Correct type of sealant for a fibreglass roof to repair heki roof light? (1 Viewer)

[me you and pogo 2]

Hi,

I've read lots in the tech forum but I am still unsure which is the correct product to use.

The moho roof over the cab is painted white on a fibreglass shell and has some curvature, the heki roof light needs to be resealed.

Do I use a mastic strip, do I use a type of sealant?

Please what is the correct product to use?

Any help and advice would be appreciated...........

Many thanks
Dave

 

[Speve]

Well I don't know what others would use but in my experience Stixall is a excellent sealant/adhesive which even sticks in the wet, others may suggest Sikaflex but that's a lot more expensive and I don't think any better IMHO.
I stuck my reversing camera on the back of the van with Stixall two and a half years ago and it's still solid with no leaks.

 

[Two on Tour]

I removed the rooflight and all the old gungy silicone that had lifted and was not sealing on our previous van and re-fixed the rooflight on a bed of white SikaLastomer 710 butyl sealant

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[me you and pogo 2]

Hi, thanks guys for your advice, it's appreciated. I'll check out your suggestions.

Regards
Dave

 

[Mike800966]

We also had a roof leak and noted that Thetford recommended a"butyl " type flexible sealant, I didnt realise that sika made one but I have used Everbuild Butyl 145 sealant, its apparently much cheaper, really sticky and non setting at about £5 a tube

 

[tonyidle]

W4 do an excellent butyl mastic. It comes on a roll in various widths and never sets. Brilliant stuff.

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[Allanm]

I had to take off a fridge vent recently and sealed it again with W4 mastic sealing strip.
It works well and will stick to almost anything. It’s non setting so if you ever need to remove the roof light, you can

 

[TheBig1]

never fit plastic rooflights using sikaflex or other urethane bonding agents. use butyl mastic strip which ensures a uniform flat seal and is non setting

 

[me you and pogo 2]

Hi everybody, we have been away for a few days, thank you all for your advice, it's appreciated.

I decided to use the W4 mastic sealing strip and tidied the edges up with Sikaflex EBT and I am pleased with the result.

Thanks once again.
Regards
Dave

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[Guigsy]

never fit plastic rooflights using sikaflex or other urethane bonding agents. use butyl mastic strip which ensures a uniform flat seal and is non setting

What's wrong with gluing stuff on?

 

[TheBig1]

What's wrong with gluing stuff on?

from experience and science, the plastics used in skylight frames etc becomes brittle and starts failing caused by uv light exposure from the sun. then when you need to remove and replace, bonding agents like sikaflex are difficult and destructive to remove

 

[Guigsy]

from experience and science, the plastics used in skylight frames etc becomes brittle and starts failing caused by uv light exposure from the sun. then when you need to remove and replace, bonding agents like sikaflex are difficult and destructive to remove

Thanks. I've recently replaced my skylights on my PVC conversion because the domes went brittle and one tried to make a break for it on the motorway. The frames were in good nick, but the complete units were virtually the same price as just the domes and a more modern design. The old frames were stuck down with 3 different types of sealant in various states of degradation, so the previous owner had an issue at some point. I think they'd just used bathroom silicon sealant from the look of it. I just took a sharp knife to the gap and ripped the old frames out. It took a while to clean up the old gunk of the roof.

For the replacements I used Sikaflex. I should last 10 years and I shouldn't have a reason for taking the frames out again. I did consider sealing strips, but the van roof is ridged, so I figured a gloopy bonding sealant would give a better seal. I was also worried that strip stuff is more likely to let water sit in cracks and crevices than a beaded sealant. /shruggie

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