The Truth Window of a Straw Bale House Tells All

Published by Lily Korhonen under Green Building

Many of us dream of moving to another part of the world, changing lifestyles, and starting life anew. But how often do we make these dreams come true?

For Hubert Den Draak and Jacomyn Gerbrandy, this dream became a reality when they moved from Holland via Toronto to the beautiful boreal forests of northwestern Ontario, Canada. There they found the perfect piece of property on which to build their dream of an eco-friendly lifestyle, and back in 2006 they began building their home powered by the sun and wind.

What does their sustainable lifestyle look like? I paid a visit to Hubert and Jacomyn to familiarize myself with life off the grid.

During my house tour I began imagining myself waking up in the morning and walking into the bathroom for my morning routine. I hop into the shower, heated by solar hot water tubes, and use the waterless composting toilet, which consumes no water and provides compost for the garden.

As I head downstairs, I feel the warmth of the sun coming through the large south facing windows, heating the concrete floor and lighting the stairway. I enter the open concept living area, where warm air circulates throughout the house. Depending on how much energy is stored in the battery bank, I plug in my coffee maker or boil water the old fashioned way—on a Mennonite-built wood burning stove.

I pass by the utility room that houses a battery bank (with six lead acid 24-volt batteries fed from eight solar panels and a wind generator), an on-demand Rinnai water heater that serves as a backup to the solar thermal heat system, a propane tank, a grid connection using an Outback Power System, and a low-watt water pump system for the well.

As I head out for work, I pass through the enclosed front porch where I look into the ‘truth window’ shown here, one of most powerful images I have of the house. Most straw bale houses are built with truth windows to expose the straw bale construction method, insulating the house from fierce winters, yet allowing the walls to breathe—continuously purifying the interior air, temperature, and humidity.

The last stop, and perhaps the most curious to me, is the empty mailbox. I have long since forgotten what an electricity or water bill looks like.

My recent visit with Hubert and Jacomyn led to many stories and insights about their sustainable lifestyle and the wonderful B&B they run here. I captured the conversation on camera and video, so look for more blogs from me, detailing the features of the straw bale house with the truth window that tells all.

In the meantime, let me know your straw bale story…

Video from May 2007 of Nolalu Eco Centre

12 Responses to “The Truth Window of a Straw Bale House Tells All”

Hubert Den Draak says:

October 23, 2008 at 4:52 pm

Just curious to hear what others think about building with straw. Visited a straw bale home? Got any experience with it? Thinking about it?
We are still surprised to see how everything works exactly as the text books said it would. Comfy cool in our (short) hot summers, toasty warm in our sub-arctic winters. Now who’d ‘ve thunk that?!

Hubert
(You’ll soon be reading more from me here as one of the bloggers on your friendly neigborhood eco-site!)

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Kacey Cramer says:

October 26, 2008 at 10:31 am

I am an Environmental Student working to present Advanced Energy ideas to the student body and local community. I am researching straw bail construction and finding concerns with mold growth. My first question is, have you found any mold growth? Have you done anything to combat the issue? My second question is simply what kind of solar panels do you have for your setup and what is some of there specs? Thank you for your time.

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Jacomyn Gerbrandy says:

October 27, 2008 at 11:03 am

Hi Kacey,
-No we have not found any mold growth. The walls can handle a certain percentage of moist. The walls are breathing because they are porous, we did not use the poly vapour barrier and we plastered the walls. Also we did not use latex on the walls which kills the breathabillety. If there is at some point moist in the walls it will dry out again because of the breathing effect. So we did not find any mold so far. It works. We made as sure as possible that straw bales were dry and stayed dry during building. During rainy building days we covered the straw walls with building paper to keep them dry.

-About our solar panels: We have 8 solar panels 175 watts each. so they produce all together 1.4 Kwhrs. It is hooked up as 24 volt dc. The solar array sits on a manual tracking system on the ground.
Hope I have answered your questions well enough.

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Bill Christensen says:

October 31, 2008 at 12:07 am

Nice article!

Here are a handful of other straw bale building links which may be of interest to anyone intrigued by the idea of building with straw bale:

International Straw Bale Building Registry: http://sbregistry.greenbuilder.com
Over 1400 bale buildings listed as of Oct 08. Find straw bale homes near you to visit. Find out which companies have mortgaged and insured straw bale homes in your state. If you’ve built a bale building (or know someone who did) please add it to the list.

(for instance, I don’t see Hubert’s place listed there…)

StrawLocator.com – free/donation classified ads for buying and selling straw and straw building tools.

The Last Straw Journal – http://thelaststraw.org
The definitive quarterly journal of straw bale and natural building. Subscriptions and 10+ years of back issues in PDF or paper available.

Sourcebook strawbale: http://greenbuilder.com/sourcebook/strawbale.html

My favorite discussion lists:

SB-R-Us: http://groups.yahoo.com/group/sb-r-us
Probably the most active of the strawbale lists. Many folks there with a lot of knowledge – and many ‘newbies’.

Global Straw Building Network (GSBN) private, with public archives: http://greenbuilder.com/mailman/listinfo/gsbn
GSBN is essentially a high level think tank for a group of people deeply committed to straw bale construction. They wanted to get beyond the “strawbale 101″ questions that had been answered on other lists 101 times and put their energies into extending the knowledge base on a professional level, and to connect with their peers in other countries and continents. GSBN also serves as the technical editing arm of The Last Straw Journal.

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Bill Christensen says:

October 31, 2008 at 12:21 am

Kacey wrote: “I am researching straw bail (sic) construction and finding concerns with mold growth. My first question is, have you found any mold growth? Have you done anything to combat the issue?”

As Hubert mentions above, straw bale is fairly tolerant of small amounts of moisture if it is able to dry out within a reasonable time frame.

Mold is certainly a possibility in strawbale construction if it is subject to prolonged exposure to moisture. There are several simple steps which can be taken to prevent any problems though. The first is to build in such a way that liquid water never touches the bales. That includes keeping bales dry before, during, and after construction.

Keeping water out of the bales once built is typically accomplished by using wide overhangs or rainscreen construction to keep rain off the walls; attention to detailing around doors, windows, and other penetrations; insuring that condensation will not occur within the bales or at the plaster-straw interfaces; and if possible keeping plumbing runs out of the bale walls or at least in sleeves.

Many builders will also spray the bales with a borax solution, which retards mold, reduces flammability, and inhibits pests.

See my previous post for more depth.

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Mishel says:

November 4, 2008 at 4:12 am

Hi I’m a final year Architecture student conducting my thesis on sustainable housing. I’m thinking of using straw-bale as a construction material for it has many advantages over any other conventional material. I have a no. of queries in my mind which i believe you can solve.

1). What are the possible foundation systems for such type of construction? and what is the best foundation system for asian region particularly Pakistan specifically Lahore, which has agricultural soil?
2). Concrete is not an environment friendly material and my aim is to make the houses as much environment friendly as possible. while suggesting material for foundation, plz suggest an alternative material.
3). Sloping roofs are not required for climate like Lahore, How can flat roof be constructed with such construction?
4). How many floors can be errected with straw-bale?
5). Does the use of lime mortar as finish, has any disadvantage?
6). Of what material should the internal partition walls be made of? possible options?

Thanks.
Regards,
Mishel

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Change, it will come. « Hans27026’s Weblog says:

November 6, 2008 at 12:28 am

[...] Story of how a family completely changed their way of life… for the better. [...]

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Stefan Carpentier says:

November 7, 2008 at 2:20 pm

HI Mishel
I am very interested in Straw Bale construction, took a 2 day workshop in Hopland to learn how to do it and then read a bunch more from a variety of sources.
1)2) Foundation systems
There are a variety of foundations possible, it really depends on the localities which one to use. Concrete is not really sustainable, but in some cases it might be the best ‘insurance’ for your building to last 100+ years. Here is what I heard of in terms of alternatives. Caged rock; take local large base rock and stuff it in wire mesh cages, they have obvious sustainability advantages and do an excellent job in keeping you bales dry and ‘ventilated’. They also keep your bale wall off the ground and away from ground born moisture. I saw people use baged sand and cover it up with plaster to avoid UV exposure and therefore prevent the bags to disintegrate. In class we used a concrete foundation and bolted a wood composite frame onto it (just 2×4), into this frame nails where then driven to assure the bails wold not move on the frame.
3) Roof
Once you have the walls built up, stitched the walls and compressed them for stability you can really put any roof shape you like on it. Anything. Go wild or go traditional, just make sure you have good 60cm(2ft) of roof overhang to protect the walls from splashing rain.
4) # of floors
If you want to construct a building with a conventional wood or metal frame, you can make a straw bale building any number of stories high 2 or 100. You are using the straw bales only for insulation and building the frame-infill. If you want to construct a straw bale building with what is called “load bearing” walls, then I heard of a 2 story limit here in California. I am not sure how much is actually possible though.
5) Finish
I am not familiar with the name ‘lime mortar’ but what I read on Wikipedia it seems like it is pretty breathable and sufficiently stable to be applied to the walls as an external/interior moisture barrier. I was told it is very customary to use Natural plaster on Straw bale buildings. Natural plaster is very sustainable and has an incredible wonderful scent to it. I applied it with my hands and LOVED it, it is so natural and non toxic, I think you could eat it. It also creates an amazing interior atmosphere and the sound qualities are great too.
6) Internal walls
You can really make the walls from any material or construction method of your pleasing and local availability. If your local contractors or helpers are most familiar with one and you like it, use it.
Straw is for me the ultimate building material, I am looking forward to hear of your progress.

Please look at this site for more information: http://www.strawbuilding.org/
Here is my writeup from the workshop. It is not pretty, but might contain info for you. http://docs.google.com/Doc?id=dfgz223m_180fsk8mfgt

CIAO

Stefan

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Bill Christensen says:

November 7, 2008 at 4:35 pm

1). We’ve heard of many different types of foundations – from the rubble trench and earth bag methods described above to “earthship” type foundations (soil rammed into old auto tires) to more conventional concrete slab and pier-and-beam construction.

Just make sure that the bales are isolated from any potential moisture sources – capillary action, flooding, heavy rain splash-back, etc.

You may want to get in touch with the folks at Pakistan Straw Bale and Appropriate Building (paksbab.org).

3). Sloping roofs are not required for climate like Lahore, How can flat roof be constructed with such construction?

I would strongly recommend against flat roofs anywhere unless it *never* rains! Especially so with straw construction, as moisture and bales don’t mix well. It’s simple enough to put a slight slope on a roof to insure that moisture is not a problem, and as pointed out above you’ll probably want an overhang for rain protection. It’ll also help to shade the home in the summer – it’s a good passive solar design principle. DO NOT attempt a parapet wall – they’re a nightmare waiting to happen.

4). How many floors can be errected with straw-bale?

You could probably go 3 stories with load bearing straw bale, but I’d suggest that you do a real good job on the structural analysis for that.

5). Does the use of lime mortar as finish, has any disadvantage?

Lime plasters are wonderful. They beat out cement plaster by a long shot, and have more stability than straight earthen plaster. Go for it.

6). Of what material should the internal partition walls be made of? possible options?

compressed earth block or other thermal mass inside will serve to even out the temperature swings, though that’s not usually necessary with straw walls. Pretty much anything that is commonly used for interior walls in the area will work fine.

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mark vineyard says:

April 2, 2009 at 5:33 pm

This is awesome. We are planning on building a straw bail house in Euphrata, Wa. soon and are very excited to use all green materials.

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Mishel says:

May 22, 2009 at 4:51 pm

Thanks a lot Stefan and Bill for elaborated replies. The info has been really helpful in clearing out the ambiguities. Unfortunately, for some reasons, I had to drop the idea of using straw bale in this particular project but I ain’t giving it up forever. I’ve gathered much info. regarding straw bale construction and i’m interested in its practical implemention in near future. I might be comin back for more help and advices. Thanks once again.

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Weaning Off the Grid | Green By Design says:

November 23, 2009 at 10:39 pm

[...] to our Nolalu Eco Centre always marvel at our energy independence. Especially, our solar panels and small wind turbine, that [...]

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