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The mastic seals on my van are decaying and need renovating - so


Can anyone give me tips and advice on the removal and rebedding of awning rails and trim.

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This is from another forum some time ago, from David Halley who is a knowledgeable chap!


"Remove all the screws, then gently heat the rail with a hot air gun or powerful hairdryer and gently ease the rail off, trying not to bend it.


Clean off all the old mastic using a plastic scraper and white spirit.


Now would be a good time to have a look under the joins and see if there is any water visible. It would be better if you were able to open the joint, carefully and get some heat in to dry out the damp. If you don't, you are going to seal up the hole it got in and its only way out will be down the wall, unless you take the precautions detailed below.


Thoroughly clean the rails you have taken off and make sure the gaskets are intact.


Remove any screw shafts that the heads have come off.


Use Sikaflex 221, or Geobond SMP round all the joints and leave it to go off for 48hours. Your caravan will be sealed by this time so don't worry if the van is outside. If you rush the job it will not seal as well as it could


Once the bond is dry apply a decent bed, and I mean bed, not a mispelled bead, of oil based mastic, like Secomastic. The stickier the better.


Also apply some mastic to the rail and push the rail onto the van so that mastic comes out through the screw holes. Before putting each screw in wind some of the mastic that has come through the hole around the thread so that you are taking mastic into the hole in the caravan.


The reason for the two beds of mastic is to fill the grooves in the rear of the rail as there have been case of water getting behind the rail at one point then travelling along the grooves until it finds an unprotected screw hole.


Tighten the screws a bit at a time in sequence to achieve an even finish gradually forcing the excess mastic out.


Clean off the excess mastic with your plastic scraper and white spirit, but don't wet it too much as the white spirit will get into the mastic and weaken it.


The infill (screw covering) goes in much better if warm. Use the heat gun or a bucket of hot water. New infill is softer than old and only costs £1 per metre.


If there is evidence of water getting in bore a 25mm hole in the inner panelwork, probably inside a roof locker, and fit a vent into the hole. This will allow any water to come out rather than travel down the wall.


Hope this helps




David Halley


www. halleycaravans. co. uk"

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Guest Hobbybod

Excellent tips via David Halley, but here's a few I noted when I last did it!!


It's important to be very careful removing the rail without distorting it and causing crazing of the anodised aluminium.

To this end I used a 'cheese-wire' approach to break the seal between the rail and the 'van. Most rails are in two halves.


David's dual sealant approach is very good; I just used Sikaflex, which is an adhesive as well as a sealant. OK until you wish to re-seal (which should not be necessary) and then it's the very devil to remove.


Do not re-use the screws, but use new stainless steel ones, and if any original ones are rusty then inject some wood hardening resin into the hole, as you may have some rotten wood there.


Again make sure sealant/mastic exudes from each screw position. Add some extra, new screw positions, countersinking so that the awning bead isn't fouled.


And the best of luck; it's quite a job to do properly.

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The mastic seals on my van are decaying and need renovating - so


Can anyone give me tips and advice on the removal and rebedding of awning rails and trim.




Thanks guys - I feel confident (but not over confident) that I can do the job

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