Damp and prevention?

[ckp82]

Hi all,
I first noticed I had damp when I decorated my lounge. At the time I was unaware.
When I stripped the paper off the walls I could see the outline of the bricks on the plaster, I thought the steam from the stripper had got into the mortar and created the outline. However, when I lined the walls the paper would not stick in areas, all below a metre from the floor. This is when I realised something was wrong.
I went outside to investigate and noticed the slabs and soil were all tight against the walls and at the damp proof height. I dug back the soil and moved the slabs back away from the walls to create a channel. The next thing I noticed was that the first 4 rows of bricks were rendered. The first row was under the slate damp proof course and the next 3 rows being above it. The render was hollow in places and cracked all over. I'm in the process of hacking this off now and have noticed that the hollow parts are where the bricks have blown. Once I've taken this render off I'm going to be left with a lot of bricks with no facing and a lot of pointing up to do.
I'm stuck now as to how I should proceed. Could I replace the whole 4 rows of bricks, point up the mortar and paint with masonry paint to seal the bricks or render the 3 rows of bricks above the damp proof course but not below to prevent bridging which I think happened first time round. I also read I should use lime based mortar/render rather than cement based So the walls can breathe? Would applying masonry paint prevent the walls from breathing? I'm confused at which path to take and want to get it right before hacking off the plaster inside.
Thanks for reading and any advice would be much appreciated.

 

[vinn]

Why not show pics of the exterior and the interior areas of concern?
Is the wall solid?
Is the interior floor solid?

 

[ckp82]

Thanks for your reply vinn, if I get home early enough I'll take some photos.
The wall is a solid wall and the interior floor is concrete.

 

[ckp82]

 

[ckp82]

The red area is the last of the render to be removed and the other photos show the state of the walls after removing the render. It looks unsightly and not very weather proof.

 

[vinn]

Thanks for the photos.
Pics of the interior please?

Where exactly is the slate DPC?

Is that the back of a chimney breast where the brickwork jogs out a little - to the right of the window? I dont mean the bottom lip where render has been removed.
Do you have a render plinth going further round the property - eg under the door step & further on?
Does the ground level bridge the DPC anywhere else around the property?

The re-pointing, and the rendered plinth have been attempts to protect against penetrating damp.
The remedial pointing, as usual, is almost useless because the old pointing was not hacked out deep enough.

 

[^woody^]

That has had an injected damp course put in. Does it have any warranty left - you normally get between 10 and 20 years.

 

[^woody^]

I also read I should use lime based mortar/render rather than cement based So the walls can breathe?

That's only if the property has lime mortar in the first place.

If it is determined that the cause of any dampness is penetrating via the wall, then in addition to dealing with poor pointing, you could coat the exterior surface with a clear water repellant which would be breathable.

 

[John D v2.0]

Does that wall get the prevailing rain and not much sunshine/wind? Solid walls (as opposed to cavity) keep the rain out by drying out faster than they get wet. By lowering the slabs preventing splashback and removing the plinth you might have solved the dampness problem already. Just make sure that any damp that does get into the wall can dry out again.
We had the same situation, that's how I know, and once I lowered the path and replaced the hard pointing with original lime there was no trouble whatsoever.

 

[ckp82]

Thanks for the replies.
Inside the walls are lined and I stripped back the parts that would not take to the wall, all just above skirting level and put a border paper on which looks normal at the moment.
The dpc is in the first joint above the slabs. It crumbles when I touch it.
The part where it jogs out a bit to the right of the window is the corner of the house, if you see the left of the last photo you can see it jogs out. This is to make the corner look like a column, an original detail on all the houses around here. There isn't a chimney behind it.
The plinth is also a detail of the house it runs along the front of the house and the side of the house but not at the back. Under the front door there is a row of of grey brick. The porch has to be removed as that has been built on top of the slabs and inside higher than the dpc.
The dpc is now higher than the ground all the way around the house, the renders mostly gone and the slabs at the back have been moved back from the wall and soil from the front moved back from the wall.
The injected dpc was done before we moved in and we have no paperwork to show who or done it or any certificates.
The house was built in 1920, I've read that lime was used a lot back then but I guess over the years the repointing has probably been done with cement based mortar.
A clear waterproof sounds a good idea. It would still show how bad the brickwork is though.
The brickwork gets all weather thrown at it good and bad. The slabs will be lowered as we are having the drive way tarmaced. I guess I could replace the worst bricks if I can source any from a local reclamation yard, hack out and repoint with a lime mortar and then waterproof it all over?

 

[vinn]

Without a pic of the interior plaster (stripped of wallpaper) then I cant advise you with certainty?
The extent & pattern of damp is unknown.
The skirting might be rotted.
There's probably no DPM below the floor slab.
The odds are that interior hacking off & remedial sand & lime render will need to take place.

The pointing appears to be sand & cement - sand & lime mortar should be used to repoint after hacking out to a depth of 25mm to 35mm.
A fillet of sand and lime could be used on the brick lip to prevent water pooling & penetrating.
The lower pointing seems to have perished into a mix of soil & crumbling mortar.
As above, a clear water repellant would be better than cutting out - how many bricks?


So the projecting bay window (aka an Oriel) is the neighbour's?

 

[ckp82]

The bay window is ours. That part of the house sticks out a bit and has a corner either side of the window.
A brick count would probably be about 1 in 4 all around the property, the render really does ruin the bricks.
I changed the skirting when I decorated and it was rotten. The wooden fillets in the wall that the nails went into were rotten and also the nails were brittle.
The pattern on the wall looks like wet mortar. By that I mean it looks like wet lines both horizontal and vertical, the latter being the same height as a brick, they all join together to make an outline of a brick.

 

[vinn]

Unless I can see what I'm commenting on then its not much use my making any further comments ref the interior.

What you are calling a corner might be, FWIW, a brick pilaster.

 

[ckp82]

Just looked up what a pilaster is and they are pilasters.