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I have a set of pressure treated stairs that lead from ground level up to a wooden deck, providing access from the pool to a water slide (salt water and chlorine). I originally built these stairs about 10 years ago using galvanized nails to secure the stair treads.

Over time the galvanized nails rusted and eventually split the stringers. I replaced both about 4-6 years ago using deck screws. The deck screws didn't last long at all, split stringers and rusted screws, I replaced the stairs again, about 2 years ago. This time I used stainless screws.

I've noticed that the stringers are splitting yet again. When building the stairs, I predrilled every hole for the screws, even removing the tread when drilling to make sure the hole was deep enough to cover the length of the screw. The treads are not loose yet, but I only see it as a matter of time. The slide stairs are still plenty strong, just aesthetics at this point.

I live in the US, Atlanta, GA area and we did see a good number of frozen days this winter as well as snow, I don't know if that helped in the stringer demise.

split stringer

I'm thinking of rebuilding another set of stairs (no direct exposure to pool water, but limited access to sun), whose stringers are split to hell, and I'm looking for some tips to make them last longer.

EDIT:

I took a good look and noticed that only the center stringing is splitting like this. The left and right strings have the same number of screws and the exact same placement. I think they are just a bit less exposed.

  • That's pretty strange. I almost never pilot for deck screws, and I haven't seen what you are as far as splitting. Modern code calls for risers to be installed, which would reduce sun exposure and maybe prolong stringer life. I will also suggest that you run your screws in all the way. They should be at or below flush. If they're stripping before pulling in you're piloting too big. – isherwood May 3 '18 at 13:36
  • Thanks, the screws were flush when newly built, but the wood has shrunk a bit since the instal, the screws still have plenty of bite. I may also consider risers on v3. – Gary Bak May 4 '18 at 11:34
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I've never had that problem either. But you could use long screws, say 6". The stringer would be over bored the first 2-3", then piloted for the remaining depth so that only the distal 2" of screw thread into the stringer. The aim is to get the thread to bite into only the solid length of the stringer, not the triangle. Fill the bore with caulk to keep water out, then drive the screw.

I prefer my screw heads flush or 1/32" proud, never counter sunk.

Alternatively, you could use lengths of angle iron. The stringer screws would go into the face of the stringer, not the edge. The tread screws would go into the bottom face of the tread (and be hidden). See: https://duckduckgo.com/?q=angle+iron+to+attache+treads+to+stringers&iax=images&ia=images

  • I get where you're going with the long screw approach, but the availability and cost of a stainless screw that long complicates this. The idea of removing the center stringer and using the angle iron is promising. I'd have to go with a wooden cleat since even galvanized steel doesn't last in this area, and I'd have to use a thicker thread but an idea to consider. Thanks. – Gary Bak May 4 '18 at 11:44
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Definitely believe it's the absence of risers and the weather/sun causing the wood to weaken at an exposed edge. Ultimately water and sun will creep in and the split will start, then more weather will only make it split more. Risers will give a good look and add protection, and follow instructions they should go in first before the treads butt up, so stringer dimensions may change.

  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know how best to contribute here. – Daniel Griscom Oct 23 at 2:40

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