Ramtec^®

Rammed Earth Specialists

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FAQs

The following are a collection of 'frequently asked questions'. Just click the question to expand and read the answer. Should you have a question or enquiry that is not adequately answered here, please do not hesitate to contact us.

• Basic info
  • What is rammed earth?
  • Rammed earth is a precisely controlled mixture of gravel, clay, sand, cement and sometimes lime or chemical admixtures which is carefully proportioned, mixed to the correct moisture content, and then machine-compacted in removable formwork to yield a dense, hard, stone-like wall.
  • Where is it used?
  • Our successfully completed projects throughout Australia include houses, home units, wineries, chalets, hotels and motels, tourist resorts, studios, taverns, schools, and a cathedral. As well as being structural and predominant walls for almost any building, Ramtec walls can also be used as retaining walls, boundary fences, floors, fireplaces, and feature walls.
• Thermal and acoustic advantages
  • What are the advantages of rammed earth walls?
  • Besides their striking beauty and characteristic deep reveals, rammed earth walls have outstanding thermal and acoustic benefits. They have an ideal thermal transmittance (U-factor) and density or thermal storage (known as the "thermal flywheel" effect). This unique combination of properties creates a high thermal mass building, which evens out day/night temperature fluctuations and forms a comfortable building in which to live all year round.
  • Does sound transmit or echo between rooms?
  • No, quite the opposite. Ramtec walls have good sound-absorbing characteristics and can be built to have very high sound attenuiation (up to STC 57) which inhibits noise transfer between rooms extremely effectively. Common sound reverberation levels are simply not present in our buildings and visitors usually remark on the tranquil ambience of our Clients homes.
  • How thick are the walls?
  • Although walls can be from 200mm to over 1000mm, the optimum thickness is 300mm (12") thick.
• Colour and texture
  • What is the colour choice in rammed earth?
  • Most natural earth colours are available, from the warm reds of central Australia, through the yellow and brown spectrum of gravel ridges, to the creamy finishes with coastal limestone materials. Sophisticated artificial colours and textures are also available, though more expensive.
  • Does rammed earth have to look pebbly?
  • No. Coarse, medium and smooth finishes are available both with and without pebbles. The ingredients used, together with the placing and ramming techniques employed, determine the colour and texture of the walls. These can be tailored to suit most colour and textural preferences.
  • Does a pebbly finish rub away?
  • Under normal circumstances, no. A clear surface coating applied to a pebbly finish or a smooth finish prevents dusting or pebble dislodgement.
  • Can conventional surface treatments be applied to rammed earth walls?

  • Yes, but generally none are necessary. Unlike standard walls, chipping or scratching Ramtec walls does not expose a different material or colour behind the surface. Nor do our walls ever need painting!

    If desired, our walls can be tiled, rendered, bagged, plastered, painted, or virtually any other finish that can be applied to brick or concrete can be applied. Additionally, lime washes, earth renders and other soft earthier finishes can be applied to our walls.

• Strength and durability
  • Does rammed earth wash away?
  • Ours do not! That is the reason we only use Ramtec walls. Ours will not even disintegrate any faster than other masonry systems with time. While Ramtec walls are inherently waterproof to a substantial degree, integral admixtures can be used and/or clear surface coatings can be applied to walls if needed for even higher performance.
  • Are verandahs necessary?
  • Verandahs represent good usable living space in the Australian climate at reasonable cost. While they do protect walls and are considered desirable, they are not absolutely necessary. Architectural styles do not always include verandahs but these too have been constructed successfully by us.
  • How well do rammed earth walls withstand fire?
  • Fire tests to AS1530.4 (1985) on a 300mm thick rammed earth wall with 6% cement gave 240/240/240 for structural adequacy/integrity/insulative capacity. Ramtec walls can be built to have a four-hour fire rating which is the highest needed in Australian general building codes. Furthermore, our Ramtec walls do not burn or evolve smoke or toxic chemicals, as do some other building products.
  • How strong are the walls?
  • Building Codes call for a characteristic compressive strength of not less than 2 MPa which Ramtec walls exceed. Standard 300mm Ramtec walls can be built as load bearing constructions for up to four stories high, but can be designed to go up to ten stories if required.
  • Will white ants be a problem?
  • No. Physical conditions such as cavities or timber framing do not exist within our walls. The CSIRO has even published technical reports stating that termites will not burrow in rammed earth walls. We have also developed a range of techniques to prevent termites from entering a building.
  • How durable are rammed earth walls?

  • Thousands of rammed earth buildings constructed centuries ago are still giving excellent service in France, Algeria, Morocco, Central America, China, and the Middle East.

    In Australia there are many rammed earth buildings over 100 years old still in use. One of the oldest buildings in Western Australia is in Albany at Strawberry Hill Farm where the rammed earth building (built of local materials, with no cement and no verandahs) is over 160 years old and still giving good service. We can only imagine how long our Ramtec walls will last!

• Earthquake and cyclone performance
  • How good is rammed earth in earthquake areas?
  • Rammed earth walls are built as articulated free-standing masonry panels. This method of construction is preferred in seismic areas and/or problem sites where ground movement occurs due to subsidence, subsoil movement, or from clay heave and shrinkage. Where the panels are articulated, movements of the ground are naturally better accommodated than in conventional brick buildings.
  • How good is rammed earth in cyclonic wind areas?
  • Excellent. We design further precautions into the structure, to hold down the roof by having steel "hold-down rods" from the concrete foundation through the wall to the roof. Rammed earth buildings have now been successfully built in most cyclone areas of Australia. The Directors of Ramtec built the first modern rammed earth house in Australia in Darwin in 1976 following Cyclone Tracey and it still meets all subsequent cyclone codes to this day!
• Environmental attributes
  • What is the environmental impact of rammed earth?

  • Rammed earth is probably the single lowest environmental impact building system that is readily and commercially available today for solid masonry buildings.

    Rammed earth walls are structural immediately upon completion of compaction and removal of formwork. There is no firing process as used in brick manufacture so there are no kilns, toxic emissions or damaging greenhouse gases. Kiln gas pollutants associated with brickworks are simply not present in the manufacture of rammed earth walls and therefore not emitted into the atmosphere.

    Because of the outstanding thermal performance of rammed earth buildings, heating and cooling requirements are minimised and substantial energy savings can be enjoyed over the life of the building by generations of occupants.

    Rammed earth walls look as if they've "grown out of the ground", especially where materials have been taken from the site to construct the building. Rammed earth buildings are supremely environmentally friendly, blending harmoniously with their surroundings. The natural walls are sun dried and completely non-toxic.

• Costs
  • We hear rammed earth is very expensive, how does it compare to everyday brick?

  • Because of our advances, we have dramatically brought down the cost of our walls to compete with the 3 meter high double-brick/plaster/paint combinations.

    When the thermal properties of Ramtec walls are considered, together with their superior low maintenance qualities, then the costings show that Ramtec walls are cheaper than any other method of providing similar thermal mass and acoustic attenuation. Naturally, factors affecting costs also include such things as size and complexity of project, locality and site considerations, raw material costs and availability, but generally all our clients are delighted with the outcome.

  • Can on-site material be used for the walls?
  • Yes, especially on larger land holdings with greater areas for selection.
  • Is rammed earth cheaper than conventional materials in country and remote areas?
  • Generally yes, since rammed earth materials can usually be found on site in open country areas. If accommodation for our workmen is cheaply available near the site, if the design suits the Ramtec system, then rammed earth is often less than the double brick alternative.
  • How is soil tested for suitability?
  • This requires expertise and detailed laboratory measurements. While an experienced visual assessment of a soil being suitable can sometimes be given, there is no substitute for a detailed technical evaluation. RED provides a full range of soil testing services.
• Bank loans, shire approvals and insurance
  • Do banks lend for Ramtec walls?
  • Yes. Most major banks and building societies have financed Ramtec walls for housing and commercial projects. Generally, their most favourable terms apply.
  • Is it difficult to get shire approvals?

  • No. Ramtec was instrumental in having rammed earth written in to the Building By-laws of Western Australia and then in to the Building Code of Australia.

    Rammed earth has been approved for use in every shire in Australia. An Australian Standard on Rammed Earth and other forms of Earth Building is under preparation and RED's Managing Director is a continuing member of that Code Committee (BD83).

  • Is insurance a problem?
  • No. Most major insurance companies have insured buildings with Ramtec walls and usually their lowest ratings apply.
  • What is the resale value like?
  • Very good. Real estate agents have commented that rammed earth buildings are much easier to sell than conventional buildings. Certainly in some areas, it has even been proven that rammed earth is a definite plus when selling a house or commercial project.
• Construction
  • Is a concrete slab put down first?
  • Yes.
  • Does the slab differ from that used for double brick?
  • Yes, the configuration is different. However, a similar or lesser amount of concrete is generally required so that overall the foundation and slab costs for a rammed earth house are similar to a typical brick house.
  • Can you have rammed earth foundations?
  • Yes. Whilst these are complex to construct successfully, they are nevertheless cost competitive. Using rammed earth for the foundations, floors and walls totally eliminates the need to get concrete to site and hence, one trade.
  • Can you ram a wall above a few courses of brickwork?
  • Yes. Brick, stone, layered rammed earth and other special effects are all possible and the outstanding appearance generally outweighs the increased cost.
  • Can you have a timber ground level floor?
  • Yes. Wooden floors can be built at ground level or at every other level desired.
  • Can you have a rammed earth floor?
  • Yes. These harmonise wonderfully with surrounding rammed earth walls in the house and garden. These floors can be used inside the home and also outside for verandah and patio areas. Thicker rammed earth floors internally (using Ramtec blends) also allow economical realisation of some powerful passive solar aspects.
  • What material is best for internal walls?
  • Rammed earth. When rammed earth is used for internal walls, the house gives a much better overall thermal and acoustic performance. Internal mass of all buildings is an important aspect of comfort. While internal walls can be constructed of other materials the use of rammed earth both inside and out has structural, aesthetic, and thermal advantages.
  • How high can rammed earth buildings be built?
  • In Australia the highest single rammed earth wall is 9 metres high, while a four-storey resort/hotel is the overall tallest modern rammed earth building. About 10 stories would be the highest that rammed earth walls could be built in a modern setting. Double and triple storey houses are built with 300mm thick, load bearing rammed earth walls.
  • Is it possible to add a second storey on to rammed earth walls?
  • Yes. Rammed earth walls can be designed to adequately take the weight of an upper level of masonry or lightweight framing.
  • Can concrete floors be used for upper stories?
  • Yes. Any floor can be concrete, timber, or steel framed.
  • What about electrical conduits and plumbing?
  • These are built in at the construction stage. Conduits are built into the wall for electrical wiring to be run after the walls are completed. Plumbing can be built into the walls directly, or provided for in embedded conduit, or chased into wall areas that will be tiled over later, such as shower recesses, et cetera.
  • Are there special requirements for tiling rammed earth?
  • No. A simple render coat is first applied to the wall to even out any irregularities, followed by the standard tile adhesives.
  • How fast is your rammed earth construction?
  • Well-designed rammed earth buildings with good access and services, etc. will always go up faster than double brick and plaster.
  • Do windows and doorframes have to be on site during construction?
  • No. This also improves site security and eliminates the typical building site damage to these items. Furthermore, this allows our Clients to budget their cash flows more smoothly without having to lay out for all the major purchases at the beginning.
  • What types of windows do you recommend?

  • Styles and designs can vary dramatically, and will be to your own taste. The materials used however are normally from three categories.

    Timber framed windows are considered aesthetically appropriate, but should have substantial sections to balance against the "size" of the rammed earth walls.

    In most cases, our clients prefer aluminium because it is very low maintenance, glass can be easily replaced in cases of breakage, there are new colours coming out every year, and it's termite proof. Steel can be used, and can be quite artistic, although generally it is substantially more expensive.

  • Can aluminium windows be fitted easily?
  • Yes. Aluminium, like timber and steel windows can easily be fitted into our walls, and in all cases they are positioned and fixed after completion of the walls.
  • Are rammed earth lintels difficult to construct?
  • Yes, lintels above windows and doors are relatively difficult to construct compared to regular ground level walls. Aesthetically however, rammed earth lintels are desirable and there are several methods of constructing them cost effectively to achieve the outstanding appearance they can give to a project.
  • Is maintenance a problem?
  • Ramtec walls generally require no maintenance. Unlike brick or stone, there will never be any re-pointing or mortar repairs needed, and if our walls are exposed to fierce or extreme weather conditions, we not only formulate our walls accordingly, but any additional surface coatings thought necessary can be easily applied afterwards.
  • Is it better to use an architect experienced in rammed earth to draw up plans?
  • Yes. The cost of having plans drawn up by an architect experienced in rammed earth is the same as any other architect. However, cost savings for clients are guaranteed if the architect is well versed in the methods of construction, the formwork, access, and sequencing parameters of Ramtec.
  • Do retaining walls need special treatment?
  • Yes. Rammed earth retaining walls are economically viable but like all walls, they also need specific designing and damp treatment. We structurally engineer and certify as required.
• Do-it-yourself
  • Can you DIY?

  • Like all aspects of building construction, the answer is yes.

    However, specialist knowledge and equipment is essential and you would be wise to pay for this. Modern rammed earth construction is sophisticated and it is not easy to achieve the high specification, longevity, and quality finish of a Ramtec wall.

• Why Ramtec?
  • Why use a Ramtec stabilised wall?

  • Ramtec was the first company to build rammed earth commercially in Australia and maintains its lead in experience, technical innovation, trained personnel, and well proven techniques.

    We have built more than 500 rammed earth buildings throughout Australia and our clients have confidence in our recognised expertise in this specialist area of wall construction.

    Managing director and engineer Stephen Dobson is acknowledged as a world authority on rammed earth construction and is Australia's leading exponent in the initiation and exchange of ideas on the subject. He is also well known as a keynote speaker at international earth building conferences.

• Comparisons
  • Ramtec vs. other walls: comparison table
  • The following table is a comparison of Ramtec with other complete wall systems at 3m heights.

    Feature	Straw-bale	Mud-brick	Timber frame	Double brick	Ramtec wall
    Wall thickness	600mm	300mm	120mm	270mm	300mm
    Impact strength	very low	moderate	very low	moderate	very high
    Compressive strength	very low	moderate	moderate	high	high
    Durability	vague	75–175 yrs.	50–100 yrs.	150 yrs+	250 yrs+
    Fire resistance	moderate	high	moderate	high	very high
    Cyclone resistance	very low	moderate	moderate	high	very high
    Tremor resistance	very low	moderate	moderate	moderate	high
    Termite resistance	low	moderate	low	questionable	very high
    Pest resistance	very low	moderate	very low	high	very high
    Cavity problems	vague	none	yes	yes	none
    Maintenance	vague	low	high	average	very low
    Thermal insulation	very high	moderate	moderate	moderate	moderate
    Embodied energy	low	very low	low	extremely high	low
    Thermal mass ability	poor	very good	poor	moderate	very good
    Greenhouse gases & toxicity	good	good	good	very poor	good
    Humidity equalisation	poor	excellent	very poor	poor	excellent
    Bullet resistance	poor	good	very poor	good	very good
    Natural harmony	moderate	good	moderate	poor	good
    Acoustic properties	moderate	very good	poor	moderate	very good
    Major lender-approved	vague	vague	reasonable	good	good
    Approved by insurers	vague	yes	yes	yes	yes
    All govt. depts. approved	vague	yes	yes	yes	yes
    Cost to have built	115%	120%	90%	100%	105%
    Resale value	unclear	moderate	unclear	moderate	good

The information contained on this site is of a general nature. Before proceeding on any matter, please obtain detailed professional advice from us.

If you have any comments or contributions to the above information, or feel we have been inaccurate in any way, we would be pleased to hear from you.

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