Reverse Brick Veneer

The Australian Bureau of Statistics (ABS) notes that brick veneer in 2008 accounted for 45 per cent of outside wall materials used in Australian dwellings. Double brick was the next most common at 24 per cent.

In 1994, 65 per cent of dwellings had walls of either brick or brick veneer. For the same period, the ABS also observed households with air-conditioning or evaporative cooling had grown from 32 per cent to 67 per cent.

This latter aspect of contemporary housing raises the blood pressure of Glenn Marcus, possibly our most renown residential architect. He says: “It is just absolutely appalling that evidently up to 50 per cent of housing now in NSW is air-conditioned. That is an indictment on our abilities to design buildings appropriate to our place, our climate, our technology and our time.

“The problem we have mostly is the buildings we’re putting up are totally inappropriate. From Darwin to Melbourne to Western Australia, it’s a disease … They’ve all got to have air-conditioning because they’re built the wrong way around.”

Murcutt says the mass of material ought to be on the inside and the lightweight material on the outside so there is good insulation between the two, “so the outside takes up the thermal lag [and] the inside takes the response of all the internal factors so that you keep the hot sun out from the mass inside … so that in the summertime it’s beautifully cool inside.”

If we were to take Murcutt’s lead and turn our housing construction the ‘right way around’, we would get what is known as reverse brick veneer (RBV). The highly awarded and acclaimed Your Home Technical Manual has this to say on the sub ject: “Despite its popularity in the mainstream marketplace, conventional brick veneer is not an ideal construction system for climate responsive design. On the other hand, reverse brick veneer, in which the brickwork is the inside skin of an otherwise conventional stud framed construction, takes advantage of the thermal mass properties of clay brickwork and can result in high performing buildings with lower than average energy demands for both heating and cooling.”

With RBV, the outside of the well insulated wall frame is clad in the likes of timber weatherboard or sheets of iron or fibre cement. RBV’s internal brick walls act as a heat battery. Positioned in rooms with a northerly aspect, they absorb daytime winter sun, slowly releasing that stored energy inside the house at night where it is contained within the insulated shell. They also better hold the warmth of any internal heating source.

Steve King, former associate direc tor of the Centre for Sustainable Built Environments (CSBE) at the University of NSW has said “It’s really important to understand that it’s the internal thermal mass that does the work, not an external skin of brick. Internal thermal mass works to even out the temperatures. And it works best when you insulate it from the outside.”

Ross Maher, sustainability manager for Think Brick Australia, informs us it has been working with the University of Newcastle for the past 12 months to better understand the real world attributes of this form of construction. Although the university’s study results may not be released until the ninth Australasian Masonry Conference in February 2011, Maher did note that preliminary findings indicate that RBV has better thermal performance than traditional brick veneer, though not much different to insulated double brick.

Earlier research from the Faculty of Engineering & Built Environment at the University of Newcastle was presented in a 2007 paper entitled Effect of thermal mass on the thermal performance of various Australian resi dential constructions systems, where researchers remarked that “Overall, from this study it can be concluded that RBV provides the least amount of energy consumption in all cases.”

When James Hardie commissioned computer modelling of various wall constructions, it found that reverse mass was the wall system that most achieved 5 stars under AccuRate modelling in all climate zones and some orientations.

The Insulation Council of Australia and New Zealand (ICANZ) has recorded the thermal performance or R-value for a RBV external wall as higher than respective clay masonry veneer walls. However, research collated by Think Brick Australia, and separate ly by the Forest and Wood Products Research & Development Corporation, suggests that R-values for RBV are near identical to that of standard brick veneer.

Whilst insulation isolates the brick from external heat variations, RBV’s improved performance comes foremost from its thermal mass, as the Australian Bureau of Meteorology (BOM) observes. “Brick veneer walls do not store heat inside the house, as the bricks are on the external leaf of the walls and do not interact with the internal environment. Reverse brick veneer, with the bricks on the inside and a light insulated shell (eg. fibro-cement sheeting) on the outside, is a much better option.”

Why then, with green architecture advocates across the country lauding it, is RBV not so widespread? Whilst the design profession might be getting up to speed, their building trade brethren may not.

We enquired of George Dragovic, head teacher of bricklaying with TAFE NSW (Illawarra), if brickies were learning how to construct RBV.

“No, I’ve never seen that,” Dragovic says, who with 40 years in the building industry, including 30 years for the ter tiary and further education system, was excited that there might still be more to learn. And to teach.

Maher says that changing building practices is hard enough, but there are also a lot of staunchly held views out there amongst consumers too. “The market wants face brick. They like the look. They grew up in a brick house. It gives them a sense of security, it can’t be cut with a hacksaw like some other products and won’t dent or damage. There’s no maintenance.”

Maher also posits that external cladding is generally more expensive than internal plasterboard, though he was at pains to advise that housing design needs to be separated from construction materials and that good design can save lesser materials, where as sound materials choice is unlikely to compensate for poor design decisions.

Others we spoke with cited brick veneer’s external fire resistance as another possible hurdle.

Regardless of the construction materials employed, Maher observes it’s really up to tenants “to drive the house properly”, which is a view also held by Murcutt, who believes “You should be able to operate a building in a way like you operate a yacht”.

This is an aspect of passive solar design not often conveyed to home owners and tenants – that although design attributes like RBV may be pas sive, the inhabitants have to be active, adjusting ventilation and shading. Two businesses who think they can educate clients to ‘drive’ their houses have both won national green design awards. And the Ecobodes 8 star project housing design and Energy Architecture’s Next Yo4u’re Home design both employ RBV construction.

Might they point to a future where housing beauty is more than skin deep?

Source: BPN (Behind the facade: reverse brick veneer) 5 July 2010

http://www.bpn.com.au/features/bpn-reports/behind-the-fa-231-ade-reverse-brick-veneer

 

Reverse brick veneer

Reverse brick veneer on concrete slab

Reverse brick veneer puts the brickwork on the inside and timber framing on the outside i.e. the reverse of traditional construction. This form of construction enables a timber-style home to achieve the same level of thermal performance as a double-brick home.

By reversing the traditional construction type, the high thermal mass of brickwork can be used to great advantage.

Instead of being on the outside of the insulation and hence isolated from the room, the brick skin is within the insulation envelope.

Reverse brick veneer can be used in conjunction with either a concrete slab floor or a timber floor.

Reverse brick veneer with timber floor

Reverse brick veneer does not have to be used for the entire home – sometimes it is only used for north-facing rooms.

The external skin can be any type of lightweight cladding suitable for exterior use.

http://www.resourcesmart.vic.gov.au/sustainable_housing/thermal_mass_special_construction_types.html#

 

 

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