This week saw the second airtest at Grove Rd. The contractor had done a thorough job of sealing the draughts identified at the last test. However with a result of 2.8ach-1 (airchanges per hour) the airtest showed that the property still had some unwanted draughts. These draughts were identified as being at the base of the elevations and in the airtightness layer in the attic.

The base of the elevations will now be sealed with a parge coat to prevent draughts in this area. The airtight parge coat is a polymer-modified cement based leveling coat that is applied directly to the existing face of the external walls prior to the application of external insulation.

The airtightness layer in the attic at Grove Road is an OSB deck sealed with airtightness tape at the joints between the boards. At the eaves the airtightness layer is continued with the use of an airtight Intello membrane which is taped around the roof timbers and sealed to the parge coat on the exterior walls. There were a number of small perforations in this layer which the contractor will now seal. As mentioned in the previous post the aim is that these measures will improve the airtightness of the property to a level of one airchange an hour so that the property can reach the Enerphit Passivhaus standard. Please read more about the Enerphit standard at Passipedia the Passivhaus institute’s Passivhaus resource website:  http://passipedia.passiv.de/passipedia_en/certification/enerphit

The area to the base of the elevations due to have a cementitious airtight parge coat applied to it.

The airtightness layer in the attic. The OSB deck is sealed with airtightness tapes where the boards meet one another. The photo shows where the Intello membrane is taped to the OSB boards, externally the membrane returns down to meet the parge coat on the exterior walls. To increase insulation and to avoid interstitial condensation Kingspan boards have been inserted between the rafters at this point

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