Old Damp Proof Holes

[oldbilly]

I just removed some old kitchen units and was surprised to feel a draught around my feet. Turns out some of the old damp proof holes have gone right through to the outside. No wonder I've been getting so many mice and slugs...

Obviously I'd like to fill the holes, but I'm not sure what with. It's a Victorian house, maybe 1850s. Any suggestions welcome. Thanks.

 

[hansPulesh]

What do you mean by damp proof holes? Has the house had a damp proof course injected and those holes have been drilled right through to the inside?

 

[^woody^]

Mortar. Mastic

 

[gregers]

put up a pic.
if they really are dpc drilled holes then it aint doing its job now is it.

 

[oldbilly]

Thanks guys. Actually, the problem's even worse than I thought -- the mortar's falling out all over the place. I think this might be a job for a pro.

 

[theprinceofdarkness]

No damp proof injection holes go right through the wall, because if they did you would just be squirting the chemical through to the other side. The holes should end in the centre of a brick, so the brick is impregnated with the chemical. It sounds like a primitive bodge has occurred, drilling the holes ventilates the wall causing the damp not to rise any further up the wall then the line of holes.
Mortar only falls off internal wall due to some very severe stress, on the other hand plaster just gets loose with age, is it white and dusty and over 50 years old?, could be lime based plaster which just "ages", especially if it as not a good job to start of with.
We need more details, how old is the property? how thick is the wall, is it actually damp?
Frank

 

[oldbilly]

Thanks Frank. It's a half-brick wall. The holes were drilled from the inside, and most are only about 5-7cm deep. Must have been done in the 80s or 90s, before I moved in, and yeah it was probably a bit of a bodge job. Some of the holes were drilled into the mortar rather than brick, and now go all the way through to my neighbour's garden, since the mortar on their side of the wall is non-existent in some places. All in all, I've decided this is beyond my DIY skills.

Anyone know of good repointers in South London?

 

[hansPulesh]

You say that, but it's honestly not that difficult to put right depending on how much damage there is. A pic might help if you have one? You can buy damp proof courses from a builders merchants as well as a gun to inject it with.

drill holes into the wall (about 6" - 9" apart), only go half way into the wall (not the whole way through). Then inject the solution and cover the holes with a sand and cement mix.

You can use the same gun to inject a sand and cement mix into the existing holes which go the whole way through the wall and also to repair any pointing.

 

[theprinceofdarkness]

For a very small outlay , you could do this job your self. £20?, you need a pointing trowel (about 4" long and diamond shape) ~ £4 and a small bag of mortar £3. A large old tray sort of thing (look around the garden, some saucers from plant pots are good N.B. no holes), something you can use as a hawk, a flat board say 6" square, a small hand spray (ex-kitchen cleaner) and borrow the brush from the dustpan and finally some sort of pointy thing to scrape of loose material. Scrape off any loose material, give it all a brush down and give it a good spray, so water just runs off the surfaces. Now get about a cupful of the mortar, gently pour about an egg cupful of water on it and mix it. It must be all the same colour and stiff, no water present. If it still in small lumps add a very little water, less then half a thimble full and give it another good mix. It should be so stiff that if you cut a bit off it stays the same shape. So put a spodge on your hawk, knock it down so its about 1/4" thick, put the edge of the hawk against the hole/slot you want to fill, cut of a small piece of mortar and push in into the hole/slot. Thats it, if you are right handed, start at the right hand side and work towards the left. Try not to get too much mortar on the bricks, though you can't help it trying to fill the holes. As you get more practice, you will speed up, put in more mortar then you need and leave it proud.
After a couple of hours the mortar should be quite sandy and will brush off without staining the bricks. For an added flourish, rub the joints with a bit of tubing/dowel at an angle, it should give a nice rounded depression.
Frank
P.S. you don't have to look at it