Now the actual build is underway this sixth blog is a bit of an update on the work completed so far.
The ‘Thermally Broken Slab’ of our Passive House has been poured……. and we were lucky to get a break from the rain!!!
Background to Blog:
It’s not every day you get to design and build your own home! We are in the process of building an ‘eHaus’ certified passive house.
Even as building company owners we go through the same thought processes and have similar desires, fears and constraints to everyone else when it comes to our new home.
This series of blogs is all about our own build journey!…………What we have learnt, what worked well and how we worked through any hurdles that arose. We will experience similar situations to our clients and maybe by following our journey you may learn something, or perhaps feel more relaxed, or confident, about the build process, or at least have a laugh!
Our house was designed with a ‘Rib Raft’ insulated foundation system. Now, I am not the builder in the family so I just needed to know that it was designed to insulate the house and also remove any thermal bridges where heat may be lost or cold transferred inside. How did we know this would work? Well, the science, experience and successful applications elsewhere go some way to assuring all of us that these systems work, but additionally the design of the house as a whole was tested with the PHPP package and information such as the foundation details were inputted to demonstrate the house designed would perform at a certain performance level. In our case, that of an internationally recognized passive house . If we changed the figures to reduce the levels of insulation, or add thermal bridges, the results would show lower performance levels as a result of the energy transfer.
After excavation the usual hardfill and sand were laid first followed by the insulation layer, in this case 150mm of EPS high density expanded polystyrene sheets.
Around the perimeter of the excavated slab area 50mm layer of XPS was used for slab ‘edge’ insulation.
This in simple terms creates a blanket of insulation around the homes building envelope, and assists to reduce thermal bridges. In this case as the garage is not part of the thermal envelope the edge insulation went along the internal garage wall. This was not an issue to achieve as the garage floor is 150mm lower than the rest of the house. Note: an airtight door will provide internal access to the garage whilst minimizing the air transfer between the two.
As discussed in our previous blog, certain things had to be allowed for in the slab pour. Some of these were detailed on the plans, such as allowing a rebate for the garage door, but other things required decisions to be made to ensure we got what we wanted, particularly as our house was all one level, and therefore the floors were the slab.
This included locations of plumbing hardware and any items requiring drainage. Our MHRV , for example, could have been located anywhere in our large storage cupboard so we agreed on its exact location in relation to what else we wanted to locate within that cupboard, and provide adequate access to everything (i.e. linen and storage shelving).
It was fortunate we had draft kitchen and laundry plans as these had changed from the working drawings. The kitchen was only minor adjustments, but the laundry had a more significant change. As the laundry was inside the garage which was outside of the airtight envelope, and therefore outside of the MHRV operating area, we needed it to be vented outside, so we moved our laundry area closer to the outside wall.
We also wanted a channel drain for our ensuite tiled shower – this rebate for the drain was allowed for in the slab pour, as opposed to a standard central drain.
Once the insulation, pre-plumb, mesh and other prep work was finished the concrete could be poured….and what a joyous day that was!!
Well, mainly for the fact it didn’t rain!! In fact, we had a really hot day and measures had to be taken to stop it going off too quickly!!
What’s next??……..well a lot of timber has already arrived ready for our panel assembly, and a rather large xmas present is about to arrive on our shores!! Two containers of our Formance SIPs panels are due at our ‘transitional facility’,which is also our indoor panel assembly plant, on the 7th January……..’happy xmas to us’!!!!