There are many types and styles of decks. However, from an inspection point of view, your main concern should be safety rather than appearance. When inspecting a deck, unless it is a rooftop or cantilever type, you should begin with the supports on the underside. If the deck is more than a few feet above the ground, it will generally be supported by wood or metal columns (posts). Unless wood posts have been pressure-treated, they should not be in direct contact with the soil. Untreated wood in contact with the ground is vulnerable to rot and termite activity. Also, the dampness normally associated with the soil can promote rust deterioration of a metal column.

Each column should rest on a concrete pad that has a footing below the frost line. Otherwise, the footing is subject to frost heave. Probe the base sections of the columns with a screwdriver to determine whether there is deterioration. If the screwdriver can penetrate the column beyond the surface, a problem exists that should be corrected. In some cases, the column might require replacement. Push the column to see if it moves. It should not. Occasionally I find columns that are loose and not adequately supporting the deck. (See FIG. 6-14.) These columns should be shimmed and fastened securely to the deck. The condition usually results from uneven settlement of the support footings and inadequate fastening at the top or bottom of the column.

When the deck is less than a few feet above the ground, it is usually supported by masonry piers. Inspect the piers for cracked, broken, loose, or deteriorated sections. They must be repaired. With some “groundhugging” decks, usually less than a foot above the ground, this inspection might not be possible. Most of the support piers are not visible.

Real Estate Home Inspection photographs of house defects

When one side of the deck is attached to the house, there are usually no support posts below that section. Consequently, if the joint between the house and the deck should weaken, there is a potential for that portion of the deck to collapse. Check the joint between the deck and the house to see if it is securely fastened. Is it pulling away from the house? It should not be. In some cases, the deck is fastened to the house with undersized or too few nails. I know of one community where this type of installation resulted in two decks collapsing. Because of these failures, the town passed an ordinance that requires using lag bolts rather than nails to secure the deck to the house. (See FIG. 6-15.)

Next, check the joist supports at the portion of the deck attached to the house. Since there are no posts, there will not be a girder to support the joists. In this case, the joists should be supported by metal brackets fastened to the header or by being toenailed into the header with a ledger below them. The former method is preferred because the ledger used is often skimpy. I have seen many decks where the joists were toenailed into the header but the ledger was never installed. If you find this type of installation, you should install angle brackets to support the joists or at the very least install a ledger as a precautionary measure.

In addition, depending on the size of the deck, there might be a need for diagonal bracing. This provides additional rigidity to the deck and can be achieved by placing a 2inch-by-6-inch board between two diagonal corners and nailing it to the underside of each joist.

When deck planks are installed, there should be a space of about 1⁄4 inch between them. This space allows rainwater and melting snow to drain. In some cases, the planks are butted up against one another so that there is virtually no space between them other than the crack of the joint. Water entering this crack does not readily drain and instead promotes decay. If you can reach the underside of the deck planks and the top portion of the joists, probe them for rot. If there are rotting sections and the decay is advanced, you might see the fruiting bodies of the decay fungi. (This is discussed in detail in the section on rot in chapter 8.) If steps lead to the deck, the treads, stringers, and handrails should be inspected for decay. As with the deck support posts, the stringers should rest on a concrete pad rather than soil.

Real Estate Home Inspection photographs of house defects

After inspecting the underside of the deck and the steps, you should inspect the top portion. When the deck is more than 30 inches above the ground, there should be a guardrail around the perimeter as a safety precaution. Naturally, the higher the deck, the greater the need for a rail. If the deck is to be used by small children, additional protection is needed to block the open area between the railing, railing posts, and deck planks. When balusters are used for this purpose, they should be spaced 4 to 5 inches apart.

The guardrails and deck planks should be inspected for cracked, rotting, and loose sections. (See FIG. 6-16.) Depending on the quality of the wood and the upkeep, a deck need not deteriorate to a point where it requires complete rehabilitation. Repairs or replacement of deteriorated sections should be performed as needed. If you find sections of the deck that are in need of repair, you should indicate those areas on your worksheet.

Real Estate Home Inspection photographs of house defects

One last point: If the deck was not built when the house was constructed or the deck is a complete replacement of a previously deteriorated one, check with the seller to see if a certificate of occupancy (CO) was issued by the local building department at the completion of construction. A CO is required by most municipalities. If one was not issued, record that fact on your worksheet for future discussion with your attorney.

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Jack's Avatar
Jack replied the topic: #14121
WOW!!!! What a photograph of that old deck post! That post looks like the wind will knock it over or all you have to do it give it a light push and it will fall down. That's the main corner support post for that deck. I can't believe someone didn't see that or fix it long before the home inspection. It's amazing how lucky the house occupants are to not have walked on the deck and had it collapse and kill someone!