Sub-Divided Block Issues

Want to build a new house in an established suburb?

One way is to look for a subdivided block, or even buy a house on a big block and sub-divide yourself.

I see quite a lot of large suburban blocks sub-divided with one, or more, house blocksadded.

In a number of cases the original house the original house is demolished and 3 houses are built on the block.

If you want to build the available block will normally at the rear known as a Battle Axe Block

So what do you need to think about when considering a subdivided blocks?

Here are some issues to consider:

Vehicle Access

Any shared vehicle access can be a cause of contention so a separate driveway is much the preferred option.

If you have the rear block and put a gate near the front this can provide extra play space for young children. That can be very useful as the backyard area will be fairly limited.

Adequate Off-Street Parking

With two properties sharing one frontage and the loss of parking if there are two crossovers On-Street parking will be at a premium.

I would recommend having space for at least two vehicles off the street (this can include the garage)


When you are squeezing a house on a small block windows are going to be closer to your neighbours on all sides, so overlooking, and being overlooked, is a potential issue.


A South facing block with living rooms to the rear (North) is going to give the best results if you are looking for a passive solar house to minimise heating and cooling costs.


For a rear block you could be hit with extra costs for:

  • 15m plus driveway construction.
  • Extra utility costs due to distance from existing services.
  • Builders charging a restricted access fee in addition to the typical/normal advertised price.

Sewer and Drainage Easements

Easements are often run along the back fence of the original block.

A typical 2-3m easement can severely limit what you can build on the block, particularly when you might also have an easement to service the front block running through your block.

I have heard of sewer lines on subdivided blocks running down the middle of the block, so its important you check this before you buy!


As part of arranging the subdivision the sub-divider will often get planning approval for a type of house.

If that’s not what you want make sure you get the owners written agreement to the design you offer to buy.

It might even be worth making an offer subject to planning permission.


As I haven’t personally built on a subdivided block I may have have missed an issue you have experienced. If you think so why not leave a comment?

To better understand what you can build see Restrictions in the Blocks section


Understanding Title Plans

Title plans are quite a bit different to Survey Plans.

The above is typically what you would see when looking at the title plan for a small subdivision.

This is what it tells you about block No 2, which I have coloured in pink.

  • The total width of the Road Reserve of Smith Court including nature strips and future footpaths is 20m.
  • The *survey grid bearing for Smith Court at the front of the block, is 2 degrees 0 minutes and 15 seconds (200’ 15”) almost due North.
  • The width on the road frontage is 18.00m.
  • The top boundary runs at a bearing of 92 degrees 0 minutes and 15 seconds (9200’ 15”) which is almost due East for a distance of 38.00m (the depth of the block is therefore 38m)
  • The rear boundary runs at a bearing of 182 degrees 0 minutes and 15 seconds (18200’ 15”) which is almost due South for a distance of 18.00m. so the width at the rear of the block is also 18m.
  • The bottom boundary runs at a bearing of 272 degrees 0 minutes and 15 seconds (27200’ 15”) which is almost due West for a distance of 38.00m (the depth of the block is therefore consistent at 38.00m)
  • There is a 2m wide Easement at the rear of the Block Labelled E-I. This means it will be VERY difficult to build on this part of your Block.

Within the title documents you will find a reference to each easement on the subdivision saying what the easement is for.

Generally you will be lucky if there are no easements as over 50% of blocks will have at least one easement

Each corner of the site should be marked with a Boundary Peg which needs to be protected from damage.

*ASurvey Grid Bearing’ is a fixed direction unlike a bearing from Magnetic North which can change over time.


For similar posts see Block Dimensions

To find out about Easements see Restrictions


When I worked for a drainage contractor almost every month I have to tell people that they are going to have to take down their shed, dig out part of their raised garden bed, or take up part of their paved patio.

Why? ……………because they have built them on top of a manhole on a drainage easement that needs to be cleaned or inspected.

How Common Are Easements

About 50% of properties will have a drainage or sewerage easement generally running along the back fence.

These will be shown on the title plan.

Between 5 and 10% of all properties will have a manhole within their property.

This will be used to access the sewer or drain for maintenance.

When buying a house block be very careful if you find a block that has an easement running from front to back, as this will severely restrict your options on what you can build.

Why are there Easements

Easements are a method of giving other people some rights over your property.

Examples are:

  • The right to have a pipe or other underground, or above ground, service laid under your property. The most common easements are for drainage and sewerage pipes. You will sometimes come across utility easements for water supply, electricity, telecommunications and gas.
  • Right of access, for example; to come onto your property and maintain, repair and replace the services.
  • Right to use a shared driveway

Although the person or organization having benefit of the easement has the responsibility to restore the land after maintenance and repairs this does not usually extend to rebuilding any structures such as sheds or replacing expensive paving.

Building on Easements

It can be difficult and expensive to be allowed to build any permanent structure such as part of your house over an easement.

The actual width of a pipeline easement will depend on the size and depth of the pipes, and on having enough room to carry out maintenance and repair.

Another factor is keeping the foundations far enough away that they don’t damage the pipe.

Do you check your  Title Plan?


To better understand what you can build see

Restrictions in the Blocks section


Building On Pipeline Easements (Or Close To)

Previous posts have talked about Sewer and Drain Easements but you build close to or over a pipe on an easement?


You must get permission from the owner of the easement to build on the easement.

Some easement owners won’t permit any building.

However some will allow certain works after a fee is paid.

This fee can amount to several thousand dollars particularly if you want to build right over the sewer.


The minimum costs are likely to be a CCTV survey of the pipe which could cost over a thousand dollars.

Additional costs may include either exposing the pipe and encasing the whole line in concrete, or re-routing the pipe and paying for the cost of establishing a new easement.

Getting the Design Right.

When building close to a buried pipeline, whether the building is in the easement, or close to it, the designer needs to ensure no loads are placed  on the pipe.

To avoid placing any load on the pipe the base of any foundation should be below the zone of influence of the pipe.

This zone of influence starts at the base of the pipe and rises at a slope of 1 in 1 to ground level.

In the diagram above

  • Foundation A is unacceptable The base is inside the zone of influence.
  • Foundation B is acceptable Even though it is the same horizontal distance from the pipe as Foundations A because the base is outside the zone of influence.

The base of the foundation is the lowest point of the foundation, that is the bottom of the slab, In the case of piers the base of the piers.

Building Over the Pipe

Some water authorities do allow building right over a pipe. in that case the base of foundations on both sides of the pipe needs to be outside the zone of influence.

Any beam or slab over the pipe needs to be designed to span between the foundations.


To better understand what you can build see

Restrictions in the Blocks section


Cubby House – Fail

What do you think of this Cubby House that someone built in their garden, soon after moving in?

Well it looks pretty good…………………………. Solidly constructed building, nice colourful paint job,  and securely bolted down to a convenient concrete slab.

So why is it a Fail?

Well have a look at this close up of that convenient concrete slab.

That solid concrete slab is actually the top of a sewer manhole on the Easement.

This particular manhole has two covers (You can see the front one on the photo) which need to be accessed for cleaning about every 18 months!

How would you like to move this?


For more Unusual Houses and Fails see What the………………….?

To find out what you shouldn’t build on your block see Restictions



When I started in the drainage business 40 years ago we called them Manholes.

Since then due to political correctness we have had; Person Holes, Access Points, Inspection Pits, but now we seem to be coming back to calling them Manholes.

We are not talking about the small inspection covers less than 300mm across for the individual house system but pits big enough for someone to climb down to inspect the public sewer or council storm drain.

Some manholes look like the photo, some have round concrete covers and some have square concrete covers.

But what does it mean to you?


The initial issue is that the manhole may spoil the look of your driveway or paved area of the garden.


Hopefully with most new developments it will be quite a while before something goes wrong. Rebuilding in a long established area you may not be as lucky. For older sewers tree roots getting into the pipes are a big cause of problems, which might need action a couple of times a year.

Well if something goes wrong with the public system someone will want access to the manhole

Don’t bury the manhole or cover it with paving. You don’t want to delay things if there is a blocked pipe which affect you.

When you plan your house It’s going to be easier if you can give access to the manhole without workmen going through the house, or garage. If not you might have to take some time off work.


Also see Easements