Wood sidings come in the form of shingles, shakes, plywood, panels, boards (applied vertically and horizontally), and hardboard. The siding is generally available in cedar, spruce, firs, redwood, and hemlock, as well as pines and other soft woods. Other kinds of wood may be used in thin veneers on the exterior of the panels or plywood siding. Wood siding is prone to insect attack and water damage, so it should be closely evaluated where the wood is in close or direct contact with the soil. Areas where vegetation overgrowth has occurred are especially susceptible to deterioration and mildew/molds. Use a screwdriver to probe for suspected areas for deterioration or infestation. Areas where the soil is in contact with the wood components should be regraded so that a reasonable amount of space is available between the bottom of the wood and the soil or graded surface.

Inspect the wood for peeling or blistering paint; warped, split or cracked shingles; delaminated plywood; dark stains; or mildew and buckled boards. These problems typically indicate water damage or deferred maintenance. The sources of the water penetration may be from open seams or improperly sealed joints in the siding and trim; separations at the outside corners; missing or damaged caulk in these areas; loose and missing pieces or sections; or rusty nails and holes.

When inspecting the siding, you should also inspect the eaves, fascias, soffits and other outside trims. Closed soffits may pull loose, or birds, squirrels and insects may be able to access this area for nesting. Faulty guttering can also cause water damage and deterioration in the soffits. Suspicious areas should be probed with an ice pick, pocketknife or screw driver blade.

Some of the more popular styles of wood sidings:

Clap board is an overlapping wood material. The boards are typically installed horizontally. It is generally a good material, but should be painted and properly sealed. Older siding had a 3/4 inch butt edge; modern sidings could be 7/16 inch or as little 5/16 inch These modern sidings are susceptible to considerable cracking/splitting in 2 to 6 years.

Hardboard is a material that has been used for a number of years, and it should be kept painted and sealed at all times. Hardboard material can follow any form from basically a cardboard type composition to the modern day pressed wood or particleboard sidings. When this type of material is not properly maintained, it deteriorates rapidly. Hardboard, whether a cardboard variety, pressed board or particle board, should be probed in suspect areas, to ensure that the material is sound. Manufacturer recommended installation details and clearances should also be inspected for compliance.

Plywood has been used for quite some time as an exterior siding. Originally, it was only used on the gable ends of the residence. Since the early 1980s, it was relatively common to use plywood on most or the entire house. The most common of the plywood sidings is T1-11. It is typically fir or cedar, 7/16 inch thick, and has vertical grooves. All plywood used on the exterior should be painted or sealed to prevent delaminations. When the wall to be sided is taller than 8 inches, the plywood will have a horizontal butt joint that needs protection. A “Z” flashing should be used to protect the top edge of the lower sheet. Both of these edges should be painted before the sheets are installed.

Tongue and groove siding is very similar to clapboard, except that its tongue and groove design allows it to interlock, and it is installed vertically. It should not be installed horizontally or on a 45-degree angle. Check for water stains above sliding glass doors and windows that have draperies. This siding needs protection with a preservative stain or paint.