Stains on newly painted bedroom wall

[chuckey]

The property is a traditionel rock and rubble limestone cottage. I had the roof redone last November and from Febuary the stains appeared. I have installed an en-suite in the bedroom and went into the loft to install a heat exchanger for the shower vent and noticed that the gable end is damp.
At the time of the new roof going on, the builder (aged 64 so loads of experiance?), said to me " your should have facia vents under the slates". What the h**l!, he was doing the job!. :evil: The sarking cloth was the a permeable one but it just is not as permeable as the old draughty slates. So here I am knocking holes in the gable ends for air bricks.
FWIW:- The builder in question is reputed to be one of the better ones, but now I can add him to a list of of builders who don't know much about building. The score is 5/5 . How does one find a knowledgeble builder? :roll:
Frank

 

[Lime]

I hope the shower vent goes outside and doesn't vent directly into the loft space.
Also any leaks of warm damp air will cause condensation to form readily.
Electric lights on the ceiling below the loft often have quite large unimpeded holes in the ceiling where the cables run.
These holes allow damp house air to enter the loft too.
Modern sarking is almost as impermeable as the old pitch roofing felt so I would not rely on it to ventilate the loft properly.
Also thicker loft insulation creates a greater need for ventilation.

 

[MdB]

http://www.lapvent.co.uk/ may be a solution for you. I know nothing about it good or bad so read up on it first. Sounds better than knocking holes in your end walls though.

 

[Schoolmarm]

Lapvent is an invention by a former PPUK member. He is a very clever man and I would not hesitate in recommending it.

He is a proper roofer.