How to Tell When Your Deck Stairs are No Longer Safe

Making sure your deck stairs are sturdy and safe is just as important as maintaining your deck. If you have serious concerns about your deck stairs, only a licensed contractor can determine whether your stairs comply with local building codes. However, you can check your deck stairs for general safety issues, and then call an expert for advice and repairs.

Before you start, clean your deck and remove all debris from between boards. Accumulated leaves and dirt hold moisture and encourage rot, so it’s important to check every nook and cranny. This is our recommended procedure for inspecting deck stairs:

Old deck stairs before
Old deck stairs before

Do Your Deck Stairs Comply With Building Codes?

If you’ve inherited a deck along with the purchase of your home, its construction may pre-date your area’s current building codes. Older decks may not meet current standards for your family’s safety – small children and pets can slip through gaps, and poorly-designed stairs create a tripping hazard. While different localities have different building codes, there are universal safety standards to look for:

● Railings on stairs are between 34″ and 38″ high

● Railings continue the entire length of the stairs, with support posts every 4 feet

● Stairs have a landing at the bottom, at least three feet long

● Landings more than 30″ off the ground need a guardrail

● Spaces between balusters and slats must be less than 4″

● The space between the bottom guardrail and stair treads must be less than 6″

● Support columns are required every 6 feet along a flight of stairs

● Stairs longer than 147″ need a landing halfway up

● Stair treads should be 10″ wide

● Stair risers should be 7 3/4″ high, and partially closed, so any openings are less than 4″

● Support columns should be set in concrete, below the frost line

If your deck stairs don’t meet these standards, they’re a potential liability. We recommend bringing them up to code or replacing them. Stair treads that are the wrong size create a serious safety hazard, catching people off guard so they fall. Gaps larger than 4″ between balusters are dangerous for small children.

Stair guard requirements diagram
Stair guard requirements diagram

Once you’ve reviewed your deck’s construction standards, the next step is to assess its general condition. It’s important to thoroughly inspect the deck from above and below, and check for the following:

Loose Stair Treads and Popped Nails:

Changes in temperature and humidity cause boards to expand and contract, loosening nails and screws. Nails that have popped up can injure bare feet or cause a fall. Loose boards can be hard to spot if they’re laying flat, but they’ll warp if not held down firmly. It’s important to find and repair every loose board or popped nail.

Warped and Weathered Boards:

As boards begin to weather, moisture penetrates the wood, causing it to warp and split over time. Stair treads that have warped and no longer lie flat are a tripping hazard.

Wood decay from moisture
Wood decay from moisture

Guardrails and support posts must be solid and immobile. They require a thorough inspection, especially at the points where they attach to the deck and stairs. Make sure they are firmly attached with bolts or brackets, and have no signs of rot.

Every baluster needs to be checked to ensure it isn’t loose or cracked. Make sure handrails are solidly attached and free of splinters. Badly warped, split, or cracked boards must be replaced. Heavily weathered wood should be sanded to remove splinters and smooth the surface.

Weathered wood
Weathered wood

Guardrails and posts are the most important safety feature of your deck stairs, so make sure they’re in top condition.

Correct Use Of Stair Stringers:

Stair stringers (those zig-zag boards that support the stair treads) are a critical part of your deck stairs. We always check for any cracks or splitting, especially at the top where they meet the deck. Stringers may split if they were improperly attached, or if the ground has settled. Stringers should be attached with metal brackets, not just nails. The entire end of the stringer should sit against the deck for proper support.

Stair stringer attachment detail diagram
Stair stringer attachment detail diagram

It’s common to find stringers that were installed lower, leaving only the top few inches of the end leaning against the deck. This is a hazard – it puts too much pressure on the stringer, causing it eventually to crack.

Support Columns and Footings:

Deck stairs should have a support column every six feet to ensure the stringers won’t shift or crack. They should be bolted, not nailed, to the stair stringers. All support columns should be set in a concrete footing – the colder the climate, the deeper your footing should be. Inspect the base of all support columns for cracks, rot, or insect infestation.

Check For Waterproofing:

Make sure deck stairs are waterproofed, just like your deck. Protecting wood from the elements prevents damage and alleviates safety concerns. Checking for waterproofing is easy – sprinkle water on the deck, and see if it beads up or forms a puddle. If the water soaks in immediately, the wood needs to be waterproofed.

Waterproofing wood water beading
Waterproofing wood water beading

If you’ve found during a preliminary inspection that your deck stairs need repair, or they’re a safety hazard, we’re here to help. Our expert staff can perform a thorough inspection and provide detailed recommendations.Just give us a call at 1-877-SEALADECK, or contact us online to schedule a deck stairs check.


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