Julie Foresman
Hello, the original metal roof on my home is over 115 years old (approx). They are embossed interlocking metal shingles. We had the roof painted 7 years ago and it is already due for a repaint job! I've been looking at the use of a silicone coating i.e. GaCo. I've seen it used on flat surface metal roofing. Can you see any downside of using this product on interlocking metal shingles? Appreciate any advice.
Eric Novotny
An informed customer is the Best Customer!
There might be a couple of issues. Issue 1: Depending on the interlock and overlap of the panel, a thick/viscous coating might obstruct the drainage that happens between the panels. Issue 2: Those coatings require a clean and "bond-able" surface. If the old paint is coming off, you are going to have the same issues with the Gaco coating coming off as you would with the paint.
Todd Miller
Isaiah Industries, Inc.
Thanks for your inquiry. One of the issues with these older roofs is that, 115 years later, they often have many different layers of paint. And any new layer is only as good as the adhesion of all of the previous layers. I am not familiar with the silicone coating you mention. However, I would ask them three things: 1) Will it help guard against loss of adhesion (peeling) of any of the previous layers of paint? 2) How well will it adhere to the last layer of paint? 3) What is the method of re-coating if this finish ever wears out / needs to be replaced? From a technical standpoint, I have no issue with putting this coating on the roof you have.

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