What Caused This Wood Deck Failure?

   / What Caused This Wood Deck Failure? #1  

Runner

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Did the skirting around this deck cause the treated lumber to decompose like this in 13 years? Was I crazy for expecting more time before having this type of problem? Deck was built in 2011 and there is a concrete patio under the entire deck with this solid skirting all around. Note, a couple of the 2x10 joists are rotted all the way through. Main beam, joists and floor boards are Yellawood. Oddly enough the parts that are still holding up (the skirting and guard rail) are plain old green treated wood from Lowes. I started noticing the rot in 2018.
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   / What Caused This Wood Deck Failure?
  • Thread Starter
#4  
My builder would say yes, you trapped moisture under the deck, that was caused the rot...

I have a deck to be replaced, I placed the boards too tight together and trapped moisture, too.
I guess I naively thought that the purpose of treated wood was to resist rot and decay under such conditions.

No new deck for me, as soon as this one is hauled off in the dumpster, I'm going back to the concrete patio.

On a humorous note, I see a bunch of advertisements for hardscape patios off to the side of this posting right now :)
 
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   / What Caused This Wood Deck Failure? #5  
That's moisture coming up from the ground.A plastic barrier with gravel on top would have worked. I've read many times that most decks rot from the bottom up.
 
   / What Caused This Wood Deck Failure?
  • Thread Starter
#6  
That's moisture coming up from the ground.A plastic barrier with gravel on top would have worked. I've read many times that most decks rot from the bottom up.
I would have thought the concrete slab underneath would be somewhat of a moisture barrier?
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   / What Caused This Wood Deck Failure? #7  
I did something similar. Initial 6 x 12 deck is basically a porch for the back door, about 18-24" above ground with no skirting/siding of any kind (early 2000s sometime). No rot there. But a few years later, I added an 8 x 12 section to one side, only about 6" above ground. Blocked two sides against digging critter entry. Wasn't long before I noticed various issues and had to replace some boards. I eventually took the side section out and went with patio stones.


Main section is still fine, but have added wire fencing and screening to keep stuff out, but allow full air flow.

But I've also added a full awning/cover over the whole area to keep direct rain off and prevent it from soaking the ground underneath.


.
 
   / What Caused This Wood Deck Failure?
  • Thread Starter
#8  
On the brighter side, I will now be able to fit my mower between the corner of the patio and the retaining wall again.....
 
   / What Caused This Wood Deck Failure? #9  
If you're going to put skirting around a deck, put vents in it. Treated lumber (most) is for insects not moisture. You need to allow crossflow ventilation.
 
   / What Caused This Wood Deck Failure? #10  
Ours is doing the same thing and it’s not over concrete. Ours has skirting but it’s far from air tight. I suspect some of its from moisture and some from the fact treated lumber isn’t as good as it used to be. Sometime in the next year or two we will have to redo it and I’ll find out.
 
 
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