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Adding ventilation to a Victorian roof with no eaves

Posted: Thu Jan 14, 2021 10:28 am
by TriTim
Help! I am tearing my hair out trying to get some advice to solve a roofing problem I have......
I have a Victorian end of terrace house loft that has no ventilation. The roof has no eaves, with a king post truss and sarking boards with slates.
The roof was leaking in several places so I took several steps to correct this. The house had two chimneys. Both leaking. One, on the gable wall, was a false chimney that was leaking and soaking the gable wall. The other was about to fall down and leaking around all the flashing.
I had the real chimney rebuilt and all lead work replaced. I dropped the false chimney, extended the ridge over the gable wall and replaced all the rotten rafters on gable end.
In addition to this I had the roof stripped. The old felt that was causing the roof to sweat removed and replaced the felt with breathable membrane. The slates were replaced.
Since replacing the felt I have had huge problems with condensation in the loft. Every board is now soaked with condensation. The problem is four times worse than it ever was!
I know I need ventilation but where? How much and how? I have spent days reading up on this issue but got no where. There is literally no information about sarking board roofs. I'm at a loss and don't know what to do.
The loft had issues when I bought the house. I had to rip out all the ceiling timbers in every room upstairs and replace them. Everything was rotten due to damp. I fitted all new timbers, added a visqueen layer before boarding over. The loft is insulated. But with no ventilation it is getting wetter and wetter...... Can anyone please help?

Re: Adding ventilation to a Victorian roof with no eaves

Posted: Thu Jan 14, 2021 10:17 pm
by stoneyboy
Hi tritim
Suggest you fit slate vents hi and low in the roof, you could also fit vents into the gable end.
Regards S