Porch Wooden Stair Stringers

wolfsburged

Bill
Corporate Member
I rebuilt my front porch and steps about 8 years ago. For the stair stringers I purchased pre-cut treated outdoor stair stringers from Lowes thinking that they would be the best option to retain the pressure treatment throughout. Now fast forward to today and multiple sections of stringers have rotted out from the top down, basically where the open grain was exposed upwards and water soaked in.

Since I am going to have to replace and rebuild again, wondering what is the best way to protect from this happening again? Epoxy coat the exposed grain? Stain/paint? Metal flash?
 

JimD

Jim
Senior User
I built stairs from a deck on my last house that was about 10 feet off the ground (the house had a walk out basement). The stringers were cut, by me, out of pressure treated 2x12s. I've sold the house now but we lived in it over 10 years with no problem with the stringers. I did not do anything to the stringers, just cut them and installed them. The treads were trex.

On the dock of my current house, I've noticed degredation of some pressure treated boards where there is not good air circulation below the boards. The boards with good air circulation show no rot, the boards over dirt with a little air space below them are rotted on the ends.

So my conclusion is that you need to allow air circulation around PT wood exposed to the rain. If it stays wet most of the time, it will rot. Is it possible that your stringers didn't have good drainage or air circulation below them? Otherwise, I would say they may not have been pressure treated properly.
 

junquecol

Bruce
User
First thing is to buy GROUND CONTACT rated wood. Almost all of HD's is, while some of Lowes is. You can take some Weather Guard, or Weather Watch (same product, different manufacturer) and cut pieces to fit on top of notches for treads.
 

Martin Roper

Martin
User
I made my own stringers from PTL. I used an oil-based stain on them. They rest on concrete footers I buried into the ground and I tacked some exterior-grade plastic trim to the bottom where it contacts the footers figuring they'd most likely rot from the ground up like the ones that came with the house did.
 

tvrgeek

Scott
User
If you read the fine print, every cut end needs treatment. Can't say I have seen it on the shelf but do some research. I suspect they were cut after pressure treatment.
Any sort of flash might trap water, so not too sure about that. Maybe that ice-shield stuff that will seal around the screw hole so as not to trap. Some sort of 100% caulking. Aldex maybe. Not too good or you can't replace a tread. ( One person used PL and it was strong; so strong one tread meant total replacement) If the treads are one piece, maybe caulk between the vertical face and stinger.

I find them flimsy and my trick is to glue a 2 x 4 along the side basically doubling the "uncut" portion. Cheaper than doubling the stringer. I calk the top edge so water can't seep between. I had to replace my deck for the same failure. My solution was a full roof. So even the PT sides are susceptible.

Maybe more tips on GreenBuildingAdvisor.
 

McRabbet

Rob
Corporate Member
I would suggest adding at piece of fiberglass shingle or heavy tar paper with some roofing cement on the top of each stringer run cut before the steps are added. I've done this atop joists when putting decking down to avoid rot even when not in ground contact.
 

Oka

Board of Directors, Vice President
Casey
Staff member
Corporate Member
Or, just buy copper green or copper brown or buy pine tar.
Or, if you can find creosote (you can make it) then use that on the tops
Or make the stringers out of Redwood (this is probably expensive in the east coast).
You can also use Ice n Water shield used around windows. Cut 2-3" wide x 12 strips and place between the tread and stringer. Architects call for this from time to time but not really sure of the efficacy.
 

Martin Roper

Martin
User
I would suggest adding at piece of fiberglass shingle or heavy tar paper with some roofing cement on the top of each stringer run cut before the steps are added. I've done this atop joists when putting decking down to avoid rot even when not in ground contact.

They also make butyl joist tape for that. I'm using it on my deck rebuild.

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