This is part of a series of posts – find an introduction & links to the other sections of wall here.
This section is adjacent to a window in an external, north facing wall, but in itself is a single skin internal wall with the (very damp) kitchen the other side. There is a radiator mounted on the other side of this wall.
The pipes to the right bring the central heating loop down to the radiators from the boiler above. There are no obvious leaks that we can find, but we have yet to take up the bowed and cracked concrete floor in the kitchen or fully lift the floorboards in this room.
There is a gutter that leaks slightly at the corner adjacent to the photographed section, and old drains approximately 2.5m away that will need investigating.
We had removed some internal cement tanking plaster from this wall 2 years ago since it wasn’t fixing the damp problems (the wallpaper was falling off regardless) and to give it time to dry out, which unfortunately it hasn’t done.
The images below document how this section of wall behaved after being limewashed at the beginning of August, followed by external cement render removal at the beginning of September.
Friday 04/08/2017 …12 hours after 1st coat of limewash :
Friday 11/08/2017 …4 days after 2nd coat of limewash :
Saturday 12/08/2017 …5 days after 2nd coat of limewash :
Monday 14/08/2017 …1 week after 2nd coat of limewash :
Monday 21/08/2017 …2 weeks after 2nd coat of limewash. After returning from a week away. You can see that there has been some spreading sideways of the damp ‘tidemark’ – you can almost see a trail on the left, up towards the windowsill. As we found in the kitchen, this unusual pattern with more defined edges has now appeared. My guess is they are formed a bit like marks in the sand caused by tides, by the wall wetting then drying out, since it only seems to develop over time. You can see a more extensive change of this nature on the other side of the window. Whilst away, we clearly haven’t been generating excess humidity from our usual activities (showering, cooking etc), which suggests this probably isn’t just occupant-caused excess humidity & condensation :
Monday 04/09/2017 …1 month drying. You can see there a slight improvement in places but overall the pattern of damp is relatively static :
Tuesday 05/09/2017 …1 day after removing the external cement render from the bottom section of the wall :
Wednesday 06/09/2017 …2 days after removing the external cement render from the bottom section of the wall. There is an noticeable and immediate improvement :
Thursday 07/09/2017 …3 days after removing the external cement render from the bottom section of the wall :
Friday 08/09/2017 …4 days after removing the external cement render from the bottom section of the wall :
Saturday 16/09/2017 …just under 2 weeks after removing the external cement render from the bottom section of the wall :
Monday 18/09/2017 …2 weeks after removing the external cement render from the bottom section of the wall :
I was surprised at just how immediately the removal of external cement render improved things. I was also surprised at the way it affected this internal wall which is only adjacent to the section that had the render removed.
Clearly there are still extensive problems to be rectified, but this is all relevant data that can build up a picture of what is going on with this house, maybe be a resource for someone dealing with something similar or even provide a cautionary tale.
If anyone reading this is considering rendering in cement to ‘keep the rain out’… please, whatever you do, stop that thought right there and take some time to read around the topic more extensively – I have some useful resources detailed here.
I think this useful raincoat analogy is key in explaining the concept of retaining breathability in older solid-walled properties :
“…a raincoat will shed water and, theoretically, keep the wearer dry; however, if the seams fail then the raincoat is hopeless. Water that gets through the fabric takes a long time to evaporate, and combined with the wearer’s natural generation of vapour, it means conditions can become very uncomfortable. By contrast, an overcoat does not shed water but absorbs it until it becomes saturated; water can evaporate and, because the coat is highly permeable, it can escape from inside as well.”