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ASK THE EXPERTS FORUM This forum quickly settled into an enlightening free-for-all after moderator Mark Piepkorn (former editor of The Last Straw Journal, writing here uncomfortably about himself in the third person) declined to appoint a panel of experts, opting instead to bestow the dubious title onto all present. The principal topic was moisture behaviors and controls for straw bale wall systems. Most of the experts in attendance (new or old) were in accord that design and implementation are still the superior avenues of pursuit to keep bale walls dry. Overhangs, porches, and stem walls of reasonable lengths and heights for the given climate and site, appropriate detailing of windows and doors... the usual. The relative merits and liabilities of cement, lime, and earth finishes were touched on briefly in the course of things. The move toward non-cement finishing materials appears to be very strong, and growing, among professionals and owner/builders alike in all climates. Siloxane-based applications were given approval as moisture-resistant yet vapor-permeable cement stucco sealers by those who have used them, with an admonition to keep an eye on things over time. Their use does not justify eliminating installation of moisture monitoring devices in the wall. Various sealers and admixtures for earthen materials were given mixed reviews, and the simple wisdom that "Dirt Ain't Cement" was reiterated. All structures, by design, need to appropriately accommodate the materials to be used (including bales). The importance of sealing the bales with direct-applied wet plaster if a "rainscreen" type finish, such as plywood, sheetrock, board-and-batten, clapboards, etc., is to be used was emphasized. Toward the end of this all-too-brief forum (we could have gone on all day and then more), talk turned toward exterior pins vs. the traditional pounded pins. Most seasoned experts seems to be in accord that pinning of any type helps stabilize the wall system to varying degrees, depending on the quality of the bales, before the plaster is applied, but does not likely contribute anything structural to the completed wall, particularly where cement stuccos are used. Exterior pins were given a good review for being simpler and stronger, and potentially adding some structural strength to weak-finished walls (e.g., when earthen plasters are used), depending on how the pinning is implemented. |