Thread: Sealed crawlspace with a drain

Yesterday I inspected a new construction home with a really nice and clean sealed crawlspace. It was insulated and the entire ground was covered with a heavy mill plastic barrier. All of the columns were sealed as well.

However I discovered a flaw that the builder said that they were unaware of.
At the crawlspace entrance was a subsurface drain and drain line that went out to the rear of the home and ended in a swell along the rear of the property line. The problem was that where the end of the drain line ended it was about 3' higher than the bottom of the crawlspace.

In the picture you will see that that water is white or milky in color. Thanks to the painters dumping their extra paint at the rear of the lot in the swell, this is how I found the end of the pipe! When I looked in the backyard, it was not hard to see the white spot on the ground and the end of the pipe was a few feet away.

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The plastic sheeting looks to be part of a passive radon mitigation system. If you didn't see a fan or piping, it could be inactive and they decided not to run piping until they have a test performed.?
I am sure you would have noticed a fan in the attic or attached to the outside of the house.
Was that drain actually piped?

Originally Posted by Scott Patterson

At the crawlspace entrance was a subsurface drain and drain line that went out to the rear of the home and ended in a swell along the rear of the property line. The problem was that where the end of the drain line ended it was about 3' higher than the bottom of the crawlspace.

After a big rain storm they would a giant water bed under the house.

Seriously though, sealed crawlspaces are ridiculously expensive, you just expect a minimum level of competence when you spend that much money.

Originally Posted by Scott Patterson

Yesterday I inspected a new construction home with a really nice and clean sealed crawlspace. It was insulated and the entire ground was covered with a heavy mill plastic barrier. All of the columns were sealed as well.

However I discovered a flaw that the builder said that they were unaware of.
At the crawlspace entrance was a subsurface drain and drain line that went out to the rear of the home and ended in a swell along the rear of the property line. The problem was that where the end of the drain line ended it was about 3' higher than the bottom of the crawlspace.

In the picture you will see that that water is white or milky in color. Thanks to the painters dumping their extra paint at the rear of the lot in the swell, this is how I found the end of the pipe! When I looked in the backyard, it was not hard to see the white spot on the ground and the end of the pipe was a few feet away.

The entire system is a flaw. Why would anyone spend the money for footers, foundation wall, piers, sealing the entire system, full framed floor, etc etc etc.

If someone is going to spend that kind of money on a brand new home why on earth do they not just spend extra money on property prep and drainage of the property and pour a slab with deeper thicker ridge beams around the perimeter.

All that trouble for years and years and years of future maintenance and problems forever. If it is clay soil they have an injection processs that keeps the water from attaching to the clay , add proper slope and soil prep around the home and be done with it. Even if it where full piers around the home before the pour it would be cheaper.

Sorry about that. Just a sore spot for all these expensive set ups and still have problems later.

I have seen many sealed crawl spaces and don't like what I see. I've been a PCO for 36 years and I M O they are a big waste of time and money. One that I saw before Christmas was destroyed when an HVAC company had to remove an old furnace and replace it. I was called to see what I could do. I suggested removing the rest and putting the crawl back to it's original design. They called the company that did the work to start with and got talked into spending more money to have it done over.

Originally Posted by Jerry Martin

I have seen many sealed crawl spaces and don't like what I see. I've been a PCO for 36 years and I M O they are a big waste of time and money. One that I saw before Christmas was destroyed when an HVAC company had to remove an old furnace and replace it. I was called to see what I could do. I suggested removing the rest and putting the crawl back to it's original design. They called the company that did the work to start with and got talked into spending more money to have it done over.

Jerry, what is it you don't like? I've inspected 8 or 10 closed crawlspaces, some conditioned and some with de-humidifiers, and I liked the heck out of them. Dry as a bone in Aug. while vented crawls had puddles of water on the vapor barrier form condensate dripping from insulated flex duct.

If an HVAC contractor can't figure out how to get the unit in with out destroying property they should stop hiring knuckle dragger's.

I agree with sealed crawls being expensive and increasing future maintenance cost. I'm not a firm believer in them, especially when the area that the home is in really does not have moisture problems.

The area this home is in has no clay and a good amount of limestone. Sometimes they have to blast to make a hole for the foundation. I was told that there is a 4" layer of sand under the plastic barrier. The land is pretty hilly so that is the reason for the crawlspace vs a slab. I actually prefer a slab foundation, my home is on a built up slab.

This builder markets the sealed crawlspace as being the best thing since sliced bread.

As for a radon mitigation system; it does look like one I will agree. But this home actually has positive pressure in the crawlspace, conditioned air is being introduced into to it. I'm thinking that radon might not be an issue with the positive pressure in the crawlspace.

good reference site

http://www.crawlspaces.org/

http://www.advancedenergy.org/buildi...0Reference.pdf

To prevent the indoor swimming pool...

A roof runoff system to direct water away
from the house
■ Site grading and landscaping that directs
ground surface water away from the house
■ Foundation drains and foundation dampproofing
or water-proofing to protect the
structure from sub-surface water
■ Air sealing of the access door, perimeter wall
and perimeter framing to prevent the entry of
moisture-laden outside air and to separate the
crawl space from areas under porches or decks
■ An access door that is protected from roof
runoff, at least 4" higher than the exterior
soil grade and made of a non-corroding
material, especially in coastal communities
■ A fully sealed vapor retarder on the floor and
perimeter walls to reduce evaporation of
water into the crawl space
■ Appliance discharge pipes and exhausts
from kitchens, bathrooms and clothes dryers
that terminate outside the crawl space
■ A mechanical drying system to reduce
humidity (for example, a supply of
conditioned air or a dehumidifier)
■ Drains with backflow valves or sump pumps
to remove liquid water from the crawl space
if necessary
■ Flood vents that minimize standby air
leakage, when required

My biggest problem with them is that everything is covered up. When one of my termite customers has their crawl sealed it voids thier termite warranty. I get called all kinds of names then and refere them to their contract with us.
The other thing is when the cost to do this is upwards of $4500.00 it just seems a bit much for something I could correct for less than $1000.00. I am talking about retrofits not new construction. I have had radon barriers that I placed torn up by service people doing work under the house and they don't care. Plumbers, HVAC people, carpenters and such. They appreciate the nice "plastic" to crawl on but not enough to patch it back up even though I have at least four signs in the cralw space. I know they would have no more respect for a closed system. Let's face it most of the younger guys today don't take the time to be carefull.

Originally Posted by Jerry Martin

My biggest problem with them is that everything is covered up. When one of my termite customers has their crawl sealed it voids thier termite warranty.

When installed properly the liner does not go to the top of the foundation wall and leaves a few inches of the foundation wall visible for termite inspections.

The reason for the sealed crawl space is not for radon mitigation, but for moisture control. The exterior walls of the crawlspace are insulated with a 2-inch thick, foil-lined, foam board to within 1 inch of the bottom of the sills (to allow for termite inspections - required by code in NC) and then the entire space is covered with 2 layers of 7-10 mil poly for moisture control. The space is heated and cooled - just like a traditional basement - so there is no temperature difference that would permit any condensation should a tear in the plastic occur.

As for cost differences, since there is no need for floor, pipe, or HVAC insulation for the crawlspace, there is actually a cost savings from the perspective on initial construction. From the homeowner's perspective, there are indications that the sealed crawlspace is an energy saver, because the floor and crawlspace are always kept at the same temperature as the room above, so no cold floors when you walk in your stocking feet.

Water pipes do not freeze within the crawlspace, so no need to "let the water drip" during the winter. Because the space is conditioned, there is a considerably reduced risk of mold developing.

Having studied extensively about sealed crawlspaces and after building a few custom homes with sealed crawlspaces...I wouldn't build a home without one. I give them a BIG two thumbs up!

The OHJs in NC are liking what they have seen and read about the sealed crawls and many are now pushing the builders in their jurisdictions to construct with sealed crawls. They seem to be inspecting the non-sealed spaces with a considerably keener eye toward preventing the moisture problems associated with them.

Bruce that is not the case here. Our county inspectors require it to be sealed completly. Even if it weren't this way we still can't inspect the ground area and many areas are covered that termites can get through undecteded and cause major damage. Too much liability for my insurance company....

With our Green Code in Santa Fe

Hot water circulating loops are required and you don't get any Green energy (brownie) points if you don't insulate the hot water piping. Regardless of the insulated / semi-conditioned status of the crawl.