Dicor caulk removal to install a skylight

When you remove Dicor caulk from the roof what can you use to clean it down to the membrane without damaging it? I am going to change a skylight. Do you normally use a heat gun? Do you use butyl tape under the skylight. Are the screw holes big enough(or do you have to open them up?) when mounting to use self drilling screws-do they make screws with rubber washers. I figure some of you have done this before and I would appreciate your knowledge. Thanks for educating me.
Steve

I replaced my bedroom vent assembly (noisy 12V mini fan) with a MaxxAire fan assembly. On the roof I simply cut away the dicor sealant on the flange of the old vent - enough to uncover the entire flange assembly and remove the old unit. I left the extra old dicor sealant on the EPDM roof - under the flange of the new vent I used butyl tape (or equivalent). Screwed down the new vent assembly, cleaned up the old dicor and applied new dicor self leveling sealant to reseal.

Brian

If you really want to know, go to a repair shop and you'll see how they hack it out with a utility blade, scary stuff. Brian did a much better job than a shop IMO, follow the steps he mentions and you should be fine.

BTW I was at the dealer picking up supplies to do the skylight and I was told to not use dicor to seal it. It causes the skylight to spider crack-seems dicor and the material in skylights don't like each other. They sold me a tube of caulk to use in place of it. I also saw this on U tube when looking at this repair. Just passing this info along.

I have not tried this, but was told if you do want to scrape off the old Dicor, use heat and a credit card---not a putty knife as it is too harsh for the roof.
al
currently in Kenai, AK

I did the skylight replacement. Caulk removal- I used wood scraper and plastic putty knives-I did not clean it all way down. Used butyl tape underneath and the Superbond SB-140 caulk. The butyl tape was sticky to work with even to the paper it is mounted to-I wonder if it was to old or to warm. I did not like how the caulk worked-it is very stringy-I wonder if it will self level.. I will use dicor next time as I had originally planned. All in all not a difficult job.

I use a very thin blade metal scraper, purchased from Lowe's, round the corner on the scraper to about a 1/8" radius, bend the blade about 1" from the end to about a 10 deg. angle. Lay the end of the scraper flat against the EPDM rubber roof and proceed to work the handle back and forth. You will be amazed how well the caulk is separated from the rubber roof. After removal of the bulk of the caulking, use non-chlorinated, non-hydrocarbon "Brake Clean" to do the final clean up. Do not spray the "Brake Clean" on the EPDM, rather spray/saturate a rag with the cleaner first and then proceed to remove the caulking. I got these tips from a RV repair center and they have worked well for me over the years.

mobilcastle said:

BTW I was at the dealer picking up supplies to do the skylight and I was told to not use dicor to seal it. It causes the skylight to spider crack-seems dicor and the material in skylights don't like each other. They sold me a tube of caulk to use in place of it. I also saw this on U tube when looking at this repair. Just passing this info along.

Click to expand...

That doesn't make sense to me since its caulked in with Dicor from the factory. There would be far too many failures to count if using the two caused the skylight to become brittle and crack. Did you buy eternabond instead?

I used the superbond SB-140

I used a plastic putty knife and rounded the corners to be safe. If its a sunny warm day let the sun warm the sealant it will help. I replaced my vent with a fantastic fan on a cool day and used a heat gun on low to warm the sealant to help it come off. Don't get carried away with too much heat or you will damage the membrane.