and weather). I found the coating for sale at Pacific Supply, a builders supply company. See http://pacificsupply.paccoast.com/locations/california.html. About $120/5 gal. bucket of "APOC 252 Sunwhite Premium Elastomeric Roof Coating" (there are other similar products on the market). My roof area is approximately 2,100 sq. ft. and I used 5 buckets to cover it.

The first step is thoroughly cleaning the roofing surface. This took about 2 days using a powerwasher. You can buy a powerwasher for less than $150, or rent one. I co-own one with a neighbor. It is time consuming to do properly because you are working with a jet of water about 2" in diameter. I do not believe you can properly clean a roof with a hose and a spray nozzle, you need a powerwasher. If the surface isn't clean, the coating won't adhere well.

Then there is the issue of the very fine white granules (some kind of crushed rock) that roofing companies typically apply as the final surface on foam roofs. I think they do it for looks, as in my opinion it has no practical purpose. When my roof was installed in 2001, I asked why they were putting it on. Believe it or not, the answer was "It keeps the birds from pecking at the coating, they like it because of the sugar content". That sounded like nonsense to me, and I wish I told them to leave it off. For the past 8 years those granules have been coming off the roof down into my yard and into the downspout drains.

So as I was powerwashing I was also periodically stopping to vacuum up the piles of granules so I didn't wash them into the yard. I picked up a total of 12 gals. worth of granules. I was very happy to get all that junk off my roof. I will never use that stuff again.

Once the roof was clean and dry, I rolled on the coating with a paint roller, making sure to go both directions and get an even application. On warm August days it dries in a few hours. Applying the coating took another 3 days.

So I saved over $5,000 but of course spent five full days doing it. Roofing companies probably use a team of 2 or 3 guys and do the job in two days. Your choice. But if you have an SPF roof and don't re-coat it, in a few decades it will probably have degraded to such a point that it will have to be torn off and completely redone. Maybe on balance the dollar cost is the same, but roofing is a messy business and that's a lot of foam to go into a landfill.

In a decade I'll do another re-coat, but next time it will go much faster: no messy granules so the roof surface is smoother and easier to clean, plus it should require less coating to cover it.

Barry Brisco
San Mateo CA