What do you inspect in the crawl space under a house?
Saturday, August 25, 2018
The first question we get asked when arriving to inspect an older home is “Are you going to go in the crawl space?” And our answer is “Yes, we will get in there if it is accessible and has no safety hazards.”
In order to be accessible, the crawl space has to have an entry that is large enough for the inspector to get through, which is a minimum of 16-inches high by 24-inches wide. If there is an access panel, it has to be removable without using any special tools or damaging it. The dimension from the dirt to the bottom of the floor joists needs to also be a minimum of 18-inches high. While it is possible to crawl through a smaller area, it is difficult lift your head to view upwards or twist around readily in a shorter dimension. The access opening shown at right is approximately 10” high and closed with loose concrete blocks.
Also, not all areas of the crawl space may be accessible due to plumbing or air conditioning duct obstructions or reduced clearance because of a rising slope of the ground under the home. The inspector may state in the report that the crawl space was entered but was only able to examine limited areas.
The second issue that may prevent an inspector from exploring the crawl space is personal safety. If there are loose electrical wires on the ground, glass or other sharp debris, evidence that an animal is occupying the space, leaking sewage on the ground, or evidence of poisons, then we will only view and photograph the area from any available openings. The determination of whether the area is safe to enter is at the discretion of the inspector.
The two photos below are from a recent inspection in which the crawl space had extensive mold growth over large areas, and both ducts and plumbing drain piping obstructed access. We entered the crawl space only briefly because of the mold spore hazard and were unable to examine some areas because of the obstructions.
Here’s what we check for once under the house:
1) Adequate ventilation - The rule of thumb is one square inch of venting for each square foot of conditioned floor space. Also, the ventilation openings should be screened and distributed around the perimeter of the crawl space to allow for cross-ventilation, with at least one vent within a few feet of each corner to avoid a dead air space. Sometimes the vents get covered over with mulch and leaves, rendering them useless, as shown below.
2) Moisture level in soil - This can be caused by natural water movement through the soil or plumbing leaks. It can be observed visually by discoloration of the soil or by touch. Fingertips are actually an excellent moisture evaluator. Follow-up with an electronic moisture meter determines the precise level of wetness. Excessive soil moisture can cause multiple problems, such as mold growth, wood rot, and corrosion of metal fasteners. Lack of ventilation will compound the problem.
3) Damaged masonry stem wall or piers - Most damage to foundation piers and stem walls is caused by settlement or heaving due to clay soil. If the damage appears to be structurally significant, we recommend further evaluation by a licensed engineer.
4) Temporary supports - concrete blocks or wood supports placed below floor framing are usually there because of foundation settlement or the sagging of undersize floor joists. They are a quick fix that will not last. We document them and recommend a permanent repair be made.
5) Termite guards - A termite guard (also called termite shield) is a metal strip on the top of foundation piers and stem walls that sticks out into the crawl space at an angle and deters the building of mud tubes up into the home by termites. They cannot build a tube around the sharp edge of the metal. We look for termite guards under the home and the lack of them increases the risk of Subterranean Termite infestation. If we are also performing a WDO (termite) inspection, we look carefully for mud tubes on the foundation and evidence of termite or beetle damage to the framing. Drill holes in the foundation and other evidence of treatments are also noted.
6) Things that shouldn’t be in the crawl space - Stored wood or debris on the ground, chemicals, air conditioning condensate drain termination, or dryer vent termination, for example.
7) Condition of floor framing - We observe the sill beam, floor joists, sheathing, and bridging, along with mechanical connections to the structure.
8) Evidence of mold-like substances - Any areas that look to be mold are noted and should be sampled and evaluated in a lab. Mold in a crawl space is always related to a high-moisture problem in the area.
9) Vapor barrier and insulation - We note the presence or absence of both, and describe the type where present.
10) Evidence of animal damage - Torn insulation, fecal pellets, shed snake skins, and burrow holes all indicate current or previous animals in crawl space.
11) Plumbing, HVAC ducts and electrical where visible - We examine and describe these components and note any defects observed.
Because homeowners don’t ordinarily get under their home and examine the crawl space, an inspector’s findings are often a surprise to everybody. Also, see our blog posts and Should I buy a house with a crawl space? and Are there any minimum inspection standards that a Florida licensed home inspector must meet?
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To learn more strategies for getting the best possible home inspection, here’s a few of our other blog posts:
To read about issues related to homes of particular type or one built in a specific decade, visit one of these blog posts:
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