The final work on the house was to seal up the chimney and to install mechanical extract fans into the kitchen.  Unfortunately neither of these small tasks proved simple!  The original plan was to insert a chimney balloon into the chimney to prevent draughts coming into the house.  However, in order to do this a cap needed to be put on the chimney to prevent things falling onto the balloon.  Although we still had the scaffolding up access to the chimney from the roof was impossible due to the position of the solar panels on the roof.  The solution we decided upon was to brick up the chimney and install a “hit and miss vent” to provide ventilation.

The layout of the kitchen was such that there was no room in the wall for the extract fan.  Usually in houses like ours the fan would be placed in the window.  However, breaking the seal on the glass to install a fan would have had a very detrimental impact on the air tightness of the house.  We therefore had to put the extract fan in the ceiling and run pipework to the outside.

We had wanted to use the pavatherm woodfibre board for the external wall insulation at the back of the house as well as internally.  However, we were unable to find a system (render + insulation +fixing) that was guaranteed.  Unfortunately we therefore decided to use a more tried and tested system using 70mm of PIR (poly isocyuranate) insulation with a coloured render. The external insulation went on without any problems and the rain stayed away until the render had been applied and dried.  We did have to extend the flue for the boiler so that it protruded from the external insulation.  The photo shows the finished render.

We are installing pavatherm woodfibre insulation on the internal walls at the front of the One Planet House.  This is a breathable system that will be finished with a lime plaster.  The lime plaster has a 7 day drying time and therefore to minimise disruption to the tenants we are internally insulating one room at a time.

A piece of the pavatherm board ready to be fixed and the interstitial sensor

A representative from Natural Building Technologies came to the property last week to show the contractor how to put up the woodfibre board and plaster it.

We have decided not to insulate all the way up to the joists of the intermediate floor.  When carrying out internal wall insulation, common sense suggests that we need to insulate all surfaces of external walls to ensure that we are minimising thermal bridges.

However, at this point there is also high susceptibility for uncontrolled air changes through the narrowed mortar joints. Research that Parity Projects have done with the EST and a variety of other contributors has shown that if these parts of the house are insulated, the risk of moisture build up is increased.   This risk is increased when using a breathable insulation system because moisture is able to travel freely through the wall.  As can be seen in the photo opposite, we are also putting interstitial sensors in the walls where there is insulation to measure the moisture of the wall over time.

The timber frame windows that we are using for the project were a significant hamper on our progress.

Their manufacture was delayed due to the snow, which meant that they were not delivered in time to go into the bathroom pod during manufacture.  Because the delivery of the bathroom pod could not be postponed (road closures were required in order to crane it into place), it was decided to leave the PVCu windows in the bathroom pod.  Replacing the windows on site with the timber ones would have led to some very high embodied energy windows and potentially a worse seal around the windows.

The saga didn’t end there.  When the windows arrived at site, five of the windows were not the right size and did not match the dimensions that had been sent to the manufacturer.  These have now been re-made and will arrive on site next week.

A solar thermal panel (sufficient to supply 60-70% of the household’s hot water demand) was installed on the south facing roof along with solar photovoltaic panels to produce electricity.  The output of these two technologies will be closely monitored.  A pyranometer is also being installed on the roof to monitor their output in comparison to the level of daylight.

So far only the the new kitchen has gone into the Decent Homes house.  Last week some of the new windows arrived.  However, 2 of the windows sent by the manufacturer were the wrong size and have been sent back.  The replacement windows will hopefully be arriving next week.  Meanwhile the electricians are hard at work with the rewiring.

The new bathroom pod in-situ still to be rendered

The new bathroom pod in-situ, which the resident is able to use while the other work goes on.  The bathroom pod will be rendered to match the render that will be put on top of the external wall insulation in a couple of weeks.

Work started on site for both the One Planet House and the Decent Homes house at the beginning of December.  However, the heavy snowfall in December led to significant delays for the windows and other deliveries.  In addition, more asbestos was found in the Kitchen at the One Planet House, we therefore had a further 2 week delay whilst the Health and Safety Executive were informed. The new kitchen has now been installed in the One Planet House and the Decent Homes house.

The bathroom pod is going into the One Planet House tomorrow and the re-wiring is also happening.  The new timber double glazed windows will be going in at both properties this week too.