Additional Fees

Typically most people only take on a house extension once in their lifetime and as result we have zero experience therefore you can't expect not to make mistakes especially when it comes to unforeseen costs.

I've never heard anyone taking on an extension for the first time talk about it coming on or under budget everyone seems to go over. "Allow for an additional 10% in your budget" I was told then when I took on this extension by the end I understood why. Below are some of main reasons why my budget blew out.

To review the complete additional fees report download here.

Materials

Its important to know your materials given in my case the contract didn't stipulate the exact type of concrete they were using for the floors or roof tiles for that matter. More often than not the builder had budgeted on the less expensive material which isn't the type you want.

In my case that happened with the concrete I paid extra along with the builders margin given they were both listed as a provisional cost furthermore the same with terracotta roof tiles they had only budgeted for concrete.

Provisional Costs

Items listed in your builders contract as provision costs can vary for example take the following from their scope of work:

Roof tiling

Supply and install new roof tiles to entire roof as required.
Supply and install new sarking to entire roof as required.
Supply and install new timber roof batons to entire roof as required.

In my case the builder included a provision cost for the roof tiles which they stipulated:

Roof tiles supply only $35/m2 x 160m2

Turns out terracotta roof tiles cost more than $35/m2 when compared to concrete therefore I had to pay extra plus builders margin.

Here is a complete list of other items listed in the contract under provisional cost items:

Homeowner's Warranty Insurance
Demolition
Windows Supply only quoted by B & W Windows
Electrical
Supply and install new Velux skylights
Wall and ceiling insulation
Terrace balustrade
Brick support 8000 @ $1.50 per brick
Concrete polishing 79 m2 @ $80/m2
Stormwater tank galvanised corrugated iron

Note

Having provisional costs in the contract makes sense for particular items however given the varying nature of these fees I would watch out for builders that have a large sum of the project listed as provisional sums. In fact you will probably find the bank would have an issue with this, given the varying nature of it, when it comes of securing a loan.

Variations

Variations are anything outside the original scope of work during the build which can be costly due to the unforeseeable costs, paperwork/approval, builders margin or simply undoing work that has already been done.

Here is a complete list of variations that I countered during the build:

Spoil (soil) removal from demolition
Tipping taking spoil to the tip
Structural steel beams for carport & dining area
Internal kitchen brick Wall
Internal rendering
Internal linings
Additional plumbing

Tip

My advice would be to make sure you understand the dimensions of your plans, materials and ensure that you are onsite always to consult with your builder to make sure you are on the track.

Builders Margin

At the end of the build when my builder tallied up the total variations and differences in provision sums they then apply the 15% builders margin on top.

The contract clearly stipulates:

Provisional sums and PC items have a 15% builder's margin to be added to the amount exceeding the nominated amount.

Tip

My advice would be know what is not included in the scope of work to avoid incurring percentage builders margin on top of your costs.

Unforeseen

I want to clearly list some of the unforeseen costs that I was either caught out or unaware of during the house extension:

Engineering: Engineering steel work for the stacking doors.
Concrete: Concrete cost of material for different concrete.
Roof tiles: Terracotta although I knew about this given he did have the m2 costs.
Additional Brickwork: Kitchen internal brick wall and the privacy wall. To be fair this was my doing.
Windows: Upgrading from domestic to commercial.
Retaining Wall: Retaining wall for council water regulations.
Electrical: Rewiring house only included for extension not existing.

Exclusions

List of the items that weren't covered in the proposal such:

Permits: Council foot crossing deposit, environment enforcement fee, soil/water management warning, long service levy.
Certifier: Surveyor, engineer or auditor onsite fees every time I need to get sign-off.
Spoil: The spoil or soil left over that needed to be carted away,
Floor sanding: Sanding the existing floorboards.
Landscaping: Excluded any landscaping, paving and fencing.
Joinery: I took it upon myself to handle the joinery in the bathroom (vanity), laundry and storage throughout in the dining and lounge room.
Bathroom & Laundry Fixtures: I supplied my own taps, toilets, bath .etc
Tiling: I sourced my own tiles for the bathroom and laundry.
Lighting: I sourced my own lighting for the house.
Painting: I handled the painting.

The exclusions with joinery, bathroom plus laundry fixtures, lighting, tiling .etc depending on the finishing these costs can add up and did with this house extension.

Tips

Items in your contract maybe loosely defined whether it be materials or scope address these with your builder before putting pen to paper to avoid additional fees.
I made sure I sourced my own lighting, fixtures, tiling and joinery purely because I wanted to make sure I got the best quality products I could afford and furthermore avoided the builder having to make design decisions when it comes to finishes.