Is crawl space conditioning a good thing or a waste of money? My builder thinks it's a waste of time?

My builder thinks it's a waste of time. I've had two estimaters out--each says the cost is about $10K; the builder doesn't see the need. I could use some advice.

Thanks. Asked by OysterRock 54 months ago Similar questions: crawl space conditioning thing waste money builder thinks time Home > Home Improvement.

Similar questions: crawl space conditioning thing waste money builder thinks time.

Most people think it's worthwhile, but your estimates sound really high There's a very good discussion on this topic from last year at this site:ths.gardenweb.com/forums/load/build/msg0... person who initiated it and was asking a very similar question also happens to be from Delaware, so the information there should be very useful to you. Here's the best comment on it, though he does talk quite a bit about some of the other alternatives the original asker was thinking about:First, conditioned crawlspaces are accepted as a design alternative by the Inthernational Residential Code which has been adopted by nearly all jurisdictions in Delaware. While it is true that crawlspaces are required by code to be vented as the general rule, the fully accepted and code compliant exception is to use the closed crawlspace design.

I highly doubt that your code jurisdiction will not allow a closed crawlspace, and are simply misunderstanding the Code requirement and it's intent. Second, the design of a closed crawlspace for a 1400sf basement 3-3.5 feet high should cost no more than $2000-$3000 all inclusive. Whomever quoted you $16,000 for a conditioned crawlspace either has no clue what they are speaking of or is trying to rip you off.As others have mentioned, all that is required for an effective closed crawlspace is:-a vapor sealed floor (which you already have)-insulated crawlspace walls to a thickness and depth recommended for your region (In your case, R-11 to a depth of 4 feet)-Conditioning of the crawlspace.

-No vents to the outsideTo add 4ft of R-11 insulation to your crawlspace walls will in no way cost $16,000....and if using even expensive rigid foam R-12 polisocyanurate insulation, this only works out to be about $962.50 plus tax and labor. This is something you could do yourself. What you have also apparently been misinformed about is that closed crawlspace design is much more energy efficient than an open crawlspace.

Insulating your crawlspace walls with a closed space design will reduce your overall energy consumption and pay for the transition in no time, especially since your heating/cooling ducts run through this currently unconditioned space. Installing the vent fan/dehumidifier will actually increase the costs to heat and cool your house perpetually with no appreciable effect on reducing crawlspace moisture. The biggest drawback to installing the fan system is that it probably will not work, and when it does, will do so ineffeciently.

First, dehumidifiers run in small spaces like crawlspaces tend to ice up and become non-functional in short order. Second, they will only work in cooler months when the crawlspace moisture level is higher than that of the outside air. For the hottest months of the year, the fan will not work at all because it's net result will be to actually bring warmer moister air INTO the crawlspace from the outside, in fact HUMIDIFYING your crawlspace making condensation much more likley.

Since the mosture dynamic for a crawspace in warmer months is for moisture to migrate INTO the crawlspace from higher outside concentration levels, vented crawlspaces need to be kept CLOSED in summer to prevent this moisture from entering in. Using a fan/dehumidifier in warm months in a crawl is like putting out honey in a dish to attract flies just so you can swat them...you will attract flies all right and be able to swat them, but the cycle will never stop, and you will have more flies than if you simply never put out the honey at all. Installing crawspace vent fans will do the same: it will draw in unwanted moisture just so it can be dehumidified...when the most sensible approach is to keep the moisture out in the first place.

Humdidity is also not the enemy...Condensed moisture is...and unless your dehudifier will only turn on by calculating when the potential dew point will be reached based on ambient temperature vs. relative hunidity....well, you'll be dehumdifying the air for no reason at all most times....and wasting energy in so doing. You've gotten some very bad information about closed crawlspace designs and are deciding in favor of a poor alternative based apparantly on initial expense alone. I'm with Rollie and the others: Only closed crawlspace designs for me.

They are the cheapest, most energy efficient and driest types of crawlspaces to construct. ***************************************************You might also want to take a look at some of the info here:http://www.google.com/custom?domains=buildingscience.com&cof=GALT%3A%23095209%3BS%3Ahttp%3A%2F%2Fwww.buildingscience.com%3BGL%3A0%3BVLC%3A%23D06838%3BAH%3Acenter%3BBGC%3A%23F8F8E9%3BLC%3A%23095209%3BGFNT%3Agray%3BL%3Ahttp%3A%2F%2F

%3BALC%3A%23999999%3BT%3A%23000000%3BGIMP%3Ablack%3BAWFID%3A7131a4c3237ffe09%3B&q=crawl+space&sa=Search&sitesearch=buildingscience.comSpecifically, there's an excellent abstract on the topic here in PDF format:http://www.buildingscienceconsulting.com/resources/foundations/conditioned_crawl.pdfThe bottom line is that they're worthwhile as long as you're not getting ripped-off on the price. I hope that helps!

Sources: http://ths.gardenweb.com/forums/load/build/msg0712550018699.html .

And you got to have a air tight air tight crawl space. Over the past two decades, studies have shown that crawl space ventilation is counter productive in humid areas such as the South and along the coast. fpl.fs.fed.us/documnts/techline/crawl-sp... exchange rates are much lower in crawl spaces than in under-floor spaces of houses on posts or piers.

As a result, seasonal temperatures in crawl spaces are more effectively moderated by the ground than in the under-floor spaces of houses on posts or piers. This means that crawl spaces are not as cool in winter or as warm in summer. This can reduce heating and cooling costs, and it reduces the chance of plumbing lines freezing in cold weather.

In short, crawl space construction was recognized as having thermal benefits relative to post or pier construction, but it was also recognized as being more prone to moisture accumulation. Crawl space humidification by evaporation of soil moisture is related to soil moisture content and temperature. Evaporation is generally greatest during summer, when the soil is warm, and least during winter, when it is cold.

Vapor barrier ground covers appreciably inhibit evaporation from crawl space floors, thereby lowering crawl space humidity levels. When codes began mandating crawl space ventilation, the long-term durability of ground covers was in doubt. The assumption was that ground covers might eventually cease to function, which could cause appreciable evaporation of soil moisture into the crawl space area.

Polyethylene has become widely used as a crawl space ground cover since code mandates for ventilation were promulgated. It has proven to remain functional for extended periods. Although sometimes valid, the assumption that outdoor air functions as a moisture sink?

In other words, as a place to dissipate moisture? Is often invalid.In cold weather, the vapor pressure of outdoor air is usually low, or at least lower than the vapor pressure of crawl space air, and the assumption appears to be largely correct. In warm weather, however, outdoor vapor pressure is significantly higher, often higher than the vapor pressure of (relatively cooler) crawl space air.

This is especially true if the building above the crawl space is air-conditioned. Thus, in warm weather in humid climates, outdoor air is more likely to be a source of crawl space moisture than a sink. In these climates, the assumption that outdoor air would mostly serve as aPolyethylene is widely used as a crawl space ground cover.

Sources: Spartan Caver Says: .

In my opinion builders know how to do what they have always done... ...but are rarely experts on new procedures, things not commonly done in their local area, or anything that will make it take longer to build a house. I still remember how adamant one builder was about nit putting a window in a bathroom that had an outside wall. He felt it just couldn't be done since there was an exhaust fan.

When I was growing up, exhaust fans were primarily for bathrooms that couldn't have a window because there was no outside wall to put one in. I could tell you more stories, too. So the fact that your builder says its a waste of money may say more about the fact that he's never seen it done before.

However, many nfolks are looking into doing it in various ways. In humid areas they srtongly recommend that the ground be covered with something impermeable and that the crawl space be unvented as a way to control moisture. The cover, which in my dad's crawl space was polythylene held in place by gravel, keeps ground moisture from coming up into the house through the crawl space, while keep it unvented prevents condensation (since his house is in the humid south).

The following is an article on it tah makes some good points :Non-Vented Crawlspace Moisture Control Though homeowners rarely think about that small space under their houses, builders should give crawlspaces careful consideration. Some of the most common—and damaging— building problems stem from moisture in crawlspaces. Poorly constructed crawlspaces can contribute to mold problems, indoor air problems, and inefficient operation of the home’s mechanical equipment.

Carefully considering design and construction of crawlspaces, as part of an overall quality construction strategy, can reduce problems for both builders and homeowners. Preventing Moist Crawlspaces. Moist crawlspaces can contribute to rot, mold, and fungus growth, which can damage wood floor joists and beams.

Furthermore, moisture in crawlspaces can lead to health problems associated with mold, mildew, and bacterial growth. A carefully engineered moisture management strategy should be implemented to control moisture in crawlspaces. These key preventative steps are part of such a strategy:Install a continuous and sealed high quality 6 mil polyethylene vapor retarder on the ground in the crawlspace and protect it with a concrete scratch coat.

Minimize moisture during the construction process. Create an external sloping grade so that rain water flows away from the crawlspace. Install a foundation wall system that does not leak.

Install rain gutters, extensions, and leaders to carry excess water away from the home. Provide a capillary break on top of footer. Install a footing drainage system to prevent rising groundwater from flooding the crawlspace.

Bring conditioned air into the crawlspace. Insulate the exterior surface of the crawlspace wall. Seal the crawlspace against air leakage.

Benefits of Unvented Crawlspaces. Crawlspace vents effectively become the “determined hole” in a home. In winter, warm air exiting the attic or ceiling creates a negative pressure at the lowest openings in the home.

This negative pressure causes cold air to enter through the crawlspace vents and rise through holes in the subfloor to the first floor. This phenomenon creates the “cold floor syndrome” prevalent in cold climate homes with vented crawlspaces. The cold air can also carry unwanted moisture and gases from the soil, and odors from the crawlspace into the home.

Typically, the floor above a vented crawlspace is insulated. In unvented crawlspaces, the walls, instead of the floor, should be insulated to limit heat transfer from outside to inside the crawlspace, and vice versa. When properly built, an unvented, insulated crawlspace helps to eliminate problems with comfort, odor, and health associated with mold, mildew, and bacterial growth.

However, unvented crawlspaces aren’t recommended in certain locations. For example, a warm crawlspace in an extremely cold climate may eventually melt the perma-frost beneath the home, allowing the home to sink into the ground. Also, when homes are built in high water table areas (near rivers at the bottom of steep valleys, for example), it can be useful to seasonally vent the crawlspace to allow for drying after flooding.

Conditioning the Crawlspace. Once the crawlspace is insulated and unvented, it should be treated the same way as any other space in the house—supplied with a certain amount of heated or cooled air from the mechanical system. Conditioning the crawlspace can help the mechanical components that are housed in the crawlspace (the air handler, ductwork for the first floor zone, and plumbing line, for example) operate more efficiently and last longer because they are not subject to temperature and humidity extremes.

Ideally, the crawlspace temperature should be about 55°F to 65°F year-round. All ducts should be well sealed with mastic to prevent unwanted air leakage. This air leakage increases energy consumption because the outside air has to be heated in the winter and cooled in the summer.

The Bottom Line. Will these improvements increase construction costs? Probably not.

You can save money when replacing underfloor insulation with wall insulation, because the square footage of crawlspace walls is typically significantly less than the square footage of the first floor. The required insulation R-value is generally lower for crawlspace walls than what is required for floors. Treating the crawlspace as an unvented conditioned space also eliminates the cost of insulating ductwork and water lines.

While this type of approach may not currently be allowed by the letter of the code in many areas, the 2000 International Building Code allows unvented conditioned crawlspaces (see section 1202.3.2, # 4). Many builders have gotten permission by showing their code officials that what they are proposing isn’t actually a crawlspace—it is just a really short basement! Sources: http://www.buildiq.com/fndn702.htm .

2 newbie2563067, regarding your answer "Darn good question:": Really appreciate the response. We finally did have the space conditioned in spite of the cost. Hopefully we'll recoup a bit in air conditioning and heating cost across the year.

I've begun tracking it already. Again, thanks! .

Newbie2563067, regarding your answer "Darn good question:": Really appreciate the response. We finally did have the space conditioned in spite of the cost. Hopefully we'll recoup a bit in air conditioning and heating cost across the year.

I've begun tracking it already. Again, thanks!

What is the best type of pipes for replacing galvanized, in a raised foundation home, almost all in crawl-space . . ." "my home's crawl space smells moldly and the smell permeates the house.

I done plastic, dehumidifier, etc.. what's next.

What is the best type of pipes for replacing galvanized, in a raised foundation home, almost all in crawl-space .

My home's crawl space smells moldly and the smell permeates the house. I done plastic, dehumidifier, etc.. what's next.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.