What type of caulk to use around skylights ?

Make sure you get a caulk that can be used for exterior uses. Silicone is probably best but acrylic is usually easier to work with. Clean/scrape all the old caulk away and clean the area before you re-caulk. If there is a mold issue, now is the time for a bleach and water scrub and let that dry before you re-caulk. Take your time, don't glob on the caulk but it's easier to apply more if you need to than to deal with too much material. Keep a couple of rags and or a bucket of water handy for cleaning your hands. I just run a bead of caulk and take a wet finger and smooth it into the joint. If the first pass doesn't get everything covered well, make a second pass and do the same wet finger thing. You want light but firm pressure on the finger. Enough to push the caulk into the cracks but not so much that you push all the material out ahead of your finger. It takes a little practice but it's not hard. And while you have the caulk all dug out, that's a good time to look at the flashing ...  more

either use one with a silicone base or one with a none hardening rubber compound,last but not least you can even use bull (tar like substance used for patching roofs) any of these will work but bull cost less and does the best for all around use and longevity.  more