Buying a Home – Wet Crawl Space

You are getting ready to make one of the largest purchases of your life. You love the house. The kitchen is fabulous. The closets are spacious. You are not thrilled with the paint but you can deal with that. You decide to put in an offer and schedule the home inspection. The seller accepts your offer and you are starting to dream about your family playing in the back yard.

Unexpected Findings: The Problem Down Below

Wait, there’s a problem with the crawl space. The home inspector sees moisture in the crawl space. The inspector notices the HVAC air ducts are wet and dripping water onto the moisture barrier. He doesn’t see standing water in the crawl space but it is a little humid. There is adequate ventilation so why is there high humidity? In fact, there are several crawl space vent fans running at full force. He sees something on the wood but he can’t say if it is mold so he recommends you have an environmental company take a look.

Seller’s Dilemma: The Unnoticed Issue

Well of course the buyers are concerned and the sellers are shocked. They never knew there was a problem, “We have been here for years and never had a problem. We have the home inspected yearly for termites and no one ever mentioned water in the crawl space.” Why is the crawl space wet?

“Any sign of water damage or mold should be traced to its source, Wagner said, so that potential home-buyers can get a realistic idea of how extensive repairs will be. Mold should also be tested to determine what type and how virulent, it may be.” Liz Weston, MSN Money

Why Is My Crawl Space Wet?

If your home is located in the Southeast, chances are your crawl space is wet if:

  • You have an open crawl space (vented crawl space)
  • You have fiberglass insulation installed in the sub-floor between the joists
  • You keep your thermostat below 74 degrees in the summer (below 70 degrees makes it worse)
  • You store your lawn mower in the crawl space
  • You store cardboard in the crawl space
  • Your crawl space vapor barrier does not cover the entire ground
  • Your air ducts are not properly insulated
  • Your HVAC unit is less than 10-years old

Why Is There Mold In My Crawl Space?

Mold can grow anywhere the relative humidity is 60% or higher if there is an adequate food source. Crawl spaces have a lot of food for mold to feed on and grow. Did you know temperature also affects the humidity? For example, if your humidity is 60% and the temperature is 65 degrees the air is less moist or contains less grains per pound (gpp) of water than if the relative humidity is 60% and the temperature is 75 degrees. For more about mold click here to read what the EPA has to say.

Another factor is the temperature outside. If your region is experiencing 90 degree days, your air conditioner is running harder and longer to keep you cool. The longer the AC runs, the more your air ducts in the crawl space will sweat or condensate especially if they are not properly insulated and air sealed. Air Sealing the ducts will make sure more conditioned air makes it to the destination, your living space.

Why Are My Crawl Space Air Ducts Wet?

When you run the air conditioning the air ducts become cold. If the relative humidity and temperature is high around the air ducts, condensation will occur. Think about a soda can. When you take the can from the refrigerator and you are walking around the house there isn’t a lot of moisture on the can. If you take the can outside on a warm humid day the can begins to sweat almost immediately if the can is cold. The warmer the can becomes, the less condensation it produces. This is also called the dew point.

What Is Dew Point?

Dew Point – The dew point (or dewpoint) is the temperature to which a given parcel of air must be cooled, at constant barometric pressure, for water vapor to condense into water. The condensed water is called dew. The dew point is a saturation point.

Sounds complicated but if you want to know more about dew point click here to see a video and explanation from a meteorologist. Maybe she can explain it better.

So how does all of this affect the home you are trying to buy?

You may decide the risk is worth the reward. You love the house and the sellers are healthy and well and have had no apparent health problems. You ask for a discount on the home of a few thousand dollars to get the crawl space repaired and the moisture under control. You are so excited! The movers are scheduled and deliver all your stuff. You and your family are happy happy happy.

Picture of poorly sealed and insulated ductwork image of crawl space vapor barrier

Which crawl space would you choose?

Crawl Space Repair – Never Happened

Two years go by and the summer has been extremely warm. The house seems warmer than usual so you decide to set the thermostat a couple degrees cooler. You do this because the HVAC doesn’t seem to be keeping up. The bonus room over the garage is downright hot. The upstairs bedrooms are uncomfortable at night. Let’s get the HVAC contractor out to look at the unit. He recommends you change the HVAC system because your system is 15 years old. You knew this when you bought the house and the home inspector found no problems so you decided to not replace it until it went out. Remember, YOU LOVE THIS HOUSE!

OK, you get the Furnace and AC unit replaced and it is able to keep up with the demand and you are happy.

Crawl Space – Year Three

Summer comes again and you had your one-year old HVAC system serviced and you are ready to crank it on. All goes well for a couple of week but then you notice something. Why is there a musty smell in the family room? Why does it feel sticky in the house? Why are my utility bills higher this year than last year?

When you had the HVAC replaced, did you have the air ducts insulated better? Did you have the air ducts sealed? Most older homes have less insulation than homes built today so the HVAC systems today make the ducts colder. Less insulation on the ducts and colder ducts in a warm humid crawl space creates more condensation. OH YEA, The Crawl Space.

Well you are not sure what is happening so you decide to call a crawl space company. Well, hello again. It’s the same person you called out three years ago to write that estimate so you could use it to get a better deal on the house. Remember, YOU LOVE THIS HOUSE!

Crawl Space Repair Costs

The crawl space inspector comes out to evaluate your situation again. Houston, we have a problem. The sorta damp crawl space three years ago is now so wet it is almost raining in there. The air ducts are soaked. The crawl space insulation is hanging like stalactites and falling. So, your house is now under insulated because wet insulation loses its R value and falling insulation has no R value.

The insulation has been leaching water into the surrounding wood for a while and now the wood is so saturated that wood rot fungus has been growing. Wood rot fungus has caused the studs to warp and the crawl space inspector can shove a knife into the wood. That thin layer of mold the home inspector found three years ago (that was ignored) has now manifested into a full-blown mold problem. It has been feeding on the studs and sub-floor and has been fueled by high humidity and condensation.

Unfortunately, the price you had three years ago to fix the crawl space has tripled. Now what do you do?

This is a true story that happens more than you think. When you decide to purchase a home with a crawl space make sure it is dry, clean, healthy and efficient. I would also recommend you and the sellers choose a contractor together. One that each of you trust. Low ball fixes rarely offer long term results. The seller wants out of the home so who could blame them for going with the lowest price. The buyer wants the problem fixed because they don’t want to inherent a problem that will need to be addressed later.

Crawl Space Encapsulation?

Here are 5 things every crawl space should have:

1. Low humidity

2. Proper insulation

3. Active ventilation

4. Moisture barrier

5. No visible mold

Every crawl space is different so reaching these five goals can differ from one home to the other. Some choose to install more fans and more crawl space vents while others choose a dehumidifier and crawl space encapsulation. Some choose to insulate the crawl space while others feel it is not necessary. Discuss the options and come up with a solution that makes sense to you.

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