Parging to Passivhaus levels of airtightness

[Nick Grant]

Working on a project where contractor wants to use internal parging on blockwork to achieve airtightness then use plasterboard on dabs to cover cables without chasing.

Anyone got any definitive info on best products, practice, thickness etc given that we need to do better than 0.6 airchanges (not sure what permeability but will be tested flat by flat so party walls also to be airtight).

Currently thinking 8mm of gypsum based parge.

Thanks

Nick

[Anonymous]

Haven't tried the paint on stuff but it looks interesting

http://www.blockfiller.co.uk/#im

and quick!

[Nick Grant]

Thanks Peter

I'll check it out. Definitely want to avoid troweled on hand mixed sand cement.

'Too low to detect' obviously depends on how they tested!

Nick

[Mark Siddall]

Nick
Studies by Lecompte (dating from 1987) show that plastered walls achieve an air leakage of about 0.04 m3/m2@50pa (no plaster, but with pointed joints the walls leaked 1.2-20 m3/m2@50pa). The thickness of the plaster was not specified but I'm guessing that it was probably about 15mm. The problem with thinner plaster would probably be greater risk of cracking, particularly at corners and junctions.

Elite say that “The test was carried in accordance with BS EN 12114:2000 Thermal performance of buildings – Air permeability of building components and building elements.” I wonder what pressure is required? …and whether this was just for a simple area of wall. Which leads me to: How are interfaces with other materials achieved? How are corners and movement/drying out addressed? Do any of these factors impact upon long term performance? etc.

Mark

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