# Forum Home Renovation Pergolas, Gazebos, Strombellas & Rotundas  Failing veranda footing - rising out of the ground

## Cluster10k

Hi, 
First time poster here, with a problem where the footing of my veranda has created a bulge in the surrounding paving.  It appears to me that the footing is rising out of the ground, possibly being pulled up by wind loads (I live in a W40 area).  I first noticed the problem about three week ago.   
The veranda was constructed in mid 2017 (Adelaide soggy winter) in reactive clay soil.  The ground is original and not fill.  Stratco flat roof veranda, 7.8m long and 3.2m wide.  Three posts concreted in with paving all around.   
The problem:   
Photo of the offending footing right before concreting:   
Overall the bulge height is about 1cm.  The pavers are laying directly on the concrete footing so I can't just scrape away some sand and relay the pavers.  Measuring the levels of the beams either size of the post, one is dead level while the other has a slight incline.  I don't know if they were perfectly level when the veranda was constructed.  There's a drain right next to the footing so I'm worried that if the footing is indeed moving it will compromise the drain too. 
Only the center post is affected. 
I have contacted the builder and his opinion over the phone and looking at the photos was that there's nothing to worry about.  We've had a very dry summer in Adelaide and he said it's more likely the surrounding soil is shrinking, therefore the bulge.  He said he made the footing hole larger than required by Stratco as there's a very large retaining wall about 2m from the footing and I have had problems with subsiding soil levels right next to the wall.  Builder says the corbels were made as required, but I can't tell from the photo whether that is true or not. 
So, the builder's opinion is that there's nothing to worry about. 
Has anyone seen something like this before?  I'm worried about the problem becoming worse and will continue to monitor it.  I've had thoughts of digging around the concrete, adding more, and chipping away at the top of the footing so I can relay the paving properly, but that may be wasted effort if indeed this footing bulge is normal.

----------


## Tools

I'm with the builder. What does the beam on top of the posts look like? 
Tools

----------


## cyclic

The Builder said the surrounding soil is shrinking, so therefore the bulge.??
I would say the opposite is occurring, the clay is expanding and therefore the bulge.
Clay expands when wet and shrinks when dry.
You say it is dry so the water required to wet the clay may be coming from hosing the pavers, or maybe, just maybe, the Builder cracked/damaged the drain when digging the hole.
It would not be the first time.

----------


## droog

Agree it is most likely the surrounding area that has sunk.

----------


## Cluster10k

Thank you for the replies.   
The beam at the top of the post is dead level on one side and slightly raised on the other.  I didn't measure the beams when the veranda was newly constructed so don't know how much they have changed. 
The theory that the ground drying out, shrinking, and therefore falling away from the footing is possible.  If true, I should expect the bulge to even out again after winter.  The entire backyard is paved (it's quite small, and had drainage issues that were corrected) and the paving was there 4 years before the veranda was constructed so in theory the ground had time to settle.  Could the drain be leaking and slowly adding water around the footing?  I can't know without digging around it. 
I have marked a few reference points on the veranda in relationship to the ground and house to measure movement over winter.  I hated the reactive Adelaide clay soil when landscaping in winter and certainly am not a fan of it now.

----------


## commodorenut

The drain looks like the type where modules are clipped together to form a long drain - each joint has the potential to leak unless the joint is sealed during assembly - which isn't normally done - it's pretty much not required, because  the amount of potential leakage would be quite minimal. 
If the drain is freely draining the water away, and you're not left with standing water, then you'll get more water into the clay/soil from seepage between the pavers than you would from a "leaky" joint in the drain. 
I'm also on reactive clay, and exactly what the others have said - it shrinks dramatically when it dries out (and would be responsible for the dips).  If you took that photo when it was wet clay, then I would suggest the post was concreted in when the clay was dry, and the clay, when wet, has lifted it.   However, being that it's now dry with that photo showing the pavers, there's no "power" in the clay to lift the post, so it has to be shrinkage. 
I have a crack in one of my retaining walls.  When it's been dry for a while, you can get your fingers into it.  When it's rained for a few days, it closes up.   
If you're really worried, then I'd suggest doing the following test now while it's dry, and again after the next lot of week-long rain: 
Get a very accurate read on the angle of the beam/rafter from the house to the post.  Put reference marks on the beam closest to that suspect post, that runs back to the house.  Sit the spirit level under the beam, aligned to your marks, and lower the end near the house to get the bubble centered.  Once centered, measure the gap between the level and the beam at the house end (where you've been angling it away) and write it down.
Then do the same, at the same reference marks, when it's been wet for a week, to see if that measurement changes.  If it does, then the post is moving up.  If there's no change in the angle, it's simply the pavers sinking as the clay shrinks.

----------


## Cluster10k

> If the drain is freely draining the water away, and you're not left with standing water, then you'll get more water into the clay/soil from seepage between the pavers than you would from a "leaky" joint in the drain.

  When the drain was laid I put silicone sealant in the joints and it's also concreted around the base, but both may have cracked or weakened over the years.  There is virtually no fall in the drain so water does tend to stick around for a while.   

> I'm also on reactive clay, and exactly what the others have said - it shrinks dramatically when it dries out (and would be responsible for the dips).  If you took that photo when it was wet clay, then I would suggest the post was concreted in when the clay was dry, and the clay, when wet, has lifted it.   However, being that it's now dry with that photo showing the pavers, there's no "power" in the clay to lift the post, so it has to be shrinkage.

  During the month of installation Adelaide had wetter than usual conditions. Adelaide in July 2017 
The last four months have been unusually dry so it's possible the clay has dried and shrunk around the post during that time.  So in theory the bulge should become less visible over the next few months.   

> I have a crack in one of my retaining walls.  When it's been dry for a while, you can get your fingers into it.  When it's rained for a few days, it closes up.

  My property has a large (2m+) retaining wall at the back, about 2m from the post.  I've had all sorts off issues with the paving there.  I relay it once every 2 to 3 years due to soil subsiding.  One area has fallen 2cm in 2 years.  It's very annoying, but not as bad as my neighbours who put veranda posts right next to the retaining wall.  After a few years the ground pulled the veranda down and was threatening to literally break it, so they were forced to redo the footings. 
The soil never swells up during winter: it just keeps going down near the retaining wall.  I suspect the builder just back filled with loose clay and declared it job done.  I dug 70cm down right next to the 2m+ high retaining wall and noticed there's no evidence of a stone layer to aid drainage.  It's just all super soggy clay, in the middle of summer 2017.   

> If you're really worried, then I'd suggest doing the following test now while it's dry, and again after the next lot of week-long rain:

  Thanks, I'll try that suggestion and post the results after a period of rain.

----------


## Bloss

This is non-problem you are overthinking and over-worrying. A ~1cm movement of anything on or in reactive clay soils is not material. If there was evidence that the post was moving loosely or some other issue then maybe, just maybe more investigative work is needed. From your descriptions no action is needed other than continued occasional observation.

----------


## r3nov8or

It's good for drainage away from the post. This one will last longer than the others  :Smilie:

----------

