Q: I’m looking at cladding an old brick two-storey house in a way that it will work with a new extension. I’m looking for a product or system that will reduce heat and noise. Can you advise the available options, including budget?
A: The first consideration should be how much of the existing building is to remain and why would you not make the new work consistent with the old?
Double brick is a high embodied energy construction system that can yield high thermal efficiency and is worth maintaining, if possible. Cladding over the brickwork will not provide cost effective thermal or acoustic benefit, whereas insulating the cavity will.
Foam or granulated rockwool injec tion systems have proven track records in this field. For instance, Icynene is a fast expanding foam injected as a liquid which does not allow moisture to cross the cavity and adds significant R-values, thus effectively releasing the internal skin of brickwork to be the servant of internal temperature regulation, rather than the slave of external temperatures.
However, if there is little of the original building remaining and budget prevents the new work from being built as insulated cavity brick, the next question should be, is the new work too big? Can the size be reduced to allow the quality to increase? If this is not practical — and it usually is — then the new cladding system might be best specified as an EIFS (rendered foam) system, of which there are several competitive systems on the market. The rendered finish can then be extended to cover the old brickwork and produce a consistent result.
Either way, the existing cavity should be insulated — it just makes so much sense (refer to previous articles in BPN on the benefits of insulated cavity brick construction in southern Australian climate zones).
Dick Clarke is principal of Envirotecture, which provides design and consulting services. He is an accredited building designer with 30 years experience, focusing exclusively on ecologically sustainable and culturally appropriate buildings. Clarke is director of sustainability and past president of the Building Designers Association of NSW.
