Paint around windows bubbling...

27 Jan 2016
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United Kingdom
We are at the end of all option so really hoping someone can shine some light on the paint that is bubbling around the stairs window.

Firstly a builder said it was the roof, so they redid the gable end (5 years ago), we took it back to plaster, and repainted. Bubbling came back.

Damp Company said it was maybe a re-pointing issue or cavity wall insulation breaching. Cavity insulation company looked in the cavity and the insulation was dry, So we got in a an independent damp inspector who said repointing was only needed on the ground floor and that the bubbling was down to condensation.

Damp inspector told us to take it back to plaster, paint with mould paint and them emusion. That was June, and its returned in the recent wet weather ( flank wall is quite exposed to the driving rain).

Its spread quickly in the last week of so (despite dehumidifier running ) and seems to be some moisture getting int to the back of the window sill.

Had a Window repair company come out yesterday who said window is straight and tested that the frame was draining properly which it was.
He said he had not seen this bubbling before but thinks the moisture in the window sill is just condensation running along the back of window sill and going behind it where its not glossed. He advised to put in new window sill but make sure its glossed at the back before it is installed and to run a bead of sealent along it, then just wipe away the condensation when it happens. But that still leave the issue of the bubbling paint!

Bubbles are mainly on the lower left and top right and some have salt like deposits on them

Does anyone know if it is just condensation causing the paint to bubble and what is the best way forward?


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why not post pics showing the frame and frame details from the outside?
and an internal pic of the area below the window board down to the skirting?
and a pic showing the outside elevation?
show details of sealants.

does the frame have a Cavity Tray in-situ?
how was the cavity insulation inspected?

6:10, the moisture pooling on the window board looks to be condensation.
but the bubbling higher up on the angle bead suggests penetrating damp. is the angle bead metal or plastic?
are the reveals solid plaster or have they been done in plaster board?

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