The Cost of a Rammed Earth House
One of the most common questions we’re asked is ‘How much will it cost to build my rammed earth home?‘ This is often then followed by ‘Well I suppose it’s like asking you how long is a piece of string…’
So in this post we’re going to get specific about exactly what can influence the final ‘cost’ of your rammed earth home. And how to incorporate rammed earth on different budgets.
Budgeting is crucial for any successful build. This involves having a clear understanding of each component’s cost.
The overall cost of any home -rammed earth or otherwise- is dependent on the choices you make. And factors that may be out of your control.
A rammed earth house is generally in a similar price bracket to many other quality custom built homes.
The major difference between rammed earth and other mediums is the ongoing benefits and savings the medium ensues.
Prioritising and Budgeting
It’s easy to get distracted by choice. There are so many options going into a new build.
To help work with this you need to clearly understand…
“What is my budget?”
and just as important
“What are my priorities?”.
It’s so important to be clear about your priorities and budget to avoid not being able to afford what is really important to you.
By considering these two things, you can determine what will have the greatest impact on making your home more sustainable and functional, while remaining within budget.
Budgeting for what is important to you. And having allowances for the things out of your control is key for any build.
Some things to consider are:
Soil Classification, rock and access.
Soil classification will determine the depth of footings, the amount of steel mesh etc. that your site will require. In turn, this affects the cost of your home.
If your soil is classed as highly reactive (H) or a problem soil site (P), your footings will need to be built accordingly. As opposed to a stable (S) or less reactive soil.
It’s also important in your budget to have extra allowances for the the things you may already know about, as well as the ‘unforeseen’s’, like rock.
Good access to your home is also crucial. You might not be considering retaining walls at the start of your build. However, if you’re working on a site with slope, it’s a good idea to make allowances for retaining walls.
You cannot overlook the site, as the foundations of your home must be built well. This is not an area in which you should consider cutting costs. Your home needs to be structurally sound.
The design of your home can influence the cost in either a positive, or negative way.
There are design considerations for using Rammed Earth that will ensure you benefit from maximum ongoing cost savings. And others that are more for aesthetic purposes.
Knowing what design elements will affect the cost is very important.
Where your budget is tight, you can still often incorporate Rammed Earth in your home. But you may need to consider carefully where you place the Rammed Earth walls for maximum benefit.
See below (or keep reading) to understand how design can influence the cost of your rammed earth.
Large quantities of windows and doors in your home can also increase costs. However, increasing the size of a window will often have a lesser impact on the cost. (Unless the size increase affects the frame or glass thickness).
Looking at the most cost-effective way to achieve cross-flow ventilation and reduce window quantity will also make a significant difference to your build cost.
Fixtures and fittings
Your choice of heating, fans, appliances, plumbing fittings and fixtures, joinery etc. can all majorly impact the overall cost per m2 for your home.
Keeping the structure of your home timeless rather than going with fads and fashions is key when choosing your fixtures and fittings.
Opting for cheap, low quality fixtures and fittings will lower the initial cost. And often over time end up costing you a lot more in replacements. (There’s also the labour costs for replacement to consider).
So when it comes to quality and functionality, choosing very cheap options is not a practical or sustainable choice.
However, it’s also a good idea to do your research and ensure you’re not just paying for a brand name. Or the latest style. (That you’ll probably end up wanting to replace in 5 years because they’ll look out-of-date).
With some research you can often find quality items for reasonable prices. That also give you the look you’re after.
Smaller homes (although more sustainable) frequently work out more expensive per m2. As there are many one-off costs for a home. Such as service connections, kitchens etc. which are required whether your home is 10 squares, 20 squares or larger.
While anything extra does end up costing more, and we certainly do not advocate building larger than you require…
The cost of an extra room is far more than the cost of a larger room.
This is because inclusion of an extra room affects doors, windows, electrical and walls. Rather than mostly just flooring, roofing and walls for a larger room.
Understanding How Design Can Influence the Cost of Your Rammed Earth
The design of a rammed earth home is incredibly important in achieving the best outcome within a given budget.
Rammed Earth walls need to be placed effectively for maximum thermal and aesthetic gain.
However, it is also important to remember designs with lots of small sections of wall (e.g. columns) will increase the overall cost. This is because there are lots of rammed earth over-fills, which take longer to build.
Your choice of straight or curved walls can also influence the price. Curved walls typically cost more.
Wall height can also increase costs. Walls over 3m high are more expensive, due to extra time requirements. Set up, equipment, scaffolding and elevating the soil mix to build a wall above the standard height all add time and therefore money to your project.
Openings for windows and doors require lintels to support the earth above the opening. Which means more time and equipment involved in the setup and building of these walls.
Complex roof lines requiring raking or angling of walls to bring them up to the roof increases your costs.
It takes more time to construct a raking wall than to finish at the top of the formwork section.
Whilst raking walls are common in Rammed Earth construction, it is worth considering limiting their use if your budget is tight.
Set-up costs of transporting equipment, machinery and formwork to and from site for construction are factored into the overall cost per m2 of your walls.
If you only need a small quantity of walls, the price for set up and transport per m2 will be higher. As it is averaged out over a smaller quantity of walls. Sometimes it is worth considering if there are other areas in your design where rammed earth can be incorporated to increase the quantity of walls.
It may be able to provide greater thermal and aesthetic benefits, while also reducing the overall cost per m2 of your rammed earth.
Wanting it all…
So, what if your budget is restricted? But your priorities are to have a beautiful sustainable home… with rammed earth walls… and still have those expensive fixtures and fittings…
At this point, it may be best to consider reducing the quantity of walls in your home. (Keeping in mind the set-up and transport costs). There is likely a way to achieve maximum value for money and thermal benefit. We work with our clients to find this point.
Often this is obtained by building a central internal wall. This allows for the walls thermal properties to be maximised by reducing the walls exposure to the outside elements.
By customising your design, you are often able to incorporate many of the things you want into a smaller home with multi-use rooms. It will remain comfortable and functional, while reducing your footprint (becoming more sustainable) AND reduce cost.
Cost Savings and Benefits of Rammed Earth
Rammed earth walls have many inherent benefits. From their sustainable properties working to reduce energy costs to their natural, texture and unique aesthetic. They suit many different styles. From modern and contemporary design to more rustic and traditional homes.
Rammed Earth’s high density, paired with the specific soil used in construction create a medium with high thermal mass.
Thermal mass increases the comfort of your home’s temperature in summer and winter. And reduces temperature fluctuations within the home. When paired with solar passive design and used correctly, thermal mass can have a major impact on reducing your energy usage.
We also construct insulated rammed earth walls up to R3.5.
If you want to learn more about thermal mass, we have written about the Thermal Properties of Rammed Earth.
Rammed earth is incredibly low-maintenance. Rammed earth walls do not need to be painted. And the initial sealing of the internal walls never has to be repeated, external walls rarely need re-sealing.
The clear dust-proof water repellent sealer protects your walls internally and externally.
Building with rammed is one of the oldest forms of construction. Even used to form sections of The Great Wall of China. Some of these sections span up to 2,000 years in age, and are still standing today.
Since then, the construction process has evolved and adapted into the refined and versatile medium it is today, maintaining its durability.
Being a distinctive and sought after medium, resale values are high. As is the interest in these homes from prospective purchasers.
When you’re just starting to think about building a new home, resale value might not be something you’re considering. However, we have found rammed earth homes have an excellent resale value. Its unique qualities and exclusivity of the number of houses built this way mean that when one comes onto the market… it doesn’t last long.
Because of the mediums longevity, you will also see greater returns. As your home will be built to last.
The Dollar Figure
So after all of that, here’s the outcome…
Cost per m2 for a rammed earth home
The price range for the full build (to completion) on average can fall between $3,500 per m2 to $4,000 per m2.
The final cost per m2 for a high quality fit-and-finish custom rammed earth home can vary greatly. Depending on size, design, finishes etc. as we’ve discussed.
Cost per m2 for a rammed earth wall
The cost per face m2 for a rammed earth wall can vary from $450 per face m2 to $750 per face m2, on average.
As with the full cost per m2 for a house, the cost per face m2 for a rammed earth wall will also vary depending on the quantity of wall, design, hight etc. – as with any other wall medium.
Is it worth it?
‘But I can build a home cheaper than that…’
Of course you can.
But your cheaper project homes aren’t the same. More often than not they sacrifice energy efficiency, functionality, quality and longevity to achieve their cheaper price.
When you choose a project home, you can customise it to a certain extent with add-on’s and extra’s. You can change the floor coverings and maybe even move a room or two around. But, unfortunately, these project homes aren’t designed for you or your property.
It likely won’t maximise on your northerly aspect and reduce westerly exposure. While also incorporating the views you love…
When it comes down to it, a rammed earth home is an investment for yourself and the environment. So while it may initially cost more than a project home, the benefits of rammed earth will produce ongoing savings.
And, (if you ask us) a rammed earth home is absolutely beautiful to live in.