Energy Matters Forums

[tparkinson]

I am currently building what commenced as a strawbale house extension but after realising the exorbitant cost of construction of straw bale walls I have changed my mind. I now plan to use reverse brick veneer which will halve the cost. Can anyone provide construction details of this method especially how insulation is placed in the cavity between the timber frame and the internal brick?

Cheers Parkin

[moemoke]

I was hoping some one with more knowledge than me would answer but I'll give it a go.

This is a great building method as you are using the bricks as a thermal mass inside the building
and not just a veneer which does nothing for the buildings sustainability.

I would think that you'd build the stud frame then put up a layer of foil wrap on the outside
of the frame then fill the cavity with insul batts then put up another layer of foil on the inside
then build up the brickwork with ties back to the studwork.

Are you building on a slab or strip footings/ timber floor?

I'm a draftsman for strutural engineers and we had a client wanted to use a new product called
'Green Energy Bricks". they have and R rating of 8.0 and are fire proof, look good and look like
they might be easy to install. Their web site http://www.greenenergybricks.com.au/
I dont know what they cost but they do seem good.

[jdaley]

Use of wool bats and then Corrugated iron horizontally is a great way to do reverse brick, the iron gives fantastic rain proofing, it cools quickly at night, the batts prvide insulation and if you provide a breathing space as well, air can move behind the iron to keep it cooler in summer with no difference in winter.

[Tracker]

I like all the suggestions.. The Horizontal Corrugated Iron (CI) is know to have an additional benefit, ie. that of shading.. I saw a research article showing a decrease in inner temp through the use of the corrugated iron.

Imagine the insulation achievable from Iron over foil, + Bats between the studs etc. + more foil, and then the use of HEBEL AAC Wall-Panels on the inside.

http://sawallsystems.com.au/products/powerpanel.php

If a more modern look was wanted , then replace the CI with blue-sheet and then render it.

The advantage of the Hebel would be a smoother surface for finishing.. A material that is more-easily worked (holes for power points etc---- Cables chased into the surface and re-finished).. A material with an insulation rating of R8 - (I think)

The only detraction would be it's low thermal mass, but I suspect that the Insulation factor would be better than the low thermal mass .

Using the outer stud-wall would mean that you could incorporate power cables in all walls, like I do when building.. ie. every wall has a power cable "Looped" at hammer-head-height through holes in each vertical timber. ADD - a new GPO whenever or where ever you want it.
Even with the Hebel inner wall, you could easily cut a GPO hole and reach in to grab the Power-Cable.

[jdaley]

Thermal mass could be created by the use of mudbrick interior walls.

[Luderick]

Just a couple comments regarding the reverse brick vaneer

This system is particually suitable to climates that experience a high diurnal range (day/night) when combined with a well insulated external skin.

The high thermal mass of the internal brick absorbs the energy and stabilises the internal conditions.

The design options are numerous and quite complex, computer modelling is useful to show the effects.

it needs to be combined with:
effective night purge
well insulated external skin
good thermal passive design
low infiltration rates
etc

the link below is to a highly recommended manual


http://www.yourhome.gov.au/technical/fs49.html

peter

[Luderick]

sorry i failed to mention

that Hebel should not really be considered for use as a high mass approach as it's density is about 1/3 of single skin brick and is really a low mass material

peter

[Cherokee Solar]

Hi! I don't remember seeing where you are located as this would affect your choice of using a reverse brick veneer for it's thermal mass properties.

For a cool area, this is an excellent idea. I used to live in a house in North Fitzroy in Melbourne which had double and single brick walls inside the house. The house temperature was always the average temperature of the area and rarely changed. It ranged between 12 degrees in winter and 26 in summer (absolute maximum and minimmums). On hot days I miss that house! The internal bricks acted as a thermal battery - the sun never had a chance of rapidly altering their temperature. It must not be forgotten that bricks readily transfer and store heat - they are great conducters.

The reverse brick veneer would work as follows (a drawing would be better) from inside wall to outside wall:

Plaster either solid or sheet plaster (or you could paint the brick work directly)
Single skin brick wall
Brick cavity ties (brick walls move around a lot if unsupported. The timber walls do all of the structural work in a brick veneer house. The cavity ties provide for a 50mm gap between the brickwork and the timber frame. They are embedded in the mortar between the bricks and then nailed to the timber frame)
Timber frame (the insulation sits in this - a single 90mm timber wall can get at best R2.0 rating insulation - bricks are worse as I think they are R1.0)
Cladding (this can be all sorts of materials from timber weatherboards, corrugated iron / zinc alume / colourbond, fibro cement, or a combination of wet area plaster and fibro cement)

If you live in a hot area, I wouldn't recommend this as you will turn your house into an oven and it will never cool down. If you live in a cool area, it's an awesome idea. Good luck!

[Luderick]

Hi
Cherokee - I agree with most of what you have said - however - for the thermal mass to work it needs to be exposed to the space you can NOT cover it with plaster

and also as far as the thermal transfer (R value) goes it is possible to achieve about R=4.0 for the composite
wall, if i new how to post a sketch I would

peter

[SaraHill]

We live in Bendigo and are thinking about an energy efficient / low embodied energy extension - The only space we have means it will have a large west facing wall (no windows) - what would you recommend for our climate? - I like the idea of zinc alum on the outside with well insulated cavity - is it useful to have thermal mass on a west wall internally in a climate with hot summers? What is the R values for the hebel product mentioned? - I had a quick look and couldn't it. I also wondered about shading the wall with retractable shade cloth that we raise after the autumn equinox(it will be within a metre of our boundary fence)
Sara