rocksaplenty Posted February 17, 2014 Report Share Posted February 17, 2014 (edited) I'd be grateful for some building advice. The rsj above our patio doors is rusting and expanding and cracking the render. I've inspected and it looks like there was no cavity tray fitted when built (c1970's). Apart from fitting one, i'd been thinking about cladding the outside of the building with wood. On the basis that it would provide an adequate moisture barrier so that in theory no more moisture would get into the cavity wall. Would that solve the problem?Thanks Edited February 17, 2014 by rocksaplenty Quote Link to comment Share on other sites More sharing options...
bobt Posted February 17, 2014 Report Share Posted February 17, 2014 it cant hurt things are you sure the rsj was in from new? its the sort of thing builders add when widening an opening, Quote Link to comment Share on other sites More sharing options...
rocksaplenty Posted February 17, 2014 Author Report Share Posted February 17, 2014 (edited) Yeah. I think they might have added the patio door opening some time after the building was up. That said there are a few other places that seem to be cracking. I don't think that the cavity wall insulation they put in a few years previously has helped the situation. Edited February 17, 2014 by rocksaplenty Quote Link to comment Share on other sites More sharing options...
bucksshooter Posted February 17, 2014 Report Share Posted February 17, 2014 either that or seal the wall to prevent moisture penetration Quote Link to comment Share on other sites More sharing options...
kent Posted February 17, 2014 Report Share Posted February 17, 2014 Its not easy to do well especially with cavity wall insulation, rusty RSJs are still very strong non the less. I should try sealing the wall externally and checking for water ingress from higher up (like badly fitted windows etc?) Quote Link to comment Share on other sites More sharing options...
Fisherman Mike Posted February 18, 2014 Report Share Posted February 18, 2014 (edited) I'd be grateful for some building advice. The rsj above our patio doors is rusting and expanding and cracking the render. I've inspected and it looks like there was no cavity tray fitted when built (c1970's). Apart from fitting one, i'd been thinking about cladding the outside of the building with wood. On the basis that it would provide an adequate moisture barrier so that in theory no more moisture would get into the cavity wall. Would that solve the problem? Thanks Really depends how much money you want to throw at it and if the Local Planning Authority will allow you to clad it in timber. Is the existing building brick built ? I would be tempted to temporarily take the Doors out, whip out the old RSJ and build in a new Galvanised steel cavity lintel with cavity tray above. I would have thought that would have been cheaper to do than cladding the building. You can then seal the brickwork above ( giving special attention to the mortar joints where the water will be driving through) with a silicone water repellent applied with a garden sprayer. Its important to re seal it every 5 or so years though. Do you know what type of insulation was installed in the cavity...was it blown fibre or poly beads. ? If you are looking at Timber cladding, cedar or larch is possibly going to be the most cost effective long term and it might be worth considering an insulated render system which will have the benefit of reducing the U value through the wall and also your heating costs. All steelwork in a cavity wall should be either galvanised or if not given at least two coats of Bitumen paint. Edited February 18, 2014 by Fisherman Mike Quote Link to comment Share on other sites More sharing options...
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