Is Your Deck or Porch Safely Installed?
As spring turns into summer, there is one thing on Chicagoans minds……spending a lot of time outdoors. The air will soon smell of meat being cooked on a charcoal grill from a back porch or deck. Outdoor parties will be hosted celebrating holidays, graduations, and birthdays. The last thing you want to be thinking about is whether the deck or porch you are standing on is installed safely. Sure it’s withheld you and your family for many years, but having 20 plus people on it will cause some serious loads on the deck structure.
There have been a lot of improvements to deck codes over the last 20 years or so, and if you have an older deck, there may be new safety elements your deck is missing. In this article, I will go over 5 common areas where older decks (or improperly installed newer decks) are lacking.
- Improper connection of the ledger board – The structure of a typical deck is kind of like a chair. The front legs of the chair are self-supporting but the back end is tied to the backing of the chair. For a deck or porch, columns supporting the ends farthest away from the home and end closest to the house are actually tied into the home’s structure utilizing something called a ledger board. This ledger board in most instances will be taking around ½ the load of the entire deck, so you can tell that it is an important piece.
As you can probably imagine, an improperly fastened ledger board can be a significant safety concern. Weak ledger board connections will cause the deck to pull away from the home and eventually fail. So what should you be looking to ensure proper ledger board connection?
- Only Lag Screws, Through Bolts, or Concrete Anchor bolts should be used to anchor the ledger board to the home. The diameter of each should be at least ½” diameter
- The screws or bolts should be installed more than 2” from the top or bottom of the board.
- Horizontally, the bolts should be spaced no less than 16” on center for decks 12 feet or short without additional support.
- Bolts or screws should zigzag vertically to give better torsional resistance to the deck.
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- Connections of joist and beams by Toe Nailing – The term toe nailing means driving a nail at an approximate 45 degree angle to connect two perpendicular wood structural members, such as a joist to a beam or girder. This is considered an inferior connection nowadays, but was used a lot in old construction. Joist and beam hangers are now considered standard in deck construction and should be utilized whenever possible. It is also to make sure that nails or screws are added to all the openings for the hanger, otherwise the structural rating of the hanger is diminished.
- Post to Ground Connection Issues – The posts (front legs) of a deck or porch also bear about ½ the weight of the deck. The posts should be properly connected to a footing (concrete pad) either by embedding the post or a steel post bracket. All wood members should be raised at least 8 inches above the ground to prevent water damaging the connection. If you touch the post and it can move, or if there is a gap at the connection, it is not bearing and the weight of the deck is being unevenly concentrated.
- Deterioration of the Wood Structure – It is important to inspect annually for wood deterioration and rot. Check your decking and the structural members underneath the deck floor. Re-coating the deck every 3-5 years will help prevent deterioration. If you notice any softening wood, contact a contractor or inspector immediately to get it assessed.
Additionally, if you notice any warping wood members it is also important to have that evaluated. 4 x 4 posts are inadequate for taller decks and porches and will tend to bow unless laterally braced.
- Balusters spaced farther that 4” apart – While this is not necessarily a structural concern, it is an important safety concern. If the railing or balusters have openings of greater than 4” apart, then it is possible for a child to squeeze through them and fall. Properly spaced balusters and railings will ensure you can worry more about hosting.
If you note any of the above decking issues, it is important you talk to a licensed inspector or a contractor to understand your repair options. Sometimes these issues can be easily remedied, other times they do require a larger investment. But you can’t put a price on safety. As always please feel free to send feedback and questions to email@example.com.