Greetings,

I am currently designing a natural house for the cold climate in Saskatchewan, Canada, using Compressed Earth Blocks.

The greatest complication in this is how to insulate?

Strategies I am considering:

Straw bales on the exterior but in combination with an already 12" thick wall, that will lead to some seriously thick walls, as well as involving a 2nd labour intensive process to an already labour intensive build.

Double Wall construction, with a natural insulation infill such as cellulose, wool, or rice hulls. Wool and hulls would involve some transportation and its associated embodied energy, not to mention the fact that they are not "local"

Hempcrete on the exterior wall---havent fully learned of its potential applications as I am awaiting a reply from inquiry to a Hemp tech company. Seems like it is a redundant doubling of thermal mass though?

Cork - expensive and not local

Flax - Ive not yet contacted the local company doing work on using it, but to my knowledge they haven't yet got the insulation product side of it down yet - though I believe in the UK you have companies doing so?

Foregoing a natural insulation for a high performance material such as xps, rockwool, etc. and pretending that the environmental costs of these materials are minimised through the rest of the build design and the fact that the house will last hundreds if not thousands of years (give or take )

I eagerly await your thoughts and advice. This is my first post on the forum but about 5 years ago, I went through many thousands of your informative posts in a 1 month period of being glued to a computer!(thanks!)

Warm Regards,

S

What is the point of the compressed earth blocks? It seems like an awful lot of effort just to prop the roof up and keep the wind out. Surely there's some local timber or, as tony suggests, straw which can do that with a lot less hassle.

I'd agree that a house has to last a long time to justify plastic insulation but mineral wool isn't so bad.

Hi All,

Thanks for the replies.

Legitimate suggestions for sure, as I spent many years as a straw bale fan-boy and thinking that they were the obvious choice as well. However, the more I talk to people who have experience building with them or doing renovations on existing ones, the less convinced I am.

Things I have been told that have reduced my zeal for straw bales:

2 different people (one being a firefighter and natural builder himself) telling the story of a fire in a home, that resulted in entire walls smoldering just below flashpoint. In one case, after extinguishing the fire and leaving, he returned with a "bad feeling" and started pulling off chunks of the plaster from the internal wall and the straw was all smoldering still. When a handful of straw was pulled out of the wall, it immediately burst into flames in the presence of oxygen.

I have heard rodent problem stories from a few people in regards to straw bale buildings, I once spoke with a renovating contractor who was asked to add on to a straw bale house. When he chopped into it to make a doorway/access to the "new" addition it revealed an absolute labyrinth of tunnels in which rodents had moved in to "housing heaven". They ended up tearing the whole house down!

Another person I spoke with when we were discussing the rodent issue, said that a bale builder he talked to said they solve this problem by poisoning the entire first course of bales in every build! What to even say to that?

Bales come from an organic source, that have been outside and exposed to weather to a certain degree even under ideal conditions, which means there is always the potential for mold/fungus, and water damage until they are plastered into the wall. And then, just because they are plastered in, can those issues be negated or forgotten completely?

The reality is, I could probably build my own house and conscientiously address all potential problems, issues with the bale source and install, keep up to any plaster maintenance that needs to be done to ensure mice dont find their way in (any hole or crack the size of a nickel I'm told), ensure that a wood stove isn't too close to the wall, etc. etc. However, I am looking at starting to do this as a business building natural homes for others, and that is an entirely different story when it comes to their desire/ability to do maintenance and ensure their home continues to last properly.

Other challenges/issues - availability of quality baled, organic straw and the fact that you are now removing a product out of the natural soil building cycle in nature.

I don't mean to tar straw bale building in general by just a "Few" events and there's a part of me that still wants to (and likely will) build with them, but ...

As for the use of timber framing, I love it! Looks amazing, incredibly functional and fairly simple to erect. However, it requires trees. And I just can't get over the fact that we need every possible tree on this planet to be producing oxygen for us to breathe. All conversations about carbon sequestering and sustainable lumber aside, the reality is, I don't really believe it makes sense to be building our homes out of wood just for the reason of their necessity for oxygen production at a time when global deforestation is at beyond-scary levels. And again, they are technically a flammable material.


I believe if you are going to design a proper functioning passive home, it should last for damn near ever. It should be as water/fire/pest/bullet/earthquake/maintenance - proof as possible. It should have a minimum impact on the environment with a long term life-cycle. Considering all those factors, I find it hard to think of a building material other than earth that fits?


Thanks again for your posts so far. Looking forward to seeing the rest of this topic play out :)

S

Posted By: stulutionsensure that a wood stove isn't too close to the wall, etc. etc.

Why would you consider burning it if you don't wish to build with it?

For my current house I did consider building with a structural frame of timber and then encasing it all in hempcrete walls produced with formwork but I chickened out as I was worried about possible resale value.

Ed's right - cut a mature tree and make sure a new one will grow, at its most vigorous when young - soon enough equals out. What is most valuable is that the old tree can then have its carbon sequestered unoxidised, resulting in that much less CO2 or even CH4 in the atmosphere. Especially if it's a local tree, extracted by horse, to eliminate the huge release of sequestered CO2 that's caused by diesel vehicles chawing up the forest floor.

You've said why not to straw bale, timber frame etc - but not why yes to compressed earth. Would you by any chance compress your own blocks from site excavated clay? Or even build uncompressed/unshuttered, cob-style? That seems eminently 'natural' to me.

That still leaves the question of insulating it. Remembering that bead-board Expanded Polystyrene has far lower eco-bad points than Extruded Polystyrene and all the other foamed-board insulants, external EPS is practical, lo cost, reliable and risk-free and 'pays back' environmentally after very modest life-of-building. Ideal - heavyweight interior inside a thick unbroken 'tea cosy' of insulation.

yes to compressed earth block because:

fire proof, rodent proof, bullet-proof, sound proof, masonry techniques are easily taught to others, minimal maintenance,mold/fungus proof,maintains humidity levels in home, thermal mass, breathable, life span in multiple hundreds and potentially more than a thousand year, no VOCs or other pollutants (though that can be called into question when using portland cement instead of lime)

ideally, i would source material on site whenever possible/feasible, but I would also use "overburden" from local aggregate yards when the build does not call for major excavation for some other reason.

Not sure I understand what you mean by unshuttered? Definitely wouldn't build uncompressed unless I was living somewhere in the tropics with lots of hot drying sun and space to dry adobe bricks.

re:bead board - how does one cut/rasp it without allowing those nasty lil beads to spread all over the environment?

Thanks again for the replies, though I am quite surprised that there is no fans of this method on the forum so far. I must admit, its a bit of a shock to my system! :)