Damp Wall, High Drive and Cavity Full of 'Stuff'...

NealHarman · 3 May 2005

Hi all, have an approx. 80yr old house, with one wall very damp.

The adjoining drive was higher by about 10-15cm, and the cavity was (and in places still is) 1m deep in compacted (presumably) old mortar that's fallen down over time. (At least, that's my interpretation - I guess the whole bricks and bits of rotten 4x2 have been there since it was built though

I've dug a channel in the drive along the house wall about 15cm below the inside floor level, and about 30cm wide. Eventually the whole drive will be lowered, but we've got other priorities for now. Also, I'm in the process of cleaning out the cavity. Anything else I should do now to dry it out? I know I've got to remove and replace the plaster - with something lime based?

The soil is basically clay, and doesn't drain well, and the trench I've dug already reaches the bottom course of bricks - under that appear to be some flat stones. I'm guessing this is all the foundation we've got (which was more or less true on the opposite house wall) so am reluctant to start digging deeper.

Any suggestions gratefully appreciated,
Neal

chappers · 3 May 2005

I doubt you have cavity walls in an eighty year old house, when you look at the wall from the outside are there any headers (bricks built end on into the wall) these tie the two leaves of the wall together.
How on earth are you cleaning out this "cavity".

NealHarman · 4 May 2005

Definitely do have a cavity - with metal wall ties. Must admit though that the age is a bit of a guess - based on surveyor's estimate when bought (1925) and the recollections of some of the 70-80 year old neighbours - the house was present when they were young children (it was the village shop).

As I said, it's currently in places about 1m deep in debris - quite damp at the bottom. So I've been taking out a brick at the bottom (outside leaf) and scraping it out with whatever bent bits of metal that I can lay my hands on and will fit. Need to do this with about every 8th brick. At one point, I had to take out two to get a couple of complete bricks out - lying loose at the bottom of the cavity, and presumably dropped when it was built. I am, obviously, putting the bricks back

Neal

wossie6 · 4 May 2005

ive got cavity walls to,and my house is older than 100 years

Slugbabydotcom · 7 May 2005

Best of my knowledge is that it wasnt standard practice to have cavity walls up until 1928. Also that the first cavity walls had only 1" gap. I know of nothing to say that they didn't pre-exist this apart from the fact that I haven't seen or noticed any.
I can only make the assumptions that prior to 1928 cavity walls were a hallmark of better quality accommodation, perhaps parts of buildings damaged during the war had some damaged walls rebuilt with a cavity and maybe some had extensions built with cavity walls.

Its up to you if you want to invest in or hire an industrial heater to help dry the brickwork out. It may be more benficial in the long term and cheaper just to fit a few airbricks say every 3m above the dpc as you replace it. Thompsons water seal or say wickes own variety which is cheaper will be beneficial too as it expels moisture and reduces the absorbency level of the bricks

NealHarman · 12 May 2005

Slugbabydotcom said:
I can only make the assumptions that prior to 1928 cavity walls were a hallmark of better quality accommodation, perhaps parts of buildings damaged during the war had some damaged walls rebuilt with a cavity and maybe some had extensions built with cavity walls.

Nothing 'better quality' about the original construction of this one

- or most of the work that's been done on it since

Why do people spend vast amounts of money and time doing stuff so badly?

Its up to you if you want to invest in or hire an industrial heater to help dry the brickwork out. It may be more benficial in the long term and cheaper just to fit a few airbricks say every 3m above the dpc as you replace it. Thompsons water seal or say wickes own variety which is cheaper will be beneficial too as it expels moisture and reduces the absorbency level of the bricks

One room is coming on nicely so far - was/am considering injecting a DPC in a bit, when it's a bit dryer. The other has a chimney breast/fireplace which is still, well, dripping wet basically. There's no ventilation at present (breast removed and capped at ground floor ceiling level) and it's full of piled-up stones and mud. I inadvertantly opened up the back (no cavity behind it) and decided there was no way I was risking trying to pull stuff out that way. So open it up properly, clear it out, and block it off again with proper ventilation? Since it's not holding anything up, I guess I'm better off cutting a proper physical DPC into the mortar than injecting?

Thanks for the replies,
Neal

masona · 13 May 2005

NealHarman said:
I guess I'm better off cutting a proper physical DPC into the mortar than injecting?

Yes, the dpc injecting doesn't really work and not effective.

Slugbabydotcom · 13 May 2005

I'm better off cutting a proper physical DPC into the mortar than injecting?

You are taking the bricks out anyway to clean the cavity .... seems pointless not to put a dpc in while you are at it.
Dont forget to splash the Thompsons water seal about before you lay the dpc as this acts as an 'injection back-up' to the phsyical dpc.
Just incase you didn't know dont do too long a stretch in one go. I remember seeing a job where someone took out 4 metres of the outer leaf causing the triangle of brickwork above to crack and hang on the wall ties.

masona · 14 May 2005

I wouldn't do the dpc just yet as it's not a easy job. Do you have dpc?

Firstly I would try and improve the outside area such as french drain at the moment.

NealHarman · 15 May 2005

Slugbabydotcom said:
You are taking the bricks out anyway to clean the cavity .... seems pointless not to put a dpc in while you are at it.

Not taking out every brick - I don't need to just to clear the cavity, and a builder I trust advised against it. His view is that it permanently weakens the wall. And the inner leaf has a lot of weight sitting on it (existing first floor structure, new steel and timber for attic conversion) so ...

As a matter of interest though, what do you think? Is he right? How do you put a physical DPC in, in practice? Just doing the odd brick it strikes me that the tricky bit is getting a good solid layer of mortar in above the replaced brick.

masona said:
I wouldn't do the dpc just yet as it's not a easy job. Do you have dpc?

Firstly I would try and improve the outside area such as french drain at the moment.

Nope, no DPC - in the process of doing a French drain at the moment. To be honest, now the outside is 15cm below the inside, instead of the other way around, most of the wall is drying out pretty well - so I'm not 100% convinced I need a DPC. (Weather's dry at the moment of course.) The fireplace is still looking bad though.

Slugbabydotcom said:
Dont forget to splash the Thompsons water seal about before you lay the dpc as this acts as an 'injection back-up' to the phsyical dpc.
Just incase you didn't know dont do too long a stretch in one go. I remember seeing a job where someone took out 4 metres of the outer leaf causing the triangle of brickwork above to crack and hang on the wall ties.

Don't worry - most I've done so far is two bricks at a time

Neal

masona · 15 May 2005

NealHarman said:
How do you put a physical DPC in, in practice? Just doing the odd brick it strikes me that the tricky bit is getting a good solid layer of mortar in above the replaced brick.

They use a saw cutting, see this but you must be 100% certain that you cannot stop the damp in any way before doing this. Also have a read here

Slugbabydotcom · 15 May 2005

most of the wall is drying out pretty well

Not taking out every brick

I'll go along with what you've been told then.
I was thinking of the traditional method of renewing the DPC taking a couple of courses out 1m at a time but that is a lot of hard work and you do seem to be getting results with what you are doing.

NealHarman · 15 May 2005

masona said:
They use a saw cutting, see this but you must be 100% certain that you cannot stop the damp in any way before doing this. Also have a read here

Slugbabydotcom said:
'll go along with what you've been told then.
I was thinking of the traditional method of renewing the DPC taking a couple of courses out 1m at a time but that is a lot of hard work and you do seem to be getting results with what you are doing.

Thanks - I don't really fancy either of those

so I'll see how things go with decent drainage and ventilation. BTW, found a nice brick arch on the bricked-up fireplace today

(and the link made interesting reading too).

Thanks again,
Neal

Tom. · 16 May 2005

Restore the wall to its original condition, and you won't need a DPC.

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Damp Wall, High Drive and Cavity Full of 'Stuff'...

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