Roof/wall seam (1 Viewer)

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Moodybrook

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Jul 7, 2013
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When renewing the roof/wall corner seam with some new mastic/non drying sealant. Do I have to religiously remove all of the old mastic from the seam joint ? I was thinking of using a cut down wooden spatula of some sort or a modified wooden clothes peg to scrape it out.

Do I just need to remove enough so that I can apply a liberal dose of fresh mastic/sealant ?

I don't have damp. I have tested everywhere with my new non invasive damp meter. I just want to reassure myself that the brain dead numpties that made the van weren't just lucky. Hence for making sure I won't have problems in the future. I have no intention of paying £40 - £50 + an hour for what should be a simple job. I haven't done this before, so before I started I thought I might get a few pearls of wisdom from the initiated. Thanks in anticipation :)
 

DP+JAY

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If its not leaking then they weren't such numpties after all
There is usually some sort of capping over the seam and this needs to be removed. Sometimes it's screwed down but often glued
It's not a job for the faint hearted and can be very messy & time consuming
If it looks in good order & it's not leaking I would leave well alone
 
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Personally I work on the basis of if it aint broke don't fix it!! But to answer your question the answer is yes you do need to remove all the old mastic to ensure you get a good seal. I wouldn't attempt such a job as this unless my van was somewhere warm and dry, as in "indoors" at this time of the year.
 
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if its not leaking then leave well alone, once you break the original good joint - its a hell of a job to make sure it stays that way - lesson learnt the hardway!!

If you really must do it, especially this time of year, then id just go over the top of what is there already - but first apply some sikaflex activator so the new sealant bonds to the old
 

FJmike

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I also would not attempt such a job at this time of the year but when you do make sure all the old mastic is taken out. When I did my rooflights I bought a plastic tool from Been & Qued , its a bit difficult to describe but was black and had a pointed bit at one end and If I remember correctly was sold as a mastic removal tool. It worked a treat on getting the old mastic off and was surprisingly sharp despite being plastic, but not sharp enough to damage anything.

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Moodybrook

Moodybrook

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Thanks for all your replies. She will be inside so I can fiddle around to my hearts content.

There is a feeling of leaving well alone but while I have the luxury of a convenient dry home, I have a stronger urge to make sure and "it sees me out".

Believe me, if the constructors of vans do anything correct, it is by mistake ! The more I look at how mine is put together, the more I am convinced they threw it together with a shovel from 20 yards.

After the 15th Dec, (I have to vacate her residence for the next two weekends), I then have till March to work on her. I have some aktivator from fitting my solar panel, and the total refurb of the bathroom. I saw some plastic mastic extractors in Lidl some time ago and should have bought one then, there were several different shaped cutting fitments, bummer.

I think I will assess the situation when I get one side of the aluminium trim off, It is a screw on job, the screws are under a black plastic insert, I will try a complete extraction but if the original sealant does have a good hold and appears to be not drying out, I may just top up with fresh stuff, and then clean up behind me.

If anyone spots this and has done the job I am meaning to do, please add their experiences for me. Thanks again
 

DP+JAY

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Yes I've done it which is why I warned against it.
I found the screws were some sort of soft alloy, making them very hard to get out, & once the screws were removed it was difficult to remove the ally beading from the sealant without it bending. Then there is the job of removing the old sealant from the beading, all in all a nightmare. I too thought the dealer price for the job was ridiculous until I did it.
If you must do it then good luck.
 
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Moodybrook

Moodybrook

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Jul 7, 2013
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Wet and cold place outside of M25
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still in nappies
Yes I've done it which is why I warned against it.
I found the screws were some sort of soft alloy, making them very hard to get out, & once the screws were removed it was difficult to remove the ally beading from the sealant without it bending. Then there is the job of removing the old sealant from the beading, all in all a nightmare. I too thought the dealer price for the job was ridiculous until I did it.
If you must do it then good luck.

Now that is what I was wanting to hear ! Thanks very much, your experience is valuable. I can visualise the problems. Sealant in my relative novice hands can be a bit of a b....r .

Crap soft alloy screws sound like par for the course with the "Professionals". The whole concept they have used is a design F..k up. Oh, we have a floppy edge what shall we do, Duh, splodge some mastic on it and try and cover it up with a bit of ally. Wonder what species of cretin crawled out of the primordial soup to bless us with this. :eek:

Anyway your caution is well noted, if you have an Elddis and want some help with your washroom, I am just up the road from you (y) :)
 

DP+JAY

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We have an Adria now but the resealing job was on a Frankia.
Dumfries not far away & an area we love when no midges about.
 

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