I am replacing two plexiglass skylight domes. They are both dual-pane (bronze over clear) 1/8" thick plexiglass domes mounted on an aluminum curb. The curbs are fine and the skylights do not leak. The domes are old and show some "glazing" (spiderweb-like cracking of the plexiglass) and the outer domes have some minor cracks at the edges, which allow moisture to accumulate between the domes during heavy rains or snows (again, no leaks to the inside). I have the replacement domes. Question is what adhesives to use to mount them on the curb, how to seal them to each other, and then how to seal them to the outer frame that holds them to the curb.

When I pulled the outer frame to see how it was done initially, I can see a black rubber double-stick mounting tape was used to mount the clear dome to the curb. Where can I find this tape, or can I replace it with silicone or polyeurathane sealant? One person has suggested polyeurathane, but another said it might not be compatible with plexiglass and might cause damage to the lenses.

Can I use polyeurathane or silicone sealant between the panes to seal them together? What about weep holes at the bottom edge to allow moisture to evacuate from between the panes?

Finally, when I remount the aluminum face frame, should I mount it with mounting tape or seal it with tube sealant? Polyeurathane or silicone?

I was going to pay a roofing contractor to do it, but they are all booked for weeks right now. I'm selling the house and need it done now. Besides, it really looks like a simple and straight-forward matter I could do in an hour.

Any knowledgeable help would be appreciated.

Tony

 

Did you get the domes from the manufacturer? Didn't they come with any instructions?
Are there no instrctions on the makers website?

Anyway, stop by a glass shop that does window repairs. I think you probably want to use glazing tape between the domes and maybe a rubber type glazing bead in a tube on the curbs. The glass shop will be able to advise you I'm sure.

Don't drill any holes, they aren't designed that way.

Personally I probably would have replaced them with Velux brand, but you have what you have.

 

I ordered replacement domes from a place called Savannah Trims, through Buy Skylights. They make acryllic or polycarbonate domes to your specs. Skylights are such that you either have to be able to order from the original manufacturer or have them made to order....or do a complete new installation. Replacement domes for two skylights amounts to $465, inc shipping, as opposed to over $2500 for replacement of two skylights with new Velux units. Since the curbs are fine, frames are fine, and they do not leak or sweat, replacing only the domes made $ sense. They do not provide instructions, as they deal mostly with contractors. They just make 'em and ship 'em. Their phone salesperson said to use "polyeurathane", but, as I said, somebody else told me it might damage the plastic domes, so I'm left wondering whether the salesperson really knew what she was talking about or whether the other guy was just spouting off.

This really is a no-brainer one-hour job if I can just get some good information. I hate to hire something like this out. The glazing tape and rubberized glazing bead, like you mentioned, sounds right to me, but I'm not sure how they will interact with acryllic domes.

I guess I'll wait until Monday and contact Savannah. Hope the weather holds. Thanks for the reply, though.

 

FWIW, over at the Buy Skylights site they show a "Santoprene Gasket" in their domed skylight installation illustrations for both BUC and self-curbing installations. Santoprene is a thermoplastic vulcanizate seal material, this is a common material for this application, for example it's the material used in the Anderson product line.

 

What size were the skylites? Velux makes a couple of diff sizes for the commonly installed domes. I guess you know that though, sounds like you did the research. I had some out here that had heavy aluminum curbs (well installed, no leaks) and I just cut about 1/2" off the entire perimeter of the curb flange with an angle grinder to be able to use standard Velux 2222's as replacements. It almost sounds like you could have the same style as I do/did.

Can't imagine glazing tape or sealant would hurt anything. They use the same stuff on vinyl and aluminum framed windows. I think you're justifiably right to be concerned about the poly though.