re-paint over exterior wall

[foofoo]

I have a damp internal wall which I think is being caused by penatrating damp from the exterior. The damp starts half way up the wall. Nothing wrong with the roof. Ground levels OK.

The house is Victorian and at some point the exterior wall at this part of the house has been painted with bitimum (spell) and then an exterior paint over the top. I suspect water has seeped into cracks and cannot escape due to the paint retaining the moisture.

Should I go with the cheapest option and sand down the paintwork, stabilize it and re-paint with good quality exterior masonary paint? Meanwhile I am going to hack off the internal damp plaster allow the wall to dry and then put on insulated wall board with poly back about 20mm thick.

Or should I take the expensive route wih a lot of hassle and remove the paint and bitimum with a sandblaster and leave it paint free and able to breath again?

Any advice or alernative suggestions are very welcome. Thank you for your time. My first post, hope I have done it OK!

 

[Third_Eye]

I would, "Meanwhile I am going to hack off the internal damp plaster allow the wall to dry and then put on insulated wall board with poly back about 20mm thick."

How high up on the wall is the Bitumen ?

 

[foofoo]

The bitumen (thanks for the spelling) covers the entire outside wall of a one storey old extention, it has a layer of external paint on top. This was all applied many years ago by previous owner.

I think it was originally applied because of damp caused by ground levels being too high and a leak in the roof. These have been fixed so must be penatrating as damp half way up the wall.

Do you reckon I can just stabilize the outside paint work and put on a good quality exterior paint and hack off plaster inside and put up the boards?

Thank you.

 

[Third_Eye]

This is my own opinion but Bitumen should not be used 60cm above ground level externally.

This traps miosture ! ! !

However, i would apply an Microporous/Miosture Vapour Permability non-water based Paint on your Exterior.

Though internally i would use this links method http://www.newton-membranes.co.uk/newlath.htm