Our Dream Renovation: 05 Strip footings and Piers

With everything all excavated we are now ready to start getting this build out of the ground. One of the most rewarding parts of any build. However, due to unfortunate bad weather, our first task at hand was to clean out the footings and pier holes. A submersible pump made the job a lot easier!

Getting the job out of the ground is a critical part of any build. You must start right to end right. Therefore, we took our time to double check the set out. Here are a few checks we did to guarantee we are right on where we needed to be:

• Check all stringlines are the correct measurement from the boundaries and each other.
• Measure all stringlines are parralell with each other and the boundary.
• Confirm stringlines are square to each other. To do this we used the 3-4-5 rule. Note: You can only check for square if the lines are level with each other. In my case they were, as each profile was set up level with a laser level.

Pier Holes

The pier holes specified were a nominated 400mm in diameter and 500mm deep. The diameter of the piers are a perfect size to fit a 230 x 230 brick pier. In some cases, where the piers will be higher then 1.2m, I increased the pier diameter to at least 450mm. I did this to accomodate a 350 x 350 brick pier base.

A 230 x 230 brick pier should not be built any higher then 1.2m. For example, some of my piers needed to be 1.7m high. To bridge the difference, I built a 350 x 350 pier base at least 500mm high. I then am able to continue the pier up as a 230 x 230 brick pier.

The set out of the piers was pretty straight forward. I set the holes out 50mm from the external walls. This was so the brick pier wasn’t sitting on the edge of the concrete, it also gave me a little more wiggle room. Each pier hole was spaced out to be no more then 1.2m away from each other. This is the maximum span of the bearers I am planning to use.

The Garage Slab

Compared to the pier holes, the garage slab footings were a lot more detailed in their construction. It was originally designed to be a suspened slab on bondek sheets, with a steel midspan beam supporting the weight. Although, unfortunately, in the design phase I had a little oversight with the R.L’s on our survey plans. Long story short, suspending a slab 400mm off the ground is a lot more costly and inefficient then other methods.

Considering we had plenty of good fill stored from the cut. As a result, it proved a lot more economical to fill and compact this soil under the slab. This way we lose the extra soil wenhad left over, win win! We made a quick call to our engineer to confirm our intentions and to get his input and approval.

The Strip Footings

Our first step was to build the reinforcement cages for the strip footings. I got a delivery of N12 deformed reinforcements bars, 2 different sized ligatures, to suit the specified footings, and started building them on site. Then, once built they could be placed into the strip footings. Lastly, the cages then had to be tied off to each other where each cage overlapped the next. I also checked that I had at least 30mm concrete cover around my reo bars, but 50mm was preferred.

The reinforcement was all now in place and we can now start forming up for concrete. The picture above shows the completed formwork ready for the concrete pour. The slope of the land was accomodated for by installing the formwork in intervals. These intervals are set out from each front corner to suit 230mm bricks and a 10mm perp. Thus, creating a neater brickwork finish by elimating any cutting of the bricks. 86mm was the set down for all the intervals. Generally, this set down suits a 76mm high brick and a 10mm bed joint. Taking the time to set it out this way will create a better finish and make the bricklayers job easier. Particulary, an easier job is a cheaper job.

We could now book in our PCA, private certifying authority. They confirmed everything was in place, as per the engineers specifaction and our plans. With the tick of approval, I did some calculations and then booked in the concrete truck and a line pump.

In the picture above, you can vaguely see how the brickwork has finished in conjunction to the strip footings. The set out worked a treat.

Strip Footings & Piers Stage Costs

Total Project Costs To Date

• (02) Designing and planning stage: $13, 428.20
• (03) Council application stage: $6,171.20
• (04) Excavation stage: $1,163.82
• (05) Strip Footings & Piers: $3,079.13
• Total costs: $23,842.34