precaud said:
OK, I'll bite. Big roof on the garage/storage building, SBS Brai torchdown, New Mexico climate. Major blisters/wrinkles have developed in areas. I'm cutting them, removing the buckled asphalt layers underneath making it smooth, then cementing it back down. Then I'll coat the whole thing with Henry 107 asphalt emulsion and then white acrylic.
The quiestion is about the cementing down. When I started, I was 3 coursing using roofing cement (Henry 505). But that stuff has to age 30 days or more before it can be coated. So I tried using the 107 emulsion with polyester mesh. It's dry and ready to coat in less than 2 days. So far I'm impressed.
Whadya think?
Some photos would be helpful. When you cut the blisters, was there water or moisture underneath? Does the roof have like a 1/2" fiberboard underneath the roofing?
When you cut it, if cut to the decking (what is the decking material, steel corrugated?) you should find in this order. The torch down top ply, a gritty "base" sheet underneath which is usually screwed down with screws & metal plates, or if over wood, cap nailed down. then usually a 1/2" of fiberboard insulation. then the decking.
SBS is a decent brand btw. Is the SBS smooth & black? or White or colored granulars on top? The problem is in the heat out there, the SBS expands & contracts, which causes alot of wrinkles. If not properly based. insulated, and fastened etc. If the blisters aren't leaking, I personally would leave them alone. Your cutting holes in an otherwise tight roof. The cement patches will only last so long. The wrinkles will last longer. Unless they are showing signs of severe open cracking.
Make sure the acrylic is spec'd for modified bitumen, or else it will peel, flake let moisture between it & the modified and just compound problems.
If already coated in the white acrylic, then don't bother aluminum coating, the two don't mix. Just keep it coated well with what you have on there now.
Honestly, in roofing industry, one does not have 30 days to wait for a repair to be completed.
Heres what I would do if, cutting blisters out.
Cut down to deck, apply roof cement to the deck surface, save what you cut out roofing, insulation etc., not super thick, but enough to make sure the perimeter of the cut & the deck surface was one layer of cement, and that it is sealing the perimeter of the cut. Then take the pc. of insulation you cut out if any, set that same way it came out into the layer of muck you just applied, some muck should ooze out the sides all the way around, press it down in good. If there is base sheet, leave that pc
out of the patch. Cement the top of the insulation you just out back in, again cover completely and the perimeter around the cut sides. Now is when I would torch down a new patch. But if cementing, fill the remainder of the hole with muck. A bit more than level with the roof surface. Then cover the entire hole and about 4"-6" of the roof surface around the perimeter of the hole. So you prolly now have the hole filled in and a round or square etc spot of muck over that area. Now no blister, no hole, just a spot of muck. Take your mesh tape and cover the hole extending the tape the 4"-6" beyond the holes sides onto the existing roof surface, If the tape does not cover the hole in one shot. Start at one side laying tape on, and each next pc of tape, overlap the previous one an inch or so. until the tape has now formed one big mesh patch over the area. Then with your trowel, press the tape in by slightly pressing and sliding trowel over length of the tape. Apply your top coat of muck over tape. going another 2"-3" past the tape edge. smooth out with trowel. Don't go too thick on top, it will only crack if too thick. Say About 1/4" to 3/8" layer of muck over tape. Not an exact science, just use your best judgment. Now if, coating with acrylic, yes now wait until muck has cured. Whatever the can says.
One note. By asphalt emulsion I am thinking your talking bout the black roof coating. If your coating over the patch with the white acrylic, I would skip the black roof coating & apply the white coating directly over the much when cured. Of course if the manufacturers can specifies the the roof emulsion over the muck & under the white acrylic, then do that. I never have. Your basically putting two roof coatings on, and I am not sure that the white acrylic will jive with the black emulsion so well.
The emulsion usually never really hardens, and th acrylic I would think would not adhere great, and harden as the coating underneath doesn't. I have seen this, and the acrylic basically cracks and flakes off due to the black roof coating underneath not hardening., and giving the acrylic a solid surface to harden and bond to.
Muck if too thick also takes a long time to harden, but it will skim on top. I'd let it cure good and not go too thick. I have aluminum coated over fresh muck. it can be done, but the silver coat will crack and flake off in a few months to a year. You have a soft layer, with a hard layer on top, the hard layer loses cause not adhered to the surface below. Personally cost wise. I'd aluma coat, and go back after a few months, check and touch up. Then touch up as needed. I am pretty sure the aluma coat is less expensive as the acrylic.
I hope i haven't made it more confusing. If I did, sorry, let me know and I'll try and explain better and simpler. I confuse myself while thinking, trying to spell & type all at the same time
Ge some photos if ya can, I'm curious to see this roof. and a couple close ups of the blisters, and if possible a shot or 2 of the open cuts, when/if ya get a chance.
