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I ordered a new polycarbonate skylight to replace the cracked factory original acrylic one. The skylight I ordered came with SB140. For some reason I was under the impression that I would put a bead of SB140 between the EPDM and the skylight and then use dicor to seal the edges and the fastener. Going over the instructions it looks like I am supposed to use butyl tape between the skylight and roof and then use the SB140 to seal the edges and the screws where I was going to use dicor. Not using the SB140 will void the warranty so I'm assuming that goes for not using butyl tape as directed.
My issue is that I don't have any butyl tape and no one in this town sells it. And of course I already removed the old skylight and started cleaning the old tape and dicor off the roof. Fortunately there is no rain foretasted for the next week, which I can trust as I live in the desert. So does anyone know a way around using the butyl tape or am I going to be finishing this project in a few days?
Your best bet is to just get some butyl tape. I ended up ordering a role of 50ft for the project I was working on and future projects. It has come in handy a couple of times. You could put some dicor down as butyl tape and then pull it back up when the tape arrives. Another option is to seal it off somehow until the tape arrives.
You might be able to pick some up at a Camping World or RV supply store near you.
You will seldom find manufacturers using butyl tape on skylights, at least the ones I have replaced, although I guess some might. While it may provide a more secure hold, tacky (putty) tape works just find and despite all the concern about which sealant to use, you will find lots of skylights with Dicor and no problems.
I personally don't like butyl as it is so much harder to get off if a repair is necessary. If no RV supplier near you sells it, that may say something about what they themselves use.
You will seldom find manufacturers using butyl tape on skylights, at least the ones I have replaced, although I guess some might. While it may provide a more secure hold, tacky (putty) tape works just find and despite all the concern about which sealant to use, you will find lots of skylights with Dicor and no problems.
I personally don't like butyl as it is so much harder to get off if a repair is necessary. If no RV supplier near you sells it, that may say something about what they themselves use.
Just my two cents worth,
Steve
I drove over to the mom and pop hardware store in the next town and they sell tons of mobile home stuff. As expected they had some putty tape. Used that and the "free" SB140 that came with the skylight.
It was close to 100 today, but it made the old sealant nice and soft! All installed and looks great. I'll do a leak test in a few days before I put the inner dome back on.
I found out Friday that my skylight has a huge leak and needs replacement.
I just ordered a polycarbonate exterior dome since mine was cracked and broke on removal. They had a plastic one in stock for about $20 but I really dont want to do this again if possible, so I ponied up the extra $100 for the polycarbonate.
So far im into this for one dome, three tubes of dicore, one roll of butyl tape and one can of solvent they said is amazing, all for the princely sum of $200.
I really just wanted to use it .... Not work on it. But I digress...
Got mine done last night (Finally!!!) about midnight.
how's it look? I used the butyl tape underneath across the screw holes, then covered them with dicor, and the went around the edges +1/2" with dicore and then filled everything in.
how'd I do? never done this before.
one thing that really sucked, is the old dome flanges were quite a bit wider than the new so some of the old screw holes were left exposed and I had to just cover them with dicor. I had thought about running a strip of tape across the old screw holes, but thought the dicor would be good enough. used two full tubes of dicor, and have left "just in case"
A tip for anyone doing this: use a heat gun on low to warm up the butyl tape and dicor during removal. judicious use of a heat gun on low makes the clean up a BREEZE. the stuff will scrape right off leaving very little left to try and remove with a rag and adhesive remover. at least that's what I found.
is there anything I need to touch up, or is this about right?
It looks better than factory.
Naturally, now that the job is done, I'll say I would have used Eternabond tape for the project and skipped the butyl rubber and dicor altogether.
Double sided the width of the flange for between the flange and roof, with single sided twice the width of the flange for on top.
The top layer is probably overkill, but that thing will never come off or leak.
Got mine done last night (Finally!!!) about midnight.
how's it look? I used the butyl tape underneath across the screw holes, then covered them with dicor, and the went around the edges +1/2" with dicore and then filled everything in.
how'd I do? never done this before.
one thing that really sucked, is the old dome flanges were quite a bit wider than the new so some of the old screw holes were left exposed and I had to just cover them with dicor. I had thought about running a strip of tape across the old screw holes, but thought the dicor would be good enough. used two full tubes of dicor, and have left "just in case"
A tip for anyone doing this: use a heat gun on low to warm up the butyl tape and dicor during removal. judicious use of a heat gun on low makes the clean up a BREEZE. the stuff will scrape right off leaving very little left to try and remove with a rag and adhesive remover. at least that's what I found.
is there anything I need to touch up, or is this about right?
It looks better than mine. I used to SB140 for the top and screws and it didn't "self level" even though I thought it was supposed to so now I have 3 or for beads going around the perimeter. I'm going to leak test it this weekend, it if does leak I'll probably end up fixing it with Dicor.
I didn't need a heat gun to remove the old stuff on mine since it was 105 the day I did it and that was plenty hot enough to make it easy to remove
Here are pictures of the repair process for reference purposes....
Cracked Skylight:
Slight discoloration, but no water damage:
Inside dome was dirty and dusty mostly from dust getting in from dust storms more than water:
Measure inside...
...and outside for proper dome and flange coverage:
Carefully remove old sealant from screws, remove all screws, and pry off the old skylight by carefully working a putty knife under the flange all the way around being careful not to damage the roof:
And clean well with a plastic putty knife. If you have a rubber roof like this you will want to be very careful. Used denatured alcohol sparingly on my roof as it is EPDM. I taped a bag inside the bathroom to catch anything that would fall into the tub (I would also recommend putting the plug in the drain to catch any screws you might drop from going down the drain:
New skylight screwed down pictured from inside. I went with a darkly tinted one as we live in the desert and want to reduce heat loading:
And finally, SB140 sealing all screws and the edges of the flange.
I'm not super happy with the sealant job, so I'll have to see if it leaks at all.
I taped a bag inside the bathroom to catch anything that would fall into the tub (I would also recommend putting the plug in the drain to catch any screws you might drop from going down the drain:
What a good idea to use a plastic bag!
I now have some spotting on the floor of my tub as a result of acetone dripping down during the cleaning process (my roof is TPO, not EDPM).
Would have saved a lot of mess for me.
Remember that poly-carbonate (Lexan) can be damaged by some common solvents, and I'm not sure what is in Dicor. That may be the reason that the manufacturer won't warrantee when it's used.
