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Straw as a Building Material  Supplemental informationPage 1 Page 2
Moisture Straw is vulnerable to high levels of moisture, however the principles involved in moisture control are the same for all buildings. Avoiding moisture problems requires an understanding of materials and how moisture affects them. It is always best to design moisture problems out of a building early on in the design process. With proper attention to moisture control straw should last as long as wood. Moisture in the materials. Wood, concrete, and plasters will often contain large amounts of water which can be wicked up by straw.
Rain and splash back. Driving rain is usually the largest source of water entering into a building. Keeping out rain is the most important moisture control measure. Driving rain on walls, splash back from rain hitting the ground, and details around windows should be addressed. Wide overhangs will reduce rain on walls by 90% or more. Splash back can be greatly reduced with good grade separation (at least 6”, 8” is better) Ground water. Water and vapor resistant materials are required to prevent water wicking up. Plumbing. Plumbing should never be run in straw walls. If plumbing must pass through a wall a plastic sleeve that drains to the exterior should be used. Transport and storage. If straw panels become wet they must be dried out or discarded. If a straw panel is wet to its core, it should be discarded. Water vapors in air. Vapors brought in by air movement can deposit surprisingly large amounts of water. Air barriers are used to stop air flow. Correctly applied plaster is a good air barrier. Areas around window frames, floor, and ceiling should also be sealed. |
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Water sources