week 23: a sealed envelope

bi-folding doors installed

The last of the doors and windows are fitted to the extension area. The last of these units to be fitted was the bi-folding doors on the lower ground floor. With some of the scaffolding out of the way temporarily (to allow the balcony to be built), we are able to see what the house will look like.

More importantly, we are now able to start proper drying-out. A de-humidifier and a heater are now set-up and the space is now heated!

week 18: new window installation begins

Living room window removed  Bedroom window removed

At last, the new triple-glazed windows are being fitted. The old windows are removed, temporarily exposing the house to the elements. A timber frame surround is constructed around the structural opening as we are moving the new windows forward of the existing elevation. This is to allow them to be installed within the external insulation layer, thereby reducing thermal bridges.

Bedroom window fitting  window detail

The windows are fixed into the new surrounds and then taped to form the air seal using Tescon tape. The timber surround is taped to the masonry wall using Contega EXO tape and Orcon F sealant. However, because a lot of this work has happened in between wet and cold weather, adhesion has not been optimum. We have therefore taken the additional precaution of applying a second render base coat on top of the Contega tape.

week 17 and 18: extension roof progresses

vapour barrier being laid

The vapour control layer to the new extension roof is now laid. The roof will be a warm roof construction, so the insulation will sit on top of the vapour control, followed by the final waterproof membrane. Before that, the roof light kerbs are cut in. The studio space below the roof will need very good natural daylight and we can’t fit windows along the long (party) wall. So, we are fitting three large roof lights instead.

rooflight kerb

The kerbs are flat pack units from Velux. Whilst they are fine for accommodating the Velux window units, they are not as well insulated as I would have expected. We will need to review the abutment of the kerb with roof insulation to see how we can add/improve the performance.

week 14: windows and doors arrive


The new triple-glazed windows arrived this week. Made in Lithuania, the EcoContract windows, sourced via the Green Building Store, arrived in-tact. They are still mostly in their packaging, so have only really checked the colour match is correct. But they look good, really good. The bi-folding doors (top left photo) weighs some 400kg and we will need to dismantle this before we can move it into place – more to follow.

bathroom window wall (or sieve)

The toilet has come out, freeing up the remaining floor for re-boarding and the window wall for the rest of the re-plastering. Around the soil and vent pipe (shown) there were huge holes through the inner leaf brick wall, measuring approximately 350 x 150mm – a very significant air leakage path (sorry no photo). Bathrooms and kitchens are key culprit areas for air leakage, particularly over the years as trade plumber after trade plumber make alterations for new appliances, sanitaryware, etc. It is always worthwhile looking for air leakage paths and dealing with them before the new installation goes in. In this case, the hole was infilled with masonry and mortar and plastered over. Continue reading