Stair supports?


I have outside stairs on the side of a hill. All pressure treated. Im using 1/5 x 2 x 12 blocks to support 2 x 12 steps. WHat is the best way to attached the support blocks to the riser? I used 3 deck screws on each block for one set of steps but Im not sure if those are the right hardware to use as deck screws may not be meant to take that shear stress. I could used 16p 3 inch nails, but I would think those would work out eventually. Lags are very expensive and I was trying to avoid those.
Any thoughts?
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Would not the risers and treads attach directly to the stringers? Dave
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What are "support blocks?"
| | ________ | |
http://www.hammerzone.com/archives/decks/oldporch/steps/stringer.htm
If the above is a "stringer" (2by PT), the steps or tread lay upon (and are fastened to) the horizontal face of the parallel stringers.
For this, Exterior grade decking screws would seem best (well, stainless would be nicer).
For an "open" stairway out of doors, this should suffice.
http://www.hometime.com/Howto/projects/decks/deck_11.htm Pg 11 Decks Building Stairs To frame a deck stairway, you need to figure out the number of treads (steps) required and the rise and run (length) of each tread. First, measure the height of the deck. Then divide the height by 7 (a typical stairway rise). If the answer's a whole number, then that's the number of treads you'll need. If the answer ends in a fraction, then round it off to the nearest whole number which'll be the number of treads and divide that into the height. That gives you the rise you'll need for that number of treads. To determine the most comfortable run of your treads (the length), divide the rise into 75. So with a typical rise of 7 inches, a typical run might be 10-1/2 inches. A rise of 7-1/2 inches would work best with a run of 10 inches. But this so-called "comfort formula" does allow some leeway, so layouts of 6-12 (72) and 7-11 (77) work out fine. TIP: On deck stairs, a run of 10 inches always works great because you can use 3 2x4's (for a total width of 10-1/2 inches wide) or 2 2x6's (11 inches wide) for the treads, leaving a nice 1/2-inch or 1-inch overhang at the front of the tread. Laying out Stringers You can lay out a stair stringer very quickly with a framing square by finding the rise on one leg and the run on the other leg and then lining those up with the edge of the board. Mark along the edges of the square to create the first step. Then move down the board, line up the square and draw the next step. Continue that until you've drawn all the treads. Cutting Stringers Use a circular saw to start all the cuts. But use a handsaw to finish them, since the circular saw blade leaves a little bit uncut at each corner. Tracing Stringers TIP: All stairways require at least 2 stringers, and taller ones require 3. But rather than lay each one out individually with the framing square, cut the first stringer out and use that one as a pattern for the others. Bracing Stringers You can install each stringer separately, but it's usually quicker to connect them together with braces before setting them in place. Notch out each stringer for 2x4 braces at the top, middle and bottom. Screw the braces in to each stringer. Attaching Stringers Set the stringers in place against the rim joist and nail through the top brace into the rim to hold it. Lag screw through the brace into the rim joists to secure them permanently, pre-drilling for each screw. Installing Treads Cut the treads to fit over the stringers, leaving a 3-quarter inch overhang on each side to serve as a drip edge and keep rain from dripping down onto the stringers. Screw or nail the treads down into the stringers to finish the stairs.

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Actually, I cannot figure out what you are doing but, Screws will snap while nails will bend under pressure.
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wrote:

3
are
shear
work
I am equally confused by what the OP is asking, but both screws and nails are commonly used in the construction/hanging of stairs. Neither will fail is properly installed. Heck, I've heard of complete houses that were put together with nails...
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its not a stringer, but solid 18' length of 2 x 12 as a riser with nailing blocks attached to it for the stairs to sit on.
Deck screws are not made to deal with lateral or shear stress and they snap pretty easily so Im concerned about using then to attach the nailing or now screwing blocks as they will carry the weight of anyone standing on the step.
Nails would be much better in shear, but would, over time work loose with the constant movement of foot use.
Lags would be best but even a 1/4 3" lag get pretty expensive when looking at all the stairs I have.

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Cut stringers and attach them to the inside of the 18' solid with some screws or bolts. Easy and fast. Forget making a ton-o-blocks. They will never last and the alignment alone would take more time than cutting new stringers.
Dave
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snap
now
Do you have any pictures you can post in the binary group? More than a couple of us are not understanding what you are saying. Screws and nails have been holding houses together for quite a while and unless there is something very unique in what you're doing, I just can't understand all of this concern over shear strength and nails backing out. You know what they say - a picture is worth a thousand words.
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If I understand the OP correctly, he is not cutting the typical "sawtooth" in the stringer, just laying a complete 2x12 on an angle. The stair treads are then mounted to nailers, which are attached to the stringer at the appropriate angle to make the tread level. Seen from the side, you would not be able to see the ends of the treads.
I have a similar set of deck stairs, but mine are done with dados in the two end stringers, and a traditional third stringer in the center.
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Sorry I did not see this before I posted. Same approach but I've used a router for a more finished look....i.e., the tread does not exit the front of the Stringer,,,can also use a circular saw set to depth. I believe you can go up to 30" without the center stringer that gw mentions if the treads are 2x10 or 12.

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I was wondering about that. My steps are 39" wide so longer then the engineering says they should be I guess for unsupported. I had not planned on putting a center stringer, but as these steps have been there for 20 years with no problems (except for termites and rot which is why Im replacing them with pressure treated) I think they will be will be fine without the center support.

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planned
Ok, I understand what you're doing now. It's what I thought you meant in the beginning but the manner in which you stated that you weren't using stringers caused me to wonder exactly what you meant with your chosen terminology.
You're over-engineering this issue. Screws properly secured (seated) are not going to shear from use. You'll break the tread before you shear the screw. Likewise with nails. You've got to think - how long have stairs been built this way? Hundreds of years? Want it to be a bit more secure? Glue and screw the cleats to the stringers.
Thirty nine inches is a bit wide for just two stringers, but it will work. You can always stiffen them with a batton of 1x3 on edge in the middle (of the of the width) of the 2x12 tread, running the length of it. You will be surprised what an increase in strength this provides.
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Well, the 2x12 sounds like it is a Stringer. Instead of cutting out triagular shaped pieces for the tread to sit on you are attaching a block for the tread to attach to. Is that correct?

Correct! Under increasing load screws will snap while nails will bend. Typically screws were developed for drywall and then they became the fastener of choice due to ease of use. However, most structures move around and nails will bend with that movement while screws will snap at a certain point.

I use a lot of lags in the framing phase and yeah they are costly compared with nails, etc. I buy them in 1,000's (actually by weight) which becomes more reasonable.
It would take a bit of extra time but you could use a router to cut slots on the stringer for the tread to fit into. Then, using screws would be well suited as the would not be any shear.

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OK...thank you for the input. it was a big help

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In some areas you can buy the pressure treated stringers already cut. I was lucky that the precut worked for me I guess.
I take it you are trying to avoid the tedium of laying out the stairs with a square..
You could nail the treads in from the side in addition to laying them on support blocks if you wished to have some extra support. You can use galvanized ring shank nails which would hold pretty well. I used some galvanized ring shanks in an air nailer for my back deck and it seems to have worked well. And the air nailer was pretty fast.
Ron T
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well........im just rebuilding what was already there. Its 3 tiers of stairs....about 18 steps per tier with 2 midrise landings and a deck at the top. The riser spans are 18'. Those are only supported top and bottom and with a 4x4 post in the center. I would think the stringers with sawtooth cut would be very much weakened over this span

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