<font><font face="arial,helvetica,sans-serif"><b>Sometimes the best solution to problems, such as Moisture is to remove the problem material. Wood Rots but we still use it as a major Construction Material instead of removing it and replacing it for a better more suitable one. Not a band aid but a total replacement, a material that is better in many ways. </b></font></font><div>
<font><font face="arial,helvetica,sans-serif"><b><br></b></font></font></div><div><font><font face="arial,helvetica,sans-serif"><b>Today's wood is not yesterdays wood and should be avoided not only for our health but for well being during Climate Change, where Water and Moisture may become a real big problem. Poly is to short an answer, Expanded Polystyrene is a better one because it not only has little affect with Water, it also Insulates and has a very, very long lifespan. More on EPS floating raft and othe foundations information at: </b></font></font><a href="http://styrohomeconstruction.yolasite.com/" target="_blank">http://styrohomeconstruction.yolasite.com</a><div>
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<br><br><div name="sig_f947d861ac" style="margin:0pt"></div><div class="gmail_quote">On Sat, Jun 2, 2012 at 6:22 PM, nick pine <span dir="ltr"><<a href="mailto:nick@early.com" target="_blank">nick@early.com</a>></span> wrote:<br>
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Stuart Fix <<a href="mailto:sfix@renubuildings.com" target="_blank">sfix@renubuildings.com</a>> wrote:<br>
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Humidity within the crawlspace should be controlled via poly on the ground<br>
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That would seem to invite condensation from warm moist house air in a cold climate, without a vapor barrier below the floor and insulation below that.<br>
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and proper ventilation (either passive screens or active fan/humidistat).<br>
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Passive screens would seem to invite condensation from warm moist outdoor summertime air. So would automatic foundation vents that are open at 70 F... <a href="http://www.amazon.com/AIR-VENT-RABL-AUTO-FOUNDATION/dp/B000IJWOV6" target="_blank">http://www.amazon.com/AIR-<u></u>VENT-RABL-AUTO-FOUNDATION/dp/<u></u>B000IJWOV6</a> How about a smart vent, ie a fan with a differential absolute humidity control... <a href="http://www.smartvent.biz/" target="_blank">http://www.smartvent.biz/</a> ?<br>
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If a simple humidistat turns on a fan to move outdoor air through a crawlspace when the crawlspace RH is too high, say higher than 60%, what prevents the fan from moving warm moist outdoor summertime air through the crawlspace, with condensation?<br>
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<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Eli's comment:<br>
The issue I am trying to understand is how to maintain in a ventilated crawlspace to be warmer than dew point. The vapor barrier on the ground only stops ground sources of humidity. A high standard thermal barrier in the floor keeps the ac cooling from cooling the bottom surface. However, the shading will keep the crawlspace cooler than outside. Could this cause condensation?<br>
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Response...<br>
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The only way to STOP condensation from occurring, in the situation you've described, would be to heat the crawlspace, or to ventilate the space at a high enough rate that it maintains the same conditions as outdoors. Both are likely a waste of energy.<br>
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The second way seems especially wasteful, since maintaining exactly the same conditions as outdoors requires infinite fanpower :-)<br>
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Gary BIs <<a href="mailto:gary@builditsolar.com" target="_blank">gary@builditsolar.com</a>> wrote:<br>
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I converted my crawl space to a conditioned space as discussed in this:<br>
<a href="http://www.builditsolar.com/Projects/Conservation/Insulation/CrawlSpace29238.pdf" target="_blank">http://www.builditsolar.com/<u></u>Projects/Conservation/<u></u>Insulation/CrawlSpace29238.pdf</a><br>
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Do they suggest a vapor barrier under the floor? They say "Air sealing between the house and crawlspace is less critical" with crawlspace wall insulation.<br>
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I put two layers of poly on the dirt and sealed it around the edges and at seams. I blocked all the vents and I foam can sealed all around the rim joist. Then insulated the crawl space walls with polyiso foam board with tape on the seams... its been about 6 years, and its worked fine for me. The crawl space feels dry. I do live in a dry climate (SW MT)...<br>
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Amen?<br>
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Nick <br>
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