Cutting in a DPC

Hi all - I’m after any comments on my approach to prevent damp. I’m rennovating a period property (near London, UK), the external walls are solid construction, no insulation,cavity or DPC. There is evidence of a chemical DPC (regular holes in the concrete plinth, since filled in) though it’s not know when this was done) There is evidence internally of damp. An internal wall had a clear tide mark at around 500mm, and the external walls have had years of differing patches of render applied to manage the situation. My plan is to insulate internally, with a wood fibre warmshell plus lime render finish and remove the external painted render to allow the brickwork to breath, accept there will be damp (winter) but it will dry out (summer) across the year. (Plus manage damp with background and source ventilation) To prevent any rising damp I want to chop in a DPC - to go meter by meter around the building perimeter and remove the mortar and slide in a 1200 gauge DPM and reset the mortar. Yesterday I exposed the wall on the interior, and then removed the external concrete plinth and found the brickwork is pretty rough - it’s been scored to adhere to the plinth, and the lowest course is still damp and looks pretty weak. Time to abort? My new plan is to replace the damp course with some fresh non porous engineering bricks, put the DPC above this (though really for 150mm min it should be above the 2nd course) and then install a splash strip to take away future runoff from the wall. submitted by /u/AdLongjumping7289 [link] [comments]

Jun 15, 2025 - 13:24

Hi all - I’m after any comments on my approach to prevent damp.

I’m rennovating a period property (near London, UK), the external walls are solid construction, no insulation,cavity or DPC. There is evidence of a chemical DPC (regular holes in the concrete plinth, since filled in) though it’s not know when this was done)

There is evidence internally of damp. An internal wall had a clear tide mark at around 500mm, and the external walls have had years of differing patches of render applied to manage the situation.

My plan is to insulate internally, with a wood fibre warmshell plus lime render finish and remove the external painted render to allow the brickwork to breath, accept there will be damp (winter) but it will dry out (summer) across the year. (Plus manage damp with background and source ventilation)

To prevent any rising damp I want to chop in a DPC - to go meter by meter around the building perimeter and remove the mortar and slide in a 1200 gauge DPM and reset the mortar.

Yesterday I exposed the wall on the interior, and then removed the external concrete plinth and found the brickwork is pretty rough - it’s been scored to adhere to the plinth, and the lowest course is still damp and looks pretty weak.

Time to abort?

My new plan is to replace the damp course with some fresh non porous engineering bricks, put the DPC above this (though really for 150mm min it should be above the 2nd course) and then install a splash strip to take away future runoff from the wall.

submitted by /u/AdLongjumping7289
[link] [comments]