I've just discovered 2 major problems with my house, it's about 40 yrs old and is built in the way of the prevailing wind and rain. They've built an extension about 20 years ago, which seems to have a few issues:
1) With the ceiling stripped, after very heavy rain, a damp patch appears on the ceiling, in the middle of the partitition, where a first floor extension has been built onto the side of the house, I'm guessing this has no cavity tray as there's no weep vents in evidence.
2) There's a chimney stack, where they've taken the chimney away from downstairs, but left the stack resting on the plywood forming the basis for the extensions flat roof. When it rains after a couple of hours of continous rain we see a lot of damp patches appearing in the room below.
3) On windows on the prevailing weather side, we've got retro-fitted concrete lintels, after ripping of the tiles on that wall it's become clear the dpc which acts as a barrier to the water above the windows is no longer bridging the cavity and therefore rather than directing the water to flow around the window, it now comes straight through on the inside of the window.
I'm proposing to use cavity trays like these http://www.dpcproductsdirect.com/product-detail.php?pid=23 straight ones for the extension wall and lintel, left and right corners for chimney stack.
I'm guessing these problems require cavity trays, but there are a few potential issues I'd like advice on, in all cases it's only when there's very heavy rain do we notice the damp, but I'd like to stop it for once and all:
1) The house has cavity wall insulation, would this make it hard to insert after market cavity trays, such as those from DPC Products Direct, or is it simply a case of removing enough insulation to get the tray in?
2) The chimney stack is an external left and right angle, but is narrower than the 2 proposed cavity trays, should I cut them down and perhaps use sealant? Removing the chimney is not really an option at this moment.
3) Above the concrete lintels, is it sensible to fit a cavity tray? or is there some other technique that's used by the trade to ensure water on the inside flows back out. I've see lintel end stops and weep vents, but presumably a concrete lintel is flat and level, so there's nothing forcing the rain water to the outside, and a weep vent wouldn't help?
4) If I do fit cavity trays, are these best done at the same level as the flat roof membrane enters the wall, or should it be fitted a brick course higher?
5) Is it normal to to put mortar under the tray or should the tray rest directly on the brick below (or roof membrane in the case of 4) above), presumably the brick that sits in the tray is then mortared into place with mortar on the tray and under the brick?
I hope I've made these questions clear enough? Are my proposed solutions going to work or is there a better way?
thanks for any help
mike
1) With the ceiling stripped, after very heavy rain, a damp patch appears on the ceiling, in the middle of the partitition, where a first floor extension has been built onto the side of the house, I'm guessing this has no cavity tray as there's no weep vents in evidence.
2) There's a chimney stack, where they've taken the chimney away from downstairs, but left the stack resting on the plywood forming the basis for the extensions flat roof. When it rains after a couple of hours of continous rain we see a lot of damp patches appearing in the room below.
3) On windows on the prevailing weather side, we've got retro-fitted concrete lintels, after ripping of the tiles on that wall it's become clear the dpc which acts as a barrier to the water above the windows is no longer bridging the cavity and therefore rather than directing the water to flow around the window, it now comes straight through on the inside of the window.
I'm proposing to use cavity trays like these http://www.dpcproductsdirect.com/product-detail.php?pid=23 straight ones for the extension wall and lintel, left and right corners for chimney stack.
I'm guessing these problems require cavity trays, but there are a few potential issues I'd like advice on, in all cases it's only when there's very heavy rain do we notice the damp, but I'd like to stop it for once and all:
1) The house has cavity wall insulation, would this make it hard to insert after market cavity trays, such as those from DPC Products Direct, or is it simply a case of removing enough insulation to get the tray in?
2) The chimney stack is an external left and right angle, but is narrower than the 2 proposed cavity trays, should I cut them down and perhaps use sealant? Removing the chimney is not really an option at this moment.
3) Above the concrete lintels, is it sensible to fit a cavity tray? or is there some other technique that's used by the trade to ensure water on the inside flows back out. I've see lintel end stops and weep vents, but presumably a concrete lintel is flat and level, so there's nothing forcing the rain water to the outside, and a weep vent wouldn't help?
4) If I do fit cavity trays, are these best done at the same level as the flat roof membrane enters the wall, or should it be fitted a brick course higher?
5) Is it normal to to put mortar under the tray or should the tray rest directly on the brick below (or roof membrane in the case of 4) above), presumably the brick that sits in the tray is then mortared into place with mortar on the tray and under the brick?
I hope I've made these questions clear enough? Are my proposed solutions going to work or is there a better way?
thanks for any help
mike