Aging decks create the possibilities of deck failures throughout the area. Here are some steps to prevent your deck from failing in the future.
Ledger Pulls Away from House
Bad Ledger board attachment
One of the most common and potentially most damaging reasons for deck failures is for the ledger board to pull away from the house. The ledger board is usually a 2×10 or 2×12 that is attached to the house. The joists for the deck are attached to the ledger board. The ledger board should be attached to the house with ½” lag screws or 1/2” carriage bolts. Many decks were installed over the years using nails to attach that board.
Because of the weight carried by that board and the constant movement of the structure as it is used, those nails can loosen. At some point they will eventually fail and the deck could fall off of the house.
SOLUTION—Inspect your ledger board to see how it is attached. If it is nailed, supplement the nails with ½” lag screws or LedgerLocks at 12” intervals. This inspection is especially important if the deck is over 15 years old when building codes did not require lag screws.
Ledger Board Splits
If a ledger board is installed with lag screws, but they are all in a straight line there is a risk of the board splitting. If that happens, it may not be able to carry the weight and cause the deck to fall. Today’s codes require that the lag screws be staggered to prevent the board from splitting.
SOLUTION—Inspect the ledger board to see what pattern was used for the lag screws. If they are in a line there are a couple of options. Look to see if there are signs of splitting that align with the lags. If there are no signs, inspect the board annually to look for signs of splitting. You could also install new lags in alternating spaces to create a staggered pattern. You would then need to remove the ones you are replacing and plug the holes.
Improper Joist Installation
Joists are usually installed using joist hangers (galvanized metal braces) that have flanges. The hangers have holes in them that should have a galvanized joist hanger nail in each hole. If the nails are not galvanized they can fail causing that joist to fail. One joist failure won’t make your deck fall, but enough of them failing will create a structural problem.
SOLUTION—Inspect the joists to see how they are attached to the ledger board or band board. If there are holes in the hangers without nails, put hanger nails in them. If the nails are rusting, try replacing them one by one.
Improper Post Installation
All of the weight for your deck is transferred to the posts, so they are supporting your deck. Properly installed posts will sit on concrete footings that go about 30” deep. Some installation methods
Faulty deck support
may have the concrete above the ground with the post attached to it. Another method is to bury the post in the hole, but it will still sit on a concrete footing. If they sit on anything else, there is a risk that they will cause your deck to sag. You could eventually have a deck failure. It is also important the beams sit on or attach to the post correctly. Beams should be attached to the posts with carriage bolts and/or sitting fully on the post.
SOLUTION—Inspect the posts and beams to make sure they are properly installed. If not, this is a job that is best handled by a professional. Contact your deck builder or a skilled carpenter to remedy the problem.
Whether you want someone to build your deck or you are building it yourself, at Outdoor Living Inc. we can help you with these types of questions and more. Protect the safety of your family and friends by assuring that your deck is structurally sound.