So just a quick update… at the end ofour second week on site week we have managed to get the wall knocked out and the steel inserted to open up the dining and kitchen area – carefully insulated at the end of the beam to avoid cold bridging. This is to stop the beam creating a cold point running through the central living area of the house.
A cold bridge, or more usually referred to as a thermal bridge is (defined by Greenspec and quoted here):
A thermally conductive material which penetrates or bypasses an insulation system; such as a wall tie, metal fastener, concrete beam, slab or column. Thermal bridging lowers the overall thermal insulation of the structure by creating areas where heat loss is greater in one area than it is for another. The effect is to reduce the overall u-value of the construction element. The heat loss per unit length of thermal bridge is known as the Ψ-(psi) value and is measure in W/mK.
This week we have also formed the doorway in the first floor which will provide bedroom 3 with an en-suite, stripped all the coving from the ceilings (and the ‘snots’ of plaster dabs). Whoever decorated the house originally did a thoroughly professional job and our decorator Gary has developed biceps of iron from stripping the wallpaper this week. As we joke on site, at least working for BGH saves on gym memberships!
Along with all of this we have been lifting floorboards to investigate the sleeper walls and devising a smart cost effective way of insulating under the floor – more about that in a later post.
In addition we have cut back the ceilings on the ground floor to investigate how the joists penetrate the inner leaf of the cavity wall. In order to properly deal with the airtightness of the building. To borrow again from Greenspec (who we highly recommend for a source of info):
Essential to the energy performance of a building, the airtightness layer is the method by which the flow of air through the building structure is controlled. The layer represents an unbroken / un-penetrated envelope encompassing the interior of the building which prevents warm air ‘leaking’ to the exterior. In timber frame buildings the airtightness layer usually comprises of a membrane integrated into the structural element (located more often on the ‘warm’ side of the insulation), whereas in masonry construction plaster usually acts as an effective barrier.
So – in the case of this property we are looking at using the wet plaster layer as our airtightness barrier, but we need to think about these joist ends, the services that penetrate this layer etc. So I am currently discussing some of these options with the real experts in this field – Ecological Building Systems.
Once we have the final solution worked out I’ll tell you all about it.
We have also been Freegling the last of the carcasses from the kitchen, the bath and taps, sinks etc. Once again a bit shout out to Cat at Freegle who is also working on the Waste House at Brighton University – http://arts.brighton.ac.uk/business-and-community/the-house-that-kevin-built a fantastic project to build an entire house (expect for windows, doors and solar PV) out of waste.
And the final day of the week really added some additional excitement with the falling snow adding some complications, over and above the simple problem of keeping warm on the site (just keep moving lads… that’ll warm you up!) it also meant we had a minor crisis with our skip lorry provider. The fantastic driver from Rabbit Skips managed to avoid taking out the wall even when the back end of the truck was sliding all over the place. There were a few deep breaths taken let me tell you!