Ghosting on extension

[DumbBlonde5]

Hoping this is the correct part of the forum.

We bought our 1964 house at the start of this year. The house had a single story extension put on the back in 1979. The extension runs across the back of the house giving a bigger kitchen and an extra room on the back of the old lounge. It has a pitched roof. In the lounge part we can see there has been some sort of issue where coving has been taken down and replaced on a section of the exterior wall. We saw some black lines on the ceiling on viewing but our surveyor didn't seem bothered and said the roof just needed some extra insulation. Since being here in April the "ghosting" has got much worse. It runs in lines and we are not sure what causes it or how best to treat it. Does it mean a whole new roof/ceiling?

The kitchen has been repainted before we bought so the issue may be lurking there too but no signs yet.

The walls are covered in very old vinyl wallpaper which we will be stripping off. Dreading what might be underneath.

Advice on where to start would be very much appreciated!!

 

[freddiemercurystwin]

Do you mean a series of parallel lines appearing on the ceiling?

 

[freddiemercurystwin]

Like this?

 

[jeds]

Did you install the insulation as suggested by the surveyor?

 

[DumbBlonde5]

Yes that photo is exactly like what we have.

The surveyor we used, although RICS etc, missed some subsidence in the front porch and isn't very forthcoming with info. There aren't any obvious roof vents so want to make sure we do any fixing, including insulation, right.

 

[jeds]

It's called pattern staining and it's caused by condensation forming on the underside of the cold rafters. You need to insulate over the rafters. It would also help to slightly increase ventilation to the room - open trickle vents if they are closed. Also make sure you have good loft ventilation before increasing insulation. You might need to treat the mould to kill it off completely.