Building a flame zone house in West Pymble on a steep site

Good luck with it, looks like a nice floor plan. Savage block of land though

imagne the boon to future business!

The journey to date:


I just wanted to give a bit of background as to how we picked up this job and the challenges we have faced to date.

Before COVID kicked in, I was building my home which is directly across the road, our driveways literally line up.

An older couple owned the home and had decided to relocate to the southern highlands so they put the house up for sale, but had no interest due to the nature of the site. So they leased the house out.

There is a really nice walking path that runs behind the property and during the COVID walks we spent a fair amount of time down in the bush taking walks. There was no rear fence so you could see directly into the yard.

I really enjoy building on challenging sites, so my designer and building brain would kick in thinking about the cool things I could do.

Then in March 2021, the house was put back on the market.

I came home one Wednesday which happened to be right in the middle of an open house. I thought why not, let me shoot my shot, so I went to the open and started talking to the agent about my ideas and then I started mingling with buyers telling them how building on this site wasn't as hard as it might seem.

One buyer was super keen but didn't make the auction as their finance wasn't in place.

The house sold, didn't think too much more about it and then out of the blue I get a call from the buyer. Apparently they had spoke to a number of builders who weren't interested and then the agent passed on my number to them.

It turns out that I have heaps in common with my new neighbours and we became fast friends. We live in a really tight nit community where most people know each other, so this being my first build in my own neighbourhood adds a certain level of pressure!

Like yesterday was the first day of demolition and in the afternoon a street party with around 20 people broke out, with beer, champagne and chips and everyone asking questions. There is definitely no where to hide!

Anyhow, the clients have been fabulous taking on my ideas to make the most of their site.

We started the design process in late 2021 and then lodged the DA in early 2022.

The DA took approximately 16 months.

Ku-ring-gai council are extremely slow, their planners only seem to work on DAs 2 days per week, and being a flame zone site there are a lot of referrals needed.

They also have an extremely pedantic landscape person who constantly wants the most minor changes and then every time a landscape plan is changed it all needs to go back to to the RFS for approval.

The other main challenge that held us up and which required a major redesign to the first floor was the right hand side neighbour who complained about some overshadowing to his rear patio. But overall I think this forced us to improve the outcome.

We also had to shift the pool from the RHS to the LHS.

For those of you who are thinking of doing an FZ build in Ku-ring-gai, here are a list of the items that they will not budge on with your design:

1. Colour - They want earthy tones to blend with the bush. No whites or dark colours
2. Articulation to side walls - they won't allow a wall which doesn't have articulation if it is over 8m in length
3. Landscaping - I still don't understand their landscaping requirements as it really seems to change from site to site. On some they want lots of grass, but I am working on one in Lindfield which they are now complaining has too much grass and they want more rocks. So just be prepared to roll with their comments.
4. Tree protection zones - we have had to cover 200m of yard with 100mm of mulch to protect tree roots, and designing stormwater around tree roots has been a challenge
5. Ecology - Even though the house backs onto bush with a million trees, and we are removing only 4 small trees, we have had to research the microbat and possum population and then install nest boxes in the trees to create a new home for them.
6. The height of the pool out of the ground - I really wanted to do an infinity pool but council didn't agree, so we had to lower the height and dig further into the rock shelf. An infinity pool overlooking the bush valley would have been nice.


I have attached some photos of the site pre demolition to show some context.

Cheers

Simeon A drone shot showing the area we had to mulch to protect tree rootsLike  ⋅  Add a comment  ⋅  Pin to Ideaboard  ⋅  Share
 Rear of the existing house pre demoYou can see the rock shelf in the foreground under the rubbishLike  ⋅  Add a comment  ⋅  Pin to Ideaboard  ⋅  Share

It's a shame that you're based in Sydney. I would be extremely interested in working with a builder that has your level of engagement with the community. It's very clear that you're passionate about building and thanks for sharing your knowledge with everyone.

I agree with Showatt,
I wish you could build in Canberra. Thanks for taking out time to share the pics for your other house last week.

Most of the builders would not even entertain you if you are not thinking of building in their zones.

Much appreciated.

Today's topic is stormwater:

When we design a house or a duplex, often one of the more complex issues we need to deal with is how to handle stormwater. Especially when site falls away from the street to the rear.

Most councils in Sydney require some type of onsite detention otherwise known as OSD.

Essentially OSD is a method to retain a portion of the stormwater onsite in big downpours so that the council stormwater system is not overloaded.

In it's simplest form, an OSD system has a tank or pit in which the roof and yard drainage system discharges into via either 100mm or 150mm diameter pipes and then slowly releases via a 50mm pipe, and in doing so, slows down the flow.

Traditionally, the lazy and most expensive way to do this is to build an underground tank, out of concrete or blocks. Depending on the engineers calculations and site conditions these are typically between 10,000 to 20,000 litres and building them this way can cost $30,000 plus.


In my opinion this can be the lazy method as it doesn't require a lot of thinking and creativity on the part of the engineer and builder. It is just easy to pass this cost onto the homeowner.

Although, sometimes building an underground tank is the only solution, however this is rare.

Over the years, with our engineers we have come up with a variety of solutions which cost a fraction of the cost and we are able to pass the savings onto our customers. In fact, over the last 5 years I have only had to construct one underground tank.

For this project, the solution we have used are two 5000L above ground tanks which work as a combination of retention and detention ( detention being for use in the home) which then release the water into an underground absorption trench system in the rear yard.

For this system our clients wont be charged any additional money.

I have attached are the stormwater plans so you can see how it works.

If anyone has any questions let me know

Cheers

Simeon West Pymble Stormwater designLike  ⋅  Add a comment  ⋅  Pin to Ideaboard  ⋅  Share

The sewer encasement went well today.

Basically what they do is locate the old clay pipes, remove them and replace them with PVC.

An inspector then comes and approves, then they are covered with 150mm of concrete.

Pretty basic and very expensive process. Attached are some photos which I hope explain the process

Our pool is close to the sewer so we need a inspection of the pool formwork prior to pouring that as well.

Have a great weekend and as always, if you have any questions ask away.

Simeon Just a photo of the vacant site following demoLike  ⋅  Add a comment  ⋅  Pin to Ideaboard  ⋅  Share

 Locating the old sewer at the rearLike  ⋅  Add a comment  ⋅  Pin to Ideaboard  ⋅  Share

 Old clay sewer at boundaryThey have cut the old sewer at the boundary ready for the new PVC connection
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 New PVC sewerSo where needed the old clay sewer is replacedLike  ⋅  Add a comment  ⋅  Pin to Ideaboard  ⋅  Share
 LHS Clay pipesThese pipes already have a PVC liner so will remainLike  ⋅  Add a comment  ⋅  Pin to Ideaboard  ⋅  Share

 Old pipes covered in 150mm of concreteThis will be covered over with soilLike  ⋅  Add a comment  ⋅  Pin to Ideaboard  ⋅  Share

Hi Everyone

Just a quick update from site.

Last week we installed the absorption trenches for the stormwater and this week we are excavating the pool.

As you can see from the photo we hit solid sandstone pretty quickly. This photo was taken after one day, so I am expecting 3-4 days of jackhammering to get all the stone out.

We are paying around $2000 a day for the machine, operator and jackhammer and then I think $600 per truck to remove the material from site. So we will hit $10,000 pretty easily.

Then next week we can start forming the pool and installing all the pool plumbing.

Cheers

Simeon


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Hi Showatt

Thank you for your really good question.

I will answer your question in two parts:

Part One Rock

In this case, due to the fact that there was a rock shelf protruding from the grass, we included a provisional sum of $12,000 for rock.

Rock is one of the hardest things to calculate the price of as a builder, as the quantity and strength is completely unknown until you are onsite with an excavator hitting it with a jackhammer.

We had another site recently with rock and the jackhammer hit it and it all fell apart, so the pool only took a day and half to excavate. This one is solid and will take 3-4 days.

Having a realistic provisional sum protects both the client and ourselves.

The client has the ability to budget for it, and also under the provisional sum provisions of our contract, they also have the ability to come to site and observe the work being undertaken.

On other sites where rock is not obvious, we will exclude it from the contract with a simple hourly rate if we hit rock, then we notify our clients immediately from site.

We run Whatsapp groups with our clients so if work is underway they will all get multiple updates during the day like videos and photos from site, and we have a really good back and forth dialogue.

So if we do hit an issue, everyone knows about it.



Part Two Site Costs

For people new to building, the cost of building the same home on two different blocks of land can vary greatly due to unique factors or site characteristics, such as:

1. Location - are you on a busy road which needs traffic control ( we have one site on Pittwater road in North Ryde and for every delivery we have to get a Police and Council permit, traffic controllers and close down a lane) It adds up

2. Trees - are there trees to come down, do we need to protect trees, do we need to install next boxes in trees for microbats and possums to live in, do we need a project arborist to monitor the trees during the build etc

3. Sewer - Do we need to encase a sewer, this involves the design work, fees and actual physical works

4. Geotechnical - Are there any land slippage issues. For instance Northern Beaches council has land slippage zones and you need to hire a geotechnical consultant to monitor excavation and sign off on the final build. This all adds costs

5. Soil Test results/slab type - ( FYI we don't do soil tests but I included this as other builders do) So typically your builder will do a soil test to determine the classification. My understanding of the soil type is that it relates in part to the amount of shrinkage that occurs when going through wet and dry cycles ie how much does it expand and contract, as well as tree roots and other factors that might impact the stability of the slab.

We assume every site is the worst rated type of site ( P) design to that and if we encounter anything additional while excavating and piering we get on the phone to the engineer and come up with a solution. We have to give a 6 year warranty on structure and we don't want to have to come back. We will, we just don't want to.


So to answer your question, sometimes these costs are hard to calculate before an approval ( mainly development approvals via Council rather than CDC) because we simply don't know what council will enforce in their conditions, so these costs need to sometimes be negotiated after a contract is in place.

On this particular build, the main costs that came up in the approval after contract signing were:

1. Ecological consultant
2. 4 x Nest boxes for bats and possums
3. A man to climb the trees to install the nest boxes - not cheap
4. Sewer encasement - Including design, inspection fees, works etc
5. The removal of 4 trees for an asset protection zone

All of these costs will add up to a touch over $20,000.

I hope this answers your question. Apologies if it was too long to read

If anyone has any questions about the individual costs of items feel free to ask. Totally open book on this one with the permission of my clients.

Cheers

Simeon