How to install composite stair treads?

Low-maintenance composite decking allows you to enjoy the outdoors better. After the composite decking is installed, composite decking stairs and deck railings are added to complete the look. Laying composite decking steps is a little different than laying wood steps. Here’s how to install a set of steps.

Deck Stair Basics

When framing a deck, it is common to use treated lumber and composite decking materials on the exterior. Most composite decking stairs are made with 2×12 pressure-treated struts that are spaced 8 to 16 inches apart. They have a sturdy base and hangers attached to the deck. They consist of risers, treads, and balusters. Skirting boards are another name for them. Stairs need to be at least 36 inches wide.

You can make your own struts or buy them already cut at your neighborhood building store. Custom-made struts allow you to match the dimensions of the stairs in your home for the best fit. Whatever you decide, make sure you always follow the building rules.

Stair Measurements

Find the location of the bottom step. Place a straight 2×4 or level on top of the trim board and measure how high you want the step to stop. Use this number to figure out how many steps you need and the height of the steps.

For example, if the height is 55 inches, divide by 7 to get the perfect height in inches for each step. Now, divide 55 by 8 to get the actual height of the steps, in this case 6-7/8 inches.

If you want to use the deck itself as the top lifting plate, you should remove one step.

Each step will have two composite decking boards that make up the tread. The length or front to back of each step is approximately 11 inches. Steps have risers or skirting boards on the back. They are made of pressure-treated wood and composite decking with no holes.

It is important to note that you may need to check the height of the steps or stairs you are used to. For example, porch steps or stairs in your home to get an idea of what feels like the right height. If the height planned for each step is too low at first, remove one step and recalculate.


Build a Stair Platform

A concrete pad is a common stair landing. It goes over the steps by about 36 inches and has a 4-inch layer of gravel underneath. There is another option for this type of deck: concrete footings, like those that support the deck framing. You’ll need to figure out where the footings should go.

  1. Add up the length of each step to get the total length of the stairs.
  2. Mark the location of the stairs on the deck.
  3. Place the footings and struts so that they line up with the two outer markings and run the full length of the run. The base can be level with the ground.

Cut the Stringer

Once the grade and ramp are known and the footings have been placed, the steps can be marked on the 2×12 dowels to create the longitudinal beams.

  1. Set stair gauges at the rise height and the length of the rungs on the framing square.
  2. Place the squares on the corners of the 2×12 planks and make a mark at the top.
  3. Move the square along the board, marking the beginning and end of the next step. Keep writing until you get the correct number of steps.
  4. Subtract the thickness of the toe kicker (treated boards and composite decking) from the running mark you made for the top step and draw a straight line. This line shows how the stairs connect to the decking. There will be no skirting board at this point in the staircase.
  5. At the bottom step, subtract the width of the tread from the height of the rise. Then, draw a straight line at the starting point. This is a cut line that moves the entire set of stairs downward. When the treads are installed, this cut line will bring the bottom step to the same height as the other steps.
  6. Cut the longitudinal beams with a circular saw. Then finish the cut with a handsaw.
  7. Using this cut longitudinal beam as a reference, mark and cut the other longitudinal beams.

Alternatively, you can draw a line on the composite decking boards based on the longitudinal beams so that you can cut two cornice boards that can be covered over the outside longitudinal beams. Note that you should use composite wood decking without notches.


Installing the Treads, Skirting Boards and Longitudinal Beams

The deck struts will rest on the poured footings and the longitudinal beams will be installed between the decking and the posts. Once the longitudinal beams are in place, you are ready to add the skirting boards and treads.

  1. To support the cross beams under the rim or end joists, cut a board to the width of the step. Use the same lumber to attach the board to the bottom edge of the joist.
  2. To secure the back of the support board to the joist or crossbeam, add an extra board. You can use joist hangers or wood screws to secure the supports.
  3. Attach the stair posts to the baseboards. You can attach the posts to the footings in the same way you would assemble deck framing.
  4. Draw a line around the hanger on the support board. Hold the stringer and hangers so they are flush with the top of the 2×8 support plate. Then, mark the position of each hanger.
  5. Install the longitudinal beams and hangers. Remove the longitudinal beam and secure the hangers to the support plate with 10d nails and screws.
  6. Attach the longitudinal beam to the hanger. Drill test holes in the hanger and attach the outer longitudinal beam to the hanger with nails and screws. Attach the bottom of the longitudinal beam to the bottom post with screws.
  7. Attach the cross member and bottom kick plate to the strut. At the bottom of the step, cut a toe kick from pressure-treated lumber. Punch holes in it and tighten with screws.
  8. Secure the struts. Put the last few longitudinal beams in place and secure the struts to the bottom of the longitudinal beams with braces, anchors, and carriage bolts.
  9. Cut the last pieces of the skirting board from pressure-treated timber and composite decking without grooves. Don’t forget to cut a piece of wood when making the bottom of the steps. Cut the composite decking stair step so that it extends about an inch beyond the toe kick.
  10. Attach the last two toe kickers. Drill holes in the toe kicker boards and attach them. First, secure the treated boards, then cover them with composite decking boards.
  11. Leave gaps between the toe-kicking boards. Drill pilot holes in the step boards and then fix them with screws. Leave drainage space between the boards on each step.
  12. Covering the outside beams with composite decking boards will give the staircase a neater, cleaner look.

Note that when using screws to connect the different parts of the steps, choosing composite screws that are the same color as the tread boards will give the steps a more coordinated and uniform appearance.

Installation of Stair Handrail

Stair handrails usually consist of a balustrade and a railing. Once the deck stairs are installed, it’s time to install the stair railings. The right stair railing not only ensures the safety of pedestrians, but also makes the deck more aesthetically pleasing.

  1. Put post sleeves around the posts and slide them. You can cut the length of the handrail to suit your needs. Polyvinyl chloride cement should be used to secure the sleeve in place. Please follow the instructions on the package.
  2. Place the railing hole in the center of the bottom rail and hold it against the post. You can mark the curves at both ends. To make room for the two mounting brackets, you will need to take adequate measures. Then cut the rail. Do the same for the other bottom rail.
  3. Mark the angle of the bottom rail on the top rail. Correspond the holes in each bottom rail to the holes in the top rail. Move the angle to the top rail and cut it the correct way.
  4. Mark the position of the bottom rail brackets. Move the brackets to the bottom rail and mark the positions of the brackets on the top and bottom struts. Punch pilot holes in the rail and secure with screws. Do the same for the other bottom rail.
  5. Find the angle of the railing using a T-slope. The balusters need to be cut to fit the rails perfectly. To obtain the proper slope, press the T-bevel against the post and bottom rail.
  6. Mark the angle of the balusters on each rail and cut the balusters according to the marks.
  7. Fit the balusters into the bottom rail. Embed the stair balusters in the holes in the top and bottom rails. Then attach the balusters to the bottom rail.
  8. Attach the top rail. Position the top rail where you want it and screw it into place.
  9. Finish the stairs on the composite decking. The post caps are the finishing part of the fence and should be filled around the footings using gravel or dirt.
  10. Once the stair railing is complete, call the building department in your area for a final inspection and to make sure everything is in order.

It is important to note that during installation, always follow the manufacturer’s instructions for fasteners and structural hardware.

How Do I Use Pressure-treated Wood?

Guidelines for Use

  • Use stainless steel or hot-dipped galvanized screws and other tools marked for use with pressure-treated wood.
  • When installing, if the timber is wet (as it usually is when bought from the store), it should be butted together tightly. This is because wet wood shrinks as it dries.
  • Pre-drilling holes in the ends of the boards will prevent the boards from breaking when nailed or screwed.
  • If the project requires it, use composite ground contact grade lumber.

Safety and Security

  • Wear a dust mask to protect your eyes and face when working with or cutting wood.
  • Always wash your hands if you are working with treated lumber.
  • Dispose of sawdust and other waste by the regulations in your area.
  • Pressure-treated wood must not be burned.
  • Do not use treated wood as mulch.

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