Another damp question!

[Impy]

I have been trawling through previous 'damp' threads on the forum but wondered if anyone would be so kind as to answer my own specific query.
We are in the process of purchasing an older property. The frontage appears to be victorian but the rear sections are considerably older (I know that is not very specific - 1800ish, we think). We have just had a fully building survey carried out by a surveyor experienced with period property.

The house has solid brick walls (a variety of 9" and 13.5"). The house is an end terrace with a pavement to the front and a tarmac road abutting the end of the property, the road is quite a steep slope, going downhill to the front of the property. The ground level outside is consistently level to or higher than inside. Inside a solid concrete floor has been laid at some point in the not too distant past. It will come as no suprise to you that the exterior walls have been found to contain consistently high moisture levels. The surveyor has recommended stripping the walls back to bare masonry to assess what is going on and allow them to dry out to some extent.

My question is where do we go from there?

I guess ideally we would lower the external ground level and re-plaster with lime internally. It will not be possible to lower external ground level as it is pavement/road. I think it is likely that it will be prohibitively expensive to completely re-plaster in lime (the property is quite large). Any tips on what we can do to make the house as dry as possible whilst being sympathetic to its history? We know there are also some issues with rainwater goods discharging at the base of the walls and these will be sorted as a priority.

Thanks in advance for your advice. I anticipate posting many more questions (hopefully shorter!) and of course pics as soon as the house is officially ours.

 

[maggie73]

We have a similar house: end terrace built into a hillside with pavement to front, concrete steps at gable end and tarmac road at back of house, built about 1860. Solid walls but renovated in the 60's and brick cavity added in livingroom to the back and gable end walls only. We have damp issues in that room, in the "deepest" corner and suspect that run-off from the road washed through the mortar joints and eventually pushed debris down the cavity walls: we think this has eventually bridged the solid and cavity walls and allowed moisture to penetrate to cavity wall and plaster. Next year we are hoping to have a little look in the cavity and clear it out if required, but regardless, strip off the cement plaster where damp, allow to dry out and take it from there. I have repointed the joints at the back of the house with lime to try and stop moisture ingress there. Im not a builder, but maybe you could dry line or something to stop the moisture from solid wall damaging decor, but allowing for ventilation in the space? In theory I think our cavity wall should work (there is a layer of rubbery membrane stuff in the brickwork below floor levels acting as a damp barrier). just a thought as I understand that the way in which your house has been situated means that you cant go down the usual routes of lowering ground levels etc.

 

[maggie73]

sorry, just noticed that you want to do a sympathetic job, which probably wouldnt include dry lining. Others on the forum have recommended going on lime-plastering courses which should lower the costs?

 

[FamilyWiggs]

[non-expert alert]

Usually the first thing to do is to ensure that the external ground is lower than your internal floors - and in the case of concrete/tarmac abutting the property to ensure you don't have run-off moving downhill towards the property.

It sounds like you might have trouble doing this - in which case is excavating a trench and installing a French drain an option? Anything that ensures the ground is not in contact with external walls higher than internal floor level will help.

Incidentally - are there other physical signs of damp walls, other than a surveyors' report?

I'm sure an expert will now be along shortly. 8)

 

[Matt Green]

sorry, just noticed that you want to do a sympathetic job, which probably wouldnt include dry lining.

Depends what you dry-line with. Battens with lath and plaster is effective and historically reasonable dry-lining for purists.

Ground level reductions are the biggest expensive and will have the most effect. I'd concentrate on that first, then see what happens. It's the hard part after all. Lime plastering without the reduction might result in the finish being poor (or not) it depends how much water there is moving through the wall. FamilyWiggs makes a fair point though: is this situation actually causing a problem...?


Matt

 

[Flyfisher]

Depends what you dry-line with. Battens with lath and plaster is effective and historically reasonable dry-lining for purists.

Indeed. Our C16 timber frame house was given a Georgian makeover at some time that included dry-lining using a 3x2-inch timber sub-frame nailed to the oak timbers then lath and lime-haired plaster. It also involved cutting through many of the original oak timbers to make room for new large sash windows. I say 'new' but it was a few hundred years ago, so home makeovers are not a modern fad.

 

[Moo]

Ground level reductions are the biggest expensive and will have the most effect. I'd concentrate on that first, then see what happens. It's the hard part after all........ is this situation actually causing a problem...?

If the ground level proves to be the cause of the problem, it would be worth your while approaching the council about it.
I had a similar situation some time ago and my local council promptly took steps to sort things out.

 

[Impy]

Thanks for all your responses. I don't think the moisture in the walls is causing a problem at the moment. We have not completed on the purchase yet but on the viewings we did not find any obvious damp patches, despite looking for them. I think we will see how we get on when we move in and monitor the situation from there.

 

[JoceAndChris]

Very wise move. Damp companies are so keen to tell you you've got desperate damp problems and levels of moisture are worryingly high. We all know what their solution is. We very nearly handed over thousands to have them hack off all the historic plaster, would have done if it hadn't been for a spot of reading on this forum. And yet there is no damp problem in the places where they said the walls were saturated.

Live in the house, heat the house, ventilate well, careful with laundry, instal a dehumidier in problem spots and just see how it is one year from now.