House underpin - need help!

Dear fellow Somersoft Forum members,

Our property had an extension added to it about 10 years ago and since early last year we noticed cracks on the extension's walls (not very big) and the floor sank below the main house. An inspector came and measured the inclined to be about 20mm, and told us this was likely due to soil movement that drew the extension's slab away from the main slab. The property is located in Melbourne west and is quite close to the beach. The site is classified H for "highly reactive clay sites".

I've spoken with three trades people and an architect trying to find a solution to this, but so far I'm only getting more confused... The advices I received from them were each quite different:

  1. A builder from a large corporate, said he must pull the extension down and rebuild it, and would likely cost $30,000-$50,000 (the extension is 8.5m X 2m, and only one storey).
  2. An architect, said he couldn't help me but suggested putting a levelling slab below the sunk part of the house, and think I can get the job done for $3000-5000. Note he has not been on site to inspect the damages.
  3. A private builder, said he wouldn't give me a quote for re-levelling the slab because he needed to see a structural engineer's report first. He did give me a quote for fixing the wall cracks and repainting, which was $4,000. He suggested I should get a structural engineer to inspect the damages first, which would likely cost $800.
  4. An underpinner, who has been doing underpinning work for 40 years (he's a bit old but I assume he has employees that do the actual work) came and inspected the house. He drew a plan of putting five concrete pours underneath the extension and use jacks to push up the extension from below. I asked him whether I needed to find a structural engineer, he said he has inhouse engineers to do the inspection and draw the plans but they all listen to him anyway so I don't need to hire someone external ? he did seem very knowledgeable so I don't think he said this to con me. He gave me a quote of $14,000 (GST and insurance inclusive).
I have zero experience in house building so would appreciate if anyone could help me with the following questions:

  1. What's the best way to fix a problem like this? Rebuild, levelling slab or underpin? Is it considered a difficult/specialised job?
  2. Is it better to give the job to an underpinner or a builder? Because the underpinner wouldn't do anything other than the underpinning, once he finishes I will still need to find a builder/renovator to fix the walls, whereas the builder can fix everything and potentially charge me less in total.
  3. If I decide to go with the underpinner with inhouse engineer, shall I still get an independent structural engineer to check it out first? I know it's a good practice but it will cost money (~$800), and sometimes you get a bad engineer that can still mislead you (had this kind of experience before)
  4. Is the $14,000 quote given by the underpinner reasonable? What about the $4,000 quote for the builder's paint job?
  5. How would the underpin affect the property value in the future? Shall I try to sell it immediately after it was fixed or some time in the next 6.5 years while it is still covered under the insurance for the underpin work?
  6. If you have done similar works to your house please share your experience. Any recommendation of trustworthy underpinner/builder would also be highly appreciated!
Thank you all for your time. I consider myself of good online etiquettes and will certainly come back to give you an update once the job is done.
 
http://www.uretek.com.au/pages/underpinning-your-house-footings.asp

This maybe a cheaper method , I know these type of companies are used by the Mine subsidence board, they can normally get the cracks to close completely.

Thanks for the reply nww. I'm generally sceptical of "new technology" that seem to be a short cut, but I've heard a number of people recommend Uretek. It's probably worth giving the guys a call and get them to explain to me why their method is better.
 
I cannot help you really except to suggest you get another quote.

Son had a badly cracked brick wall of a house and we had three underpinners to quote.

One quoted "ballpark" $12K and when he realised there might be the "Bank of Mum and Dad" behind our son, that verbal quote came in writing at $25K(ish).

We got another quote about the same (from memory).

We had a different style of underpinning quoted by a company that uses an injected product, which initially they said would be half the price of the regular type of underpinning, but that quote was the most expensive.

Luckily we learned a chap I used to work with runs one of the biggest underpinning companies around and he came around and said "no need for underpinning" and suggested the drainage work needed to stop the water getting under the slab (where it had been heading for over 50 years). He said if this didn't work and if cracks opened any more, he would do some "spot" pins under the front corners and along the sides. It hasn't needed though, more than a year later, no movement.

Hubby dug a hip deep trench right across the back of the house and part way down the sides to direct the water off the hill to stop creating movement in the soil (build 1959) and did ag pipe and rubble drainage. Once the water stopped hitting the back wall under ground level, the problem was solved. Your issue is different, but there might be a way to spot underpin?

I'm sorry for a long story, but bottom line is that I believe the job was being talked up by the underpinning chaps and we were lucky to get an opinion from someone not trying to sell us an expensive fix that wasn't necessarily required.

In the end, it was quite an easy fix.

Maybe get some more quotes.

If you can find a builder on this site, you might be able to get an opinion that doesn't involve pulling the wool over your eyes, which I believe was happening to our son (and us).
 
First you need to find out why the damage happened in the first place, then fix the underpinning and leave it for some time to settle down, observe cracks over few months, and if its seems solid then fix visual cracks.

Giving the whole job to the builder is ok, as long as he had experience with similar work, and is backed up by the engineer.

I would not suggest to demolish, only if you have too much money and you don't know what to do with it :D
 
We had a different style of underpinning quoted by a company that uses an injected product, which initially they said would be half the price of the regular type of underpinning, but that quote was the most expensive.

Thank you for sharing your experience and advice. I believe the injected product you mentioned refers to the Uretek method? I've seen mixed reviews about this product including a very scary experience posted on this forum, see:
http://somersoft.com/forums/showthread.php?p=667568#post667568

I wonder if anyone had any direct experience with Uretek in recent times and would recommend this method over traditional underpinning?
 
First you need to find out why the damage happened in the first place, then fix the underpinning and leave it for some time to settle down, observe cracks over few months, and if its seems solid then fix visual cracks.

The underpinner told me the soil movement was probably caused by a tall gumtree about five meters away from the garden. Its roots likely runs below my property and has sucked moisture out of the soil to cause the clay to move (site classified H).

There is probably no way to get the council to agree to removing the tree I'm guessing?

The other thing I was thinking about was whether I need to have the extension slab rebolted to the main slab. The soil movement per se wouldn't have caused the crack, but the fact that the two slabs were moving at different speed/direction. The builder who did the extension 10 years ago probably didn't have the slabs bolted together tight enough?
 
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Tyng,

A few questions;

1. Does the extension contain plumbing or electrical services underneath it, or in the walls?

2. What are the walls constructed from?

3. Are the walls plumb?

Please also post some photos of the cracks and the area around the outside of the extension.

Cheers

Glenn
 
Tyng,

A few questions;

1. Does the extension contain plumbing or electrical services underneath it, or in the walls?

2. What are the walls constructed from?

3. Are the walls plumb?

Please also post some photos of the cracks and the area around the outside of the extension.

Cheers

Glenn

Hi Glenn,

1. I'm not sure, but the extension footing plan drawn by the previous structural engineer didn't indicate there was.

2. From the previous structural engineer's report: "External walls, including at the upper level, are typically of masonary veneer construction."

3. I haven't measured them but I don't think they are. The extension side of the house was clearly lower than the main house.

Photos:

https://dl.dropboxusercontent.com/u/14554159/Capture.PNG
https://dl.dropboxusercontent.com/u/14554159/Capture2.PNG
https://dl.dropboxusercontent.com/u/14554159/Capture3.PNG
https://dl.dropboxusercontent.com/u/14554159/Capture4.PNG
 
UPDATE: I spoke with two structural engineers and each gave me some more advice.

Structural engineer 1: Recommended doing a soil test ($500) to determine whether soil is overly wet (potential incorrect installation of downpipe on the extension) or overly dry (due to nearby gum tree). Worst case scenario is that the nearby gum tree had roots grew towards the downpipe during wet seasons and then when the draught came it continued to suck moisture out of soil beneath the house... He suggested maybe we need to consider installing a root barrier.

Structural engineer 2: Looked at the footing plan of the extension and noted the following: 1) slab of existing house and extension slab had different depth (380mm vs. 700mm), this could have caused differential movement of the building; 2) no dowel bars were installed between the existing and extension.

I went back to the old underpinner (see original post) and asked him about the issues suggested by both structural engineers, his opinion was: 1) different depth of slabs doesn't really matter, it's the tree roots that was the cause of the problem and needed to be taken care of. 2) Root barriers don't work because tree roots can suck moisture from below/around the barrier and still cause soil movement - he used to install them for his clients but stopped doing so 15 years ago. He suggested vertical soaker hose as an alternative, which gets water down to the soil directly. Only downside is that you need water it every week. (he said this is optional and not a necessity) 3) dowel bars - he kind of mumbled a bit on this one - I guess it's not really an underpinner's job to comment on building joints. At the end of the conversation he basically stuck to his original plan of putting five pins below the extension slab to relevel it.

I'm inclined to just let this guy take care of everything for me... The $14,000 quote he gave included plans, permits, soil test, insurance as well as GST, which seemed reasonable. I tried to ring up a few more underpinners but for some reason no one was picking up their phones or returned my call....
 
UPDATEI'm inclined to just let this guy take care of everything for me... The $14,000 quote he gave included plans, permits, soil test, insurance as well as GST, which seemed reasonable. I tried to ring up a few more underpinners but for some reason no one was picking up their phones or returned my call....

I would also get a quote from the injection people because (in our son's situation) they said their price would be be cheaper due to not having to dig the holes required for the traditional underpinning. Then you can compare both quotes.

I may be cynical, but I do suspect that once they knew Mum and Dad were there behind the young son, the prices from each of the underpinners (traditional and injection) went up double. Dress down when you meet them for the quote ;).
 
I had a similar problem to yours about 5 years ago. I got Uretek to quote for me but after reading their literature I decided not to go with them They have a get out of clause which states (paraphrase) that they cannot guarantee that their work will be successful.

After heaps of quotes and discussion with structural engineers, I went with one of the biggest underpinners in Queensland who seemed to be run off his feet with work all around the state. It cost me $30,000 but since then the extension has not had any movements at all.

I think that you are making the right choice going for the underpinner quoting $14,000 as he seems to know what he is talking about. Of course you need to do some due diligence with the Building Services Authority (or Victorian equivalent) to see whether there are any complaints with his work.
 
I had a similar problem to yours about 5 years ago. I got Uretek to quote for me but after reading their literature I decided not to go with them They have a get out of clause which states (paraphrase) that they cannot guarantee that their work will be successful.

After heaps of quotes and discussion with structural engineers, I went with one of the biggest underpinners in Queensland who seemed to be run off his feet with work all around the state. It cost me $30,000 but since then the extension has not had any movements at all.

Thanks for sharing your experience. I'll report back once the work is done on my house.

On a side note, anyone know how this will affect future property sales? What sorts of documents do I need to keep for potential buyers? Shall I sell it before the 6.5yr insurance runs out?
 
Thanks for the reply nww. I'm generally sceptical of "new technology" that seem to be a short cut, but I've heard a number of people recommend Uretek. It's probably worth giving the guys a call and get them to explain to me why their method is better.
hi tyng,
I am having underpinning issues at my places, 3 x traditional builders quote re concrete approx $35,000 - 9mtrs, 3 bedrooms in total impacted at same time approx 2-3weeks to repair.
So I started researching Uretek, and had them come out for a quote. Firstly they were reliable - came on time on day arranged. Secondly thoroughly educated in laymans terms whilst quote was being conducted, made sure I understood process.
Time to complete 1 - 2 days.
Cost less than $10k
The company has been around for about 30 years, started in Finland, Italy has a big European percentage, as do USA. So to say that this is new technology is wrong, its just different technology.
I did find one singular negative forum re a house fire issue, tell me what builders haven't had job issues before?
I am leaning to using Uretek and will finalise my decision in days.
I can't believe the negativity coming from the engineer though, I think that this company could revolutionise the underpinning method and thus take a chunk of the market.
cheers
Cesspitt
 
Uretek

Hi,

This is my 1st post. Hope it helps - tip: keep researching and asking questions.

I worked as a concretor/formworker/steel fixer/underpinner for many years and have worked as technician injecting Uretek. The product is excellent, but like anything it comes to the individual using it. Also, not every situation suits its application but like any services company, they may be prone to over endorsing it. When injecting Uretek you measure the changes in structure height in 0.5mm rises so it can be very precise. 1 x thing you cannot guarantee with it though is any horizontal movement going back in exactly the same - ie pillars have rotated. We'd try and pressure them if possible and in most cases were pretty successful.

Uretek work for RTA and a lot of government agencies and are not new in anyway, its been around for years. Please note, I am not affiliated to them in ANY way and no longer work in this trade.

I think you should have them come around and check it out, just like you should seek more options as well. Some engineers are clueless in all honesty, so don't believe everything you hear.

There is a device used for testing the 'strength' of the ground (hammer and rod basically) and will pick up a void if there is one. Uretek is good for these problems, easily applied to around anything 3mtrs down and if you do get this done you can sometimes see if the ground is really wet or dry. If you do have a void issue and underpin a house to a big new pillar that is not sitting on rock, it can and has happened where the whole house starts sinking. Im surprised the new slab wasn't doweled in, although comments around 'tightness' of this aren't really correct.

The advice previously given on water is extremely important and a simple way of measuring the impact of this is to use some grey tape across the cracks and see what happens when it rains next or wet the area around the edges of affected area. Clay expands when wet, contracts when dry so if the tape stretches or bulges, you may gain some insight. In the article discrediting Uretek someone mentioned doing this with glass - that sounded silly and dangerous. The tree could be impacting your house as well.

I read the article about the fire and it looked like the Uretek product, although the 'mousse' as he refers to it is virtually identical to the spray can 'void filler' available from the hardware store - who knows...Having used Uretek I can definitely say his comment about it spontaneously combusting is false. Just before injecting, a plastic bag is held over the gun and a test is done to see that the gun is firing adequately and the resin & isocyanite (activator) are mixing adequately. Its basically a 2 x part epoxy and when they meet, the product expands violently and yes, is hot enough to burn skin - maybe start a fire...although we did a lot of driveways around service stations and I'm still here. It is also worth noting that there are at least 6 x types of Uretek product that I can remember (always new ones coming out), all for different applications. Some go hard in 20 secs, others in 2 mins.

Have there been any works near the affected area ie storm water installation, excavation, building? These can unsettle the ground so as per the previous advice: figure out the cause/problem first.

Good luck
 
What a pain!! More underpinning.

I've just found out that one of my investment properties may need underpinning. I had my PPOR done nearly 6 years and it is fine except for one section where the brick is cracking again - not as bad as last time (and no problems with the internals) but still not happy. The engineer and underpinner both said then that they could not guarantee that there wouldn't be problems again so I guess I have to grin and bear it.

With this new problem not sure where to start, bearing in mind that my investment property may have to be underpinned and my PPOR may need some more work on it. Anyone on this forum had any recent experiences of Uretek? Can anyone recommend an underpinner?
 
Your experience

Hi,

This is my 1st post. Hope it helps - tip: keep researching and asking questions.

I worked as a concretor/formworker/steel fixer/underpinner for many years and have worked as technician injecting Uretek. The product is excellent, but like anything it comes to the individual using it. Also, not every situation suits its application but like any services company, they may be prone to over endorsing it. When injecting Uretek you measure the changes in structure height in 0.5mm rises so it can be very precise. 1 x thing you cannot guarantee with it though is any horizontal movement going back in exactly the same - ie pillars have rotated. We'd try and pressure them if possible and in most cases were pretty successful.

Uretek work for RTA and a lot of government agencies and are not new in anyway, its been around for years. Please note, I am not affiliated to them in ANY way and no longer work in this trade.

I think you should have them come around and check it out, just like you should seek more options as well. Some engineers are clueless in all honesty, so don't believe everything you hear.

There is a device used for testing the 'strength' of the ground (hammer and rod basically) and will pick up a void if there is one. Uretek is good for these problems, easily applied to around anything 3mtrs down and if you do get this done you can sometimes see if the ground is really wet or dry. If you do have a void issue and underpin a house to a big new pillar that is not sitting on rock, it can and has happened where the whole house starts sinking. Im surprised the new slab wasn't doweled in, although comments around 'tightness' of this aren't really correct.

The advice previously given on water is extremely important and a simple way of measuring the impact of this is to use some grey tape across the cracks and see what happens when it rains next or wet the area around the edges of affected area. Clay expands when wet, contracts when dry so if the tape stretches or bulges, you may gain some insight. In the article discrediting Uretek someone mentioned doing this with glass - that sounded silly and dangerous. The tree could be impacting your house as well.

I read the article about the fire and it looked like the Uretek product, although the 'mousse' as he refers to it is virtually identical to the spray can 'void filler' available from the hardware store - who knows...Having used Uretek I can definitely say his comment about it spontaneously combusting is false. Just before injecting, a plastic bag is held over the gun and a test is done to see that the gun is firing adequately and the resin & isocyanite (activator) are mixing adequately. Its basically a 2 x part epoxy and when they meet, the product expands violently and yes, is hot enough to burn skin - maybe start a fire...although we did a lot of driveways around service stations and I'm still here. It is also worth noting that there are at least 6 x types of Uretek product that I can remember (always new ones coming out), all for different applications. Some go hard in 20 secs, others in 2 mins.

Have there been any works near the affected area ie storm water installation, excavation, building? These can unsettle the ground so as per the previous advice: figure out the cause/problem first.

Good luck



we demolished and rebuilt in a suburb in Perths north where the builder back filled the old pool which was removed, then a rock breaker was brought in to lower the rest of the block and subsequently raked with the large excavator for rock remnants.
Long internal dividing walls have sunken causing door height long horizontal cracking about 5mm wide which tapers off to hairline 3or4 meters away. Floors have separated from the walls leaving 2-3mm gaps at the very bottom and large vertical cracks about 2-3mm in the study about 5m away from where the pool used to be.

I'm pretty sure the earth workers failed to do proper compacting of the pool and failed to compact the rest of the ground where the rockbreaker had been.

The builder had repaired cracks 3 times before handover which we found out later.

They drilled a series of 4 holes in 2 separate areas where the worst of the cracking is for penetrometer testing which come up as acceptable compaction. Some tests were at bare minimum and deeper seemed to get overall better compaction.

The previous engineer asked to hold off repairing the cracks because they expect the settling to slow and stop soon. We waited 6 months, it hasn't stopped. Then we waited another year and still hasn't stopped. We have only been here 2 years now and this is really getting on my nerves.

Our soil is classed as stable.

The builder or engineer seemingly keeps trying to steer clear of injecting and makes excuses that they need to know or find hard ground for cementious underpinning. I am now arguing that uretek don't use cement and its a different system.

Is it true uretek does not require engineeers input in regards to depth of injection for a sinking floor? From what I've been told this is the case but engineers input can be useful.
 
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