Not sure how to tackle this damp issue

[newcountrygirl]

We have a detached property which from what we have managed to ascertain consists of a single storey part which goes back to the late 1800's The original part was originally a 2 storey house. Sometime between 1949 and 1991 it was sold and the owners had it taken down to make a single storey bungalow. We have the plans and the description of works but they are not dated and we can't find anything in the planning records as we dont have a specific date to search. After 1991 an extension was built and also they did a loft conversion. The whole house was rendered and pebble dashed. In the original part which is single storey a door from the lounge leads off down a hallway and provides 2 bedrooms and a bathroom, we are having issues with damp. We know there was a damp proof course and it has concrete flooring. On the outside wall of this part, we are having a problem with damp. We can see areas of the render have cracked and blown. There was also a concrete skirt extending from the bottom of the render to the ground going all the way around the ground floor of the house on the outside which looked to have been done for cosmetic reasons.

The damp on the inside of this wall is also most noticeable on the inside of the window reveal in the hallway. We have checked the roof and gutters and no sign of any damage. The interior of this old part was all dry lined at some point in the past too. (except for the window reveals). My husband has painstakingly removed all the concrete skirt on the exterior and we can see that the construction looks to be old brick. In some parts it looks damp and in others bone dry. We were hoping to have the render repaired but are now wondering if this all needs to come off and maybe replaced with a lime based render or just clean up the bricks and repoint with lime mortar. Does anyone have any ideas please? Having looked on various sites render removal looks to be extortionate. Also, we are loathe to get in DPC type companies who will more than likely try and get us to have some sort of chemical DPC. Thanks for reading.

 

[noj]

You may have already tackled it!

The concrete skirt would have been bridging the original dpc and locking in any water rising from the ground or sinking from cracks in the render. The wall can now dry to the outside (which is a very slow process if the bricks are saturated, rule of thumb is an inch a month).

I'd be inclined to give it a good number of months and see what happens before throwing money or dubious chemicals at it. Others may differ...

 

[MatthewC]

Let me get this clear: the part with the damp problem is the ground floor of the original property which had modern treatment when they made the place into a single storey bungalow; you think that the construction of that older remaining part is brick, and the newer works include a DPC, dry-lining, concrete floor, render (with concrete skirt?) and pebble dash?

You have done right in checking the render etc, but what you do not say is the relative height of the ground outside and the floor inside; I will bet that they are pretty well level, given an odd inch or two, and you might even have concrete laid up to the wall on the outside. In my view the main thing you should do is to lower that ground so that the floor is at least 150mm above the ground outside. Ideally you would install a French Drain (q.v. Google) around the house but this would require a soakaway and some fair expense. As a partial cheap solution you could dig a 150mm deep trench alonside the walls (removing any concrete from within 250mm of the wall) and so lower the ground level beside the wall, partially filling the trench with pea gravel, leaving at least 100mm clear.

With either of these solutions, you then leave it as it would takes ages to dry - possibly 6-12 months before even thinking of repointing.

In case you were wondering, concrete or stone paving up to the base of a wall causes splashback when it rains and thus makes the base of the wall wetter than normal, whereas pea gravel does not splash much.

 

[newcountrygirl]

Let me get this clear: the part with the damp problem is the ground floor of the original property which had modern treatment when they made the place into a single storey bungalow; you think that the construction of that older remaining part is brick, and the newer works include a DPC, dry-lining, concrete floor, render (with concrete skirt?) and pebble dash?

You have done right in checking the render etc, but what you do not say is the relative height of the ground outside and the floor inside; I will bet that they are pretty well level, given an odd inch or two, and you might even have concrete laid up to the wall on the outside. In my view the main thing you should do is to lower that ground so that the floor is at least 150mm above the ground outside. Ideally you would install a French Drain (q.v. Google) around the house but this would require a soakaway and some fair expense. As a partial cheap solution you could dig a 150mm deep trench alonside the walls (removing any concrete from within 250mm of the wall) and so lower the ground level beside the wall, partially filling the trench with pea gravel, leaving at least 100mm clear.

With either of these solutions, you then leave it as it would takes ages to dry - possibly 6-12 months before even thinking of repointing.

In case you were wondering, concrete or stone paving up to the base of a wall causes splashback when it rains and thus makes the base of the wall wetter than normal, whereas pea gravel does not splash much.

Thanks so much for your reply. We will look into the levels etc.

You may have already tackled it!

The concrete skirt would have been bridging the original dpc and locking in any water rising from the ground or sinking from cracks in the render. The wall can now dry to the outside (which is a very slow process if the bricks are saturated, rule of thumb is an inch a month).

I'd be inclined to give it a good number of months and see what happens before throwing money or dubious chemicals at it. Others may differ...

Thanks. We know we would need to wait a while. Would it still be worth having the bricks re-pointed now, where the skirt has been removed do you think?

 

[noj]

I wouldn't spend money on repointing now, it'll dry quicker without. And if you decided to lime render then I think there's no real benefit in pointing first