Crawl Space as Return Air Plenum

[A.D. Miller]

1955 house in Dallas today with return air chase dba the crawl space. Besides the wiring there, what other issues do you see that should be addressed?

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[Jerry Peck]

Aaron,

It is allowed, but bad enough, to be used as a supply plenum, but a return?

From the 2006 IRC. I would think that, if allowed, that space would have many more requirements than shown below. I would think more like a return plenum in a ceiling space, where everything is pretty much sealed away outside the plenum area.
- M1601.4 Under-floor plenums. An under-floor space used as a supply plenum shall conform to the requirements of this section. Fuel gas lines and plumbing waste cleanouts shall not be located within the space.
- - M1601.4.1 General. The space shall be cleaned of loose combustible materials and scrap, and shall be tightly enclosed. The ground surface of the space shall be covered with a moisture barrier having a minimum thickness of 4 mils (0.1 mm).
- - M1601.4.2 Materials. The under-floor space, including the sidewall insulation, shall be formed by materials having flame-spread ratings not greater than 200 when tested in accordance with ASTM E 84.
- - M1601.4.3 Furnace connections. A duct shall extend from the furnace supply outlet to not less than 6 inches (152 mm) below the combustible framing. This duct shall comply with the provisions of Section M1601.1. A noncombustible receptacle shall be installed below any floor opening into the plenum in accordance with the following requirements:
- - - 1. The receptacle shall be securely suspended from the floor members and shall not be more than 18 inches (457 mm) below the floor opening.
- - - 2. The area of the receptacle shall extend 3 inches (76 mm) beyond the opening on all sides.
- - - 3. The perimeter of the receptacle shall have a vertical lip at least 1 inch (25 mm) high at the open sides.
- - M1601.4.4 Access.Access to an under-floor plenum shall be provided through an opening in the floor with minimum dimensions of 18 inches by 24 inches (457 mm by 610 mm).
- - M1601.4.5 Furnace controls. The furnace shall be equipped with an automatic control that will start the air-circulating fan when the air in the furnace bonnet reaches a temperature not higher than 150°F (66°C). The furnace shall additionally be equipped with an approved automatic control that limits the outlet air temperature to 200°F (93°C).

[Ted Menelly]

1955 house in Dallas today with return air chase dba the crawl space. Besides the wiring there, what other issues do you see that should be addressed?

The crawl as a return plenum.

I think you may remember, I think it was a franchise, Killed an entire family after one of the techs drilled the slab and there where returns in the slab and treated for termites. Cannot remember the product used but it was years ago. Anyway, leaks in plumbing, mold, sewer gas, insects etc etc etc.

Way to many concerns with that. I do not even like supply ducts or return ducts in crawls because of all the potential problems.

I do know the company but that was a pretty bad story with the whole family dying to mention.

[A.D. Miller]

JP: House flipper. Put down 30lb. felt on soil and foamed the lapped edges. All of the return grilles in the baseboards terminate at the bottom of the subflooring AND the bottom of the air filter compartment is open to the crawl space.

Plumbing cleanouts and gas piping and wiring are all there. Not to mention a large plumbing leak. Plus, just from this photo alone: softwood shims at the piers. Over-notched beam. OK, just for the heck of it I'll throw in the picture from the furnace closet/laundry room above the leaking p-trap.

I hate house flippers!

[A.D. Miller]

The crawl as a return plenum.

I think you may remember, I think it was a franchise, Killed an entire family after one of the techs drilled the slab and there where returns in the slab and treated for termites. Cannot remember the product used but it was years ago. Anyway, leaks in plumbing, mold, sewer gas, insects etc etc etc.

Way to many concerns with that. I do not even like supply ducts or return ducts in crawls because of all the potential problems.

I do know the company but that was a pretty bad story with the whole family dying to mention.

Ted: I remember that. Screeded slab. Lots of dead bodies. Bad scene.

[Ted Menelly]

Ted: I remember that. Screeded slab. Lots of dead bodies. Bad scene.

Yep, begins with the same first letter in my name. they had to sell a complete division of the company to pay for it.

[Rick Hurst]

As long as I've been in the business I've never heard any story of anyone actually dying from a termite treatment.

I have heard of a case against a prior Dallas based company (wasn't the "T" named company) that had treated a house with Chlordane that had been injected into the return air duct. Seems the area where the termites were coming up was inaccessible at the crawlspace area due to low clearances. The applicator drilled through the hardwood floors and drilled indirectly into the return air duct. After pumping a Chlordane based product into the ducts, the homeowners begain feeling ill.

They realized it was the chlordane. Never knew of any deaths caused from this anyway. This is when the media news team 20/20 got involved and then came the downfall of Chlordane a few years later. I knew of where this home was and it was finally bulldozed down to the ground.
Now there is another McMansion built on its site.

rick

[A.D. Miller]

As long as I've been in the business I've never heard any story of anyone actually dying from a termite treatment.

I have heard of a case against a prior Dallas based company (wasn't the "T" named company) that had treated a house with Chlordane that had been injected into the return air duct. Seems the area where the termites were coming up was inaccessible at the crawlspace area due to low clearances. The applicator drilled through the hardwood floors and drilled indirectly into the return air duct. After pumping a Chlordane based product into the ducts, the homeowners begain feeling ill.

They realized it was the chlordane. Never knew of any deaths caused from this anyway. This is when the media news team 20/20 got involved and then came the downfall of Chlordane a few years later. I knew of where this home was and it was finally bulldozed down to the ground.
Now there is another McMansion built on its site.

rick

Rick: Aw now, why did you want to come along and spoil the big BS session we had going direct from the pages of "Urban Legends". Shoot, we could have strung some of them along for days.

Damn! You're no fun.

[Ted Menelly]

Schtinking spoil sport

Anyways, bad news using a crawl for a return air plenum. To much to concider for using it as such.

Well, I will not discount it all together though. Brain damge, yes, deaths, etc etc etc cancers, Dursban, Chlordane and many many other chemicals pumped under homes and slabs for years have contaminated millions of homes.

Also there is no telling what a home owner could pump under there because he sees a roach or termite for that matter.

The part about a screeded slab is correct though with a termite treatment. I think I heard of Ricks case as well.

You can always tell a Chlordane treated crawl. There is never even a web from a spider down there. Hmm, just how many have I been under in the past with out the *proper* breathing equipment. Maybe that is why there may be just a dead brain cell or two floating around between the ears.