Airtightness - A Breeze for Commins Builders

Builder, Joe Commins thought “he had a very big mountain to climb” when told that the 35 house development he was working on in Oldtown for Fingal County Council was to be based on renewable and sustainable energy and needed to achieve exceptional airtight standards to improve energy efficiency.

That was at the turn of the year. Ten months down the line Joe has scaled the mountain a few times and is now a leading light on airtight buildings, regularly showing groups of architects and councils around the exemplar site.

Joe and his team are achieving an average air permeability rate on the houses of 0.5 m3/h/m2 at 50 pascals. Considering that the upper limit for Building Regulations is 10 m3/h/m2 at 50 pascals and Passive House requirement is not more than 1.0 m3/h/m2 at 50 pascals that’s something to shout about and has instilled a great sense of pride for the Commins Building team. Fingal County Council, itself at the forefront of energy efficient housing had specified an air permeability rate of 3.0 m3/h/m2 at 50 pascals, so they were delighted with these results.

Here, Joe describes the process of building such energy efficient homes.

“The houses being built for Fingal County Council are a mixture of 98 square metre three bedroom houses and 76 square metre two-bed bungalows. The timber frame system was developed by Keenan Timber Frame and is part of their Future Frame and Future Frame Plus System. Basically the semi-closed timber frame panels are made air tight in the factory, using the Pro Clima range of Intelligent airtight membranes and tapes, in this case Intello Plus and Uni Tape supplied by Ecological Building Systems in County Meath. This ensures an exceptionally high standard of airtightness before it even arrives on site! “

Once on site, Joe and his team quickly had to come up to speed on airtightness with advice from Keenan Timber Frame and Ecological Building Systems. The workmanship on site ensured such a successful result with detailing and sealing to the highest level.

Joe reported; “We ensured all the overlaps on the Intello Plus were sealed with Uni Tape. The windows and doors can be a difficult area to seal, but with Tescon Profil tape, which is designed to fit around awkward corners and edges it proved much easier. The connections from the external walls to the ground floor are also an important area and Orcon F non-aging adhesive was used to bond the membrane to the floor.”

Joe commented; “Achieving airtightness is all about thinking two steps ahead all the time, ensuring that you have a continuous seal to minimise any damage to the Intello Plus membrane and that’s why a service area in the stud is essential. We use airtight grommets to seal service areas or ensure that they are taped.

The best way to show the whole team on site the effects of any air leakage is a device called a Pro Clima Wincon, which Keenan Timber Frame have invested in, again supplied by Ecological. It basically acts as a tool for checking the workmanship as we go along, it is fitted in exactly the same way as a blower door test and generates a negative pressure on the building enabling us to see where air is leaking, we could then seal the leaks, we then have total confidence that the building is airtight before the blower test is performed.”

As well as being airtight, the houses are well insulated, feature renewable energy systems, with air-solar collectors that link into a heat recovery ventilation and solar hot water system.