This is part of a series of posts – find an introduction & links to the other sections of wall here.
The images below show the alcove to the left of the chimney breast.
Friday 04/08/2017 …After 1st coat of limewash :
Saturday 05/08/2017 …After 12 hours of drying. Note the band part way up the wall which has gone white first. We believe from other areas of the house that this behavior tends to correlate with where there are salt deposits :
Sunday 06/08/2017 …36 hours of drying :
Wednesday 09/08/2017 …2 days after 2nd coat of limewash :
Friday 11/08/2017 …4 days of drying since last application of limewash :
Saturday 12/08/2017 …5 days of drying :
Monday 14/08/2016 …7 days of drying :
Monday 04/09/2017 …1 month drying. You can see there is very little change :
Wednesday 06/09/2017 …2 days after removing the external cement render from the bottom section of the external wall. Unlike the alcove to the right of the chimney breast which is next to the removed render, there is no noticeable improvement here:
Friday 08/09/2017 …4 days after removing render. Still no improvement – I would be surprised if there was considering it is over the other side of the room :
The base of this alcove is clearly still damp and it rises sharply next to the chimney breast (this damp section is mirrored inside the chimney breast also).
Although the spine wall to the left is also damp, the height of the damp where the two walls meet in the corner does not correlate at all – there is a marked difference with the damp on the alcove wall being much lower down, maybe around 30cm or a foot up from floor level.
On taking up the floorboards, I found that the foundations have an original victorian bitumin damp proof course & the subfloor is also coated in bitumin. I will probably remove this as I have done in the front room, since there is a theory that impervious materials such as this or cement flooring can actually drive moisture up the walls of solid-walled properties since it cannot evaporate any other way. With the bitumin subfloor covering removed, the idea would be that cross-ventilation from the airbricks would dry any moisture from the subfloor. There is no obvious or immediate dampness visible underneath the floor level although I suspect there may be some.
Other explanations for such manifestations of damp would be excessive humidity and condensation, although this is maybe more common on cold external walls, whereas this is an internal party wall in the centre of the property. It has been suggested that cold air falling down the chimney could be making the base of the chimney breast cold, bringing it below the dew point & thus causing water vapour to drop out & condense here. Such phenomena would also explaining the extreme damage to the bricks at the base of the chimney. Additionally there could be some rainwater coming down the chimney due to the roof/parapet/chimney stack repairs needed, although how likely it would be for it to make it all the way to the base of the walls is debatable.