Frequently Asked Questions
The costs can vary according to factors such as the design of the structure, the source of materials, and the kind of labour that is utilized, site logistics etc.
For a Formblock wall, the material costs, for cement and earth if purchased from a suppler, would be approximately $7-60* per block or approximately AUD$42-00* per square metre. Using your own earth can greatly reduce this cost to just the cement component only of the blocks. Costing you approximately $4.25* or $23.50* per square metre, that is about 2 blocks per 20kg bag of cement. Refer Estimating construction cost .
Labour is always one of the biggest cost factors. Supplying your own labour can lead to considerable savings.
Using contract labour costs are comparable to that of double brick construction. (more information)
* Figures quoted are based on average Australian retail prices as at 2010 and are subject to variation and change.
The Formblock system will help improve your building confidence as it is straight forward and easy to understand. It also fits neatly with basic building principles that apply to any method of construction.
The Formblock system allows you to easily maintain a straight and level wall. Plus you are able to carve and shape the blocks once they have set. Also, you may do as much, or as little as you like. Making the process of construction both predictable and forgiving. The wall progress is unaffected by interruption, i.e. weather.
Steve McGregor, whilst constructing a rammed earth home as an owner builder, first conceived the Formblock system as a better and easier way to build in earth.
When compared to the traditional methods of earth building the Formblock system significantly reduces materials handling and hence the labour required.
The blocks are made in -situ (i.e. on the wall, in their final resting place). The Formblock method cuts out the many handling steps involved in making and laying mud bricks, as in the Adobe method of earth walls.
Earth is poured into the Formblock form work, and it is not required to be rammed or pounded, as in the rammed earth method of construction, saving a lot of manual effort.
The Formblock form work is uniquely designed into robust yet lightweight and easy to manage components.
Labour saving translates into dollar savings. Refer to Estimating Construction Costs page
What is meant by 'in-situ'?
'In-situ' is Latin meaning, 'in appropriate position'. A Formblock wall is comprised of blocks that are made on the wall, in their final resting place.
Poured earth is a method of earth construction in which formwork is prepared to cast a wall in-situ. The earth material is prepared by mixing with a cement stabilizer (Formblock recommends at least 10% cement), and water to slump similar to that of most concrete mixes, and simply poured in the moulds and allowed to set.
Formblock is different to rammed earth as the earth is not required to be pounded or ramming as part of the procedure.
Formblock is different to adobe construction, in that, adobe mud bricks are first made and allowed to dry or set, a sufficient area is required in which to do this, and bricks need to be kept under shelter to dry before they can be finally laid on the wall.
The kind of soils that are suitable for Formblock are earth such as sandy loams (containing less than 10%clay), decomposed granite soils, friable sands and aggregates as per concretes. The Formblock system does not require the higher clay ratio soils normally used in earth-wall construction. If the soil available to you is high in clay, it can be adjusted by simply mixing in friable sand. Refer Materials that can be used in the Technical Information page
Are Formblock earth walls vulnerable to being washed away by exposure to rain, or water from garden hose?
Myth; 'Earth walls wash away when they get wet.' This is only partly true, non stabilized earth walls will suffer if they are exposed to constant dampness. However, well constructed earth walls can effectively resist incidental wetness from a rain downpour or garden sprinkler.
Due to the cement stabilization of the earth blocks in Formblock method, the walls are very resistant to water damage or water penetration. Refer C.S.I.R.O. 'Certificates of Test' in the Technical information page.
Note: Long term exposure to puddling water is not good for walls of any type of construction. If your walls are in a damp situation that may cause you concern, there are available many treatments that can be applied to masonry walls to prevent any possible water penetration.
Not Necessarily, various soils can be suitable for use in the Formblock system. Suitable materials such as sandy loams (containing less than 10%clay), decomposed granite soils, friable sands and aggregates as per concretes are usually available at your local quarry or landscaping supplier. Refer Materials that can be used in the Technical Information page.
Although walls of any length can be produced, keep in mind that the Formblock system is designed around unit lengths of 300 millimetres (one foot). By keeping dimensions of your plans, where possible to multiple of 300millimetres, the production of each course of blocks can be easily executed in one session. Walls with other lengths merely require each course to be done in two sessions.
Common grey, type A or GP cement at around 10% of the mix has little effect on the colour of the original raw material. It still looks like an earth wall. The colour of the wall can be heighten by using different cements such as 'off-white' cement or mixing the earth with different coloured sands. Colours and finish textures can be varied according to how the walls are finished- 'off the form', bagged or rendered, and by the types of cement, sands and oxides that can be used.
Depending on the materials used, an earth wall will take anchor bolts, etc, even ordinary carpentry nails. provided the fixing device has deep enough penetration into the wall.
The Insulation properties and Thermal mass properties of building materials are two separate issues in term of energy saving.
Insulation properties; the ability to prevent the transfer of heat from one side of a lining to the other, such as a vacuum flask, woollen clothing, insulation batts, polystyrene foam icebox.
Thermal mass properties; the ability to absorb heat and release heat, such as hot water bottle, hot coals in fire, a recently vacated seat, sauna rocks. Eg; in a heated room where a door has been left open allowing all the warm air to escape, then upon the door being closed again, the thermal mass of room will begin to release heat back into the air and reheating the living space. In summer, shaded and enclosed areas in the building will absorb heat from the surrounding warm air, cooling the living space.
It is worth noting that the benefits of the properties of any material are dependent upon how it is designed, how it is constructed and how it is operated. refer Benefits of Thermal Mass page.
An indication of a local building authority's acceptance of earth building is a presence of other earth structures
Councils in Australia may require sample blocks to be tested by industry authorities such as the C.S.I.R.O. and an engineer to certify the design of the structure. refer Building Considerations in the Technical information page
Yes, Formblock earth walls constructed with the recommended earth and stabilized with a minimum of 10% cement are considered load bearing. Note: your building should be constructed to engineer specifications and according to all the relevant building codes.
The size of the kit you may need, is best determined by the size of your labour force for acheiving a productive day. As a yardstick estimate your needs to around 10-20 blocks, per person, per day, refer to Catalogue page for a guide.
No problem. If you are in the middle of pouring a run of form work, and you must stop work. Simply cover the job from impending rain and go. The Formblock method allows you to do as much or as little as you wish, one block at a time if you so choose.
By building in raw earth, you are be building a structure with a very low "Embodied Energy" factor. For further information www.yourhome.gov.au/technical/fs52.html
The Earth itself, that can be used in the general earth building construction is, of course, an abundance and a sustainable resource for housing.
The Formblock formwork is made from very durable materials and is designed for long term repeatable use, hence, no need to be using specialized, single-purpose form work. this means no wastage.
The 300 millimetre (one foot) thick walls provide excellent thermal mass, and will compliment structures with good energy efficient design reducing the "Operational Energy" component of building. That is the ongoing heating or cooling of your home. Refer The Benefits of Thermal Mass page.
Termites are attracted to timber and do not eat cement stabilized earth material. As well, Formblock walls are of solid construction and have no cavity. Pests such as termites and other like cockroaches and rodents have no wall cavity in which to thrive and nest. This makes pest control much easier to manage. However, we do advise that you consult a pest control expert, in order to incorporate the best elements of pest control into the design of your house regarding your regional circumstances.
The Formblock Kit components are made from the finest durable materials. The partitions are made of cast aluminium and the shutter boards made from heavy gauge form-ply. The Formblock kit is built to last a many a project.
I have a Question that is not answered here? Or, I seek further information.
For Phone, fax, or postal details. Refer Contact page.
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