Thursday, April 6, 2017

Post and beam construction


One of the most popular ways to create strawbale and cob homes is to use a post and beam structure. In this system large posts are used to support the massive amount of weight from the roof and distribute this load evenly on the foundation of the house. Many will be familiar with this technique, as load bearing houses--buildings that use the strength of the bale/cob walls to support the roof--are not building code and inspector friendly. Once again, the fact that load bearing structures do not comply with building codes has nothing to do with their structural capacities, but because these types of systems are unfamiliar. I suspect as our forests continue to disappear and our lumber industry continues to increase the cost for dimensional lumber, new codes will be created to accommodate smarter construction methods.

Of course there are a huge number of benefits from post and beam construction beyond code compliance. What we believe to be the greatest benefit of post and beam construction is that roof construction can immediately follow the building of the foundation. Both cob and straw are prone to moisture problems during the building phase. In our first cob house build we spent
Cheap blue tarps work but only last 1 year
a large amount of time covering and uncovering the walls with tarps so that the rain wouldn’t damage any of our house. Without a proper covering, bales and cob can easily become saturated from heavy rainfall causing an increase in time or money to fix problems.

At Spiritwood, the new house will mostly consist of load bearing walls with three large posts supporting a center beam that
will help distribute the load of the heavy living roof. Each of these three posts function to carry a tremendous amount of weight and take stress off of the rafters spanning the width of the ceiling. The width of the posts are determined by the amount of weight each needs hold. This is a great place to over-engineer building plans as even an extra few inches will lend a huge amount of strength to your building. The timber we chose has an average diameter of 14 inches.



The second benefit of post and beam construction is the amount of lumber and embodied energy the builder saves when compared to modern stick-frame construction. Remember that not only do modern stick-frame houses use much more wood to support the weight of the building, but the energy used to saw, plane and kiln dry construction grade lumber is substantial.

The last benefit of post and beam construction we will mention is also extremely important for the DIYer. Without a proper wood mill, making dimensional lumber is an almost impossible task, whereas cutting and peeling logs is a breeze compared and requires minimal skill with muscle-powered woodworking tools like an adze or a drawknife. You probably even have a tool laying around that will work well like our modified flat-nosed shovel debarker.

As always, remember to do an extreme amount of research and planning before starting any building process. For those interested in post and beam, check out James Mitchell’s The Craft of Modular Post & Beam as well as Rob Roy’s Earth-Sheltered Houses which gives great insight into the weight bearing capacities of timber framing under an earthen roof design.

2 comments:

  1. Fabulous online journal! Do you have any tips and indications for yearning journalists? I'm wanting to begin my own site soon however I'm somewhat lost on everything. Would you propose beginning with a free stage like WordPress or go for a paid choice? There are such a large number of choices out there that I'm totally overpowered .. Any proposals? Much obliged! Sherwood Reese

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    1. Go with free at first. I tried wordpress and liked blogger more. The nice thing about free blogging is that you can later upgrade your blogger site to a paid address such as ours. This doesn't cost more than a few dollars a month and gives you a much cleaner web address.

      I've read tons on professional blogging and stepping up to make money on it. Expect to but a good few years in before anything like that happens. Work to develop an audience. Share on as many social media platforms as possible. Ask to make guest posts and to make social comments on forums dealing with your blogging interest.

      Consistency is the name of the game, and something that is hard to do when you work 40 hours a week and are building a house. You don't need to post daily, but in a consistent manner. I try to get a post out once each week (as you can see I fail most of the time), and tweet/instagram a photo daily. I also try to post on Permies.com--a forum website dealing with permaculture-- at least twice a week. My website is in my signature on this site and I get a lot of traffic from those posts.

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