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Has anyone had concrete underpinning done?

Posted by axella (My Page) on
Tue, Oct 2, 07 at 14:44

Sorry for the length of this post - it's hard trying to explain it all.

We bought this house in March. It's a brick veneer bungalow, built on concrete piers (or stumps, as they're called here in Australia).

The pre-purchase house inspection guy noted that there were a couple of vertical cracks in the brick on the front corner of the house, so we called in a structural engineer. They are not wide cracks - I can't fit a finger into them. The engineer said that the cracks in the front corner were there because the brick exterior wall had sunk, due to the dryer weather over the past several years. He said concrete underpinning would fix that problem, for "around $3500". As the house was run-down and we bought it as a "renovator's delight", that amount of money wasn't unreasonable (given the price we ended up paying for the house). So, we went ahead with the purchase.

When the house was empty before we moved in, we noticed how the floors slope to one side (the previous owners were well-schooled in camouflage). We've since been advised not to make any substantial changes to the house until it's been leveled, because it's silly to pay for framing new interior partition walls, and plaster, only to have it crack when the floors are lifted. That's reasonable.

One company said they could level the floors (they jack up the house and put shims on the piers), and leave doing the brick walls for a later date (when we have more $$$). That way, we could proceed with renovations to the inside of the house. $1700 to level the floors.

Another company said that all of the brickwork needed underpinning, the entire perimeter (it's a 1700 sq ft house). He said the interior couldn't be done without doing the exterior, as the exterior brick walls are "tied" to the wood frame of the interior (I do know that brick ties allow some leeway for movement, but how much, I don't know). He claims if we went ahead and did only the interior floor/wall leveling, that it would put stress on the brick ties, which would pull down the exterior brick walls! He was throwing around numbers like $20,000 - 25,000, to do the whole thing! I was nearly in tears when he told us that.

I know they've got to rip up the driveway and concrete footpath that runs along part of the house. Then they excavate the footings, jack it up somehow, and pour in concrete.

I'm hoping that one side of the house can get away with only the hydration things being sunk into the ground (which will enable us to "water" the footings, and keep them from sinking).

There are two other companies in the area who do all of this sort of work, but it's next to impossible trying to get them to show up (I've worked out that it's easier to get tradesmen to show up if I get my husband to make the appointment, because they're much more reluctant to do a no-show for him. Sad, but true). We've left messages for those two other companies again today, so hopefully someone else will come and look at it. We need another opinion.

Has anyone here had to do anything to this extreme? Did the house crack badly afterwards? And how long does it all take?

And I hope I've been relatively clear in explaining all of this. :-(


Follow-Up Postings:

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RE: Has anyone had concrete underpinning done?

Hydrated footings? A house sinking because of dry weather?

I'd get a soil engineer's diagnosis of what to do, then a structural engineer's plan on how to implement a fix.

There's very little "flex" in mortar. Start jacking things and you'll start getting cracks in the mortar and bricks. They won't tumble down, but you might wish they had.

It may be simpler to just put up with a bit of a slope. I've come across a number of 100 year-old homes here that slope this way and that from settlement, but are still habitable.


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RE: Has anyone had concrete underpinning done?

One problem about finding help here might be that because of environmental issues you have there that we don't (a geologist could explain it) our 'fixes' for your problem (not something common here as homes are not normally supported on pillars) could be way off in many ways and I would stick to locals for advice. We love helping, but wouldn't want to confuse the issue even more.


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RE: Has anyone had concrete underpinning done?

"The engineer said that the cracks in the front corner were there because the brick exterior wall had sunk,..."

He is probably correct up to here.

"...due to the dryer weather over the past several years."

He has no real idea about this unless he is also a geotechnical engineer.
Have a geotechnical look at the problem.
In some places the county has data that can be used, in others you have to core to evaluate what the house is sitting on (and even with general data it can still vary in spots).


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RE: Has anyone had concrete underpinning done?

Thank you for your replies.

I, too (having been born and bred in New York), thought that all homes in the USA were had either basements or concrete slabs, but that's not true. In warmer states (Texas, California), a lot of "California Bungalows" and similar were built the same way as mine. In fact, two were recently featured on TV over there - one on "This Old House" ("the Austin project"), and another on "Monster House" (where they built the Hawaiian-themed backyard with all the surfboard stuff).

As I'd only ever had homes over here built on slabs (no basements here), I've never had to deal with this type of construction before, although it's reasonably common, especially among older homes built prior to 1960 or so. One problem which later emerged was that the same type of footings were used, regardless of soil-type. We're on clay, and it's particularly reactive (just as in TOH's Austin house) to cycles of wet and drought.

The problem here is that there's not much "wet" anymore to help expand the clay particles, so they shrink further and further. It is becoming a very common problem in the area in which I live. Couple that with the old "northern hemisphere" (non-drought-tolerant) trees planted along the streets by town councils of old, and it's even worse (the trees send roots out under the footings and suck even more moisture from the soil).

Is is explained in more detail here, for anyone interested:

http://www.greenweb.com.au/archicentre/html/diy_cracking_checklist.html

And thanks again for your replies.

Here is a link that might be useful: Why houses settle and crack


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RE: Has anyone had concrete underpinning done?

more so..what is the aftermath of underpinning...is the plumbing effected, cracked windows..how much interior work will need to be required????


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