Re-sealing skylights

[Potta787]

Afternoon, I’ve recently brought my caravan out of storage and back home to start getting it ‘ready’ for a few trips this year. 20 year old Fleetwood.

One job included giving the exterior a damn good wash (wash brush & hose), whilst cleaning the roof I noticed all the silicon (or whatever is used from factory) has started to go hard and brittle, breaking off in places as I was washing!

Question is, what to reseal with? Scratch/pick/scrape all the old stuff off, clean with meths or brake cleaner and then use a silicone? Any specific type?

[s2sol]

I do this for a living. If they don't leak, leave them. If they do, the best course is to remove them, clean the surface of the roof and the corresponding face of the rooflight. We use brake cleaner and scrapers.Ideally, prop a box under the hole to stop all the crap falling through into your bed/bathroom whatever. Then use butyl tape on the rooflight. Make sure you get a good squidge coming out of the edges when you fix the rooflight down.

We work on old motorhomes mostly, and if the rooflights are shagged, we replace 400x400s with mini hekis. They're great.

[Potta787]

Excellent! Thanks for the reply.

One of them seems to weep a little so I’ll whip it out and get it sorted.
Thankyou

[agent006]

Sikaflex 512 is what we used for resealing skylights. Your local caravan shop should have it or something similar.

[Chrisgr31]

I used mastic sealing tape from the local caravan dealership when I did one last year. Its a relatively simple job but the most difficult part is removing the old sealant.

[donaircooleone]

Definitely do not bond them in, I've lost count of the number of rooflights I've removed where they've been bonded using Sika 512/221 or ISR only for them leak or fail and become a bit of a PITA to remove.

Mastic tape (butyl tape) and make sure you get ooze when the rooflight clamps down. If you really must have a neat looking finish i.e. sharp white line with angled finish then use the mastic tape (not too much!) but overseal the edges with something like RV61 or other UV stable sealer (PU40 is another option).

Prep is everything.

[DirtyHands]

donaircooleone said:

Definitely do not bond them in, I've lost count of the number of rooflights I've removed where they've been bonded using Sika 512/221 or ISR only for them leak or fail and become a bit of a PITA to remove.

Mastic tape (butyl tape) and make sure you get ooze when the rooflight clamps down. If you really must have a neat looking finish i.e. sharp white line with angled finish then use the mastic tape (not too much!) but overseal the edges with something like RV61 or other UV stable sealer (PU40 is another option).

Prep is everything.

As above. I do this fir a living and have seen far too many cracked skylight frames from being bonded in with Sikaflex. Mastic tape is the best thing for the job. Just make sure everything is spotless and clean from all old mastic before applying.