A small extension on the back of my 1908 Victorian house has 9 inch walls. It has damp (rising and penetrating). The concrete floor has no membrane and the outside ground level does need lowering. Could these be the only 2 factors causing the damp or could it be something to do with the 9 inch walls. What do I need to do to the walls to stop damp.
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9 Inch Walls and Damp
- Thread starter Jacs
- Start date
Unlike modern cavity walls and the like, 9" solid brick walls rely on lime mortar joints and lime pointing to keep them dry. Ensure that the wall hasn’t been repointed with cement. If so, cut out the cement pointing to a minimum depth of 10cm and replace with a 3:1 mix of Well graded ,washed, sharp sand and good quality hydraulic lime. Lime acts like a wick, drawing any water from the brickwork and allowing it to evaporate. Cement will just trap the water. Other considerations (although I’m not an expert) Check that all rainwater management works efficiently such as gutters drains etc i.e no rainwater overflowing or splashing back, no leaks. Other considerations with expert advice (not just my unexpert advice) - French drains- and -Cutting out the internal concrete floor close to the wall and replacing with “limecrete”
Lime
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They could.Could these be the only 2 factors causing the damp
The outside ground level is the one factor that is reasonably easy to rectify and needs to be done before anything else IMO.
Thanks for replies.
We intend on lowering the ground level and the walls do need pointing which we can tackle after we move in. As far as the concrete floors go we have an opourtunity to remove them and replace with membrane before we actually move in. Should we do this ? or do you think it is a waste of time and effort and will never need doing.
We intend on lowering the ground level and the walls do need pointing which we can tackle after we move in. As far as the concrete floors go we have an opourtunity to remove them and replace with membrane before we actually move in. Should we do this ? or do you think it is a waste of time and effort and will never need doing.
I would lower the ground levels, do the repointing then wait at least 6 months before doing anything else.
Fitting a non breathing membrane will help dampness in the floor but will likely make matters worse in the walls as damp under the floor will be forced up through the wall. This is the situation in my house with damp rising up around the base of most walls.
I've just dug down 40cm on the outside of the living room wall at home though it was inside of the garage so nominally dry. I did this as the outside level was a lot higher than the level inside of the house. (it was just a dirt floor in the garage). This morning there was a layer of water at the bottom of the hole which is about 20 cm below inside floor level. It will be interesting to see if it is any higher when I get back this evening. Either way, I think this level is too high so I think a french drain or similar will have to be dug deeper a little way away from the wall to lower the ground water level.
Fitting a non breathing membrane will help dampness in the floor but will likely make matters worse in the walls as damp under the floor will be forced up through the wall. This is the situation in my house with damp rising up around the base of most walls.
I've just dug down 40cm on the outside of the living room wall at home though it was inside of the garage so nominally dry. I did this as the outside level was a lot higher than the level inside of the house. (it was just a dirt floor in the garage). This morning there was a layer of water at the bottom of the hole which is about 20 cm below inside floor level. It will be interesting to see if it is any higher when I get back this evening. Either way, I think this level is too high so I think a french drain or similar will have to be dug deeper a little way away from the wall to lower the ground water level.
Penners
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The usual advice with damp problems is to try the esier things first, then wait a while and see what effect these have. So in your case, the easiest thing would appear to be lowering the outside ground level.Jacs said:As far as the concrete floors go we have an opourtunity to remove them and replace with membrane before we actually move in. Should we do this?
However, if you do decide to dig up the concrete floor, you certainly shouldn't replace it with more concrete and a membrane - this will just push the moisture sideways to exacerbate the damp walls. Much better to put in limecrete, which will allow the floor to breathe.
Thanks again for all your advice. This is all new to me so big learning curve.
One of the walls which has damp (the worst I would say) is an internal wall. The wall seperates kitchen from large walk in pantry. Where is this damp coming from ? Just the floor...
One of the walls which has damp (the worst I would say) is an internal wall. The wall seperates kitchen from large walk in pantry. Where is this damp coming from ? Just the floor...
Nemesis
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Cold pantry wall - warm kitchen?
Could be condensation of course.
Could be condensation of course.
Nemesis
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My pantry is cold and a bit on the damp side - which isn't a bad idea for a pantry really.
What are the walls built from?
What are the walls built from?
Penners
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Interesting point, and I suspect the answer is probably that the condensation will appear on both sides, under different circumstances (assuming that your pantry - like ours - has a vent to allow outside air in).Jacs said:But it appears on the inside of the pantry. I would of thought condensation off the kitchen would appear on the kitchen side - is this right ?
If you're creating a lot of steam in a warm kitchen, then the pantry wall will probably be colder than the air, so you'll get condensation on the kitchen side.
If it's a cold, wet day, and your kitchen is warm but not steamy, the condensation could appear on the pantry side.
That's an amateur guess - anyone else got any ideas?
Nemesis said:What are the walls built from?
The wall is 4.5 inch brick with plaster on.
After discussing this further with my father-in-law he seems to remember that the damp was actually on both sides.
The damp is on the bottom of the wall and rises to about 2 ft. The house has been empty now for about 3 months.