This Blog is Moving to the Home Page at www.StrawBale.com

This straw bale blog has been so popular that we have decided to expand it and move it to the home page of our site. I have covered so many topics about building with straw bales and using green building techniques, that we at StrawBale.com have realized the full power of this format and want to share it with as many people as possible. From now on, all of the conversations that have taken place here will be located at www.StrawBale.com. In addition, and perhaps most excitingly, the blog format has been updated and is now a hybrid or multi-media blog with embedded videos, articles, photos and more. It is 100% searchable with a Google search bar so you can find any topic that I have written about quickly and easily.

This blog address will no longer be active after this post. From now on, please visit us at www.StrawBale.com to find out the newest and most up to date information about straw bale construction. Please visit often or make us your home page so you can stay up to date. I encourage you to post to the blog as well. The conversations are perhaps the most rewarding part of the blog format. Thanks for reading and see you at www.StrawBale.com!

2008 Workshops With Andrew Morrison

I am excited to announce the launch of www.StrawBaleWorkshops.com. This new site will list the information for all of the workshops I will be leading in 2008. As it stands now, I have three workshops scheduled for Southern Oregon. The dates are April 14-20, May 5-11, and September 15-21. In addition, I have a tentatively scheduled, special 2 week workshop in Armenia starting July 21, 2008.

I am looking for hosts for at least two more workshops. The first hosting date is for a workshop in Great Britain and the dates are June 16-22, 2008. The second planned week that I need a host for takes place in Europe from August 11 to August 17, 2008.

I plan to do a lot more workshops in 2008 than I have in the past. The demand for such workshops has always been high, and I have finally carved out some time to make them happen! If you want me to build a small straw bale cottage on your property with the help of 15-20 avid bale students, please let me know by visiting my new site and applying as a host. The workshop is then free for you and a guest.

So if you want to be a student of mine and/or if you want to host a bale workshop, please visit www.StrawBaleWorkshops.com. You will find all the information you need about the workshops, hosting, and more, including a hosting application form and a student registration form.

I'm really excited about this expanding workshop schedule. I love having the opportunity to meet new people and teach them what I know. I look forward to meeting many of you soon!

Steel Kit Framing Systems

My mother in Law is currently having a barn built for her horses. I have been very impressed with the speed in which the structure has gone up. Three to four men have been working on the site for a bout a day and a half and the entire frame is up and most of the 2x6 interior wall boards are laid. This has lead me to think about the use of metal "kit" buildings with straw bales as the wall insulation. Others have mentioned this to me in the past and I quite honestly did not see the advantages with the same sense of excitement that I do today. I can imagine having a house framed in two days and ready for bales! Wow, that would be exciting. I failed to mention that the barn currently under construction is no small affair. It is about 3000 SF so the day and half progress is very impressive. My mother in law said she had a lot of opportunities to fine tune the design to her liking, but not so many that she became overwhelmed. That is a great balance. If you have any experience with steel kit buildings and have some advice for how bales could marry this technology, please let us know!

Another Question About Plastering Straw Bale Walls

Here is an email I received today. My answer is below.
==========================================
Andrew,

We have already done the first two coats and wanted specific instruction on
the last as it is the one that will encounter the weather. We have used
ordinary clay, gritty ( lots of facets and sizes of grains) sand and chopped
straw for the first two coats and they were much drier than what you showed.
We also didn't wet down the bales first, but did sponge the first coat
before applying the second. It is very rough so we don't think we'll need
the scratch thingy. Our ratio was 3 parts sand to 1 clay and about 1/2
chopped straw. The clay was dry bags purchased through the pottery supplier
in town. It was easier to apply with more clay and we tended to put in less
sand as the walls went along. unfortunately that meant there are a few
cracks now... not really big but there none the less. It seems to be well
stuck on and really hard though. It is weathering were there are direct
winds and rain, mostly the west side of the house.

So really at this point we are just soooo tired and want someone to come do
it and FIX it! We had hoped in the beginning to get someone to use regular
stucco for the final coat and thus have a maintenance free exterior. we have
heard recently though that the mixtures would react differently to climatic
changes and might move or crack relative to each other. what do you think?

Maryann
==========================================

Maryann,
I am sorry to hear that you feel you have reached a stopping point. I know how that goes. That said, I think you still have some options to take care of your concerns. If you have a relatively smooth second coat in place, you can fix the cracks with relative ease. If you have the plastering DVD, go to the scene about floating the brown coat. That is where you use a rubber float to push ad swirl the second coat of plaster into the first. It smooths the surface and strengthens the plaster. If you have already done that, great! If not, you can still do it if you mist down the clay and start floating. This is one joy of clay plasters: you can rework them even after they harden. The same is true for the cracks. You can mist them and float them back into the plaster. For the final coat, I suggest you use a lime plaster with the color in the plaster. This will allow you to finish the plaster in one shot, no need to paint, and will provide a resistant surface for the elements. I suggest Natural Hydraulic Lime if you can fit it into the budget. You can find them at www.limes.us. That will work over the clay with no problem. It is more flexible than cement based plasters ands therefore can handle the movement. This is a thin layer, so the brown coat will need to be smooth before you can apply the lime finish coat. Good luck and make sure to rest your plaster arm. I have a friend who ruined her shoulder by working too hard for too long on plastering walls.

Andrew

Some Great Questions Answered!

Here are some questions I got from a client yesterday. I think they are worth sharing.

Q1. How much force is required to tie the bales tight. (my elbows are killing me)

A: The knot that I use, the Miller's Knot (although I have been told that the name might be incorrect)is so strong that it is possible to tie the bales tighter than the original baling machine. This requires a strong twine as well as the standard twine often snaps under the added pressure of this knot. Super blue twine works very well. In general, I try to tie the bales as tight as I can. This usually means that when I am done, the old knots are slightly loose and the new twine is very tight to the bales. In terms of foot-pounds, I have no idea. IN terms of elbow pain, I would suggest a little less than what causes pain!

Q2. How to handle situations where you are only 3 to 4" short and too small for a bale. How to stuff, how to lock the bales from moving and the use of tar paper under the bales and strapping.

A: Hey, that's cheating! That's at least three questions disguised as one. a)If I end up short by only a few inches, I always push my full or half bale into the corner and stuff with loose flakes back to the rest of the wall run. Never use loose material at the end of a wall. If it is more than a few inches, tie the flakes into mini bales before you install them. This technique will cover the installation, and "locking" of the bales. b) Roofing felt is used under the bales to stop moisture from wicking up into the wall. I cut a roll of roofing felt to size on a chop saw and then roll it into the space between the toe ups. Cutting ahead of time speeds the process considerably. c) The strapping I use is made by Cordstrap and you can find it with a Google search. I use 3.4" strapping and tighten it enough to compress the bales by at least 1-2" over the entire height of the wall. The tighter the better, but be careful not to bust the box beams or pull them out of level. It is really important that the box beams be level because you will pay the price during roof framing if they are not.

Q3. How to place the strapping in the corners where bales overlap. How to lock the corners of the top plate and how to compress the bales with the straps... i.e., over tar paper, under tar paper, over top plate, under top plate.

A: The strapping should be placed over the box beams and under the toe ups. I place my strapping every 2' on center paying attention to the location of windows and doors so I don't end up with a strap running in a window location. Start close to the corners, but do not try and lap in the corners as it will not work. That is what the rebar staples are for: tying the corners together. I run the roofing felt over the straps.

Q4. Types of top plates, ladder style, plywood sheathed style, cross members, and whether to use 2x4 's or 2x6's.

A: I use 2x4 ladder construction 24" on center with plywood tops and bottoms. Be sure to insulate the boxes before you close them up. I leave the top open until they are all nailed together and connected and then lap the plywood from one section onto the next as a final connection point. I use additional 2x4's in the ladder to make the corner connections.

Q5. What do you do around windows when they are framed and not on bucks. How close to come with bales, how much loose straw to fill.

A: If the windows are installed in a framed wall, not a load bearing wall, I place the frame flush with the outside of the structure so the bales end up flush with the window. This does not achieve the adobe look of inset windows, but I judge it better protects the bales from water damage over time. I stay back about 2 - 6" from the window edge and stuff with loose straw during the meshing stage. Exactly how the corners look after stuffing is up to you and that determines how much straw you use. It is important the get the stuffed areas tight for proper fire protection and plaster backing.

Q6. What to do with the roof members in terms of stuffing with straw and cutting notches in the roof joists, etc.

A: Do not place the straw up around the roof members. Place a strip of plywood against the rafters so that the bales stop at the base of the rafters. Ceiling insulation should be lightweight and not bales. It is also a requirement to provide ventilation from the eaves which means a clear path of air must be able to travel from the eaves above the bales to the roof ridge. Straw in this area will hinder the ventilation and potentially cause moisture damage. In load bearing, this is not an issue because the box beam acts as the stop for the bales and the roof is framed up from there.

Removing Braces and Installing Structural Mesh

Where welded wire mesh is used as the structural shear of a building, it is very important that temporary braces be used to secure the building before the mesh is applied. This is a common practice with conventional construction as well. 2x4 braces are used to support the walls and maintain a plumb line until the plywood is added. In a bale house, the system is a bit harder to deal with. Consider the placement of the temporary braces. If the braces are placed on the inside of the frame, they will need to be removed when stacking the bales and the structure ends up free of lateral support. If the braces are placed on the exterior of the building, they need to be removed before the exterior mesh is installed. The exterior mesh holds the greatest amount of strength for the structure as it is fastened directly to the vertical framing as well as the top and bottom plates. The interior mesh is only attached to the plates and then sewn to the exterior mesh. Therefore, the mesh with the greatest strength has to be installed for the interior mesh to work at full capacity.

So how to deal with this dilemma? I install my braces on the outside of the frame during construction. The first pieces of mesh are placed on the interior faces of the wall after baling. They are placed as close to directly opposite of the temporary braces as possible. Once all of the interior slices of mesh have been fully installed, move to the exterior. I remove one brace at a time from the exterior and immediately install the mesh. I continue to install the mesh as I move down the wall until I get to the next brace. Only after all the mesh on the outside of the wall has been installed from the last brace do I remove the next brace. I continue down the wall in this fashion, never removing more braces than I can mesh up to. This gives me continued lateral support throughout the meshing process and limits the risk of the walls falling out of plumb.

Free Talk on Straw Bale Construction

The Jackson County Home Show will be held at the Jackson County Expo Center in Central Point, Oregon this September 21-23. On Saturday, September 22 at 1:30 pm, there will be talk about straw bale construction by a local engineer Nabil Taha of Precision Structural Engineering, Inc. and Designer, Chris Keefe of Organicforms Design. I have done this talk with them on two previous occasions and it is a good introduction into straw bale construction. It is also an opportunity to ask those nagging questions you may have about design and engineering as it relates to straw bale construction. I will not be attending this talk this time around as I will be in LA.

Straw Bale in an Urban Environment

One drawback to straw bale construction is the thickness of the walls. That may not be something you hear me say very often, but in an urban setting, it truly is a liability. This is because most urban lots are small and do not have adequate space to hanlde the thick bale walls. The key to utilizing bale walls in an urban environment is smart design and clever construction. There is no reason why bale walls could not be used in most urban homes if th ehouse is designed well and utilizes th evertical lift of the lot in place of the horizontal sprawl. Building green means more than just bale walls as I have said before. It means using green appliances, glues, windows and more. It also means downsizing from the 3000 SF house to a smaller urban lot for many people. This well designed downsizing can then quickly become your asset and not simply a thick walled liability.

A Conversation About Plaster with an Owner/Builder

Dear Andrew,

We had quite a few days applying the "Scratch Coat" to our straw bale structure. It is so true that the whole process is really about having one stage done as completely before the next stage. But you are the best advocate for this.

Having applied the "Scratch Coat" there are a few questions:

Q: It has been a week since the "Scratch Coat" was applied, how much longer do I mist down the walls and how often?

A: You can stop misting after a week but the longer you mist, often enough to keep the plaster moist, the stronger the cure will be.


Q: What is the optimal time to wait before the "Brown Coat" is applied?

A: Again it is about curing. The longer you wait the better. After you stop misting the walls, you want to wait until the plaster dries out and watch for cracking of the scratch coat. Once the plaster is completely dry, you can prepare for the brown coat.


Q: Is there a best practice for removing plaster from wood surfaces that were accidently touched?

A: This is tough because the plaster will likely have stained the wood. The best option is to use vinegar to neutralize the lime. Be sure to check the reaction on the wood some where hidden before you go to town with this option!


Q: Is there a long range issue about the effect of lime plaster as applied to raw wood surfaces? Is there an antidote?

A: See above. That trick is the best option for stain grade wood and paint grade wood. If you go with paint grade, you may need to add an additional primer coat. With stain, additional sanding may be required to get under the stain.

Q: I have left over 10 gallons of well mixed plaster in a tub covered with plastic. Does this mixture need to be put through the mortar mixer before being applied or can I apply it direct?

A: You will need to re mix it when you are ready to apply it. Keep in mind the brown coat is a different ratio of sand to lime so you may want to mix a little bit at a time into new batches of brown.

Q: Can I incorporate the left over mixture with a new batch?

A: Yes, as long as it is mixed well and consistently. It is important the mixtures be as close to the same as possible for each batch of plaster so if you are adding old mud, add it equally to the new batches, not all at once. You cannot do this for the finish coat. It will need to be its own mix and the color quantities have to be exact in each mix.

Q: Is it ok to mix a small batch and complete sections of the project as my time and schedule allows or is it advisable to do the whole outside and whole inside at the same time?

A: You can do it over time. Be sure to locate a smart stopping point. I suggest you do entire walls and stop at the corners, actually 6” away from the corners. This way you can feather the continuation coat into the existing coat. If you stop in the middle of the wall you will have a burn mark and a cold joint.

Q: Renting a mortar mixer has a cost factor I would like to avoid. I am planning on do the brown coat and finish coat by my self on the weekends. Rather than rent mortar mixer every time I am plastering can I mix all that I will need slack, store it, and use it as I go?

A: Sort of. You need to re mix the mud before you put it on the wall once you have slaked it. You can remix by hand, but I think you find it extremely difficult to do as the slaked plaster tends to get fairly hard.

I am Leading a "Free" Workshop Sept. 8-9

I say "free" because I am sure the owners of the house would appreciate a donation towards the workshop, but there is no fee for the weekend. This Saturday, September 8th, and Sunday, September 9th, I will be leading a workshop on a straw bale house in Medford, Oregon. It will start at 9am on Saturday morning. I will be teaching the basics of bale re-tying, notching, stacking, and more. Everything you need to know to stack a house and wrap it for plaster (if we get that far!). This is a great opportunity to learn the ins and outs of baling from me and for free no less! For more information, please contact Scott at s_mackison@yahoo.com. I hope to see you there!

Plaster Artwork

Using natural plasters allow you to create fun artwork within your finish coat. The key is that the natural plasters can be built up during the brown coat application to create shapes on the surface of the wall. This is difficult to do with conventional plasters and stucco because they do not perform well in thick coat application. Perhaps the best material to work with is cob, a mixture of clay, sand and straw. This material can be built up in thick "lifts" and sculpted to fit your design. What you do with the designs is up to you. I have seen flowers, dragons, frogs, and many other designs embedded in the plaster work of homes and landscape walls. If you have skills as a sculptor or material artist, this is a great way to show off your stuff for all the guests that visit your house.

Can a Bale House Survive Without a Heat Source?

Greetings.
I have a farm in Trinidad, Colorado (although I live in Denver) and on it is an old house that I want to tear down. I would like to build a house that is so energy efficient that I can leave it with no heat in the winter and have no problems with freezing, etc. In other words, I want to create a cave-like environment where the temperature stays roughly the same as outdoors in any weather. Can a straw bale house achieve this goal? I have double pane, low e-glass windows in my farm house
now and would transfer them to the new house. Please let me know if this is possible with the straw bale construction.
Thank you.
Richard
==============================================

Richard,
The biggest aspect of this working is the design of the house. You will need to incorporate enough passive solar design to create a natural heat source for the home. Without any heat, the house will eventually equal the temperature outside, even if that is 0 degrees. If the house has passive solar design, it can generate its own heat by using the sun to warm interior floors and other heat sinks. That heat is then slowly released into the home and the4 bales insulate to such a high efficiency that they can contain that heat through the night. It is possible, and it will take some detailed planning and execution. Good luck.

Andrew

Straw Bale House For Sale in Onoway, Alberta

Here is some information on a straw bale house for sale on 3.13 acres near Onoway, Alberta. This home is commuting distance to Edmonton. Please click the link above for the website of the owners to gather more information. The we page has a picture and details about the house.

Slaking and Sand Ratios in Lime Plaster

I recently received the following questions regarding Natural Hydraulic Lime (NHL) plaster:
===========================================
As always, we appreciate your response. We finally ordered the lime,
it is arriving this morning. We are scheduled to start tomorrow. Just
lining everything up today. Some final technical questions.

In the formula you call for 4 different grains of sand. In my local
Home Depot I can only find "play sand" and "Masons Sand. I suppose
I'll have to go to a better source to find the variety of sand. When
I do, what is the proportion of different sands that I need? Probably
this information is on the DVD, yes?

I have purchased a large mixing tub from a masons supply house
thinking this would be ok to slake the lime/sand mixture in. The
after thought was that you had suggested creating a troff with 6 mil
plastic. The question is, do I have to slake all the lime/sand
mixture over night? It would make sense in this case to have the
large troff constructed. If on the other had I can mix in batches
then I would rather not build the troff and mix in the large tub.

Thanks again,

Harry
===========================================

Here's my response:

You do not have to slake the lime at all if you don't want to. It makes a better plaster if you do, but will be absolutely fine if you do not. Just be sure to mix for a minimum of 20 minutes before you use the material. If you do slake the lime, you will want a fairly big trough to put it in as a single mortar mixer load produces a lot of mud. If you plan to slake all the plaster, then you will need to hold at least four or five mortar mixers full at one time for 24 hour slaking.

The sand itself can be play sand as long as the sand is not washed. The same is true for mason's sand. The key is that you have at least four different size grains of sand. The scratch and brown should be fairly coarse sand and the final coat should be fine sands. I think most of the sand at Home Depot will be washed and graded and therefore no good for you. You can call sand supply yards and ask for their play sand and confirm the washing/grading as mentioned above. The mixing ratio of the grains is not that crucial; however, an even mix ratio is great if it can be achieved.

Good luck.

How Much Do I Charge my Clients for Baling?

This is often he most difficult part of becoming a professional bale builder. There is no book of standards out there from which to pull a "man-hour" rate for baling. So, how do you bid a house without gouging your client or digging yourself a financial hole? Experience is the best resource for any estimating question. If you have been lucky enough to work on a crew of experienced balers, you will have an understanding of just what is involved in baling a structure. If you have not, you need to either get some experience, or connect with some one who has that experience themselves. You can either work on some one else's crew, or pick their brain for information.

Here are some thoughts on the subject.

1. You will need to charge for each linear foot of window in the house. Remember that the windows and doors in exterior walls need a lot of attention in order for you to be confident that they will not fail and cause rot in the bales over time. For that reason, a lot of time and effort is spent flashing the windows. In addition, a lot of time and effort is spent on the inside shaping those openings. Charge per foot of the window perimeter to cover your costs.

2. Charge per bale you put in the house (standard and custom bales have their own rate). Don't base your estimate or bid on the square footage of the house. Instead, base it on the number of bales you will place in the walls. Consider that a 1500 sf with 8' ceilings will not cost the same as the same size house with 9' ceilings. On the same line, a house with 10 windows will not cost the same as one with 30 windows. Yes, you have covered much of the cost of the windows in the section above, but not all of it. Here's why. A window or door interrupts the running bond of the bales and requires you to make custom bales. You need to charge for the custom bales because they take time and materials to create. On my homes, I charge for standard bales, and I charge more for every custom bale in the house. A custom bale is any bale that is altered before it is placed in the house. Niches and other alterations to the bales are priced separately.

3. Is the mesh system part of the engineering or simply for plaster reinforcement and bale shaping? The engineered mesh systems require a lot of nailing so the labor is higher for this system. Is the mesh a special order item? Is there extra shipping chargers associated with the material? Make sure you cover all these questions before you give your estimate.

Adding Roofing Felt to the Structure

It is important that all wood surfaces be covered with roofing felt to separate them from the plaster. If you do not do this, the plaster will adhere to the wood and will be prone to extensive cracking as the wood dries and moves over time. a typical house has a lot of wood members that will need to be isolated so the process can be time consuming. It can also go quickly with a little planning and forethought. Here's what I suggest. Figure out the major widths of the wood components that need to be covered with the felt. Add 4" to that width for some overlap (I'll tell you why in a minute). Now the roofing felt to the chop saw (use an old blade because the felt will gum it up terribly!)and cut the roll into smaller rolls matching the width you determined. Cut slowly to stop the felt from melting to itself rendering it useless. Now you have precut rolls of the size you need to move quickly through the structure. These rolls are not only cut to size, but also easier to carry around the job site and up ladders if necessary.

Now, why did you add 4" to the measurement of the wood members? When notching your bales, I always tell you to over cut the notch rather than under cut it. If you try and hit the notch size exactly, you will miss most of the time and the trimming of the notch in the bale is hard to accomplish well. This means the bales will be harder to get into place and the time you'll spend trimming, fine tuning and installing your bales will be huge. If you over cut the notches, you will speed the process immensely; however, you may end up with a bunch of 1" gaps on the outside of the structure against the posts and beams where the over cut took place. You could stuff these, but it is hard (because they are only a few inches deep) and very time consuming (now you're back to where you started with lost time!). The extra roofing felt (4" over cut) acts as backing for the plaster as long as there is no more than an inch or so of space behind the felt. The other 1-3 inches of felt laps onto the bale, bridging the gap. There is no significant affect on the R-Value of the wall and the process is sped up greatly. Again, the faster you can move through the baling process, the sooner you can get the bales protected with plaster.