Building a wooden deck over a concrete one Installing the floor boards and skirts for the staircase

Step 3: Installing the floor boards and skirts for the staircase

Once the runners and the skirts are on, it’s time to start showing some real visual progress. The runners were placed perpendicular to the house with the original idea of running the boards parallel to it, but I changed my mind at the last minute and went for a 45 degree angle. This results in a bit more that 18 between runners (26.5 on center, so not exactly a bit more. ), but after placing a couple of experimental boards and seeing that there was very little spring to them I figured I’d be ok. The only caveat I could think of at this point was that I would need to abstain from any short floor boards (i.e. those spanning just two runners), as they would bow too much in the middle.

The first board goes on starting from the far corner and moving towards the house. It’s important to get the angle right and to choose a very straight board, because all the others that follow will laid down parallel to this one.

The boards get two screws running through them and into each runner, and where a board ends it must be cut at 45 degrees and end right in the middle of a runner. The next board starts from the same spot and keeps on going until you reach the house or need another board. When attaching two boards on the same runner, angle the screws such that they are at least 0.75 away from the edge of the board and still going into the runner. Staggering your board cuts so no two contiguous lines have the cut on the same resting on the same runner will make your floor stronger and look much better.

When laying down additional rows of wood, you need to leave a bit of space between them to allow for the wood’s expansion and also for proper water drainage. I had found that 1/8 worked fine, and the simplest spacer I came up with was a few thick nails that I just bent in the middle. This made for a sturdy spacer that was also easy to grab onto with a pair of pliers and pull out (some of them will be really stuck after the board is attached).

Not all of your boards will be perfectly straight, but that’s ok and can be fixed (to a degree. ). Simply put the board down, set the proper spacing at one end, and screw that end down. Then move down the line, set spacer, and either pull or push the board into place. Keep on screwing it into the runners as you move down, and the end result will be straight. Obviously some boards are way too crooked to begin with, so just skip them — that’s why you bought an extra 10% of material to begin with.

Install the boards with a bit of an overhang at the edge of the floor, as this will all be cut off in one shot at the end. Do not cut the boards one by one and install them flush with the edge because you can easily be a little bit off on a few boards and this will show. Instead, wait until all the boards are attached and then just cut the edges off in one shot with a circular saw. Once they’re cut, use a router to round off the edges.

Once the floor is done and the edges have been cut off, finish off the steps by installing boards on their respective runners. These can just be simple parallel boards; no need for a design at this point. Start from the front of the step with full width boards and work your way towards the back, ripping the final board to the proper width with the circular saw (or, preferably, a table saw if you have one).

When the steps are covered, use some bristol board to outline the exact shape of the skirts on the sides of the steps. The board is thick and won’t flop everywhere, so just hold it up against the sides of the staircase and crease it along the edges of the steps in order to know where to cut them. Trace the lines, add extra pieces for areas larger than the board. Once you have a complete template for the skirts, lay it on top on a 2 x 10 board, transfer the shape, and cut. Then cut additional pieces of 2 x 10 to fill in any parts of the template that extended beyond the size of the beam. Those pieces can just be attached with carpenter’s glue and some screws. As long as the pieces are well attached, you’re good. They won’t be supporting any weight so don’t worry too much about how strong they are.

Attach the finished skirts to the concrete using tapcon screws and you’re done. You can then quickly remove the stair boards to apply silicone where the skirts touch the concrete, and put the boards back on.

Cupping — if you look down the short edge of a board, you’ll see the rounded grain that indicates this was once part of a circle. The curves will either point up or down, and this is important to keep in mind. Wood will have a tendency to bend (over time) in the direction of those lines, so it’s crucial to install the boards with those curves facing down. Being screwed onto a firm surface will hold that cupping back, and if you install the board with the curves facing up its edges will rise over time and become both unsightly and dangerous (easy to trip over).

Finally, make sure you pre-drill all holes so the screws don’t end up stretching and potentially cracking the wood. This is crucial especially around the runners where two boards meet. And as always, brush on wood sealer to all cut ends.

Step 3: Installing the floor boards and skirts for the staircase

Once the runners and the skirts are on, it’s time to start showing some real visual progress. The runners were placed perpendicular to the house with the original idea of running the boards parallel to it, but I changed my mind at the last minute and went for a 45 degree angle. This results in a bit more that 18 between runners (26.5 on center, so not exactly a bit more. ), but after placing a couple of experimental boards and seeing that there was very little spring to them I figured I’d be ok. The only caveat I could think of at this point was that I would need to abstain from any short floor boards (i.e. those spanning just two runners), as they would bow too much in the middle.

The first board goes on starting from the far corner and moving towards the house. It’s important to get the angle right and to choose a very straight board, because all the others that follow will laid down parallel to this one.

The boards get two screws running through them and into each runner, and where a board ends it must be cut at 45 degrees and end right in the middle of a runner. The next board starts from the same spot and keeps on going until you reach the house or need another board. When attaching two boards on the same runner, angle the screws such that they are at least 0.75 away from the edge of the board and still going into the runner. Staggering your board cuts so no two contiguous lines have the cut on the same resting on the same runner will make your floor stronger and look much better.

Building a wooden deck over a concrete one Installing the floor boards and skirts for the staircase

When laying down additional rows of wood, you need to leave a bit of space between them to allow for the wood’s expansion and also for proper water drainage. I had found that 1/8 worked fine, and the simplest spacer I came up with was a few thick nails that I just bent in the middle. This made for a sturdy spacer that was also easy to grab onto with a pair of pliers and pull out (some of them will be really stuck after the board is attached).

Not all of your boards will be perfectly straight, but that’s ok and can be fixed (to a degree. ). Simply put the board down, set the proper spacing at one end, and screw that end down. Then move down the line, set spacer, and either pull or push the board into place. Keep on screwing it into the runners as you move down, and the end result will be straight. Obviously some boards are way too crooked to begin with, so just skip them — that’s why you bought an extra 10% of material to begin with.

Install the boards with a bit of an overhang at the edge of the floor, as this will all be cut off in one shot at the end. Do not cut the boards one by one and install them flush with the edge because you can easily be a little bit off on a few boards and this will show. Instead, wait until all the boards are attached and then just cut the edges off in one shot with a circular saw. Once they’re cut, use a router to round off the edges.

Once the floor is done and the edges have been cut off, finish off the steps by installing boards on their respective runners. These can just be simple parallel boards; no need for a design at this point. Start from the front of the step with full width boards and work your way towards the back, ripping the final board to the proper width with the circular saw (or, preferably, a table saw if you have one).

When the steps are covered, use some bristol board to outline the exact shape of the skirts on the sides of the steps. The board is thick and won’t flop everywhere, so just hold it up against the sides of the staircase and crease it along the edges of the steps in order to know where to cut them. Trace the lines, add extra pieces for areas larger than the board. Once you have a complete template for the skirts, lay it on top on a 2 x 10 board, transfer the shape, and cut. Then cut additional pieces of 2 x 10 to fill in any parts of the template that extended beyond the size of the beam. Those pieces can just be attached with carpenter’s glue and some screws. As long as the pieces are well attached, you’re good. They won’t be supporting any weight so don’t worry too much about how strong they are.

Attach the finished skirts to the concrete using tapcon screws and you’re done. You can then quickly remove the stair boards to apply silicone where the skirts touch the concrete, and put the boards back on.

Cupping — if you look down the short edge of a board, you’ll see the rounded grain that indicates this was once part of a circle. The curves will either point up or down, and this is important to keep in mind. Wood will have a tendency to bend (over time) in the direction of those lines, so it’s crucial to install the boards with those curves facing down. Being screwed onto a firm surface will hold that cupping back, and if you install the board with the curves facing up its edges will rise over time and become both unsightly and dangerous (easy to trip over).

Finally, make sure you pre-drill all holes so the screws don’t end up stretching and potentially cracking the wood. This is crucial especially around the runners where two boards meet. And as always, brush on wood sealer to all cut ends.


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