Most Frequent Questions:

Rammed Earth or SIREWALL? It’s like cob, adobe, hempcrete, or straw bale, isn’t it?

Most alternative building materials have insufficient strength to resist the forces of nature or carry the roof. Here’s the strength comparison:

  • Cob: 1 MPa (145psi) – vulnerable to strong rain and flooding, can’t be used below grade
  • Adobe 1 MPa (145psi) – vulnerable to strong rain and flooding, cant’ be used below grade
  • Hempcrete 1 MPa (145psi) – not a structural material, only R2.4/inch insulation value
  • Strawbale 6 MPa (870psi) – seldom a structural material, vulnerable to flooding and insects
  • Rammed Earth (standard) 5 MPa (725psi) – structural up to 2 storey, vulnerable to repeated wet/dry or freeze/thaw
  • SIREWALL: 20 MPa (3,000psi) – resilient to wet/dry, freeze/thaw, flooding, fires, insects, hurricanes, dynamic R50 insulation, resistant to earthquakes, has been built to 100’ tall and 51’ tall loadbearing, can be used below grade, no toxic materials, has a very low life cycle embodied energy.

Historically, the low strength of alternate building materials has restricted their acceptance by engineers and building officials. SIREWALL has seriously addressed that concern, leaving no doubts.

How is SIREWALL different from rammed earth?

There are 3 different grades of rammed earth and the most significant differences between them lies in their strengths:

  1. Traditional Rammed Earth (TRE) –1 MPa strength,  used in Great Wall of China and other dry locations,
  2. Stabilized Rammed Earth (SRE) – 5 MPa strength, since 1985 in Australia and California,
  3. Structural Insulated Rammed Earth (SIREWALL) – 20 MPa strength, since 1992, invented in BC Canada, now worldwide,

Can we use the excavation soil?

This is not practical for the residential scale of building and seldom practical at commercial scale.

We don’t have good soil here. Can we do SIREWALL?

We have always been able to deliver a mix design of 20 MPa or higher, wherever we’ve built. We have heard the concern about poor soil from locations like Maui (volcanic), Shanghai (silt), Winnipeg (expansive clay), France (limestone), etc. With excellent results from dozens of locations, we are now very confident in SIREWALL’s proprietary mix design technology.

Cost-Related Questions:

How much does it cost to build SIREWALLs?

If you want to have your SIREWALLs built for you, then you should seek pricing from us or another SIREWALL Licensee, based on a specific project you have in mind. It is impossible to provide a cost estimate without a specific project on which potential costs could be based. Contact us to discuss your project.

If you want to build SIREWALLs yourself (and labour is typically around 2/3 of the build cost in N. America), here’s the best way we can recommend to go about it:

  1. Take our Intro and Practicum courses to learn the fundamentals
  2. Purchase a custom SIREWALL Builder’s Package to avoid common pitfalls and optimize success
  3. Start building SIREWALLs yourself

Again, cost will remain undetermined until the scope and scale of your project has been discussed with us.

How much does you builder's package cost & what's included?

The Builder’s Package in N. America costs $7,000.00 USD + $40 per yard of compacted material. Note: travel and accommodation to bring the Master Earth Mason to your site is not part of the Builder’s Package and needs to be provided.

Here’s what our Builder’s Packages include:

  1. Prospecting trip – A Master Earth Mason comes to your site to sample and evaluate local soils, graph the results and insert the data into SIREWALL’s proprietary mix design program. Test cylinders are made and sent to a vetted lab. Colour samples are made, and a 3’ x 7’ test wall built.
  2. Enough SIREWALL Base Admixture (SBA) for your project – We require SBA to be used on all projects we are involved in.
  3. Permission to use any of our patented processes for your one project
  4. Eligibility for discounted purchase of SIREWALL products such as tampers designed specifically for rammed earth, rammed earth steel cylinder molds, sieve sets, books
  5. A list of typical quantities of materials that make up a SIREWALL to help with costing
  6. Consultation with a Master Earth Mason in four separate 15-minute sessions – This time can be used to get support in dealing with architects, engineers, or building inspectors. It can be used to get advice on forming details, and selection of mixers, compressors, delivery techniques, and optimal production techniques. It might be used for trouble shooting, brainstorming, or design. How the time is spent is up to you, and more time can be purchased.

Don't you have a per-square-foot rate?

Unfortunately it is not possible to give a standard cost for a SIREWALL. There are many variables such as:

  • Soil – the cost and compaction factor of soils vary in different locations
  • Rebar – seismicity varies in different locations and affects rebar density
  • Iron oxide colouring – some people want no colour and others want vibrancy
  • Labour – skills, cost/hr, and productivity varies in different locations
  • Complexity – single storey walls of repetitive size are cheaper than tall curving walls with many corners
  • Compressor and mixer – cost and availability vary in different locations

It is also difficult to compare costs with other systems as most are incomplete or have many variables that don’t correlate to our system.

It is hard to find an alternative durable wall system with R50+ dynamic Rvalue that provides abundant thermal mass, structure, health, environmental sensitivity, acoustic attenuation, hygrothermic performance, and of course beauty from every angle.
Having said all that, we know of a competitor who is quoting $100/face foot (square foot on the face) for uninsulated, 5MPa (750psi) stabilized rammed earth (SRE).


What is mix design and why is it so important?

Mix design is the process of determining the optimal mix of ingredients and proportions, given the soils that are available in a geographic area.

Most rammed earth companies don’t do mix design at all. Some use concrete mix design techniques, usually with poor results; others put soils in a bottle of water and shake to see how the soils settle out. Neither technique employs the science specific to rammed earth that allows for results with strengths higher than basic concrete, with a fraction of the cement.

Without mix design it’s not SIREWALL.

I live too far away to attend your course. Is there another training option?

In these circumstances, a solution can be that we extend our stay when we attend your site during our prospecting trip. Typically we would stay for an extra 2—3 weeks, during which SIREWALL training can take place and quality assurance protocols can be established. Contact us to discuss further.

This can be more cost effective than the travel expenses for your crew to attend our course in British Columbia.

Structural related questions:

Is SIREWALL affected by freezing temperatures?

We have had success in Edmonton and Winnipeg where the winter temperatures drop below -40°

How tall can SIREWALLs go?

SIREWALLs have been built to 100’ tall, and to 51’ tall load-bearing (carrying concrete floors and a green roof).

Can you backfill against a SIREWALL?

Yes, the most backfill against a SIREWALL so far is over 30’ deep.

How long will it last?

Well-built SIREWALLs will last hundreds and possibly thousands of years. Think about how long a concrete wall will last (SIREWALL has equivalent strength), and then add time due to the hydrophobic admixture in the SIREWALL that is not in concrete. This is a material for building a legacy!

Can SIREWALLs span across openings?

Yes. How far it can span depends on how deep the lintel is. It can easily span most doors and windows. Picture windows and compound doors will need some engineering attention. In our consulting service we will provide guidance on this.

Who engineers the SIREWALLs?

In our consulting service we will provide guidance on this but the final decision is in the hands of the Engineer of Record.
This professional, who is taking responsibility for the whole house, engineers the SIREWALLs as part of their scope. We provide support to that engineer in our consulting service.

If they are unwilling or uncomfortable, then we can jump in by suggesting engineers who are comfortable with SIREWALL.

Aesthetic Considerations:

Can you make the colours that are best for my project?

We have a design funnel that expedites colour selection, and yes we almost certainly can make the colours you want. Our one caveat is that we don’t work with blue or green pigments due to their toxicity.

Can you design the texture that is best for my project?

We are beginning to gain control over texture and sheen, but there is still some randomness in the outcome. That being said we are still the best in the world at this.

Environmental Considerations:

Can we get LEED points for using SIREWALLs?

Yes, we have experience at this.

Can we use SIREWALL in a Living Building Challenge project?

Yes, we have experience at this. (Learn more about the Living Building Challenge)

Can we use SIREWALL in a Passive House project?

Yes, we have experience at this.

Can we use SIREWALL in a NetZero project?

Yes, by simply adjusting the insulation levels. We have done work in this area too.

Is SIREWALL Red List Ready?

Yes, it has been for many years. (Learn more about what it means to be Red List Ready.)

Has SIREWALL incorporated Cradle to Cradle (C2C) thinking in its product design?

Yes, ingredients are almost all re-useable for their initial role; for example, soil, foam, rebar, metal conduit and electrical boxes. (Watch this brilliant TED Talk to learn more about Cradle to Cradle.)


Can SIREWALLs be built in the winter?

Yes, we have done this many times, but as with all winter construction, it is slower.

How long does it take to build SIREWALLs?

A simple ballpark estimate for time to build is 1,000 face-feet per month for a simple building. A face-foot is a square food of vertical wall face.

Not many can build to the SIREWALL standard. Will there be problems finding someone to build the SIREWALLs when the time comes?

It’s a good idea to lock in a SIREWALL licensee, such as us, as soon as you are able.


How do I bring my design to reality?

Start the conversation with us or another SIREWALL Licensee. Email us at action@terrafirmabuilders.ca or use our contact form.

What's the process of becoming a SIREWALL licensee?

Licensing is for people who build SIREWALLs and want to be part of the SIREWALL team. Talk to SIREWALL Inc. or SIREWALL USA to explore this option.


See examples of our best work.



We’d love to make your project the best it can be!



Getting intimate with dirt to make something beautiful is when SIREWALL really starts to make sense.