Any advice on retaining wall troubles?


This is a wonderful forum have learnt alot from reading. Today I decided to post one of our challenges in hope that someone out there could give us some sound advice. And help us with this uneasy situation.

We are building a home which is zero boundary on one side. On this side the neighbour wants to level his block but in order to do this, he must cut roughly "one" meter into the block right up against our boundary/garage wall.

I am worried if this will impact our foundation. They have assured me that they will be putting in retaining wall straight away.

Can anyone give me advice on this situation. What do I need to be aware of? What questions should I be asking? Do they own the wall therefore the wall should be payed by them?

Is it unsafe to build a retaining wall against 0 boundary garage wall? Should a specialist be involved with the construction of the wall.

much apprecation for any suggestions.:)
Based on what you've just described, I think there is reason for your concern. Although it depends on the type of foundation under your garage, and the soil conditions.. typical raft foundations require undisturbed material at a 45degree angle sloping away, called the "influence line".

I'm no property lawyer, but think its safe to say that any building works should be built while not effecting neighbouring properties. I'd recommend getting your solicitor to draft a letter to them confirming this. Also stating that the retaining wall be engineered. I don't think residential retaining walls require engineering <1m, but your solicitor should highlight this is an exception.

It's not really good enough for them to say that a retaining wall will be built straight away.. Cracking in the walls and slab may happen straight away.

It would be interesting to know if your garage was built in accordance with current council requirments at the time? Building up against the boundary isn't allowed anymore. That may come back to bite you?

Good luck :)
yep VB is correct , i know is as the exclusion zone , this is like drawing , sorry i will start again, imagine the foundations as being a long concrete square being about .4 m x .5 m and whatever long, Now cut it threough the center it will look like a square, the exclusion zone is a n imaginary 45 degrees line from the bottom right corner run the line for about 2.4 meters and this area of soil should not be disturbed , especialy with out engineers consultations,:eek:
the exclusion zone is a n imaginary 45 degrees line from the bottom right corner run the line for about 2.4 meters and this area of soil should not be disturbed , especialy with out engineers consultations,:eek:

How can you enforce an exclusion zone for your footings, if yours are on the boundary and the exclusion zone is on your neighbours property?
Hey Battler, its a common part of property law that new builds are not to effect the neighbouring property foundations.. look at multi story buildings in inner city locations, its inevitable that their pile foundations/rock anchors will be in the exclusion zone of their neighbours. Undermining/vibration damage/noise etc is the responsibility of the new builder to control.

Similarly for resi property, but council rules of not building within a certain distance of the boundary usually prevents these issues. I think consulting a solicitor to notice the neighbours would be essential.. and checking whether the garage complies with councils rules (current for when it was built) would be handy.
As VB says, its the builders responsability to make sure its all ok , in the new burbs they are in some cases 6 inches apart, but the footings should be at the same depth, as the exclusion zone is below the other at a 45 deg angle, :)
Go to your local council building/engineering/planning dept. They are the ones who will approve the work according to their development policies so they are probably liable for any problems. They will require an engineer to certify the neighbours retaining wall thus pushing the liability onto engineers. Like the others say, also consult your lawyer. :)
Sounds like your garage will need underpinning prior to the excavation. You can't excavate first and then support the structure later...