Fixing and caulking rotting joints on exterior wood stairs

[s219]

So I powerwashed the stairs down to my pier for the first time in the 5 years since I built them. The stairs weren't that dirty -- the main reason I powerwashed was to get rid of algae on some of the stair treads that was slippery when it rained. After getting the stairs clean, I noticed rot in the corners of about 10 steps (out of 45) which I assume was due to water getting trapped in the corners and lack of sunlight and air (plus poor quality treated wood).



I plan on replacing the affected treads and risers and do whatever I can to deal with rot on the stringers and side boards (the side boards are 2x12 lumber that stiffen the stairs and allow me to span 10-12' between posts). These stairs were an epic project 5 years ago, and I'm not getting any younger, so I need them to hold up.

Anybody have tips for dealing with rotted areas of the stringers and side boards? I've seen some folks suggest digging out the rotten wood and use bondo to fill back in.

And when I install new treads and risers, would you suggest caulking the joints to minimize water intrusion? Years ago when I built decks, we would sometimes use construction adhesive to seal certain joints on railings with the thought it would seal the ends of the lumber and keep water out, but I never expected construction adhesive to really hold up to exposure. I suspect silicone or polyurethane caulk might work better, but then again it could just as easily make the problem worse in the long haul if it traps water worse. And I am not confident any caulk will stick to new (wet) pressure treated lumber.

Thoughts? Advice?

thanks,
219

 

[/pine]

"bondo" is a staple of restoration work...it's not a cure all though...if the substraight can be protected from further water intrusion and the filled areas can be protected with paint etc...it is a viable technique...

a trick to prevent a lot of sanding etc is to wait until the filler (bondo) is gelling and use a "sure form" type rasp to smooth slightly over filled areas...

 

[CalG]

Funny to see this post.

I spent the afternoon pulling apart the front entry stairs to a friends house. He thought there were a few soft and cracking treads.
(Mahogany)

Well, In truth, there were a few treads that were still in OK condition, but there was not a single other element on the stair set that was even worth burning, treads, risers. stringers, newel posts, and hand rails, all rotten. And the house is only 7 years old!

They are looking to me to come up with "something that will last".

Concrete? ;-)

 

[Tompet]

I take it rot on stringers not too bad. As you stated, replacing bad treads (with slight slope forward?) and risers seems easiest solution.

In the corners where tread meets riser, could you clip a corner of one or both to create an opening for moisture/air and eliminate the boxed/closed corner? Maybe incorporate it as a decorative detail?

As far as repairing some rot, prior to filling have you ever used a wood hardener prior to fill? Minwax, PC products and probably some other brands of liquid hardener would be my first step before an epoxy type fill. Once you clean out rot, it does work in hardening/strengthening remaining wood fibers prior to fill.

Maybe some polyurethane caulk in places, but as you pointed out, you don't need to create any more moisture traps.

More commercial options in materials, but pretty expensive. Anyway, I've seen your posts and the good work you've done, so you'll figure it out!

 

[s219]

Thanks for the help guys.

I haven't yet pulled off a tread or riser to see how bad it looks underneath on the stringers. With any luck, it won't be too bad and I can soak some liquid wood hardener into the rotten spots and/or bondo anywhere I have to dig out rot.

In the corners where tread meets riser, could you clip a corner of one or both to create an opening for moisture/air and eliminate the boxed/closed corner? Maybe incorporate it as a decorative detail?

If nothing else, I would make sure there is a gap there, so the risers and treads aren't in contact with the side boards. In retrospect, this style of stair, with side boards boxing things in, seems like a bad idea. Building it tight with no gaps (which would otherwise be a good thing in carpentry) makes it worse. If I had to do it over again, I'd skip the side boards, have the treads overhang, and just plan on sistering multiple stringers to get the needed stiffness.

 

[spitter]

For stairs bondo is to soft. Use a two part epoxy wood filler and a good 2 part epoxy penetrating sealer. Clean out all soft wood . No silicon traps moisture better to let it air dry and let moisture escape.:drink:

 

[ZTMAN]

And after you get the wood taken care of , go get some "Wet N Forget" to apply to the steps. Will keep algae from growing.

I get mine at Walmart in the concentrate that makes 6 gallons. Apply twice a year and you will never have to drag your pressure washer up and down the steps.

 

[Oaktree]

Anybody have tips for dealing with rotted areas of the stringers and side boards? I've seen some folks suggest digging out the rotten wood and use bondo to fill back in.

I've had mixed results with bondo on rotted wood. You have to clean out every bit of rot, and even then if it's exposed to weather it doesn't stand up well. I'd imagine it wouldn't work very well where there's any flex either. Seems OK for interior repairs though.

Someone mentioned epoxy...not much experience with that but again not sure how it would stand up with any flex like you might have with steps.

 

[/pine]

A new 'Bondo' product that uses epoxy rather than polyester...

https://www.hunker.com/12125385/how-to-use-bondo-for-wood-repair

 

[EddieWalker]

I love bondo for rebuilding wood on older homes. Especially where the shape of the wood isn't something that I can buy, and it's just in an isolated area.

For your stairs, I would not use bondo. It wont work.

If you are going to leave them like they are, and have that sideboard there that will continue to trap moisture, I would either increase drainage by drilling a hole in the corner, and/or seal it with a flashing type caulking found in the roofing section. I would not use anything in the paint department. Roofing sealants cost twice as much, but will have more flex and bond better. Henry makes a great product, but there are several others that work really good too.

How are your steps attached to your stringers? Cutting stair stringers would have avoided this, but it's too late for that now.