DIY Deck Installation Tips #4 – Check Local Building Codes

Deck Installation Tips
Uh, oh. It looks like Doug forgot to make sure that his deck was up to code.

From the looks of it, it’s safe to assume that Doug forgot to contact his local building department to check his plans. If he had, he probably wouldn’t look so upset.

To avoid Doug’s fate, it’s important that you know what parts of your deck building plan need to be up to your local building codes.

Here are some critical parts of the deck construction process that you should pay close attention to.

Be sure to inspect and/or repair the following:

Ledger: When getting rid of an older deck, you should remove the ledger currently installed. Inspect for any decay, or wood rot. You should repair the rim joist, replace the sheathing, or anywhere else you see partial degradation due to moisture. Many professional deck builders will make sure that new sheathing stays as dry as possible by fastening it over the foundation. Many cities and towns have specific guidelines outlining approved ways to replace and repair this crucial part of your deck.

Flashing: Decks that don’t use the right flashing, or apply it to code will have a higher risk of some kind of structural failure. Even if the chances are slim, why take the chance? Professional deck installers will recommend copper flashing, siding, and housewrap. In 2009, many local building codes were updated to require that you use additional hardware to increase the holding strength between the deck and the ledger. There are a lot of details to pay attention to especially since the connection of the deck to your home is as crucial to deck safety as wearing your seatbelt while driving.

Framing: You drew up a beautiful deck design…but is the framing and your proposed joist spacing up to code? Usually you can space the joists at 16″ on center. For decking as strong as ipe, here are our recommendations:

Nominal Dimension Finish Dimension Joist Spacing
1×4 3/4″ x 3 1/2″ 16″
1×6 3/4″ x 5 1/2″ 16″
5/4×6 1″ x 5 1/2″ 24″
2×6 1 1/2″ x 5 1/2″ 32″
Note: Check your local building codes. The joist spacing shown is very conservative
and designed to pass most area building codes and to have nearly zero deflection
under standard loads. The joist spacing shown is also valid if the decking is laid
in a diagonal pattern to the joist, or used even with heavy loads such as hot tubs.

Railing: Does your design call for wood deck railing? Making sure your deck rail system is safe needs to be your primary concern. You must install guardrails at least 3 feet or higher on any deck that is at, or over 2 1/2 feet (30″) off of the ground.

Stairs: The International Residential Code says that you can install risers as high as 7 3/4 inches. Lower than that might be ok. Be sure to check with the building department.

Building codes are cursed by only those builders who think about speed, not efficiency. Lawsuits and even accidental  deaths have occurred whenever people cut corners when building a deck that wasn’t to code. Here’s an article from the NADRA that has some sobering pictures and helpful advice.

Any questions? Comments? We’d love to hear from you.

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