The most common problem with deck structures is rot and insect damage. To determine wood damage, probe the wood in question with an awl or screw driver. If the tool easily penetrates the wood or the wood feels soft, the wood should be replaced. Wood rot and insect damage can be found at a number of places on decks, railings and stairs. Most prevalent is the base of vertical support posts, especially if there is wood / soil contact, and / or excessive moisture. The wood posts should be set securely attached to concrete pier blocks to prevent the wood / soil contact.
A ledger board is a horizontal framing member that is attached to the side of the house and carries the decks joists outward forming the deck. The ledger board should not be attached directly over the house siding. If it is, the deck may not be securely attached to the house framing. The siding is installed around the ledger board after it is bolted to the house framing. To prevent water from rotting the ledger board, it is protected by sheet metal (flashing) placed above the ledger board. Water coming down the siding will go over the sheet metal protecting the ledger board from excessive moisture. It is recommended to probe the ledger board for wood rot, to make sure it remains solid. Many times damage will be found.
The floor joists are the framing members of the floor. The floor joists are usually 2 "X6", or 2 "X8" or 2 "X10", (depending on the span of the deck). The floor joists are attached to the ledger board (at the house) and extend out toward the vertical support posts and attached to the horizontal beam. Probing the top of the floor joists at random is recommended for rot.
The decking or the decks floor is 2 "thick and usually 6", 8 "or 10" wide. The decking also should be checked for rot and also deterioration from the sun (especially decks in direct sun).
Diagonal bracing should be provided to decks greater than 2 feet above ground. The bracing connects the vertical support post to the deck itself. Diagonal bracing is typically 2 "X4" framing material attached to the vertical support post starting down 2 feet from the deck floor, running diagonally up to the deck floor and attaching to the deck 2 feet out from the post. This should be done on each support post.
Deck floors should be sturdy enough not to flex, when walking, between the floor joists. If the deck is not enclosed with a roof, the deck flooring boards should not be butted tightly to one anther, but slightly spaced to allow water to run through, to dry. Trapped moisture promotes rotting of the wood.
All decks greater than 30 "above the ground are required to have a guardrail. Guard rails are also required on porches, balconies, and open sides of stairways.
Vertical guard posts are required to be a 4X4 material. Vertical guard posts are to be attached to the outer perimeter floor joists (the rim joists) .The height of the guardrail can not be less than 36 ". The intermediate rails need to be spaced so a 4" object can not pass through the rails.
When inspecting the guard rails, inspect for rot, missing sections or pieces, and loose or wobbly sections. Guard railings should be sturdy enough to resist a persons weight.
Stairs and Handrails
Deck stairs are normally made of wood. The stairway and steps should be sturdy enough not to show movement with normal use or walking on the stairs. Inspect the fastening of the stairs to make sure the steps and diagonal support (the stringers) are tightly secure. Inspect the stairs for wood rot. Rotted sections should be replaced.
For safety reasons:
The width of each stair tread should be the same.
The minimum tread width or depth should be 10 ".
The height of one step to the next, called the "riser", also needs to be specific. The maximum riser height shall be 7 3/4 ". The greater riser height or tread width, within a flight of stairs shall not exceed the smallest by more than 3/8 of an inch. These are specific codes to prevent tripping accidents.
Handrails can be a minimum height of 34 "or a maximum height of 38". Handrails are required on a set of stairs with two or more risers.
For gripping purposes of the handrails:
Handrails adjacent to walls should have a space of not less than 1 1/2 "between the wall and the handrail.
The hand grip portion of the handrail is required to be 1 1/4 "minimum to 2 5/8" maximum.
Inspect for missing or loosely attached handrails.