On Mon, 15 Aug 2016, Uncle Monster wrote:

On Monday, August 15, 2016 at 12:15:46 PM UTC-5, Don Wiss wrote:
How best to insulate? I see the various foam insulation boards. A neighbor
suggests going all out with 2" thick. I see you cut with a circular saw. I
see you tape the joints with 2-7/8" Weathermate Construction Tape. But the
Styrofoam sheathing can only take the UV for 90 days. I have to cover it
with something, either white or reflective. What do you all suggest?

You could check with a roofing supply house to see if they have a white mastic sealer or that silver sealer you see on trailer roofs. ^_^

I called Dow Chemical. Not unsurprisingly I was asking about an unusual
application. He emphasized that anything I put on it can't be solvent
based. It must be water based, like latex paint.

Looking at Home Depot I see they have a water based mastic that creates
air-tight seals on duct seams and joints.

He says sometimes it sticks out the bottom of walls and people put stucco
on it. But again, no solvents!

I supposed I could simply paint with white exterior latex paint.

Don. www.donwiss.com (e-mail link at home page bottom).