The place for a light weight wall that can achieve over R4.0 is on the sunny perimeter. It is as simple as that.
‘ve always loved building, and at the same time have always considered it medieval in selection of material. Why are we still building with mud bricks and coating them with an earthen daub? Why is a pure masonry building still favoured by so many?
With the advent of more light weight options available to today’s builders and designers, earthen building products should be put in their place….as heat sinks, and as feature walls / floors that assist in regulating the ambient temperature without the input of power. The place for a light weight wall that can achieve over R4.0 is on the sunny perimeter. It is as simple as that.
I am a builder and a Quantity Surveyor,and over the years I have done the number crunching on many methods of composite construction. Sadly the reverse brick veneer tops the list in cost of affordable composite solutions. The good new is not by far! Why do they do it the wrong way around over East, and we next to never here? I think the answer is demand, and market awareness. We are fortunate enough to be building in a period of strong marketing and increasing public awareness of the merits of light weight construction, coupled with many innovations. It is for us to change with the times, and embrace a greener and smarter approach to construction.
Using a prefabricated timber structure substantially reduces construction times, and directly helps drop the costs of time based incidentals such as scaffold. There are also other hidden benefits such as a decreased pressure on Building Indemnity Insurance limits as a result of a faster turn around on jobs. Clients may also have the benefit of a reduced rental period whilst awaiting their new home.
In the case of site fabricated timber framing, my opinion is that the job is still much quicker than having wet trades installing mass where it is not needed. On top of speed of the build being better, the general mass of waste is radically reduced by avoiding too much brick and plaster work on the job. Hence, less bin rental, and less site clean labour. Hey, lets add less final clean of dried and hardened mortar from every splattered surface while we are at it!
Coming back to a prefabricated frame job; with correct final checking procedures prior to final shop drawings, an average two storey insert can have a lid on it within 3 weeks of demolition. Good for the extension market from autumn to spring. A 100% timber 2 storey structure could have a roof in it around 4 – 5 weeks from receipt of frames on site. Weigh that against lower level brickwork, scaffold, formwork, upper slab pour, upper brickwork, scaffold, and finally roof frame then cover. Even in winter when you are dodging showers, the biggest concern is safe OH&S with regard to power and slipping; the chippies can keep putting in the hours. Their poor fellow wet tradesmen cannot go putting mixes onto mud boards if there is more than a light rain.
The hardest and the easiest thing to do is talk someone out of a suspended slab in favour of a timber framed floor. It is hard, because there is a strong user desire for a solid concrete slab that “doesn’t transmit noise”. It is easy because this slab will add about $30k over the cost of a chipboard and timber framed floor on the average job. The options available now put this prejudice to rest in my mind. We have acoustic batts, acoustic ceiling lining, we even have sound-break dropped metal grid ceiling frames. What about mass? Timber does not conduct heat as well as a slab, however if the floor were to be a lightweight aerated concrete product with a tile finish, the mass issue is remedied. These products all are readily available in Perth; a builder / designer just needs to think outside the box and get to know them. Finally, slabs will be rescheduled if there is a whiff of rain. The timber framed floor, with or without the aerated concrete, will be installed in a fraction of the time it takes to prepare and pour a suspended slab.
About 90% of our jobs are substantially light weight these days. Our single storey houses commonly have a polished concrete slab, and a feature face brick wall to the southern internal face. The rest is well insulated timber framing. In two storey scenarios, many have a lower storey of 100 % brick and an upper of 100% timber. By cladding the lower wall instead of rendering we can mimic the benefit of an external timber frame. There are many more ways to keep a house cool than there are to skin a cat. Start with timber, and think where it can be best used, don’t leave it as just an option for holding up the roof sheeting. Be active in promoting timber in your designs. It has helped Swell Homes, being so closely aligned with Shoreline Designs, develop into a better building company.
As a community, we need to embrace the better option. This needs to be across the board, and marketed correctly so that all are aware of the benefits of a composite home.