Background – why SIPs?
We are building a high performing energy efficient home for ourselves in Rangiora. It is designed and built using principals for a high performing energy efficient home which will allow a high level of indoor thermal comfort and air quality throughout the home year round, with minimal heating and cooling costs.
The major element is the building envelope – this has to be highly insulated, airtight and have no thermal bridges. The aim of this is to control all air movement in and out of the house through an MHRV, and avoid any uncontrolled air movement that allows, among other things, heat to escape, allergens in, and higher humidity (along with water diffusion).
Therefore, the very fabric of the structure is incredibly important. Structural Insulated Panels are ideal for this build type providing high levels of ‘even’ insulation that won’t sag over time, and, used in conjunction with correct joint taping provides an airtight envelope, plus, due to its high intrinsic strength thermal bridge free design is achieved more easily.
A lot has been happening on site:
The insulated floor slab, along with edge insulation was laid.
SIPs panels arrived direct to site in the container in early January. The 165mm wall, and 265mm roof panels were unloaded ready for assembly. The team had already prepared a lot of the timber work necessary for pre-assembly so the assembly process did not take long. Basically, pre-assembly is turning the blank panels into a state ready to take to site and crane into place the same day – this involves practices like cutting to size, cutting out holes for windows etc, adding timber top and bottom plates, and much more. This was all done at our indoor panel assembly plant.
The panels were then taken to site and craned into place that same day. The walls on our 260m2 house took only 6 hours to install. The garage is not part of the thermal envelope so we have a SIPs wall as the internal garage wall between the garage and main house. The remaining garage walls are traditional frame and truss. An airtight door will connect the garage and house and provide internal access.
The remaining internal framing and a couple steel beams were placed to support the roof in certain areas where we had large openings. These beams were built within the thermal envelope to avoid thermal bridging between the inside and outside.
Roof panels were then transported to site and craned into place the same day, again taking less than 6 hours so that we were able to take a walk around the house that afternoon to get a real feel for the inside spaces, and the light.
Triple glazed skylights are on site ready for install, building wrap has been completed and work is continuing in preparation for the coloursteel Dimond 5 rib – profile roof.
There will be a bit of a hiatus whilst we continue with clients jobs and await our windows to be delivered.
After a lot of consideration over the Xmas period we have now decided to opt for locally made triple glazed uPVC with Low E and Argon filled. The performance difference for what we were trying to achieve, compared with timber framed, was considered alongside the cost and logistics of overseas products, and our final decision was to go uPVC. The new APL extrusion also allows aluminium foils on the external face to match your cladding, as opposed to more limited colour options elsewhere. The pace of changes in the window industry has really ramped up with uPVC and timber options increasing all the time, a key indicator that the thermal bridging created by aluminium frames is now a key factor in home owners decisions.
OPEN DAY – Advanced Notice!!
Once the house is closed in and windows installed we will hold an open house, another opportunity for those interested in building their own energy efficient home utilising these principals for a high performing home, to come and see one first hand in its mid build state, before many of the differentiating factors are hidden by gib. Importantly, you can then feel the difference, even before the mechanical heat recovery ventilation system is installed.
Keep an eye on our Facebook page ‘Chatterton Builders’ for details of this upcoming event.
For more info on SIPs download our free guide here.