When people consider building with straw bales, they most often find their top concern is how to protect the bales from rain. All too often, snow is not considered a threat to the structure. In most cases, this is true; however, in areas where large snow drifts are the norm, the impact of snow cannot be overlooked without consequence. It is typical that climates with a lot of snow, especially powdery snow, will eventually blow hard enough to create drifts. Those drifts will pile up on whatever interrupts their path, even if it happens to be your front door!
If you expect to have snow drifts as a common occurrence on your property, you can do several things to protect your straw bale house. The first is the most simple: plant buffers. Snow drifts are created by prevailing winds working hard to move snow around. As I said earlier, the snow will pile up against anything that interrupts its path. In order to avoid piling snow against your house, give it something else to pile up on. By planting low and think shrubs around the home, you can not only improve the look of the property but also protect your house from drifting snow. A second line of defense can be planted further from the house in the form of trees. They serve the same purpose as the shrubs, but interrupt the wind further from the home which will help the shrubs handle whatever wind and snow does make it through to them. The trees can be planted such that they help with heating and cooling costs as well via solar gain and shading as well as the disruption of the winter winds.
A more drastic approach is to build the bales up on a framed platform. Instead of placing the bales on 4x toe ups, build a double pony wall: one pony wall at the exterior toe up location and another one at the interior toe ups. The height of this wall depends on the expected height of the snow drifts. Use standard construction techniques to build these walls and sheath them with plywood for lateral stability. By covering the exterior pony walls in house wrap, you protect them from the affects of standing snow. One advantage of building this way is that the installation of plumbing and electrical is made considerably more simple. The wires and pipes can be run through the open space beneath bales and then that space can be heavily insulated. The extra cost for lumber and labor to build the pony walls can therefore be recouped by the labor savings for the plumbing and electrical installations. Check out the ease of running lines in the picture below. All this while protecting the bales from snow drifts that might otherwise melt against the wall and cause moisture problems in the bales.
Top Photo Credit: Gloria Jean; Colorado
Other Photos by Gabriella Morrison
About the Author
Andrew Morison is a specialist in straw bale and green construction. He has shown thousands of people how to build their own straw bale projects through his comprehensive series of instructional straw bale, concrete foundation, and plastering DVDs. You can check these out at http://www.LearnStrawBale.com.com.
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November 28th, 2007 at 5:14 pm
The current issue of Mother Earth News (December / January 08) on page 19 talks about the benefits of a living fence as a way to keep snow off the roads. Just as you describe for around your house.
But could you not also wrap the lower section in tar paper,just as you would in high rain areas? Thanks for all the great information, Rob
November 28th, 2007 at 6:00 pm
Rob,
You could wrap the bottom with roofing felt; however, I don’t like the idea of sealing moisture in to the walls which can happen with the felt. When I have been required to use the felt, I make sure to leave the bottom face attached to the toe ups and not wrapped under the bales. This allows any moisture a way out should it get in there.
November 29th, 2007 at 7:16 am
Andrew,
Is Tyvek any better than roofing felt?
Scott.
November 29th, 2007 at 7:17 am
I live in Colorado and we occasionally get snow drifts in my area. It is not something that always happens, but I do get them every year at least once. I am concerned that shrubs would not work for me since the drifts are usually pretty high (4′ against the barn). The area I want to build my house is fairly open and I think I would have the same 4′ drifts against the house. It seems like if I use the pony wall idea, I may as well build a standard framed house since at least half my walls will be stick frame anyway. What are my options here as I really want to stay with straw bale for the insulation values? Thanks in advance for your help and your great website. It is an awesome resource!
November 29th, 2007 at 7:23 am
Wouldn’t the insulation of the bales keep the drifts isolated from the warmth of the house? It seems like the snow would simply act as additional insulation for the wall and would not cause any issues with the straw. I can’t imagine the snow would melt against the wall and cause any moisture issues.
November 29th, 2007 at 11:38 am
Scott,
Tyvek can work too. Some prefer it over roofing felt because it is designed to allow vapor to move through it. Some question whether or not it actually performs the way the company says it does, but it can be a good option to use, especially if it really does perform well. The down side is that plaster does not adhere to it at all and so it can creates issues when plastering. To remedy this, you may need to add more metal reinforcement (stucco wire).
November 29th, 2007 at 11:43 am
Alex,
Thanks for the positive feedback! I think you would do well to use the “living fence” idea. You could use larger plants further away from the house to provide a bigger “wall” while also using the smaller plants closer to the house. In combination I would expect that the wind driven snow will be slowed down enough to protect the walls from drifts. I suggest you work with a local landscape contractor who understands how “living fences” work. Good luck.
November 29th, 2007 at 11:49 am
Jennifer,
You raise a good point about the insulative value of the snow and the bales as well. My concern is that the snow could melt by the heat of the sun or the warmth of the air and with it pressed against the wall, it could cause problems inside the wall that would be hard to locate and/or identify. It may not be 100% fact that it WILL cause problems, but I am a firm believer in taking steps to minimize risk when building a new home.
December 30th, 2007 at 4:03 pm
I live in north of Norway, a place were we have a lot of snowdrifts, and in a normal situation, the snowdrift will melt from both sides, if it is into a wall or anything else, because the sun is warming up the wall more than the snow.
In the dark season (we have two full months with darkness) the warmth of the wall is melting a small glitch between the wall and the snow. If the plaster on the outside of the straw bale is sealed its no worries.
January 15th, 2008 at 8:30 pm
Rather than the pony wall, is not a weatherproof wainscot (such as brick, rock or concrete stucco) on the lower section of the outside wall not enough?
January 16th, 2008 at 7:57 am
The problem with the stucco, brick, etc… is that it is not actually waterproof enough to stop the inflow of water from melting drifts. If you make it more waterproof so that it can handle that inflow, then you run the risk of damaging your bales by trapping moisture in the walls. The pony wall is a happy medium which provides other advantages as well, as discussed.
Andrew
January 17th, 2008 at 1:24 am
In the above picture inside the ‘pony’ wall there is straw on the floor. Isn’t that a great fire hazard – especially in there?
January 17th, 2008 at 10:48 pm
James. Absolutely! You are totally correct. The only reason there is loose straw in the pony wall is that we had just finished baling when I took the picture. I would NEVER LEAVE LOOSE STRAW in the area under the pony wall for the risk of fire. Thanks for pointing that out for everyone. That is very important.
February 11th, 2008 at 6:17 pm
If you are building with straw and using natural plasters in snow country, you should have at least 30″ overhangs. We have 40″ of snow this winter and it does get close to the wall. I will shovel a path under the overhang to walk and keep the melting snow off my walls. Design with a foundation 0f 12″ height above grade
February 22nd, 2008 at 10:25 am
Living in Alpine Meadows, CA, I often see more than 8′ of snow on the ground in the winter, and it often builds up more on the lee side of the house. As far as moisture goes, I would be much more concerned by wind driven rain, than by snow. As soon as the snow is melted by heat from the wall, the snow pulls away, hence very little water is transfered to the wall as the snow melts. A much more likely issues of moisture effecting walls from snow would be water dripping off the roof as the snow melts and splashes on the walls. Gutters are problematic in areas with heavy snowloads.
April 6th, 2008 at 5:46 pm
Andrew,
A toe-up question, although not related to snow drifts. I’d like to stay away from the use of pressure treated wood in my walls (or use ACQ if necessary). If a straw bale wall is being built over a crawl space that has a standard wood joist floor (2×12s or BCIs) w/ sheeting, do toe ups still need to be added, and do they have to be pressure treated? From a structural standpoint, it seems the 20 penny nails for holding the bails could be nailed directly into the sheeting and joists (albeit the sheeting is not as strong as a 4×4). And from a moisture standpoint, the floor system gets the bales off the concrete, and if any appliances leak, it seems using pressure treated 4×4s on top of a non-treated floor system might not matter? Just looking for alternatives, if there are any. Thanks.
April 6th, 2008 at 9:44 pm
On wood decks, you do not have to use the pressure treated wood. In fact, you can use a thin layer of composite decking under your toe ups on concrete and then use regular wood. Not all jurisdictions allow this so you will need to ask your building department.
October 2nd, 2008 at 7:21 am
âõüð ÑÂтðрðѠúþýõчýþ öõ, ýþ ÿрþчøтðû ѠуôþòþÃȄ΄Âтòøõü
Russian to English rough translation: “Theme old certainly, but has read through with pleasure:)”
October 29th, 2009 at 9:53 am
My question relates to the current snowdrift dialog. I also live in colorado, and am seriously considering the straw bale method of construction. To avoid snow drift related wall damage, making the foundation 12″ above grade, and building the roof with 30″ overhangs or greater, seems to make a lot of sense. I like the ponywall idea as well, but I’m wondering what options I might have, to keep this modification from reducing the energy efficiency of my future home, as well as preventing this strategy from compromising the sound proofing perks of traditional straw bale construction. I also have 2 more questions: 1. Would building a 3 – 4 foot wall of stone or adobe brick onto the perimeter of the foundation and then adding straw bales solve the problem? 2. Over the long haul, is it better to cover all the surfaces of the house in metal lathe before plastering, or does the texture of the bales provide long term protection from major cracking in exterior plaster coatings?
November 4th, 2009 at 8:15 am
Hi Steve. The pony wall will be equally as soundproof and efficient since it is built out of two frames, separated by a relatively large distance, the width of the bales. The only sound that will be transfered through the wall will move through the plywood deck that you build on top of the pony wall that supports the bales. You could actually build some separation into this as well if you wish to fully eliminate the sound’s ability to travel. All you need is an inch of dead space.
The insulation value comes from the fact that you can stuff the entire pony wall with insulation. At 14″ wide, you can easily get R-44 worth of insulation in that space. Use 2 batts of R-22 insulation (that’s only 11″ wide) and so you could even add more if you like.
The stoner or adobe could help; however, those materials have permeability issues as well. In other words, the mortar or in the case of the adobe, the bricks themselves, would suck moisture into the wall if it was “free moisture” laying against the walls. I think the best thing is to consider the use of landscaping to stop the drifts from being able to form against the walls in the first place.
I, personally, like to use 2″x2″ 14 gauge welded wire mesh for most of my homes. It provides extra strength for the plaster, helps with attaching cabinets and other “wall hanging things,”provides out of plane wall strength (replaces rebar or other types of bale pinning), helps create great shapes at corners, and provides additional shear strength to the building.