Garage has sunk in one corner - advice

1 Apr 2012
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United Kingdom
Hi guys,

My garage has sunk/moved in one corner, that's the best way I can describe it. As you look at the front where the door is, the right hand pillar is approximately 2 inches lower than the left, the door is well off square and no longer opens and the water pools on the flat roof in this corner dripping down the dropped pillar. What's weird, in my limited knowledge of foundations and such things, is that there are no significant cracks at all, which considering the amount of movement there must have been, seems weird.

I have attached 2 pictures, one with annotations which I'll explain and one without just for clarity:

Ok, so red indicates the direction of lean or "movement" of that pillar and the connected wall on the right hand flank.The bottom red arrow is meant to indicate it's leaning forward, toward the driveway.
Pink indicates everything that doesn't appear to have moved, as it's all plumb and level.
Green indicates water direction, it tends to pool toward the bottom of that pillar and into the fence, which is nextdoors boundary.
Black indicates drainage which has been CCTV surveyed and is sound.
Blue, indicates the only hairline cracks I can see which are on the back right hand corner, it's the front that has dropped/moved. Oddly, the brick courses are all still plumb and level at the back so why it's cracked there is beyond me.

Here's the same picture without the arrows incase I've defaced anything:

What I do know, is that I've dug an inspection hole at the base of the right hand pillar. The soil underneath is very sandy and almost gravel-like, and not very compact. I could scoop it out with my hand after breaking through the concrete. I could also with relative ease scoop out underneath the concrete driveway slab to a degree, is this normal or is this indicative of it being washed away? The soil was quite wet. Also in the annotated picture you'll see a green circle, this is nextdoor's downpipe off the roof, which we can only assume goes into a soakaway as the CCTV survey didn't show it entering the main run. Whilst in itself this seems normal, I don't know the location of the soakaway, only that it "heads" toward the garage into their garden.

The red circle indicates a problem I found a year ago on the driveway, and technically on their boundary, I got out of my car and my foot sunk a couple of inches. The soil was very sandy and again appeared washed away. I filled it with an old bag of concrete so I didn't break my ankle at a later date and so far appears fine. At this stage, the house seems absolutely fine and unaffected, and weirdly so does the left flank (behind the ivy) of the garage. The side door is on the left hand side and has no problems with opening or closing, and all the frames and brick courses are plumb and level.

Can anyone offer some advice on what my next move should be. I'd like to stop whatever's happening to the garage getting worse with a view to rebuilding the right flank wall in the future. I don't want to wave this anywhere near the insurance for obvious reasons.

Thanks in advance.
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Any ideas or suggestions would be great, me and a builder friend have just about run out of ideas?!

Main suspect is the rainwater drain on neighbours house - it won't go into the fouldrain you cctv'd and may go into a common rainwater drain OR soakaway - could be broken near your garage. Also I'll bet the garage wall is on it's own ( inadequate) foundations with the floor cast inside - would have thought a reinforced slab holding the wall was better - but I'm a plumber not a builder. I would get the rain drain cctv'd
Hi Nige,

Thanks a lot for your reply, it did cross our mind too. It's on my neighbours boundary so I guess I'd have to ask permission to do such a thing. I'll have a word - we're in that awkward phase at the moment of skirting round the fact I think it's something to do with them when we chat!

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Got to agree with Nige there.......I'd be highly suspicious of the path of that white downcomer as this seems to be a typical example of subsoil having been washed away.
Maybe the garage concrete raft is sufficiently tough so as not to crack.
Do you live where there has been historic mining activity, and does anyone else in the street suffer?
I think I'd be having a look at my insurance policy here - there's quite a bit of work needed to correct this!
John :)
That's interesting, what makes you say the garage is on a concrete raft? I'm not disagreeing at all but curious to know the type of foundation it might be on. No mining activity but nextdoor had problems years ago, in the 80's, due to the area previously being farmland and their property (not ours and allegedly the surrounding areas were checked for soundness) being built on a small pit used to discard animal carcasses, perhaps our garage has caught the edge of this?

The reason I don't want to get the insurance involved is I've been told to expect great difficulties in insuring the house in the future and then ultimately potentially making it unsaleable when the time comes, which scares me. I'd have no choice if it was the main property but as it's just a garage I'm attempting to fix it myself so to speak thus avoiding these future issues.
Purely guesswork on my part of course, but its the absence of visible cracking that made me think down on those lines.
As for the insurance issues, even properties suffering from repeated flooding can still be covered - at a price! I think I'd be seeking legal advice on this one.
I do understand where you are coming from though.
John :)
Excuse my ignorance, legal advice? To what end? I'm not being argumentative at all just wondering what legal advice would help me with, is it a case of who to pursue or.. ?
built on a small pit used to discard animal carcasses

That sounds like a smoking gun to me....

But this doesn't really matter. It sounds like it has already reached a point where major repairs are needed. In the process of fixing it you'll probably find the original cause.
My plan was to arrest further movement initially, and carry out repairs, which are ostensibly aesthetic at a later date. What I had planned is digging out a trench to the footing around the front corner and inside the garage to say halfway back, seeing if there's anything obvious, and potentially backfilling with a large amount of concrete to in essence underpin to arrest the movement. Most of this is labour which I'll do myself. I have a friend who's a bricklayer who in time, once we're happy we've stopped the rot, rebuild a large portion of the right hand side wall and front pier to square it back up, we've discussed a cost and provided I buy the bricks and materials it's likely to be very little in his labour. I feel this is the cheapest option and avoids the insurance.

The only other thing that is bothering me is we can only get to my side of the foundation, which I suppose is typical if you're underpinning a house also. Nextdoor have flower beds all along that wall full of flowers as they're keen gardeners. Part of me wonders whether persistent watering has had an effect also. I guess like you say, once I start digging hopefully something will rear it's head as once I know the cause I'll be happier.

Sound like a plan?
Excuse my ignorance, legal advice? To what end? I'm not being argumentative at all just wondering what legal advice would help me with, is it a case of who to pursue or.. ?
Sorry, I didn't mean for you to get into an argument with anyone......if it was me I'd just like to be aware of the implications concerning an insurance claim, against the possible future value of your property. Its the insurers job to wriggle out of anything possible - which they seem able to do reasonably well.
Just an example......sisters property flooded in Keswick, twice. Insurance claims both times. The insurers then said they wouldn't cover her again. Apparently, they can't legally do this, we found - but of course the premiums are another thing!
Back to your scenario. I would guess that the underpinning issue started a long time ago, maybe due to drainage issues or incorrect foundations in the first place.....not to do with gardens.
Time to consider all of the options!
John :)
Hi John,

Sorry if I was unclear, it's not been underpinned that was my plan of action that's all.

One possible solution is to drill a hole through the garage floor and inject concrete under pressure into the ground under the floor and wall.

With luck ( and operator skill ) the injected concrete can lift the wall back up to it's original position. Otherwise the cavity is filled and surround soil compacted.

Requires specialist equipment and operator but does do the repair very quickly and minimum disruption. The close proximity of the drains in what seems to be soft ground may require extra care to avoid the drains being pushed out of place by the concrete.
Have you had both foul and rainwater drains surveyed, and the locations and connections marked on a plan for all drains to both yours and your neighbours?
ie you need to know where all the drains are and where they are all connected to - including soak-a-ways if any.

It looks like the paving, ground and that fence are all running down to that side of the garage. This would indicate compaction of the sandy soil, and that is either due to excess water, or drying from trees. Are there any trees or large shrubs around?

Its no good doing anything until you have identified the cause
Hi Woody, thanks very much for your reply, this issue has been causing me many sleepless nights.

I've had the foul drains CCTV'd which showed no obvious breaks and that things seemed to be flowing fine. I have not yet had the other drains looked at, presumably I'd need nextdoor's permission for this for the right hand side down pipe circled in green. I don't currently know where any of the soakaways are located, I'd guess in the middle of the garden(s) somewhere, is the only way to find out to stick a camera down them and see? I take it there's no clever way or that they would be marked somewhere? I have the deeds and information about my house from when I bought it and although the boundaries and plans are there they don't mark the soakaways which I don't know is normal or not.

There are no trees anywhere close, in my opinion. That tree that "looks" close to that fence on the right hand side is actually situated at the bottom of nextdoor's garden, approximately 30ft away and is probably about 18-20ft tall. The bush on the left is ivy and quite vigorously with it's growth. The root disappears under the garage but oddly under the other side (left hand side as you look at it) which led me to think early on that the left hand side may have lifted rather than the right hand side dropped but I've later figured out this isn't the case. In your experience is the ivy likely to be a culprit at all?

Once again, thanks for taking the time to reply.

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