January 19, 2002

Crawl Space Ground Vapor Barriers

I love builders, how can I help myself, I am a second generation builder. Most of my knowledge didn't come from any classroom, but from being in the ditch and crawling through that muddy wet crawl space. You can't have a real appreciation for a 100 foot deep foundation caisson or water well until you have been lowered into one. If you want to have a real appreciation for how high the former Wachovia building (27 stories in Winston-Salem) really is, hang out a hole opened in that top blue section from a wind storm, if the wind doesn't suck you out first. Want a better appreciation for the Moravians, crawl through the brick storm drainage system in Old Salem or experience the joinery in their attic framing. But, we builders, especially second generation builders, have a little problem which is very difficult for us to accept. What we learned from our fathers and mentors or even what we are fully convinced is right is not always the best or the correct method. To put it bluntly in good southern English: "We ain't really as smart as we think we are."

A few months ago I had several e-mails back and forth with a local builder, whom I highly regard, not only for his construction abilities and the quality of his product, but for the way he handles himself in every situation (there have been many) where I have had the privilege of being in his presence (now that is some major ass kissing, is it not)? This builder was concerned with complaints from past homes having mold in their crawl spaces. One of the first questions I ask was: "Do they have a vapor barrier (plastic) on the dirt floors?" His response was something like: "No, I think they are worthless." It's been a while so I don't remember his exact words. We communicated back and forth on the issue with him feeling very strong about the worthlessness of the vapor barrier and my expressing my strong opinion that any builder who didn't install vapor barriers in his crawl spaces was not very wise. Shortly thereafter, I had the privilege of inspecting one of his new homes (without the vapor barrier). I discovered during that inspection, not only did he intend to install a vapor barrier in the crawl space of this home, but he was installing it in past homes also at a cost of $36.00 per home. Now that's an example of a good builder. When he discovers he is wrong, he fixes it. This is the type builder you want your clients to purchase from. Man, I hate that its not appropriate for me to say who. He is one of the few builders who receive this newsletter by request. 

So, what changed his mind? He only gives me a little of the credit, what can you expect from a builder/home inspector relationship? It's kind of like the Realtor I sleep with every night. She loves we until I screw up a closing on one of her homes. Talked with him a few days ago. He said what ultimately convinced him was that he discovered the supplier of his wood flooring would not warranty the flooring unless there was a 100% vapor barrier on the ground in the crawl space. What made the conversation even more interesting was that another highly visible local builder over heard the comment and remarked: "100%, doesn't there need to be open spaces for the ground to breath?"

Why is it that some builders think crawl space vapor barriers are "worthless," some think there should not be 100% coverage, because the ground needs to breath, others wouldn't finish a home without a crawl space vapor barrier and all home inspectors insist that a vapor barrier is one of the most important elements of a proper crawl space? I have heard some builders and Realtors comment that the reason home inspectors push for plastic on the ground is that it keeps them from getting so dirty. That sounds good to me. I think I crawl in many more than any builder or Realtor, but it doesn't have one thing to do with my insistence that all crawl spaces MUST have a 100% vapor barrier. As if limiting moisture, odor, mold and keeping me clean were not sufficient there is a much better reason I make a big deal out of crawl space vapor barriers. Simply stated: 

I HAVE BEEN THERE

How many older crawl spaces have you experienced? Who do you think might be the better judge of what is important in a crawl space, some builder who once in a while might stick his head into a new crawl space, a homeowner who detest even thinking about entering his crawl space or maybe you, the Realtor who "ain't crawling in that crawl space for no amount of money?" (Don't you love my use of the English language?) HEY BABY I've been in them things. Only wish I could take you and your favorite builder on a little tour of some of the lovely spaces I have experienced and allow you to witness first hand the tens of thousands of dollars of damage attributable to two simple issues, failure to install proper ventilation and vapor barrier in crawl spaces. I could go into a great deal of technical data about why 100% vapor barriers are important before making this comment, but I am not going to waste your time. Why not just accept reality. The ground doesn't need to "breath" it needs not to breath. Your crawl space needs 100% 6 mil plastic on the ground with generously lapped joints, turned up a portion of the wall (not in contact with wood). Why? Because it is the cheapest ($36.00) insurance you will ever purchase to protect your home from thousands of dollars in damage from moisture, rot and insects damage, forgetting the fact that it also limits the growth of mold and soil odors. 

Just how big of a deal can $36.00 really be? 

The ground is wet. You don't want this moisture rising (in its vapor form, gallons per day) and invading your home and it's components leading to wood rot and attracting them little termite devils. As to 100% coverage, strange thing that house where the floor system was only rotted out in one little area where there was not a vapor barrier. GET IT? 

 
Thought for the week
 
In a study of 200,000 ostriches over a period of 80 years, 
no one reported a single case where an ostrich buried its head in the sand or attempted to do so. 
Why is it that we still accept that they do?