Friday, June 1, 2012

AIRTIGHTNESS

Previous posts on the elements that form the building envelope, have shown Intello humidity variable airtightness membranes.  The management of the membrane has needed to be considered to position it in the correct place on the inner face of the construction.  Once the insulation is all in place, the membrane is taped sealing all joins. Once complete, the building is closed up and a blower-door test is undertaken to ensure the building meets the criteria for airtightness required by Passivehouse standards.  Note that all services the penetrate the membrane are taped to ensure airtightness.


















The blower door

Previous blower door tests have not quite met the requires air change per hour (ac/h) required to meet the  minimum Passive House standard of 0.6ac/h, so a few  adjustments are made to address the building envelope.  Additional blower tests are done until this is achieved.
A ply panel with seals for the blower fan is fitted into the internal garage door that provides direct access to the house entry foyer .


Fitting of the panel for the blower door can be seen in the garage.



The fan unit

3 comments:

squashplayer said...

I see you are using steel battens to create a service cavity and that the screws fixing these are sealed where they have punctured the Intello. Is it possible to use timber battens instead? or would you only recommend your method?

PH1NZ said...

It was planned to use timber battens, however Winstone Wallboards (the supplier of GIB® plasterboard) did not recommend using horizontal battens with horizontally fixed board. The board is fixed horizontally to maximise sheet lengths, and reduce the number of joints that need to be plastered.

The timber battens could have been used vertically, but this would have created potential thermal bridges where they lined up with the studs, typically at the edge of the walls, and at the top and bottom against the top/bottom plates. An alternative solution could have been to cut the vertical timber batten slightly and replace it with a polystyrene packer as support behind the plasterboard, and also move the battens from corners and replace with polystyrene battens.

However, as GIB® Rondo was being used on the ceilings, the decision was made to use GIB® Rondo on the walls also. They can be levelled with lasers and create a very flat finish. The added benefit is that they also create a minimal thermal bridge, being only as large as the thickness of the metal screw.
Thanks for your question.

Elrond said...

Interesting, thanks for sharing so much detail of progress!

Fiddly detail around the rondo fixings to get them airtight, and loads of them!

We minimise the potential thermal bridges through studwork by using engineered I-beams for studs (Masonite beams or Steico Joists etc) and having another layer of insulation wrapping around the outside of the studs in some cases. We then use timber battens to create the service void on the inside.

I assume the membrane in continuous behind the partitions in the 3rd and 4th photos?

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