The I-joists, supplied by authorised Boise Cascade distributor A-Frame, were used to build Stephen Young’s four-bedroom house on a sloping Greenfield site in County Louth.
“The idea behind this project was to achieve Passivhaus performance but with a slimmer than normal depth of construction; and the Boise engineered timber joists, in combination with recycled cellulose insulation, allowed us to do this quite easily,” said Mr Young.
The project, currently being assessed to the Passivhaus standard, achieves U-values down as low as 0.12W/m²K.
Mr Young, who owns a design and build company, is already planning to use the same construction for a three-classroom school development in Dublin.
Externally the 200m² building contrasts cedar cladding with a through-coloured render system beneath a shallow slate roof. Stepped over three levels due to the sloping site, it relies on a heat recovery ventilation system, plus a wood burner in the living room for its space heating.
Internally, walls are lined with Fermacell boards over a batten cavity and a Siga breather membrane. Then, externally, Siga wind tightness tapes were used to seal the breather membrane to achieve an excellent airtightness figure of just 1.85m³/hr/m².
