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EARTHQUAKE DAMAGED FOUNDATIONS
FIRE DAMAGE vs MOLD DAMAGE
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FOOTING & FOUNDATION DRAINS
FOUNDATION CRACKS & DAMAGE GUIDE
FRAMING DAMAGE, INSPECTION, REPAIR
GRADING, DRAINAGE & SITE WORK
HOUSE PARTS, DEFINITIONS
INSECT INFESTATION / DAMAGE
KIT HOMES, Aladdin, Sears, Wards, Others
LOG HOME GUIDE
MOBILE HOMES, DOUBLEWIDES, TRAILERS
MODULAR HOME CONSTRUCTION
MOISTURE CONTROL in BUILDINGS
PORCH CONSTRUCTION & SCREENING
PRE-CUT & KIT HOMES
RETAINING WALL DESIGNS, TYPES, DAMAGE
ROT, FUNGUS, INSECT DAMAGE
SINKHOLES, WARNING SIGNS
STAIRS, RAILINGS, LANDINGS, RAMPS
STRAW BALE CONSTRUCTION
STRESS SKIN INSULATED PANELS
STRUCTURAL WOOD ASSESSMENT
TIMBER FRAMING, ROT
TRUSSES, FLOOR & ROOF
WATER ENTRY in BUILDINGS
WOOD STRUCTURE ASSESSMENT
This article describes a straw bale constructed home that is more than twenty years old, commenting on its construction method, durability of straw bale construction, and where strawbale home defects are likely to be observed. This article is part of our series FRAMING METHODS, Age, Types which is a section of AGE of a BUILDING - how to determine. Our page top photo shows the exterior of a load-bearing strawbale constructed home in San Miguel de Allende, Mexico. Strawbale homes are not common in San Miguel, but are popular in many areas of the Southwestern United States.
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Strawbale construction is a construction method ascribed to early settlers in the United States in Nebraska in the 1890's, and a method popular in the U.S. into the 1940's with a continuing following of straw bale enthusiasts to the present.
Prior to about 1890 straw, hay, and similar grasses were used for thatch roofing but it was the advent of the mechanical bailer using wire or twine and producing rectangular straw bales that permitted straw to be used as construction building blocks.
According to the U.S. DOE,
But how easy is it for a home buyer or home inspector to quickly recognize a straw bale built home? A glance at our page top photograph of a straw bale house in San Miguel de Allende, Mexico, may not immediately show how this house was constructed. But look again more closely: notice those thick walls that can be detected by the thickness shown at window and door openings? And if you (click to) enlarge the photo you might notice the "lumpy" building sides. Look again at our straw construction house wall photograph just below.
How are Straw Bale Homes Constructed
The window in our photo (below left) shows the wall thickness - a clue that this is a straw bale home. The outside of the window jamb was painted green, the inside white. A good outdoor construction detail on a straw bale home of this design is the inclusion of a slope on the window sill so that it drains without risking sending water into cracks in the straw bale stucco coating. Our second photo (below right) shows one of the places to look for cracks, leaks, and water entry at a straw bale constructed home - at the window and door openings.
Our photo at above left shows a thin vertical crack in the stucco covering of this straw bale home, at the center of this picture. Our second photograph of a straw bale home (above right) shows both cracks and evidence of previous repairs in that same location (click these photographs to enlarge and make the crack details more visible). Just below are closeup photos of cracks in the stucco coating of this straw bale constructed house wall.
What special steps should be taken to preserve a straw bale home?
Frequently Asked Questions (FAQs) about straw bale construction: how to build, inspect, troubleshoot, or repair a straw-bale home
Question: How easy or hard is it to repair small cracks in a straw bale home? How easy or difficult is it to cut in a new window or door in a straw bale home wall?
It has been very useful to have stumbled upon your website as I had no knowledge of straw bale construction and its special care requirements. Since you offered some support, I would like to ask you two things. As you know the house is old. It was built specifically for rental and the quality of most materials, such as window and door framing, and furnishings is below what I prefer in a home. It has potential, though.
Last summer I noticed that a small section (maybe 10 cm.) of an exterior apartment wall had cracked and was open to the elements. I did ask my property mamager to repair it, but I don't know if she is aware of the construction material. So question one is how easy or difficult is it to repair a small section like that?
The second question is how easy or difficult is it to cut a new door or window into an existing wall, as I someday want to put a room addition on the lower, one-story apartment. - N.G., Myanmar
Reply: Advice About Straw Bale Home Crack Repairs and Adding Windows or Doors to Existing Walls
Think of the straw bale wall structure as a thin masonry shell plastered over bales of hay or straw. If water gets into the interior of the shell it invites decay or pests that over time can damage the bales, leading to hollow areas that are structurally weak compared with the as-built design. So my opinion is that it would be smart to inspect the house from time to time and to try to keep any cracks you see sealed.
How we Patch Cracks in Straw Bale Wall Stucco Coating
By "re-plastering" I refer to using a cement mix, not actual "plaster". The crack may need to be opened a bit wider and cut to an inverted "vee" shape to get the best mechanical adhesion of the patch. Very fine cracks in the straw bale stucco coating, say less than 1/16" in width, might seal up ok if kept painted.
If you find actual damage that is resulting in movement of the structure - say crushing under a floor joist or beam - then it would be appropriate to open the wall to see what's going on.
It would be simple to add a post and pier if necessary, you don't have to chop open the whole wall and try replacing bales. But if you are not seeing structural movement, that more extravagant repair should not be necessary - just keep cracks sealed as best you can.
How we Cut Openings for Windows or Doors in an Older Straw Bale Home
I'm more nervous about cutting openings for windows or doors, especially when both of us are just thinking by email and are not on-site to see exactly what's going on and exactly what is inside of a wall that we cut open. In general, a too-glib answer is that you can do just about anything to any building - that is it's possible.
The devil is in the details: just how much trouble and expense are we going to face, and are we sure we're handling the change with enough thought that we're not messing up the rest of the structure.
If you cut a door where there is already a window, often that's pretty easy as there is already a header over the window opening to carry the weight of the wall above. So if the top of the window is high enough to fit a doorway, just cut the bottom wall out below the window. It's not going to change the structure.
But if we need to make a new opening where there was none, most likely you'll want to frame in a header beam to be sure there is no sagging or cracking in the wall above. The header is carried on posts to concrete piers poured into the soil deep enough that there won't be any sinking and thus there won't be any cracking in the wall. Then the door or window jamb is framed into that opening.
Find Out More About Your Straw Bale Home Construction
Finally, if by chance a neighbor can tell you who built the straw bale home, we might find out if the original builder is still around, as s/he will also be familiar with hidden structural details in the home and somewhat familiar with straw bale construction. A clue would be whether or not we can find any other such homes in the neighborhood.
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