Well, I’m not a mold expert and haven’t identified the growth here as mold, but if it is mold, here’s what’s necessary for it to grow:

• Spores – They’re everywhere and will grow if the other conditions are met.
• Appropriate temperatures – They like pretty much the same temperatures we do, and even colder. Ever seen mold in your fridge?
• Food – Organic matter is what they like, and it’s everywhere. Mold likes cellulose (wood) and the more processed, the better. Paper is called mold candy by people who work in this field.
• Moisture – To sustain growth, a mold colony must have water. When the relative humidity of the air is 70% or higher, mold has enough water to grow.

So, of the four requirements for mold growth, the one we have most control over is moisture. Keep the materials and the air dry enough, and we won’t have a mold problem.

Have you measured the relative humidity in your crawl space? When I was doing improvements on homes, I’d install a digital thermo-hygrometer with a remote sensor in the crawl space so the homeowners could track the relative humidity. If you’re not doing this yet, and you have a crawl space, get yourself one of these devices now.

OK, so you’ve measured and determined that you do have high relative humidity in your crawl space. That’s not unusual at all, especially in a humid climate like we have here in the Southeast. Where’s the moisture coming from? And why is the humidity in a vented crawl space higher than the outdoor relative humidity? Here are three reasons.

1. Bulk Water

The first problem to look for is bulk water. If there’s standing water in your crawl space, you have either a drainage problem or a plumbing leak. You need to fix this immediately. Having a pond under your home is a bad, bad idea.

In the photo above, the problem was that the back yard sloped down to the house, bringing water up to the foundation wall. Since it was just a crawl space, the builder didn’t put any kind of water proofing on the concrete block or grade the yard properly to keep the hydrostatic pressure from building up against the block wall. You can see the result here. This was a new house with a serious bulk water problem. The joists were already growing stuff, and the fiberglass batt insulation was getting heavy and falling down.

2. Moisture Evaporating from the Ground

In the photo above, the ground was partially covered with a polyethylene vapor barrier. The dirt that wasn’t covered looked dry, but when I pulled the plastic back, I found that there was a lot of moisture in that soil. The soil that looked dry only looked that way because it was constantly evaporating moisture into the air of the crawl space. The foundation walls can also evaporate moisture into the air.

What do you do to solve the problem? Cover it all up with a vapor barrier!

3. Outdoor Air Coming in through the Crawl Space Vents

Some people find this hard to believe, but when you bring outdoor air into the crawl space, the relative humidity actually increases. Think about it this way: When air enters the crawl space, it cools down. Cool air cannot hold as much moisture as warm air, so the air that enters is now closer to its saturation point (which we call the dew point). It might’ve been 60% relative humidity outside (relative to a temperature of 90° F, say), but when that air came into the crawl space and cooled down to 75° F, the relative humidity jumped up to 95%. Not good!

The numbers here come from the psychrometric chart (invented by Willis Carrier, the inventor of the modern air conditioning system), which relates temperature and humidity of air.

What Can You Do?

If you’ve got a vented crawl space with high relative humidity caused by one or more of the above, to solve the problem, you’ve got to remove the causes. Bulk water is solved by fixing the drainage or plumbing problems. Water evaporating from the ground or coming through the vents can be fixed by encapsulating your crawl space.

One thing that doe NOT work is to try to treat the symptom by installing a dehumidifier. Don’t do that!

If the problems get really bad, though, you can always keep some kayaks down there so you can get around easier.

See that little offset there right above the turn? If it looks like it’s not making a good connection, that’s because it’s not making a good connection. In fact, when the new EVER rater went up there first, it looked worse than what you see here because he’d already put the two sections near each other when I got a chance to take the photo. You can see a little better in the photo below right that even though those two sections are near each other, they’re not connected.

Yeah, this is happening in a vented attic, not inside the building envelope, so why worry about it, right? Wrong. You want those exhaust gases to get all the way outside the house. You don’t want them in a buffer space like the attic because it’s still likely they could find their way into the house. Exhaust fans and clothes dryers can cause the house pressure to go negative relative to the attic and suck those flue gases into the house, for example.

 
It’s amazing how blatantly obvious so many building science and combustion safety problems are once you know a little bit about how things work. Actually, you don’t even have to have any training to know that when a pipe is supposed to be carrying something from point A to point B, it has to be continuous for the something to reach point B. I wrote an article about duct leakage last year that shows some obvious problems that take only a pair of eyes to find.

The field test went well, though, and Luke Bertram of Green Summit Consulting is our newest EVER rater. He took our HERS rater class in February and was one of the lucky ones to have his training and certification costs covered by ARRA (Stimulus) money. The City of Doraville, Georgia is really on the ball and is getting people trained to provide subsidized energy audits to city residents. Here’s Luke in his Tyvek suit, about to enter the cave of mystery (aka crawl space) under the test house.

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The term “green” is being increasingly applied as an easy way to identify products, including building materials and new homes, as having a better or smaller impact on the environment.

That’s fine for marketing slogans and advertising headlines, but it’s also dangerous if the product (or house) isn’t truly sensitive to its environmental impact and is simply trying to ride the coattails of a sincere effort to lessen our carbon footprint.

In those instances, intended or not, the term “greenwashing” comes into play. Simply, it refers to incomplete, insincere, exaggerated, or downright untrue promises made about a product’s environmental performance, with no real evidence to back it up.

As a professional builder confronted with “green” claims from a variety of building product manufacturers and some competitors, we are keenly aware of the threat that greenwashing can have on our credibility as a quality contractor.

So, in our business, we make every effort to substantiate the claims made by our suppliers regarding reduced water use, recycled content, energy efficiency, and other performance characteristics that relate to creating a “green” building.

How? Thankfully, the “green” movement within and outside of the building industry has spawned a wealth of independent, third-party companies that scientifically verify those claims with a battery of standards and test methods. When considering a product or system, we look for certifications from those entities, as well as specific performance information (such as the precise amount of energy the furnace claims to save) to give us confidence.

In addition, several local, state, and national “green” building programs, such as Energy Star, have cropped up to help us and other builders identify materials and methods that result in better-built homes. These programs not only serve as frameworks for higher-quality housing, but also refer to the independent verification programs, such as the EPA’s WaterSense (for low-flow plumbing fixtures), to give us greater assurance that we are truly building green.

Even then, however, manufacturers and some builders may unintentionally misuse the certifications they earn from such testing or evaluation. For instance, there’s no such thing as an “eco-friendly’” or “environmentally-sensitive” product or house, two terms that have no scientific basis and smack of greenwashing.

Failing to go the extra mile to verify environmental performance claims can put us at risk of becoming greenwashers, too. It’s also our responsibility to surround so-called green products and systems with a quality-built house that effectively optimizes the energy use, water use, and durability of those products.

That way, we can all feel good, and be confident in, your investment and our combined efforts to make the Earth a healthier place to live for us and future generations.

ERHOM joins the National Recycling Coalition, Keep America Beautiful, and various other national and state organizations in recognizing America Recycles Day on November 15. America Recycles Day is the only nationally recognized day dedicated to encouraging Americans to recycle and to buy recycled products. Celebrating its 12th year, the day has grown to include millions of Americans pledging to increase their recycling habits at home and work and to buy products made with recycled materials. Through America Recycles Day, Keep America Beautiful, Inc. and the National Recycling Coalition support local communities and raise awareness by educating citizens about the benefits of recycling. Volunteer America Recycles Day coordinators are positioned throughout the country and work to organize recycling awareness events in schools and communities, and in conjunction with local municipalities.

On November 15 each year, millions of people become better informed about the importance of daily recycling
and buying recycled products. The purpose of America Recycles Day is to continue to promote the social,
environmental and economic benefits of recycling and encourage more people to join the movement toward
creating a better natural environment. For more information on America Recycles Day and events, visit
the web site at www.americarecyclesday.org.

When the outside air moves in, it brings warm moisture air with it. Warm moist air doesn’t mix well with cool dry air. As a matter of fact, it tends to make the cool air, well, not so cool! If the damper doesn’t close well, or if the fireplace is seldom used, some sort of airtight covering is in order.

Glass doors can work, if they are reasonably tight (most aren’t). A plywood door can be made and need not look too ugly. This is most appropriate for seldom-used fireplaces where an airtight seal can be obtained (this is tough to do on rough stone or brick). Other options include dampers for the top of the chimney and inflatable plugs that fit up the chimney out of sight.

It’s important to keep the damper shut when the fireplace is not in use and be aware, smoldering fireplaces produce carbon monoxide and backdraft (air moving down through the chimney back into the home) easily.

Protect the air quality and energy efficiency of your home by securely sealing the fireplace chimney.

For more energy and sustainable building ideas contact http://www.garynsmith.net.