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Wood or wood products that are close to the soil are vulnerable to rot and wood-boring insect attack. This applies to wood sidings, plywood, OSB and hardboard, as well as Insulbrick. This includes sidings that may not be wood based, but may have wood or wood-based sheathing, strapping or studs. Such products are typically used behind aluminum, vinyl and fiber-cement siding, for example.

Siding should extend down over the top of the foundation to protect the joint between the top of the foundation and the structure above. The top of the foundation wall must be well out of the soil. If the siding is to be kept 8 inches above the soil, the foundation should be at least 10 inches above finished grade level.

There are serious implications for the building structure if the foundations do not extend up well above grade level. Siding deterioration becomes a secondary concern if the joists, beams, sill plates, etc., are attacked because the foundations are too short.

Even if the foundation is tall enough, wood around window wells, crawlspace hatches, etc., is vulnerable and should be checked. Attention should be paid to basement doors and windows, decks, porches and carports. Wooden supports for railings and balconies are also susceptible to deterioration as a result of wood/soil contact.

Check garages, both those attached to the house and detached. Wood/soil contact is common here, especially on detached garages. The base of carport columns is another area to watch for wood/soil contact.

Some retaining walls are made of wood. These have limited life expectancy, even if made of pressure-treated wood. If pressure-treated wood is cut on site, and the cut ends are not properly treated, the performance of the pressure-treated wood may not be as good as untreated woods such as cedar or cypress.

The pressure treatment on wood typically used in decks and landscaping is only effective in the outer part of the wood. The chemicals do not typically penetrate through the wood. That is why the cut ends are a problem. Some pressure-treated wood is not resistant to attack by insects, including termites.

Garden planters that are raised against the building can create wood/soil contact.

Home inspectors frequently recommend improving the grading of the property around the building to get rain water to drain away from the building. There are more sophisticated solutions such as swales (shallow ditches) located away from the building, or catch basins are necessary. These solutions are more expensive. In many regrading situations, we also have to recommend the addition or modification of window wells to protect basement windows.