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Water on top of Vapor barrier


Bill H
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I did an inspection on a home built in 1993, the builder was Melody Homes which are now out of business. they built homes with wood foundations. they use the crawl space as a plenum for the HVAC. my problem is this. i did the crawl space and noticed some water standing in a couple of places, approximately 6' long 2' wide. there is no plumbing or drains close to this location, i think it is condensation but there was a considerable amount of water. any ideas?

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How deep was the puddle(s)?

Ideas..........

Drainage issues from the exterior-- how well was the plastic installed?

Owner frantically shampoo'd the crap out of the carpeting before selling and water dropped down through.

It would most likely not be due to condensation in my area. I wouldn't think condensation would be an issue in a plenum crawlspace.

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I did an inspection on a home built in 1993, the builder was Melody Homes which are now out of business. they built homes with wood foundations. they use the crawl space as a plenum for the HVAC. my problem is this. i did the crawl space and noticed some water standing in a couple of places, approximately 6' long 2' wide. there is no plumbing or drains close to this location, i think it is condensation but there was a considerable amount of water. any ideas?

Are you saying that they did not use any ductwork? Or are they using the joist bays for return air?

It could be condensation or groundwater, either way you really do not water standing in the crawl. What covers the ground; dirt, gravel/rock/ concrete?

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I did an inspection on a home built in 1993, the builder was Melody Homes which are now out of business. they built homes with wood foundations. they use the crawl space as a plenum for the HVAC. my problem is this. i did the crawl space and noticed some water standing in a couple of places, approximately 6' long 2' wide. there is no plumbing or drains close to this location, i think it is condensation but there was a considerable amount of water. any ideas?

Ideas about what? Your question is unclear.

The water is from rain.

You get rid of it the same way you get rid of water in any crawlspace.

- Jim Katen, Oregon

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Scottpat

right there is NO ductwork, they use the entire Crawl space for the Plenum, thats right all of it. but the vapor barrier is a heave mil plastic. there is no place for rainwater to get to this location with out being noticed. this water stands in the middle of the house.

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Like Jim Katen said, it's from rain.

If it was from condensation, you would know; the place would be a wet, damp stinkin mess.

What's probably throwing you off is that the water is in the middle of the crawlspace on top of the VP with absolutely no sign on how it got there. I'll tell you how it got there. The water infiltrated at the perimeter from under the footer, accumulated till it found a way on top of the VP then receded leaving the puddles trapped in the middle or anywhere else where it could not drain off.

Chris, Oregon

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Scottpat

right there is NO ductwork, they use the entire Crawl space for the Plenum, thats right all of it. but the vapor barrier is a heave mil plastic. there is no place for rainwater to get to this location with out being noticed. this water stands in the middle of the house.

Return air must come from the living area. The following is for supply air and it needs to meet the following, underline is mine:

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.Aduct shall extend from

the furnace supply outlet to not less than 6 inches (152 mm)

belowthe 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 (457mmby 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-90C

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I can only relate to this regarding hardwood installations. I am a wood inspector with the National Wood Flooring Association.

1. Is the grading sloped away from the house. If not it needs to be.

2. The crawl space needs to have a minimum 18" spacing from the dirt to the joists and covered by 6 mil poly secured up the wall.

3. Most building codes require that crawlspaces be vented to the outside and have 1.5 square feet of venting for every 100 sq ft of crawl space.

4. Have read of some inspectors testing for humidity levels in crawl spaces reading 98% and water running down the walls and pooling as described. Humidity testing should show a maximum of 50% or less or do not install hardwood until this is achieved.

Trust this helps.

Jim

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I can only relate to this regarding hardwood installations. I am a wood inspector with the National Wood Flooring Association.

1. Is the grading sloped away from the house. If not it needs to be.

2. The crawl space needs to have a minimum 18" spacing from the dirt to the joists and covered by 6 mil poly secured up the wall.

3. Most building codes require that crawlspaces be vented to the outside and have 1.5 square feet of venting for every 100 sq ft of crawl space.

4. Have read of some inspectors testing for humidity levels in crawl spaces reading 98% and water running down the walls and pooling as described. Humidity testing should show a maximum of 50% or less or do not install hardwood until this is achieved.

Trust this helps.

Jim

You might be able to accomplish 50% RH in west TX but next door in LA, even with an AC in optimum condition, you'll rarely get any lower than 60% in the house for 8 months out of the year.

Marc

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Marc you are absolutely correct every area of the country has different levels of moisture that are acceptable. In the case of too much the answer is a dehumidifier here in El Paso generally a humidifier will correct these problems. We do a lot of Sand and Finish work and advise customers if they don't want the wood filler we use to fill gaps they had better keep their humidity parameters between 30% and 50% here. When ServiceMaster is called in on flooded homes the first thing they do is apply heat, hugh dehumidifier and air movement to dry things up. Unfortunedly Plywood over concrete and nail down hardwood will never dry up even after a year, oh yeah I am sure someone will state they have seen it done, BUT experience dictates removal and replacement as it is unrealistic to wait and year and then find it won't do it.

Once water saturates plywood in this situation 15% to 99% noted it can produce mold and you know how excited people get about that.

Good comment though.

Jim

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