What caulking to use for skylight/metal roof gaps? (leaking)

[Piston]

What type of caulking or silicone would be good to fill large gaps (perhaps 1" I'm guessing). I have two sky lights (wish I didn't have any) in my roof as originally built, and then a metal roof was added after. The 'trim' work around the skylights left a lot to be desired, to say the least. My sky light is leaking in the winter when a lot of snow is piled on the roof and it warms up and starts melting. I need to re-caulk around the skylights, as well as around the brick chimney.

Here are some not very good photos...

 

[Streetcar]

I would use a silicone, with large gaps use a backer rod so that caulk is bridging gap and not trying to fill the gap full depth

 

[dougtrr2]

In the long run I think it would be worth the time and trouble to get someone to properly reflash the windows to eliminate the large gaps. Even with backer rod I think you would be fighting a losing battle.

Doug in SW IA

 

[bigtiller]

There was another thread recently where someone cautioned to use acid free silicone on metal so it doesn't eat the metal and start rusting.

I found it, post #4

https://www.tractorbynet.com/forums/rural-living/398178-ant-proof-well-pump-pressure.html

 

[jaxs]

In the long run I think it would be worth the time and trouble to get someone to properly reflash the windows to eliminate the large gaps. Even with backer rod I think you would be fighting a losing battle.

Doug in SW I

I agree. Proper flashing is the only permanent solution. When I've trained people,I take them into attic of a wood shake roof to show them how much daylight can be seen between shakes. I also talk to them about third world countries where people stay dry beneath thatch roofs. As a demonstration,we construct a roof with loose laid fiberglass shingle tabs then run a hose on it to show no adhesive is necessary. Until you can get proper flashing,I recommend asphalt rather than silicon or urethane products. The reason I like asphalt is( A.) Sun re-amalgamate's subsequent applications of material (B) Unlike silicon and urethane,asphalt can be cleaned off with solvent when and if desired.

 

[EddieWalker]

Do no use silicone on a roof. Waste of time and money.

In the roofing section of Home Depot you will find a variety of roof flashing sealants. Henry is a very good brand and what I would use.

Once inch gaps are too big for caulking.

There is a mesh tape that can be used to deal with the gaps, but it should be thought of as Plan B.

First you HAVE to clean up what's there. Get a brand new, super sharp, wood chisel and start scraping all of what's there down to bare metal.

Figure out how to get metal flashing in there to stop the rain properly. Once the metal flashing is done, then use Henry's flashing sealant.

The grey stuff is amazing, but also miserable to work with. I've never had it fail, and I've always had a horrible time getting it off of my skin.

 

[Paddy]

if it leaks it need to be re-flashed correctly. By all the gobs of caulk, it's ben going on for a while. A properly flashed opening shouldn't need any caulk.

 

[PILOON]

My favorite is polyurethane (Flextra is one brand).
The characteristics are very similar ro automotive windshield adhesive.

I have patched 3-4" holes by simply 'gluing' an overlapping patch in place and many years later (8-10) needed a chisel to remove that patch.
When dry it remains flexible so temperature changed do not affect it.

Added convenience is that there are some 20+ colors to chose from.

It is one of those go to products like duct tape and WD40.

 

[skipmarcy]

Solar Shield is another good brand and is made for metal roofs. It too is like a urethane used in windshields, requires solvent (I use paint thinner) to get it off you or what ever you don't want it on.

 

[/pine]

The larger the gap the more expansion/contraction from temperature variances becomes relevant to a lasting solution...

personally...I would use strips of bitumen torch down 120# roofing material...it can be applied neatly with a hand held (propane) torch...the curing time is seconds...