Project Size: 121sqm
Our first meeting with our clients on this project revealed the front of this property to receive basically all the wash off water coming off the hill in front, as well as from behind a retaining wall, due to this being the low spot, when getting heavy rain, the area proceeded to flood, come up over the front decking and into the weep holes of the house, of course flooding the inside.
Originally our client was asking for all falls away from the house with a box drain at one end running the entire length of the concrete, being around 22m in length, by the time we got enough falls on a box drain, the whole slab would have been completely lop sided. So instead, we decided on a plan for a “wash bay” area by installing pit drains throughout the center of the slab, creating high spots in between and running all the water to the middle of the slab to be taken away through plumbing.
Usually on something like this we would use 250mm pit drains which as considered standard, however, with our clients request, we decided to install 450mm pits and plumb them away with 150mm storm water instead of the typical 100mm storm water. Basically just leaving no room for error, making sure the job was over done so as to not have to do it again.
So upon starting the project, we took the machine out there to initially complete the excavation, getting all the ground levels down roughly to where they should be, followed by digging out the trenches for the plumbing installation. With all the pits installed and plumbed in, the skillful machine contractor we had onsite managed to negotiate the area with a 5t excavator giving everything a fairly even sub-grade as he went, while filling the trenches back in.
With the ground and plumbing works complete, we returned the next day to install the formwork, along with the SL82 steel reinforcing, 16mm re-entry bars at the internal corners and of course any other fitting required before pouring.
The pour for this one was quite simple really, we had spaced the pits out approximately 6m apart from each other and roughly 70mm down from the outside levels, so every 3m we would basically just create a level spot with the outside levels, then work around in a circle around the pits making sure it fell towards the pits from each 3m direction.
With the screeding done then the hard work really started.
We had to make some compromises on this one when it came down to our finishing, there were so many different aspects to consider that we gave it the “little bit of everything” approach.
Typically an area like this will work more effectively with saw cut control joints, but being that it was a colour through finish, and any cracking stands out like dogs balls in colour, tooled control joints were needed to be installed. This of course is usually not a problem, but given we were working with the house at our backs on one side and a retaining wall drop off on the other side, it got a bit tricky getting all the joints in, but we got there in the end.
With the finishing itself, colour always looks better with a smooth trowel finish, however it can be a bit slippery if we’re not careful with the finish not to polish the top. Given that it was an outdoor area that was primarily a drainage area that was to see a lot of water, we couldn’t go down this path, instead needing to give it a textured finish with enough grip so as no one will slip on it in the wet.
For this we have two options, either a broom or stipple finish, with the stipple not only giving a better texture, but also looking a bit neater than a broom, this option was of course chosen.
Now also take into consideration we had many storms around at the moment, and it was hot as hell with 14m.cub of coloured concrete on the ground from Hytec, that goes off like a bomb even in Winter, we certainly had our backs against the wall getting everything stippled out.
But we got there in the end, with everyone chipping in to chase the final 20sqm or so.
Overall this was an interesting project. One thing I love about the side of the industry I work in, is that every project seems a little different and has it’s own hurdles to overcome. Not only was drainage included in this one, but drainage this side is usually reserved for commercial carparks, and getting everything to not only look good, but work properly was a little bit of a challenge and in the end, mentally rewarding.
Quite literally the day after we poured, the rains finally came with around 100mm falling in a 24 hour period, with news of everything working as it should, we’re please to move on now to the next challenge.
Thank you as always to our client, your business is appreciated.