Minor leak in fibreglass hi top - best stuff to use ?

Wisewoman

Wisewoman

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Hi there,

I am currently wild camping around Norfolk with my 5 year old. Over the last couple of days we have had lengthy periods of torrential rain and my daughter noticed some dampness on the carpet lining the fibreglass hi top roof above her head, where she sleeps.

It really is slightly damp - not sodden or dripping - but there is clearly an issue somewhere. It's not near any windows, it's right in the middle.

I am going home today and going to have a look on the top with the use of step ladders. I guess I am expecting to see a small crack somewhere. Assuming I do, what's the best thing for me to use ? Can I just slather silicon bathroom sealant over it ? Or will that not work on fibreglass ? My van and its top is getting she is 26 years old - not sure if that makes any difference to anything? I suspect this crack is just the first sun caused wrinkle in her skin ;)

Any advice from people in the know gratefully received.

Thanks
Melissa
 
............Also, check the seal around any roof hatches if you have them.
 
Great - thanks Rob. If it works on boats then hopefully it will work well on the Dragon van :) I will order some capt tolleys off Amazon once I've had a good look to confirm the issue.

As you've mentioned it, I'm also wondering if it may be a seal around my skylight so I may try shoving some thicker silicon sealant around that too - just incase.

Am I right in assuming that fibreglass hi top would be one piece so the weaknesses would be Windows, skylight and where it joins van. In which case as its on the top in the middle about a foot away from skylight then a weakness around the skylight may actually be a likely cause.

Mulling it over out loud...
Cheers,
Melissa
 
Wisewoman said:
Great - thanks Rob. If it works on boats then hopefully it will work well on the Dragon van :) I will order some capt tolleys off Amazon once I've had a good look to confirm the issue.

As you've mentioned it, I'm also wondering if it may be a seal around my skylight so I may try shoving some thicker silicon sealant around that too - just incase.

Am I right in assuming that fibreglass hi top would be one piece so the weaknesses would be Windows, skylight and where it joins van. In which case as its on the top in the middle about a foot away from skylight then a weakness around the skylight may actually be a likely cause.

Mulling it over out loud...
Cheers,
Melissa
Click to expand...

I would say almost certainly the skylight Melissa, (others may think different!). Leaks often show, sometimes quite a distance from where the water is actually getting in.

If it is, it is worth removing it completely and scraping away all of the old sealant and giving it a good cleanup before resealing. I am putting my new skylight in with Mastic tape around the inside of the frame followed by Sikaflex around the seams where it joins the fibreglass.

Give it a couple of days, as others will also advise.
 
I should also mention that many people recommend a non setting sealant, the name of which escapes me, but somebody will be along with it before long.

But I am using Sikaflex 512 Caravan, which is also recommended for the job and can be removed at a later date if necessary if the job ever needs doing again.
 
silicon sealer is no good on roof vents, I always use a non setting bedding mastic such as this http://ri.search.yahoo.com/_ylt=A7x...-Mastics/RK=0/RS=wZS3bT6YfCDzsqMXbJhwM9t665A-
I normally put two good beads on the cleaned flange of the vent this uses virtually a full tube per vent it will squelch out around the vent when it is screwed / clamped down etc but guarantees a good seal and the waste can be scraped off with a plastic filler spreader or similar.
 
Tiger seal best for fibreglass just google its expensive but does work well.
 
Thanks for all the input and suggestions. :)

I have now pulled down some of the carpet on the roof inside the van and discovered that the dampness does go as far as the skylight. I've also had a nose on her top outside. I can see no obvious cracks or holes in the roof and I am feeling fairly certain it is the sealant around the skylight. There's some beading around the bottom of the skylight, just like what you would see around your bath. I can clearly see that in places it has come away.

I am going to pull away the old stuff and pump a new bead around - my dilemma now is whether to go for the sikaflex or tiger seal. So i shall do a bit of research and see if anyone else has any other suggestions for best sealant to use in these circumstances.

I'm also going to try and initially do this without removing the whole skylight and see if I can get away with just resealing the bottom.

Cheers everyone!
Melissa
 
The standard sikaflex or tigerseal which is very similar is not really suitable for sealing roof vents it sticks to the fibre glass great but eventually breaks away from the plastic of the roof vent ,the only way to do the job properly is to remove the vent and seal with a non setting bedding mastic such as that I put in the earlier link, putting a bead of anything around the outside is not likely to cure the problem and will just give you something else to remove when you do need to do the job properly.
 
If your budget will allow, it may be best to get this sorted out professionally.

I recently had a large Heiki rooflight removed and refitted to cure a major leak. The material costs were negligible, and I was charged two hours labour.

Removal and refitting is the only certain way to cure the problem. As has been said all the old sealant needs removing to be certain that the new sealant does its job.
 
OK - so I've now looked at the removing skylight video - it makes it appear a very simple job. I think I'm just a bit nervous about possibly making things worse by tampering with the entire thing too much, given my vans age!

There is a caravan and motorhome place near me but I didn't feel I had an especially good experience with them last time i went there, so am reticent to return but I think I will make a tentative enquiry as to how much it may be for them to deal with the skylight.

i hear you 'full timer' and my instinct tells me you are right so I perhaps need to stop being so gentle in my approach!

PS - does anyone know where I can get one of those 'fly mats' - my skylight is exactly the same as the one in the video and I'd thought for a while that there looked like there was something missing - now I know what it is! :)

Melissa
 
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Another thought...

If i decide to do it myself will the mastic stuff on a roll, be as good as squirting it around? In the video he appears to use the roll stuff and it seems like it would be simpler to use.

And whats the difference betwen 99 and 110?

Ive just been out to the van and after seeing that video i really am thinking I'm going to give it a bash tomorrow (weather permitting), so long as I can get the mastic stuff (on a roll?) from B&Q! If I struggle to get the skylight off then I'm going to investigate motorhome repairers in the area!

Cheers
Melissa
 
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I would definitely choose the butyl mastic in roll form. I have used this and it's much less messy and it's straightforward to apply.

I don't think you'll get it at B&Q or any DIY outlet. I bought mine on eBay.

Just make sure you get the correct width ...
 
You are right Chris -a B&Q search turns up bathroom and kitchen sealant rolls but they don't appear to have the magic word 'mastic' in them. Same with Screwfix.

As my vent is same as the video one linked to earlier in this thread, and as it looks like he is using the 19mm width one I take it this is what I want:

5m length roll of 19mm wide caravan white mastic tape sealant strip sealer TS1 | eBay

Looking again, not sure if his is a bit wider than 19mm so maybe the next width would be better.. will ebay it and will decide after getting vent off, hopefully tomorrow!

I guess i should also additionally bead around the outside bottom of vent again too!
 
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