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Crawlspace Mold, Ventilation and Insulation

Let’s wrap it up – this is the last of my Crawlspace Inspection posts and I’ll take care of the items 9 & 10 from my Top 10 list. They are somewhat correlated, at least partially. Top TEN Crawlspace Problems:

1. Cracked foundation / possible structural problems
2. Leaking foundation
3. Drainage problems / flooding crawlspace
4. Plumbing components issues – leaking water supply lines, drain pipes, crawlspace water heater installation problems
5. Heating system issues
6. Electrical components issues
7. Floor framing and structure support issues
8. Structural pest infestation – those are Termites, Powder Post Beetle, and Carpenter Ants
9. Mold problems
10. Crawlspace ventilation and insulation

9. Mold problems

Mold, as many other problems described in previous sections of the crawlspace inspection tutorial, is strictly related to moisture presence. Because it grows on pretty much anything, and often takes different shapes and colors, you can expect to find it on every surface of crawlspace components. So check it all, and pay special attention to areas along the foundation and under the bathrooms, kitchens, utility rooms containing water heaters, furnaces, and / or washers – any place that water leakage / moisture penetration might occur.

If you have a chronic moisture problem, maybe related to poor drainage around the house or a high water table (level of ground waters), the mold might appear on the crawlspace floor, walls, supporting columns and entire framing. If you notice discoloration or unusual residue / substance on any of the surfaces, have it tested by a professional – unfortunately this is the only way to find out what it is and if it is toxic.

10. Crawlspace ventilation and insulation

Proper ventilation of the crawlspace is crucial for a healthy house … well … not necessarily, or should I say – the science decided that not any more. As it often happens with some beliefs, new scientific developments change them to the complete opposite. However, the installation of 1 ft2 of venting per 150 ft2 of under-floor / crawlspace area is still a code requirement.

For our inspection purpose:

If you have any fuel burning appliances installed in the crawlspace area, you’ll need so called make-up air / combustion air, which is necessary for a proper burning process. Unless those appliances have a sealed combustion chamber and use exterior air for combustion (most high efficiency furnaces do, but not all of them), you might need an air vent installed in the crawlspace area. If you’re not sure, have a licensed HVAC contractor check it for you

• If you have a dry crawlspace, you are lucky! Your vents are most likely adequate (or you might not even have them at all) – I personally wouldn’t touch it
• Check areas around the foundation vents to ensure, that there’s no leakage – vents usually leak because they’re below the ground level on exterior, and you might need a small window well
• For wet crawlspaces (leaking foundation, high water table, malfunctioning or missing drainage system) – once again: try to eliminate the source of moisture, and then read Venting or not – the Crawlspace dilemma.

The crawlspace ventilation topic is quite large and there are a few scenarios and various options to consider. Therefore I’ll do my best to wrap it up and explain current scientific point of view in Venting or not – the Crawlspace dilemma.

Crawlspace insulation

Depending on the type of crawlspace you have under the house – above the ground, partially above the ground, below the ground level – you might have insulation installed or not.

If it’s there, and if it is a blanket type with a paper facing (also called “batt” insulation) installed on the crawlspace ceiling / your floor framing, remember that the paper (moisture barrier) has to be facing the warm side of the house. It is highly flammable, and leaving it exposed creates a fire hazard. It is easier to install blankets between the floor joists by securing paper flaps along the edges, but without fire-rated material on top of such installation … you know, accidents happen. You might also have: the spray-on type of insulation on the foundation walls, Styrofoam sheets, aluminum foil faced blankets (this one conducts electricity, so be careful if it is in contact with electrical components in your crawlspace), or some other materials – secure them if they fall off / separate from the surface they were attached to.

Insulate or not? – That’s coming in different post

Related posts:

1. Crawlspace Drainage and Flooding My previous Crawlspace Inspection post covered the first two items...
2. Crawlspace Foundation Cracks and Leaks House crawlspace is one of those critical areas, which can...
3. Electrical Problems in a Crawlspace The crawlspace inspection continues (Part Five) as we take a...
4. Crawlspace Plumbing Problems Welcome again in the Crawlspace Problems series, and this is...
5. Termites and Other Crawlspace Bugs Early detection of a structural pest infestation in our crawlspace...