The base render, or slurry coat to the existing walls and extension walls has now commenced. As well as providing a smooth substrate for the external wall insulation, this render coat also serves as our primary air barrier, highighted in blue in the section below.
Working between sub-zero temperatures (before Christmas) and the rain, the rendering is still ongoing, but having done the front of the property, our house is starting to take on a different look…
The cavity wall insulation (CWI) has now gone in. Primarily, it will be the external wall insulation that will be providing the heat loss reduction and achieving our U-values of <0.14 W.m².K. However, in order for the external insulation to be effective, we need to fill the cavity as best as possible to minimise/eliminate air currents. Otherwise, warm air entering the cavity will rise out at the cavity head to atmosphere, bypassing the external wall insulation. The picture above right shows the insulation being injected above the ceiling line of the top floor (usually installations stop just above ceiling level). This is in order to reduce air currents all the way to the cavity head.
We have selected Platinum Ecobead as the CWI insulant. These are expanded polystyrene spheres that are injected at high pressure into the cavity – the manufacturer’s claim this totally fills the cavity, which is good. It is also blown with an adhesive, which means that the beads will stay in place, and not slump, when it dries. As we are replacing the windows and sills, a few days after the CWI installation, we get a unique opportunity to look inside the cavity to see how well the Ecobead has filled it. I am impressed!
Dear readers – this blog is now quite behind due to problems updating the wordpress blog software. I am pleased to say, as of today, that the problem has now been fixed. The blog will be updated during the course of this week – so much has happened (and much more yet to happen). Please check back soon and thanks for your patience!
Ian
