# Best mastic for redoing a seam on the MH?



## GMJ (Jun 24, 2014)

One of my seams needs redoing so I plan on carefully gouging out the old mastic and redoing it.

Any recommendations for a make?

It will need to be white; mould proof and water proof.

ta


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## Pudsey_Bear (Sep 25, 2008)

You are asking too much there G, It'll Be Sikaflex but I know not the number.


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## dghr272 (Jun 14, 2012)

GMJ said:


> One of my seams needs redoing so I plan on carefully gouging out the old mastic and redoing it.
> 
> Any recommendations for a make?
> 
> ...


Sikaflex 221 is my preferred sealant for such tasks as also resistant to UV light.
Just ensure area is totally clean of grease, meths will de-grease although Sikaflex have their own de-greaser product too, Sika Activator 205.

Terry

Edit: mask area of on all sides as it is messy.


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## eurajohn (May 9, 2005)

Motorhome joint seals are never made from the exterior of the joint when being produced, the joint is formed in the same manner as a gasket does in an engine, i.e. the joint compound is placed between the two parts of the joint and when the two parts are clamped together the excess is squeezed out and form the part you see externally.
If you have a leak then the seal really needs to be done correctly, if you have no leak and it is purely cosmetic then it is OK to apply a cosmetic ribbon.


.


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## GMJ (Jun 24, 2014)

We have no leak at the moment but the capping is standing a little proud. The older stuff in there is holding but, due to its position - its facing forward - when we drive, its getting everything that can be thrown at it, so it's only a matter of time before it goes I reckon. The join has recessed somewhat by having too little mastic in there from when it was made, so has formed a little channel so crud can get stuck in there which has been exacerbating the problem I think.


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