For too long the insurance industry has held the owners of straw bale buildings captive while they sway back and forth with the prevailing winds when it comes to insuring our buildings. We begin to address this issue in the first of a series of articles on this topic.
Jame Henderson of Henderson Clayworks shares his knowledge of bale wall plaster systems and how to differentiate the most important aspects of each
In the first of a two part series article, Jacob Deva Racusin explains the differences in monitors for your walls. This is “must know” information for every builder and owner.
Alex Sparrow begins a two-part series on hemp lime, or hempcrete. Hemp lime is relatively new but is fast becoming part of the natural building lexicon.
By Andrew Morrison of strawbale.com
There are many different approaches to framing a straw bale house; however, there is one in particular that I have used on the vast majority of my projects over the years. It is a post and beam frame system with roots in conventional framing techniques. Because I came to straw bale construction many years ago as a general contractor practicing conventional construction, I brought some of that detailing over. I should preface this article by saying that there are right ways of framing and wrong ways of framing. The system I describe in this article lands in the “right way” column, but so do many other styles. As long as you are working with a structurally sound and safe system that brings you the best results possible for your style of building, then go for it.
One of the first details that often surprises people is the spacing of the posts in the system I use. I hear people talk about wanting to reduce the amount of notching in the bales by spreading their posts out as far as possible. I disagree with this approach and instead keep my posts relatively close together: no more than 6’ apart. One reason for this is that when the bales are stacked in between posts that are set far apart, there is no point of attachment for the bales other than the top and bottom of the wall. As such, the wall becomes weak as it is stacked higher. When posts are set closer together, the notches at each location provide a point of connection to the frame and make the wall much stronger both during construction and for the life of the structure.
One way I keep the posts close together is by incorporating them into the window and door frames. By using 4×4 posts as the king studs I end up with wider nailing surfaces on either side of the opening. This allows me to attach the finish trim, plaster channel and/or plaster lath, and welded wire mesh around every opening with positive attachment to the frame. These king studs serve two purposes by providing the nailing surface and by acting as part of the overall structural frame. Because windows and doors are placed in many locations around the home, and because I otherwise limit my post spacing to no more than 6’, I can minimize the wall beam size as a result. This minimal wall beam is important because the bigger the beam, the more expensive it will be. Further, larger beams are made from larger trees (unless an engineered beam is used) and I want to reduce the size of the trees I am using in my projects for environmental reasons.
Okay, let’s take a look at how the system works and why it can save time and money in your building process. I’ll simply lay out the process so you can see, step-by-step, how it comes together.
We like to share this is the type of information because the context of lime plaster is so broad and interesting. It is important to keep in mind your goals when choosing materials. The information below creates a connection between two areas of lime plaster that are very important to understand before choosing a material for your project.
The Endeavour Centre has shared their process for making artificial hydraulic lime using locally available materials. The fact that they are able to source the materials close to home and create a consistent material using a simple process is what makes this tid-bit stand out.
In Issue #62 Michel Couvreux from Transmineral explained the various types of hydraulic lime and how to choose one that is appropriate for your project based on specifications. Natural hydraulic lime (NHL) is a naturally occurring material of high consistency that is very durable and easy to work with. In contrast, an artificial hydraulic lime (AHL) is created by blending materials to create similar set times and durability performance as a NHL. As Michel points out in his article, the consistency of AHL’s cannot be guaranteed and therefore quality control may suffer. However, if experimentation is possible and a level of risk can be tolerated, following a similar to process to what the Endeavour Centre has done can be useful and beneficial.
The point here is that you must educate yourself and experiment before committing to a new mixture of materials. Most importantly, you want your building to perform as expected.
Let us know how your experiments go by sending us an article so we can share it with everyone.
As an update to this post about the Feuillette House in France, here is a patent in the United States for straw bale construction. It was filed on June 6, 1921 and is a very interesting read for the bale construction history buffs out there. The author was Emile Feuillette himself and approved on June 6, 1921.
This is not the oldest patent on bale construction as we documented back in Issue #21 in the Winter of 1998. That title goes to Josiah M. Leeds (of Indiana, not Nebraska) in 1880. The article describes and contains illustrations of three subsequent straw bale building patents (1885, 1903, and 1905). Issue 21 can be ordered on our CD of the first 40 Issues here.
Reviewed by Jeff Ruppert
Earth Render: The art of clay plaster, render and paints by James Henderson is a refreshing, easy approach to what can become an overwhelming process. As anyone knows who has worked in the natural building trades, earthen materials are highly variable and therefore require a basic understanding of those variables. James Henderson explains this process in a concise, easy-to-read format with plenty of illustrations.
What is nice about the approach of this book is that it is meant for the novice as well as the seasoned tradesman. It can be followed by anyone and needs little introduction. It focuses on how earthen materials are used to clad and finish walls, and that is it. There are no lengthy chapters espousing the virtues of earthen construction. Mr. Henderson assumes that you are reading his book to learn the finer points of his trade, and therefore an ethical discussion is not necessary.
An appendix on Light Straw-Clay Construction was also approved for inclusion in the 2015 International Residential Code (IRC). To date only the states of New Mexico and Oregon have a section on Light Straw-Clay Construction in their building code. The proposal received a 6-3 approval vote at Building Committee Hearings in Dallas in April 2013. After public testimony and immediately before the vote, one committee member encouraged approval, commenting, “This is the future.”
The appendix governs the use of light straw-clay “as a non-bearing building material and wall infill system”. It is limited to one-story structures, except it allows structures greater than one-story “in accordance with an approved design by a registered design professional.” It is also limited to use in Seismic Design Categories A and B, but this includes approximately 85% of the contiguous United States. Use in higher seismic risk categories can occur through the “alternative means and methods” section of the code with an engineered design.
The appendix proposal was submitted by architect Paula Baker-Laporte, who along with husband Robert Laporte form the company EcoNest (www.econesthomes.com) as the leading practitioners of light straw-clay construction in the U.S.
The appendix was co-authored by architects Paula Baker-Laporte and Martin Hammer, with significant input from Richard Duncan, PE and Robert Baker-Laporte. Practitioners from mid-west, including Lou Host-Jablonski, Architect, Sue Thering, and Doug Piltingsrud, contributed to the Commentary, which is expected to make the appendix more flexible in its application.
The full text of the appendix as it will appear in the 2015 IRC can be downloaded at:
Additional text and illustrations are planned to be included in the “2015 IRC Code and Commentary”
Contact: Paula Baker-Laporte at [email protected]