Sealant

[Big Jim]

The sealant on my roof windows was shocking . It had lifted and cracking . I could pick most of it off with my fingers . The side windows had a heavy bead of DIY silicone around them which was a bit messy and also cracking . It's all gone now . My caravan service guy gave me a tube of Bondit PU18 polyurethane sealant , which he swears by . What do you use ?

[rubberrat]

Sikaflex 512. But remember...like a dog at Christmas...It's for life

[Gary W]

Hi Jim

Windows, doors, roof hatches, vents etc. should be installed with a non setting mastic such as Dekalin 8936. PU adhesives are generally used to provide a structural bond. If you use a PU sealant/adhesive you can be 100% sure it will never leak leak, but if you ever need to replace the fitting you will not be able to remove it without damaging the body.

Hope that's helpful

Gary

[saDgit]

Hey Jim,
I'm with Gary on this. I use Sikaflex (pro 11 FC in my case) on anything structural and where I'm absolutely certain I'm not going to want to take it apart or service it. But on anything like a window or roof light, or even seams where I'm happy to check and re-seal very few years, I use Dekalin or a butyl mastic tape. I may be wrong but I don't think there are ever circumstances where a silicon sealant is the right thing to use.

[Big Jim]

Thanks for the advice there is never one answer is there ?
I have used Soudal Fix All before with good success and you can use it in damp condition, it seems to be a similar product to PU18 .

This other Soudal prouoct claims to remove it .




Jim

[sabconsulting]

I use Sikaflex 512.

It sticks to fingers, clothing, tools, everything. A bit of white spirit helps clean it off.

I use masking tape to ensure my lines are straight because I am hopeless with a mastic gun on its own.

All sealants fail over time, so keep inspecting them and be prepared to replace when you find they are cracked or pulling away from a surface. I suspect most of the rot problems in timber framed campers come from people assuming they were sealed forever and not inspecting / renewing the sealant. I have seen reports of US campers only a few years old suffering from rot where sealant has failed and not been noticed.

Steve.

[Mike]

Did my sealant today all the external joints with silkaflex. Used masking tape which made it easier took about 3 hrs masking and sealing for each side . Need to do the roof vents next with mastic I think. BTW use wd40 to get the sealant of my hands worked well.

[Madmountainman]

I've been liaising with a friend of mine that's worked in the industry for years and will be doing my skylight as follows;

1. Remove Skylight
2. Clean all old sealant/butyl strip - one of those scraper handles that utilises a stanley blade, used in conjunction with brake cleaner.
3. Re-line the frame area with Wurth Butyl Tape and run a seam of Dekaseal 8936 for a belt and braces finish.
4. Re-fit the skylight and see if any more Dekaseal needs adding to give a nice smooth finish.