Strengthening foundation of subsiding house.

Jimstapleton

We bought a house 1 year ago (we're Irish but don't live in Ireland), the rear bathroom and kitchen extension wasn't connected well, and had a large crack due to subsidence.

We believed that both the house (probably 30 years old) and the extension, probably 10 years old) had both settled, so were okay with it.

However, there's been a long rainy season here, and unfortunately new exterior cracks have shown up along the left side of the house. The biggest one being in a piling.

Rear piling on the extension.

And around half a dozen other hairline cracks, that look like they were done with a pencil under the windows.

This is the back and side of the area.

Jimstapleton

We were told that to stop it subsiding any more, the solution is to break up the concrete path, dig down 1 to 1.5 meters, then put in rebar and concrete under the existing foundation to stabalize it.

Does this sound correct?

Any knowledgeable advice and comments about how to deal with etc are welcome, thank you.

Pinoy adventure

Where in d world is that ?

PH ?

Jimstapleton

https://www.boards.ie/discussion/comment/121344895#Comment_121344895

South East Asia.

Calahonda52

Time to edit the title to show its off shore

what is The biggest one being in a piling.

Tow

Looks like the Philippines. The houses tend to be built from a frame of reinforced concrete columns and the walls are filled in with a low strength hollow block.

There appears of be no gutters, you need to make sure the rain is running off and also the drains are not leaking under ground.

As to reinforcing the foundations, it sounds about right.

Jimstapleton

https://www.boards.ie/discussion/comment/121344961#Comment_121344961

The biggest fresh crack.

At the beginning of the year the only crack was the big one between the main house and the bathroom and kitchen extension at the back.

All was old, so we put it down to settling and poor workman ship. The house is a few decades old so we gathered it had settled.

The rainy season has been long and wet and thoroughly soaked the ground for months.

Fresh cracks along the house have started. The biggest fresh crack is this one that is on a piling along the side of the house.

Jimstapleton

https://www.boards.ie/discussion/comment/121344968#Comment_121344968

Thanks for the information.

All the fresh cracks have appeared alarmingly quickly over the last 2-3 weeks.

Given that the house was painted years ago you would think that they would already be there, there are around 8-9 pencil line sized cracks coming down from the 3 side windows. Concrete plaster outing of course, so hopefully the actual walls are okay until we can get the foundations strengthened by reinforcing underneath them.

T-Maxx

Underpinning. A specialist job. The front might also be subsiding so would need to check that out too.

Mellor

https://www.boards.ie/discussion/comment/121344970#Comment_121344970

That's not a piling aka a pile. Piles are under a building. It may be a column. But you need to confirm if the crack is in a structure of just in the finish. A craic in a column is a massive issue and not fixable by underpinning. Or if the structure has settled, then the crack is superficial and underpinning can be the solution

Tow

https://www.boards.ie/discussion/comment/121344981#Comment_121344981

It might not have been painted 'years ago'. In the tropics building look tired faster than in Ireland, with the heat and humidity.

Jimstapleton

https://www.boards.ie/discussion/comment/121345199#Comment_121345199

Thanks, the column is one of the things we'll look at, with the local contractor.

Jimstapleton

https://www.boards.ie/discussion/comment/121345062#Comment_121345062

I knew there was a technical term. :D

A local contractor and crew will be dealing with it, hopefully sooner rather than later.

As for underpinning, is it usually a fairly straight forward job, that people with experience can usually do well without issue? Or is it akin to opening up the cylinders and adjusting the pistons in an engine? :D

How far under will underpinning usually reach from the side of the house? For example, 50cm around the edges, or would it go 2 or 3 meters under the rooms? How deep in cm should the foundation be? How deep should the underpinning be under it?

TIA.

Tow

https://www.boards.ie/discussion/comment/121346558#Comment_121346558

Depends on what the ground in the area is like. There maybe very little foundations under the columns. I doubt they will be going much under rooms. The question really is why they have moved recently, which is why drainage and gutters should be looked at. At both your and neighbours houses. The quality of construction is crap in that part of the world. My sister in law did a two story extension and within year there was a crack an inch wide in a upstairs wall. This was not a cheap job, everything had to be approved by the Subdivision/HOAs board and engineer first and big deposit paid to ensure it is built to plans.

10-10-20

OP, it would be worth reading up on underpinning or at least reviewing the methods used as the process is dependant on the installers doing the job correctly, especially if you're dealing with relatively rapid destabilisation and no way of confirming that the movement has abated. Look in your immediate surrounding area for subsidence, slip (on a slope), surface erosion or subsoil erosion. Expansive soils are another potential cause, those which readily take on water. Make sure that the installers can explain the cause before they take on the work.

Additionally if they plan on underpinning to bedrock or a more stable layer, you could try keep an eye on the process to ensure that you observe a notable difference in the sub-layers of the soil which come out of the drilling tails as reassurance that they are hitting the target.

Gusser09

Might not be subsiding. Not much there to suggest it being honest.

It needs to be measured over time.

Jimstapleton

The right side of the house is also showing similar pencil line cracks under all the windows, and from the top of a column.

Is there a reason that the walls are cracking on the outside but not on the inside?

Thanks.

10-10-20

Don't know for sure unless we know the construction methods, but the inner walls may be 'fair faced' in a way or finished with a different surface which either flexes slightly with the movement or adsorbs it, meaning that the cracks don't show through. That or perhaps the building constriction has decoupled the exterior from the interior somewhat.

Tow

https://www.boards.ie/discussion/comment/121354001#Comment_121354001

You have have not said exactly were you are. If you are were I think and the construction is what I think, the walls are probably a thin hollow block of very little strength. Not like a standard Irish hollow block which in comparison is much stronger. The concrete pillars are reinforced and provide the strength to the house. If the pillars move the walls will crack. The quality of the cement is always suspect, there are multiple grades and even then the quality can be suspect. A relation built/managed a number if the semi state cement plants in SE, so I have heard stories. We also don't know how common earth quakes are.

I would be more worried about drainage and gutters. I don't see any gutters in your photos. If there, can they handle the rain, and was the rain heavier than normal? Heavy tropical rain pouring off you roof into that narrow passage will effect the foundations.

Jimstapleton

https://www.boards.ie/discussion/comment/121354686#Comment_121354686

Thanks.

The location is Thailand.

There aren't any gutters fitted. The rainy season that is just finishing had massive overnight down pours for weeks and weeks.

But the house is around 25 years old. It didn't have these exterior cracks when we bought it at the start of the year, only the one big separation crack between the main house and the newer bathroom extension. The back wall of the extension has 2 cracks from the top to the bottom of one column, one on each side.

There aren't any issues with earthquakes here.

Jimstapleton

One idea is to have the construction guys come to look at it all and talk about underpinning the foundations.

Then get guttering put onto the roof on the 2 sides + back, plus offer it to the neighbours on each side, then monitor all cracks. If they get bigger during the next rainy season (or before) then get the team in to underpin the foundations.

I think this sounds like the first action to do.

Jimstapleton

Guttering has been added that will hopefully halt the subsidence, as it happened during the rainy season with no guttering.

A company offers this.

2,500 Euro for 3 underpins.

How much would 3 underpins cost in Ireland approx?

Thanks.

Jimstapleton

Hello, a quick question with regards to this.

It is a slab house, built on a slab. A few of the hairline cracks in the exterior rendering (36 yr old house, new cracks within the last year) also go down on to the slab.

My question is, have they also rendered the slab?

So the cracks that is visible is in the exterior rendering, or they didn't, and the crack is in the slab itself?

It is very thin, it looks bigger/wider in the photos. But is it in the slab? Or in renendering they have put on the outside of the slab?

Thanks.

10-10-20

https://www.boards.ie/discussion/comment/121995888#Comment_121995888

IMHO the only way you'll know Jim is to look at the original plans (if any) or look at how it's commonly done locally. It would be unusual to render the slab itself as that would imply that the external walls are sitting directly on the slab and a DPM would then be required to be lapped in and around the bottom of the wall with run-off to the outside - but that's not easy on a single-skin wall.

You could also look at expansion as a possible source for some of the milder cracks.

Did you end up underpinning in the end?

Mellor

https://www.boards.ie/discussion/comment/121996062#Comment_121996062

Expecting a DPM might be a bit optimistic tbh. It was built in the 80s, in S.E Asia. Buildign regs would be a fairly loose idea.

https://www.boards.ie/discussion/comment/121995888#Comment_121995888

Can't be sure from a photo But i'm not sure that section is the slab. Seems too tick, and the horizontal joint looks like an line that's be marked manually in the render. Is that not the slab lower down, the more uneven, thinner line, where the paint stops. Where is the floor level in relation to those lines?

Jimstapleton

https://www.boards.ie/discussion/comment/121996062#Comment_121996062

Thanks for the info.

There are no houseplans or any info on it, it was pretty much left deserted and we got a good price on it as seen, there was no contact with the previous owners or any info of any kind.

We didn't go for underpinning as the main area of subsidence is the rear extension with the bathroom and kitchen, it's only around 2x12 meters. The cost of underpinning is so high compared to the cost of rebuilding a new extension with proper foundation, maybe 4000 euro compared to 7000, without any guarantee that it will be successful or the Thai crew will do it properly, so it's better off just waiting and see if a full collapse of the rear extension ever becomes a possibility.

So the main issue is watching the main house, which has all of these hairline cracks pop up on all exterior walls (around 70 in total) over the last year.

Thanks.

Jimstapleton

https://www.boards.ie/discussion/comment/121996371#Comment_121996371

Thanks.

The floor level for all of the house is at the top of the pinkish paint in the photo, so I presumed that is the slab. It's 12 inches off the ground, going all around the house.

The house is 36 years old, I believe a lot of houses here would be built on a slab with almost none (or none) footings/piles.

shimadzu

In Asia on soft ground for one off houses its common to put a slab foundation on piled timber supports.

Mellor

https://www.boards.ie/discussion/comment/121997269#Comment_121997269

There is a still foundation to a degree. Likely it’s a basic raft and the floor “slab” steps down at the perimeter. With the walls built off that lower step.