Lumber Talk

Decks are easy to build. You level an area, throw down some joists and stringers for a deck foundation, screw deck boards to the top of all that, and trip finish by trimming it up. Sure, it’s easier said than done but – still – it’s not hard. For some reason, though, this question comes up repeatedly as a sticking point for weekend warriors: “How do you build deck stairs?”

How to Build Deck Stairs – It’s Easy

Deck stairs are built just like the rest of the deck. To add deck stairs onto your existing deck, you simply fasten deck boards (steps or treads) to the tops of decks stair stringers and attach the stairs to your deck. You can make the stair stringers yourself or you may be able to find pre-made stair stringers but even the pre-made stringers will need some customizing based on the height of your deck. Now, let’s build some deck stairs.

Calculating How Many Steps Your Deck Stairs Need

The easiest way to figure out how many steps your deck stairs stringers will need is to use the very simple rule of dividing the height of your deck by the riser height of your steps (and round to the nearest number). Risers are usually 6 to 8 inches high. The height of your deck is measured from the ground to the top of the deck boards (where you step onto the deck).

So, if you want 7 inch risers and the height of your deck is 48 inches then 48/7 = 6.86 steps. After rounding, you will build 7 steps into your deck stairs.

Materials Required to Build Deck Stairs

The two main components required to build deck stairs are stair treads and stair stringers.

The treads, or steps, are made from one of the following:

• side-by-side 2×6 or 5/4×6
• 2×10
• 2×12 (my personal preference)

The stair stringers are almost always made from 2×12’s, which are actually 1.5″x11.25″. You might want to use pre-cut stair stringers to ave yourself some time on measuring, layout, and cutting.

Other materials you may need to build deck stairs include:

• Coated Screws (Primeguard Plus are excellent screws)
• Metal Angle (for treads)
• Lag Screws (for treads and/or connecting stairs to deck)
• Hex or Carriage Bolts (for connecting stairs to deck)

Building and Attaching Deck Stairs – Build Deck Stairs from the Ground Up

It is easier to build deck stairs on the ground before attaching them to the deck but they get heavy once all of the stair treads are attached to the stair stringers, which makes them difficult to properly and safely maneuver into position at the deck. The best compromise is to attach your stringers together first and put only a few stairs treads on before attaching the stairs to the deck. Make to use strong hardware such as lag screws or hex bolts when attaching deck deck stairs as the consequences of failing stairs can be disastrous (hopefully this is obvious).

All I have done above is try to prepare you for a few of the sticking points that might make a deck stairs project less fun. Hopefully, by knowing those basics, you will be able to get through your building project a little faster. There are a million places online that will tell you how to build decks and how to build deck stairs. I listed the best of the best below for you.

Great Resources for How to Build Deck Stairs

Step by Step Plans for How to Build Deck Stairs: Installing Deck Stairs

How to Build Deck Stairs: Laying Stringers and Attaching Treads

How to Build Deck Stairs: Design, Layout, and Assembly of Deck Stairs (this is the best how to)

How to Build Deck Stairs Video: Video from This Old House About Building Deck Stairs