Sealants for polycarb windows

[lumphammer]

I am about to replace the windows on my Achilles 840. These do not have a frame and are fixed direct to the coach roof with stainless self tappers at the moment.

I would welcome any advice on how best to make a water tight joint when putting them back. I have read some posts on using a neoprene seal, and also about odour free silicone sealant.

TIA

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[Talbot]

3M do a foam tape that has double sided adhesive, and is waterproof when compressed. It is purchased at your desired width cut from a long roll. I had a lot of difficulty finding it and it is not cheap, but the end result is a very neat seal.

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[cindersailor]

I did this job on my replacement perspex windows last year. I used closed-cell neoprene tape available from Seals + Direct (sealsplusdirect.co.uk). They supply either adhesive or plain versions, I used the plain and some marine grade silicone sealer (3M I think). Nice thing about this as a sealant is that it can be easily removed from the perspex once hardened without need for a solvent to leave no trace. Very pleased with the result, no leaks so far. Important not to screw down too hard with the self tappers as the perspex will crack quite easily, just enough to slightly compress the neoprene and squeeze out some of the sealant. If you search around you will find various advise about not using countersunk screws as they put an undue stress on the drilled perspex, also not to use the normally curing silicone (the stuff that smells of vinegar), I did both (!) and have had no problems so far.

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