Tips & Tricks

Beware Underpinning Rip-off

I was staggered this week.

It was just unbelievable.

A client came to me for a second opinion about a quote to underpin his residential property in Queensland. The quote was from a local builder for 25 underpins to an approximate depth of 2.5m in order to ‘stabilise a single level house.

The quote was based on an engineer’s assessment. A geotechnical engineer had also attended and provided the results of a soil investigation. Both good signs.

So on the face of it, everything seemed legitimate. However, once I dug deeper the justification for spending so much money was very thin.

Very thin.

So very thin.

So how do you, as a homeowner, evaluate a quote for underpinning from a builder and determine if you’re likely to get value for money.

Let’s go through my independent assessment process together.

How We Got This Far

In this case, the dwelling was tenanted. Some cracks were identified and dutifully reported by the real estate agent from their periodic inspection.

The real estate agent recommended the owner get a quote from a local builder.

The builder engaged the geotechnical engineer to assess the ground conditions and a structural engineer to assess the cracks in the building.

So far, all very good. Excellent service and responsiveness and probably the correct course of action for an owner who does not reside at the property.

A Note about the building history

The client advised that they purchased the dwelling in or around 2008 and subsequently lived in the dwelling for around one year.

The client had purchased a building and pest report (an excellent investment that even I, an experienced structural engineer, make use of when we purchase homes).
Some minor internal cracking was noted in the dwelling in the cornices and in some ceiling sheets.

OK. So even back in 2008 there was some minor cracking. The building hadn’t been painted since then so all good.

Strike One – The Engineer Wasn’t Registered

Alarm bells started ringing when the client sent me the structural engineer’s report.

The first thing I did was check that the author of the report was a registered engineer in Queensland (RPEQ). The Board of Engineers Queensland website allows anyone to check, really quickly, whether an engineer is registered to practice in Queensland. Here’s the link the BPEQ website:

This quick search indicated that the author WAS NOT a registered engineer.

That was strange. In fact, according to the BPEQ website, the consulting engineering services company that prepared the report did not have any listed RPEQ engineers.

Strike One

The report referred to the geotechnical report which appeared to have been commissioned concurrently.

Strike Two – The Damage Wasn’t Assessed Properly

The engineer’s report identifed ‘several noticeable cracks’ but did not include any photographs of the damage or any indication of where the damage was located or any assessment of the crack width, length, severity or age.

This was a bizarre summary of damage given how much we, at Cornell Engineers, rely on crack location and width in order to determine the severity of the damage.

Indeed, the QBCC website even has this awesome Standards and Tolerances Guide which is meant to apply to brand new homes but has so much useful information for assessing older homes too.

The ‘engineer’ skipped over all those crack assessment steps and jumped straight to the floor level suvey.

Strike Three – The Floor Level Assessment Carried Too Much Weight

A floor level survey is definitely one of our favourite and most powerful tools, but the assessment MUST be taken in context with the extent and age of damage.

Anyway, the engineer found that the floor was uneven, beyond the limits contained in AS2870:2011 (the current version of the footing and slab standard) and jumped straight into the UNDERPINNING!!!! stage.

  • No assessment of the existing footings.
  • No assessment of the age of the damage.

Crazy. Lazy. Inexperienced. Unregistered. Bordering on fraudulent.

When Every Tool is Underpinning

You remember when, in my article, I wrote that “When underpinning is your only tool, every house looks like it needs underpinning.“?

This is exactly when that statement applies.

The ‘engineer’s’ client was a builder that constructs underpinning. Amazing how the solution to ‘fix’ this house was to underpin.

Is Underpinning Required?

So let’s assess whether underpinning is really required.

  • Was there one way, non-reversible subsidence of the footing? Yes, perhaps.
  • Was the slab heave caused by other issues such as broken pipes or trees? Not investigated.
  • Was the damage live and ongoing? Not investigated.
  • Could the damage have simply been repainted and plastered for the time being. Not investigated.

Look, the building was on a cut to fill site and the dropped area of house was in the fill section. Maybe some underpinning is required.

But the fact that 25 underpins were recommended including in areas where there was no fill, no real movement, possibly not even any recent damage indicates that the underpinning assessment was premature and pretty much unfounded.

Underpinning Design Drawings

The real alarm bells sounded for me when I realised that the 25 underpin design drawings were written into the first and only engineer’s investigation report.

How’s that for going from zero to one hundred?

All this under the cover of an engineering report that was not even signed by a RPEQ engineer.

The Independent Assessment

So our independent assessment included these steps that you can do yourself.

Sometimes underpinning is the answer. But it is an expensive answer and sometimes there are other, cheaper, better options.

If in doubt ask lots of questions

If you receive an engineering report, engineering drawings, a builder’s quote or even verbal advice that seems strange, ask lots of questions. Find out the justification for the assessment. Some experts can explain issues better over the phone than they can write in a report.

If really in doubt – get a second opinion and an independent assessment from a qualified and experienced structural engineer….

Or just throw your money away on underpinning rip-off reports and quotes, but don’t say I didn’t warn you.

Tips & Tricks

Solving Drainage Problems for Houses on Sloping Blocks

Have you got a house on a sloping block with drainage problems?

The queries we get go something like this:

Hi. My house is on a sloping site (slopes from the back towards the front) and water gets in under our house when it rains. The ground under our house gets wet and then takes ages to dry out. Sometimes the water gets into the downstairs rumpus room, storeroom, laundry, garage slab (pick one or two!).

How can I stop water getting under my house? Should I use an ag pipe and or should I install a better drain?

Tips & Tricks

Cornell Engineers and Palmview Homes

This year, 2020, Cornell Engineers is pleased to celebrate 14 years of working with Steve and the team at Palmview Homes Mackay.

This has been a relationship forged on trust, accountability and integrity and we are super-proud of our longstanding working relationship.

So thank you for trusting us Palmview Homes. We look forward to continuing our great teamwork well into the future.

If you are looking to build an investment home in the Mackay area, give Steve and the team a call on 0417 212 218.

Tips & Tricks

CoronaVirus Forces New Work From Home Rules

The coronavirus is taking a toll on our current, daily lives. We’ve been introduced very rapidly to the ideas of self-isolation, social distancing and working from home, in a bid to limit the spread of the virus.

We already understand that the virus spreads rapidly and that it is very important that we limit the spread of the virus so that our medical systems aren’t overwhelmed.

The changes that we’re accommodating, including the opportunity to work from home (even in organisations that never previously allowed it), are vital but will more than likely have the effect of making people feel isolated and alone.

Tips & Tricks

What is a Spoon Drain in Residential Construction

Today I’m talking about spoon drains, why we use them to improve drainage around a house site and what a spoon drain looks like.

Join Matt Cornell for an introduction video into Spoon Drains

Video Transcript

G’day. This is Matt Cornell from Cornell Engineers.

Today I want to talk about “What is a spoon drain?” and I’ll give you a detail for a spoon drain.

What is a Spoon Drain?

A spoon drain is a concrete drain formed in line with the ground surface and its purpose is to collect stormwater before it can soak into the ground.

Stormwater falling on the ground beside the spoon drain is directed towards the spoon drain and the bottom of the spoon drain then is sloping and takes the water away before it can soak into the ground.

So this is a concrete spoon drain.

The spoon drain width, when we specify it, is about one meter wide.

The thickness of the concrete is somewhere between 80 to 120 millimeters deep and the thickness around the edge is deeper because we need the shape of the spoon drain is maybe 120 to 150 millimetres.

Concrete Spoon Drain Reinforcement

The reinforcement we use is fairly light reinforcement. In Australia, we’d probably use an SL72 which is seven millimetre bars at 200 millimetre centres in both directions.

A spoon drain, because it’s concrete and because concrete shrinks, is going to need something to control the cracking. At about 2 metre centres we’re going to specify tool joint just so the concrete has somewhere to crack neatly without causing any alarm with uncontrolled cracking.

Spoon Drain in the Ground

So that’s a concrete spoon drain but sometimes we also specify a spoon drain just in the ground which is just a natural overland where, when it rains, water falls to the middle and then can drain sideways.

Normally we’ll set these up to collect stormwater before it can soak into the ground. Then we use spoon drains to carry the water along and discharge it clear of a building or downstream of a building.

Why Spoon Drains are Better than Grated Drains

We prefer spoon drains over box drains or grated drains is that they’re a lot easier to keep clean.

Any leaf litter that falls in this area or dirt is fairly easy to keep clean and a lot of the time just rainwater, stormwater will wash a lot of that debris.

Grated drains can fill up with rubbish, with leaf litter, with dirt and they’re a lot harder to maintain. So we like spoon drains because they’re just easier to maintain. In fact, they’re not really something that needs to be maintained.

Spoon Drains vs Ag Drains

The reason we like spoon drains, well in fact, the other kind of drain that we talk about a lot is agricultural drains and these are ag pipe drains inside a gravel trench.

These are a different kind of drain and we don’t really use Ag drains where we have water already on the surface.

So the spoon drain is really good for surface water – taking away surface water before it can soak into the ground.

An ag-drain, on the other hand, is really good for collecting water that’s already soaked into the ground. Maybe the water is coming from a neighbor’s property or from uphill somewhere.

So an agricultural drain is great for collecting water that’s already in the ground and taking it away.

A spoon drain is used to collect water that is on the surface of the ground.

Thank you for Joining Us

I’m Matt Cornell. This has been our quick talk about spoon drains with a spoon drain detail. We talked about why we use spoon drains instead of grated drains and agricultural drains. I hope you were able to take something away from this.

Get Your Spoon Drain Designed

Now you know why we use spoon drains. Do you need help improving the drainage aro0und your house?

We’d love to help.

We have experience in:

  • Preventing or minimising water coming through basement walls.
  • Re-routing stormwater away from buildings.
  • Solving water entry issues through retaining walls.

What sort of drainage issue do YOU have that needs solving?

Drop us a line on our Get a Quote page and let us know where you live, what drainage issue you are trying to solve and how we can contact you.

Get a Quote