bob b Posted January 3, 2014 Share Posted January 3, 2014 I've got a flexible sealed joint between the overcab and main roof on my Rapido. The joint was replaced a couple of years ago as I suspected it was leaking. I'm not entirely comfortable with the way this particular joint is sealed and my damp meter is giving me high readings in places. When the weather improves I'm going to lift the three skylights and re-bed them in sealant and will also place a length of UPVC strip along the sealed joint. A pal who fits UPVC doors 'slipped me a length'!My query is which is the best method of fixing the strip in place. As the main roof slightly 'slopes' away from the overcab, I'm thinking of using the sealing ribbon... probably a double layer where the roof slopes...and then sealing the edges with Sikaflex. Has anybody done something similar with success? Photo's below. Link to comment Share on other sites More sharing options...
lennyhb Posted January 3, 2014 Share Posted January 3, 2014 I take it you are going to cap the joint with the strip. The important thing is to make sure the sealant you use has the correct expansion rate especially as it is on the roof in direct sunlight. I would think Sikaflex is a good choice but would contact their technical department to make sure you get the right product. Link to comment Share on other sites More sharing options...
pepe63xnotuse Posted January 3, 2014 Share Posted January 3, 2014 Hi Bob.. We've got(or had),a similar looking seam on the roof of our Chausson... I "capped" ours with a 2 1/2" - 3" bevelled flat upvc moulding, bedded down and beaded in, with Sika 512... (It's been up there 1/8months - 2 years..and so far, so good! ;-) ). Before fitting the strip, while I was at it, I did also trim/chamfer out some of the edges of the existing sealant and run fresh beads into the resulting "grooves".... The roof was looking a bit "scabby" when I took these photos(...not that I suppose it's got much better since (lol)) Link to comment Share on other sites More sharing options...
pepe63xnotuse Posted January 3, 2014 Share Posted January 3, 2014 Oops! Sorry :$ Link to comment Share on other sites More sharing options...
bob b Posted January 3, 2014 Author Share Posted January 3, 2014 That's just the job Pepe. I'll make that my project as soon as the gales abate! Link to comment Share on other sites More sharing options...
Brian Kirby Posted January 3, 2014 Share Posted January 3, 2014 bob b - 2014-01-03 9:48 AM I've got a flexible sealed joint between the overcab and main roof on my Rapido. The joint was replaced a couple of years ago as I suspected it was leaking. I'm not entirely comfortable with the way this particular joint is sealed and my damp meter is giving me high readings in places. When the weather improves I'm going to lift the three skylights and re-bed them in sealant and will also place a length of UPVC strip along the sealed joint. A pal who fits UPVC doors 'slipped me a length'!My query is which is the best method of fixing the strip in place. As the main roof slightly 'slopes' away from the overcab, I'm thinking of using the sealing ribbon... probably a double layer where the roof slopes...and then sealing the edges with Sikaflex. Has anybody done something similar with success? Photo's below. The high moisture readings may be due to condensation, possibly due to incomplete thermal insulation at the joint. Would it be practical to investigate this possibility? I'm unclear what this "sealing ribbon" is. Do check with Sika (or Loctite-Henkel as an alternative manufacturer of high performance sealants), as suggested above, before buying. Some of the available ribbon type sealants contain modified bitumen, and this can react with other formulations, causing either to break down. Not what you want. If you can, I'd suggest you find out what product was used to re-seal this joint, for the same reason. It is probably a Sika product so should be compatible with what you add, but sealants are complex products, so worth checking, IMO. It would also be worth checking that the proposed sealant will bond adequately to all the materials involved. I assume just GRP and PVC. Personally, subject to technical guidance, I'd be inclined to bed the PVC on the same sealant as you would use to point it, using spacers to ensure a consistent bead thickness, and allow what exudes to form the pointing. I'd suggest you do a dry run first, and run strips of masking tape down either side of the PVC cover-strip. Then, after the bedding is applied and the strip pressed down onto the spacers, you will can peel back the masking tape which will also remove any surplus sealant, leaving you with a reasonably neat edge requiring only minimal finishing. Be warned that these sealants stick like the proverbial and are extremely difficult to remove once cured. They are also very difficult to remove from hands, and it will be almost impossible to avoid getting some on your hands. Latex gloves will be a wise precaution! Obvious, I know, but don't do it on a windy day - the lengths of masking tape beaded with exuded sealant will wrap themselves round everything as you peel them off!! Good luck. :-D Link to comment Share on other sites More sharing options...
bob b Posted January 3, 2014 Author Share Posted January 3, 2014 The 'sealing ribbon' I'm thinking of is the adhesive/sealant strip sometimes used to bond and seal skylights. I'd then finish the edges with Sikaflex or similar (using masking tape as advised) to ensure a neat and weatherproof finish. I managed to get the 'return' over the sides carefully using a hot air gun. Link to comment Share on other sites More sharing options...
lennyhb Posted January 3, 2014 Share Posted January 3, 2014 If you do that Bob you with be using two different sealants with different expansion rates to fix the same strip, not good practice. Link to comment Share on other sites More sharing options...
pepe63xnotuse Posted January 3, 2014 Share Posted January 3, 2014 I'd agree with the advice about using the same "product" to bead, as you do to "bed".. The Sika that I bedded mine on with, worked fine.. ;-) (..besides, you'll probably have loads of it left over as it is...enough to give some attention to the other "roof furniture"..) :-D Link to comment Share on other sites More sharing options...
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