# Roof window re-sealing what to use.



## coppo

We need one re-sealng.

What do you use, can anybody recommend? Hymer S820 2004.

I,ve been up on the roof. The sealant on is black in colour, it is still soft/pliable but is all cracked and coming away.

Do you just scrape the old sealant off with a plastic scraper, clean the area with white spirit to get rid of old the old sealant, mask off and then apply the new.

It seems straightforward enough. Have I missed anything?

Cheers

Paul.


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## blackbirdbiker

When i had this problem i was advised not to use white spirit because it leaves a coating and it stops the Silkaflex from bedding down properly.
I used 512 and had no problems.

Keith


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## coppo

So is it better to use Silkaflex rather than the pliable black sealant that you get from caravan outlets.

Is it better to remove the skylight completely, then refit it?

Paul.


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## TIM57

I used the black sealant on a roll, its made for the job. Yes remove the old sealant, I cleaned the area with white spirit, then T- cut the area around the opening, polished it off with a clean cloth, and refitted it with new sealant. I then t-cut the rest of the roof and waxed it whilst I was up there
Tim


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## Pudsey_Bear

All window fitting instructions I've seen recommend a none setting mastic, not a sealant type adhesive.

I'm out now but will post a pic of the caravan one I used on all my windows and it's only £3-4 each, and easy to apply and clean up afterwards.


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## coppo

Kev_n_Liz said:


> All window fitting instructions I've seen recommend a none setting mastic, not a sealant type adhesive.
> 
> I'm out now but will post a pic of the caravan one I used on all my windows and it's only £3-4 each, and easy to apply and clean up afterwards.


Yes thats what I thought.

Can you just reseal or do you have to take it out and start again?

Paul.


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## TIM57

Correct me if I am wrong, but is Sikaflex 512 not an adhesive sealant that sets.
Most seams and window unions are fitted using a none drying mastic, as they are mechanically fixed using screws or clamps.
I would not like to try to remove a window that had been sealed using Sikalex as it cures to a hard finish.

I had a leak on one of my roof seams and sealed it using a gutter sealant by removing the old sealant that had oozed out and piping a thin bead of the gutter sealant, it worked. but is now an annual event as it seems to erode with the rain and sun.
Guess I will be forced to do a proper job eventually by removing the trims and fitting a new strip of mastic on a roll.
Tim


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## cavs

I've just replaced a Heki rooflight with a Fiamma Turbo Vent fan. The instructions that came with the new unit recommended a non-setting sealant called Sikalastomer-710. I found some on eBay for just under £9 a tube (bought 3 just in case; used just under 1  ). It's white and VERY sticky but doesn't set and is not an adhesive - needs a mechanical fix as well.

As to cleaning, I used a combination of white spirit and a silicon cleaner, plus a bit of elbow grease and finish off with meths to get rid of the white spirit residue. If I were repairing a seal I would try to remove the unit completely to ensure that I left no invisible avenues for water to track through.

(BTW - I certainly didn't polish the roof afterwards 8O  )


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## Pudsey_Bear

coppo said:


> Kev_n_Liz said:
> 
> 
> 
> All window fitting instructions I've seen recommend a none setting mastic, not a sealant type adhesive.
> 
> I'm out now but will post a pic of the caravan one I used on all my windows and it's only £3-4 each, and easy to apply and clean up afterwards.
> 
> 
> 
> Yes thats what I thought.
> 
> Can you just reseal or do you have to take it out and start again?
> 
> Paul.
Click to expand...

I'd be inclined to clean as much off as possible and start from scratch. Even removing it so you can get at it properly.


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## Pudsey_Bear

T cut is a good cleaner, too, you can paint straight after it, and paint doesn't like anything even slightly unclean.


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## Pudsey_Bear

coppo said:


> Kev_n_Liz said:
> 
> 
> 
> All window fitting instructions I've seen recommend a none setting mastic, not a sealant type adhesive.
> 
> I'm out now but will post a pic of the caravan one I used on all my windows and it's only £3-4 each, and easy to apply and clean up afterwards.
> 
> 
> 
> Yes thats what I thought.
> 
> Can you just reseal or do you have to take it out and start again?
> 
> Paul.
Click to expand...

Paul I drew a little diagram for you as how is as important as what you do, see pic to explain, but a circular paring motion is better than a chiseling or carving type of motion, I use a slightly dull chisel, as you want to pare through the sealant, but not mark the roof, although some of it will be unseen, you will likely need to make a few passes, Aldra is handy for that it seem :roll: :roll: :roll:

When you re-apply the none setting mastic put some masking tape down first, as it will give you a visible edge to apply to, and also when you've smoothed it out you can pull the tap and leave a neat looking edge.


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## Glandwr

Coppo I've got a S740 of the same year (virtually identical) and have re-bedded all four of them after one leaked. 

It's a fairly easy job. Remove the 8 screw covers and srews inside the van then the light separates into the inside and out side bit. You might have to lever up the outside bit.

Clean everything (I used white spirit without problem, just make sure it is dried off) use any non-setting mastic or sealing strip for caravans. Make sure that when you re-tighten the screws you do them progressively.

I had previously re-bedded the big rising one in the front. That was a bit of a pig though. A two person job as well.

Dick


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## kimbo4x4

Having recently replaced the two rear roof lights on our Hymer E510 I would remove and refit. It was not as difficult as I thought it was going to be as the old sealant was a bit crumbly.

Removed screws from inside, removed fly screen assembly.
On the roof. Using an old hacksaw blade "cut" between sealant and roof. 
Using slight leverage removed roof light.
Cleaned /scraped off old sealant using plastic tool from DIY shop and white spirit. let this dry for some time.
Sanded the area around the opening where new sealant was to fit. Dusted off.
As recommended when fitting new sky lights I used a non setting mastic strip - this comes in 2 widths. From memory I used the narrower 18mm strip. 
Fit strip, place Sky light back in opening/on strip
Tighten up screws inside pulling the skylight down to make a sandwich.

Have a coffee.
Tighten up the screws again.
Refit fly screen and bits.
Most of the Roof / Sky Light manufacturers have good instructions on line re. fitting.
Have fun 
:wink:
Anyone looking for Hymer 400 mm roof lights ?


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## Pudsey_Bear

You couldn't make it up, I was in the van this morning, and the bloody Heki is leaking from one of the back corners, so I stuff a old towel in it for now, 2 hours later I turn round and the other back corner is leaking too, We've not even been away in it yet, so it looks like the next dry day will be spent sorting that out.


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