molding install in a granite foundation/no maintenance options?

[roger wiegand]

As the resident guy who knows how to use power tools at the museum where I volunteer I got to assist in the installation of new mosaics in former window openings in our historic mill building. My next task is to add some moldings to cover the rough edges. The surface I need to attach them to is hewn granite, thankfully quite smooth. Two questions for the collective wisdom here:

1) is there a colored PVC material or other similarly long lived, essentially maintenance free material I can use to make these moldings? I'd like to use something like Azek, but it only comes in stark white, which would look bad. History suggests that repainting by the mill owners might happen once every 50 years, whether it needs it or not. We took out some badly degraded paintings from these locations that had been untouched since the 1970's. I'd like to use a material that will look as good as possible for as long as possible.

2) How would you attach the molding? I'm considering an adhesive like Sikaflex-111 to avoid having to get fasteners into the granite. A material other than PVC would give me a wider range f adhesive choices.

[roger wiegand]

Forgot to add the picture.

IMG_7475.jpg

[Ted Calver]

If there are any wood features elsewhere in the museum I'd try and match them by creating a simple color matched wood moulding just big enough to cover the ragged edges. Double sided window glazing tape to hold it on.

[Bill Dufour]

I would look at colored plastic deck boards like trex. Maybe rip some planks or see if they make trim boards.
Bill D

[Bill Dufour]

Around an arched window I used plastic bender board. I painted it white after install. I had to rip it about 1/2" narrower.
Bill D.
https://www.homedepot.com/p/1-in-x-4...0230/202074240

[Brian Elfert]

I bought an exterior door with PVC brickmold and frame to avoid having to paint. The color is sandtone and it is badly faded after a few years.

[Bill Dufour]

Tile trim mortared in place?
Bill D

[roger wiegand]

Tile trim mortared in place?
Bill D

That would certainly be the most elegant and permanent solution! It's a project funded by the town cultural council. I'll have to ask if there's any money left for that kind of solution.

[roger wiegand]

If there are any wood features elsewhere in the museum I'd try and match them by creating a simple color matched wood moulding just big enough to cover the ragged edges. Double sided window glazing tape to hold it on.

If it were on my house painted wood is what I'd do. On this building the little bits of exterior wood are allowed to degrade badly, there's no indication the paint would be kept up.

[Jim Becker]

Roger, given the most readily available source for the kind of material you want is going to be white...painting it with very high quality paint should avoid any kind of frequent repainting need. Just keep in mind that the cut/milled surfaces will have some texture that needs to be filled and primed before the actual color goes on. One other option might be to use torrified ash or other species which is sold for exterior use and can have a pretty deep brown color.

[Mel Fulks]

I bought an exterior door with PVC brickmold and frame to avoid having to paint. The color is sandtone and it is badly faded after a few years.

It might not be as appealing as it was new….but at least it’s not peeling. The granite paint is probably harder !

[Tom Bender]

Seems to call for some kind of caulk or mortar, not solid molding. Think about tile installation.