Hi all,
We bought an 1860 Victorian House 3 years ago.
We decided to have some work done to the 1st and 2nd floors, including insulating the external walls (internally), the roof space, which had little to no insulation previously, redecorating etc.
The 2nd floor comprises 3 bedrooms and a small bathroom.
The builders have insulated the roof with PIR insulation plasterboard, which apparently has a vapour barrier and a 25mm air gap.
They have also used insulation plasterboard on all external walls on the first and second floor.
All going well until a building inspector noticed damp on an internal chimney wall;
We were told there was a leak in the roof / chimney and a roofer went up there and fixed all the lead work, cement, checked slates and ridge and said it was all good.
The builders then pointed out that there was damp on the purlins in the same room as the chimney wall and suggested that the roofer had caused an issue when up there. He went back up there with a cherry picker, rechecked everything; all okay.
The damp on the chimney wall, and purlins seemed to increase independent of whether it rained outside.
The roofer suggested it may be condensation, especially with all the skimming / plastering that had been going on internally. The builders were adamant it was the roof felt - bitumen, which needs replacing throughout, but the roofer says this tends not to fail and looks in good condition.
The damp on the purlins has increased, not just in that room, but in other rooms at the top of the house now;
The builders suggest that the roofer disturbed something and that damp is spreading across the deteriorating roof felt. They said they can’t do anything else until the leak in the roof is fixed.
This is all quite new to me, but it seems to make sense that general condensation (especially that from all the plaster) is passing through insulated plasterboard, meeting the cold air in the air gap, condensing, and then flowing down the back of the plasterboard onto the purlins making them damp?
But I wondered if other well informed people might be able to offer their opinion / advice?
Many thanks, this is becoming quite a stressful situation with 2 little children, a project that is running on in time and cost, and winter arriving!
We bought an 1860 Victorian House 3 years ago.
We decided to have some work done to the 1st and 2nd floors, including insulating the external walls (internally), the roof space, which had little to no insulation previously, redecorating etc.
The 2nd floor comprises 3 bedrooms and a small bathroom.
The builders have insulated the roof with PIR insulation plasterboard, which apparently has a vapour barrier and a 25mm air gap.
They have also used insulation plasterboard on all external walls on the first and second floor.
All going well until a building inspector noticed damp on an internal chimney wall;
We were told there was a leak in the roof / chimney and a roofer went up there and fixed all the lead work, cement, checked slates and ridge and said it was all good.
The builders then pointed out that there was damp on the purlins in the same room as the chimney wall and suggested that the roofer had caused an issue when up there. He went back up there with a cherry picker, rechecked everything; all okay.
The damp on the chimney wall, and purlins seemed to increase independent of whether it rained outside.
The roofer suggested it may be condensation, especially with all the skimming / plastering that had been going on internally. The builders were adamant it was the roof felt - bitumen, which needs replacing throughout, but the roofer says this tends not to fail and looks in good condition.
The damp on the purlins has increased, not just in that room, but in other rooms at the top of the house now;
The builders suggest that the roofer disturbed something and that damp is spreading across the deteriorating roof felt. They said they can’t do anything else until the leak in the roof is fixed.
This is all quite new to me, but it seems to make sense that general condensation (especially that from all the plaster) is passing through insulated plasterboard, meeting the cold air in the air gap, condensing, and then flowing down the back of the plasterboard onto the purlins making them damp?
But I wondered if other well informed people might be able to offer their opinion / advice?
Many thanks, this is becoming quite a stressful situation with 2 little children, a project that is running on in time and cost, and winter arriving!
