Hole/Cavity in footings

Siderealxxx · 25 Nov 2015

Hi, after clearing out the gap around my house I discovered a hole in the footings under the kitchen extension. It goes down about 12" and it's hard to tell how wide it is inside. You can see it in the photo below (apologies for the quality - taken at night & full of leaves!).

Should I just do my best to clear the crud out and pour a bag of cement down it? Any other thoughts/considerations? Thanks in advance!

CambridgeBrummie · 26 Nov 2015

Difficult to tell from the photo but would suggest this needs a little more investigation. Is it near any drainage , as it would appear that you are losing material/soil somewhere and it would be unlikely that the foundations have been designed to span cavities. I would suggest locally removing the paving slabs and digging down a little to see what is going on.

Do you know if you live in a chalk area?

Siderealxxx · 26 Nov 2015

Thanks for the reply! It's not near any drainage points and it's not a chalk area.

I've lifted the paving slab and cleaned it up and taken a slightly better photo. I could dig more but not until the weekend.

It's 1950s and this is the kitchen 'extension' at the back but I think it was part of the original build. I don't know much about these things but willing to get my hands dirty...

ree · 26 Nov 2015

The setback of the concrete flags, and the concrete or sand and cement casing(?) in the gap indicate that there was some kind of prior issue.

There appears to be something circular in pic 2. is it a pipe encased in the cement material?

Why were you digging up: "clearing out the gap"?

Is there any damp or cracking on the inside of that wall - or on the floor?

FWIW: your dashed render should end about 50mm above any ground contact.

Siderealxxx · 26 Nov 2015

ree said:
The setback of the concrete flags, and the concrete or sand and cement casing(?) in the gap indicate that there was some kind of prior issue.

There appears to be something circular in pic 2. is it a pipe encased in the cement material?

Why were you digging up: "clearing out the gap"?

Is there any damp or cracking on the inside of that wall - or on the floor?

FWIW: your dashed render should end about 50mm above any ground contact.

I've only been in the house for under a year so still uncovering things, I don't know anything about the history.

It looks like there's something circular in the picture but it's empty and just a void. If there was something there it's not now…

I was clearing out the gap because it was filled with slate chippings which seemed to be holding in the moisture (I posted about that here).

There is a hint of damp on the inside wall, just a touch of mould, can't tell on the floor as there's tiles down.

The render at this section of the house does go down to the ground but not around the rest of the house. It's strange and also the house is built on a slope so it's not really level at the back at all. It seems like they gave up digging and just set the rear of the house lower!

Who should I get to look at this? Damp specialist? Builder? Not sure who's department it falls under…

Thanks

ree · 26 Nov 2015

Cut back the render as advised above and carefully examine all the exterior for cracks.
The render should, in best practice, finish just above the DPC with a render bellcast.

If possible locate the line Of the DPC and annotate a pic with it?

Smash out and then dig out all cement stuff and debris to say 150mm depth - do it all along the wall and then fill the trench with chippings for a French drain.

A 1940's house will have a cavity, altho the cavity might be blocked and bridging the DPC's in the two skins.

Presuming that you have a solid floor in the kitchen then remove any skirting on the wall in question and see if the interior plaster contacts the floor?

Perhaps you could pic the interior "mould" and the whole exterior wall?

chappers · 26 Nov 2015

Looks like at some point in the past someone has built up the ground level at the back, maybe when the patio was laid. The lump at the bottom of the dashing looks like that could have been the original break line

Siderealxxx · 26 Nov 2015

chappers said:
Looks like at some point in the past someone has built up the ground level at the back, maybe when the patio was laid. The lump at the bottom of the dashing looks like that could have been the original break line

Now you mention it you may well be right actually. Everything in this house has been done like that… everything's plastered in and problems were just masked over. It's possible with the patio rather than dig up the old one they just laid on top of the existing one!

Siderealxxx · 26 Nov 2015

ree said:
Cut back the render as advised above and carefully examine all the exterior for cracks.
The render should, in best practice, finish just above the DPC with a render bellcast.

If possible locate the line Of the DPC and annotate a pic with it?

Smash out and then dig out all cement stuff and debris to say 150mm depth - do it all along the wall and then fill the trench with chippings for a French drain.

A 1940's house will have a cavity, altho the cavity might be blocked and bridging the DPC's in the two skins.

Presuming that you have a solid floor in the kitchen then remove any skirting on the wall in question and see if the interior plaster contacts the floor?

Perhaps you could pic the interior "mould" and the whole exterior wall?

The other thing with this house is that it's quite badly built. Even though it's 50s there's NO cavity walls! Same on the whole street. Also I can't actually see the DPC - not to say it isn't there but I wouldn't be suprised if there isn't one! The quality of the brickwork is really poor too. Amazingly though there isn't any signs of damp except the very small patch I mentioned.

I can try and provide other photos tomorrow but I'm not sure they will enlighten!

Thanks.

stuart45 · 26 Nov 2015

Solid 9 inch walls were still being built in the 50's and 60's as long as the brickwork was protected by tile hanging, render etc. If not protected a 13 inch wall was required or a cavity wall.

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Hole/Cavity in footings

Similar threads