sealant / adhesive advice for roof penetration

[tpd]

Hi Folks,

I'm about to install a cable gland (this one) on the roof to bring in my solar cabling. I'd prefer not to have to run any screws through the corners of the gland housing. I've been trying to figure out how to adhere and seal it in one go.

It seems Sikaflex-252 is a pretty fantastic adhesive - but will it also be an appropriate sealant? Or will I also need to run some caulk or something around the perimeter where it hits the roof? Or do something else entirely?

Thanks,
Toby.

 

[ajmaudio]

252 is probably sufficient but you could back it up with 221 around perimeter if you wanted to... or if 252 isn't uv stable. I've used 221 .... great stuff.

 

[toyick]

i just did this with double sided 3m tape with some 3m 4200 around it to seal it up.. worked great.. even used the same gland


blahhhhhh

 

[rayra]

100% silicone will do both, adhesive and sealant. Especially a vehicle roof.

 

[tpd]

I was on the fence about using VHB double-sided tape to stick the gland down, or just a sealant as the adhesive. I figured if I used tape, the gland would stay on for sure but then I could only get sealant around the corner of the perimeter where the gland intersects the roof. If I instead used a strong adhesive sealant I'd then get sealant both under the gland and also around it's perimeter. The sealant-as-adhesive would potentially be messier than tape, though, when trying to get the gland into place.

Six of one, half a dozen of the other?

To ajmaudio's point, I did some more reading and Sikaflex-221 looks a lot more appropriate than 252, thanks for mentioning that one. The 221 would suffice for both adhesive and sealant in this case, the gland is going to see essentially no load.

Thanks,
Toby.

 

[ajmaudio]

I was on the fence about using VHB double-sided tape to stick the gland down, or just a sealant as the adhesive. I figured if I used tape, the gland would stay on for sure but then I could only get sealant around the corner of the perimeter where the gland intersects the roof. If I instead used a strong adhesive sealant I'd then get sealant both under the gland and also around it's perimeter. The sealant-as-adhesive would potentially be messier than tape, though, when trying to get the gland into place.

Six of one, half a dozen of the other?

To ajmaudio's point, I did some more reading and Sikaflex-221 looks a lot more appropriate than 252, thanks for mentioning that one. The 221 would suffice for both adhesive and sealant in this case, the gland is going to see essentially no load.

Thanks,
Toby.

I've been happy with it.. you gotta work pretty fast, not crazy fast.. but its pretty quick if your humidity is very high at all. Also, as far as the mess part.... Just use masking tape. Mask the area, stick down the gland, shape the sealant at the gland/roof junction as you see fit, wait a minute, then remove tape to leave a nice clean sealant line. Works great as this stuff is pretty stiff and doesnt really run or sag after tape removal.

 

[karlmagnum]

I would use a high temp silicone sealant like the Black Permatex.

 

[snare]

i have some Dicor 501LSW-1 Lap Sealant on the way for mine. Was recommended for the gland i got.

 

[doug720]

If you need another option, consider roof sealants used on motor homes and RV's. They are designed for UV exposure on roofs, can be found for plastic, fiberglass, aluminum materials, are self leveling, last a long time, and fairly inexpensive.

 

[FordGuy1]

The best I have ever used is 3M Marine 5200 Adhesive / Sealant . I am not a fan of silicone at all. This stuff takes forever to set up, but it is awesome. Its used for thru hull fitting on boats.

 

[doug720]

5200 is for bedding parts and is not UV rated if exposed. But is a hell of a sealant and is rated for below waterline use...so it's good! Just not UV.

 

[ajmaudio]

Indeed 5200 is no bueno on a roof exposed. The sika products mentioned are high grade adhesives/sealants designed for exactly these uses and appear to be rated for a much longer lifespan than some of the lap sealants.