Documenting the Damp Dining Room – External Window Wall

This is part of a series of posts – find an introduction & links to the other sections of wall here.

These photos show the wall to the rear of the property. The section below the window & to the left of the window are external walls. The section to the right of the window is a single skin internal wall that has the kitchen on the other side.

There is extensive evidence of reoccurring damp problems, and poorly informed attempted remediation with the use of a cement render or tanking plaster to try and ‘hold back’ the damp.

There is an airbrick underneath the window & although there is a concrete floor outside, it is below the level of the airbrick & the original bitumin damp proof course. On 4th September, the external cement render was removed from the lower half & the concrete floor that abutted the wall was cut away by approximately 20cm & soil removed down to the level of the foundation stones (only 10-15cm or so).

Monday 31/07/2017 …The bottom section of wall has been exposed for almost 2 years at this point, to allow the wall to ‘breathe’ & airflow to aid evaporation from the vapour permeable brick surfaces & mortar joints. However, the damp remains & shows no real signs of drying out. The rule of thumb is 1″ thickness of wall drying out per month. So this ~9″ wall should only have taken 9 months if the problem was purely historic and the source of damp had been remedied.

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Tuesday 01/08/2017 …After removing the remaining plaster and cement render

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Friday 04/08/2017 …12 hours after 1st coat of limewash

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Saturday 05/08/2017 …36 hours after 1st coat of limewash

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Monday 07/08/2017 …3 days after 1st coat of limewash

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Friday 11/08/2017 …4 days after 2nd coat of limewash

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Saturday 12/08/2017 …5 days after 2nd coat of limewash

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Monday 14/08/2017 …5 days after 2nd coat of limewash.

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Monday 21/08/2017 …12 days after 2nd coat of limewash. After returning from a week away. It is difficult to tell from these photos, but there was a definite increase in the ‘tidemark’ of damp in certain areas – as can be seen in more detailed shots to the right of the window & and to the left as well.

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Monday 04/09/2017 …1 month drying. You can see there is very little change.Maybe a slight improvement in places. There had been some recent torrential downpours of rain since the previous photo (from 3 weeks ago) :

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Tueday 05/09/2017 …1 day after removing the external cement render from the bottom section of the wall :

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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. To see more detailed shots next to the window see here & here:

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Friday 08/09/2017 …4 days after removing the external cement render from the bottom section of the wall :

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There have clearly been improvements made internally after the cement render was removed externally, allowing moisture from within the wall to evaporate from two surfaces. However, there is clearly an ongoing problem that needs to be rectified before this wall is covered up again with any insulation, plaster or other finishes.

At best, wall coverings (no matter how vapour permeable) would hide or obscure/distort any small visual variations highlighted by the limewash, in the patterns of damp caused by changing variables elsewhere in the house. At worst they would quickly fail & the materials and labour would have been wasted.

This is exactly the type of problem regularly described as ‘rising damp’ – however some critical thought regarding the usual solutions offered is in order since not all of it adds up and there is no point going through the hassle and cost of ineffective treatments to cover up the symptoms if the root cause isn’t identified.

I am determined to solve the mystery with plenty of detective work, looking at the house as a whole system, considering the impact we have as occupants, using observations, scientific principles and learning more about traditional building techniques to try and avoid any unnecessary, potentially damaging work (eg. injection damp proof courses which some very well informed people consider to be fraudulent mis-selling of ineffective solutions)

In the meantime this wall will remain with it’s limewashed finish to allow drying out to continue whilst consolidating & stabilising the dust of the mortar. We may do another coat with a warmer toned version using some yellow ochre pigement to make the room feel more comfortable.





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