I have had to remove appx 2.5 inches of plaster from the internal, overhead window reveal, this is the edge nearest the upvc window frame. This is because what looks like roofing felt, which seems to have been used as a dpc in the past, was dislodged 4 years ago during lintel replacement and was causing the plaster to sag; finally got round to doing this room and investigated said saggy plaster.
Two builders have looked at the roofing felt, which as a dpc was useless, both said none was needed, the latest said the lintel was an enclosed unit. I should add at this stage we have never had any issues with water getting in or damp. I have since removed the felt but need to make good the plaster, which is my problem/question.
I have a metal lintel above the window frame, a 3/4 inch gap (cavity) and then a concrete lintel which has the original plaster directly onto it.
I have been told by one builder to use sand and cement to fill this 2.5 inch hole, however sand and cement is not going to stick to the metal lintel and the 3/4 cavity of nothing. The other said use plasterboard, which I was reluctant to do as I've read that you don't fix plasterboard to external walls, however this is the method used by the builders in the extension etc and the board won't be touching the outer brick work. I was going to use "moisture resistant" board and wrap a bit of dpc membrane round the external lintel just to be on the safe side and use adhesive to stick the board to the internal concrete lintel, from which I'll remove all of the remaining plaster..
Would this be an ok fix? Could I stick the plasterboard to the metal lintel, with some dpc in-between, which in turn would also have to be stuck to the lintel to keep it in place and then hold the board and does the cavity need to be closed and of so what with?
Any suggestions appreciated.
Two builders have looked at the roofing felt, which as a dpc was useless, both said none was needed, the latest said the lintel was an enclosed unit. I should add at this stage we have never had any issues with water getting in or damp. I have since removed the felt but need to make good the plaster, which is my problem/question.
I have a metal lintel above the window frame, a 3/4 inch gap (cavity) and then a concrete lintel which has the original plaster directly onto it.
I have been told by one builder to use sand and cement to fill this 2.5 inch hole, however sand and cement is not going to stick to the metal lintel and the 3/4 cavity of nothing. The other said use plasterboard, which I was reluctant to do as I've read that you don't fix plasterboard to external walls, however this is the method used by the builders in the extension etc and the board won't be touching the outer brick work. I was going to use "moisture resistant" board and wrap a bit of dpc membrane round the external lintel just to be on the safe side and use adhesive to stick the board to the internal concrete lintel, from which I'll remove all of the remaining plaster..
Would this be an ok fix? Could I stick the plasterboard to the metal lintel, with some dpc in-between, which in turn would also have to be stuck to the lintel to keep it in place and then hold the board and does the cavity need to be closed and of so what with?
Any suggestions appreciated.
