What Caused This Wood Deck Failure?

[bdhsfz6]

If you drill the holes too big, yes, it will weaken the board. If you drill them too small, they will clog with debris & mold. Sometimes, you can add fasteners to help remove the bow. Sanding with a belt sander can also remove the bow if it isn't too deep.

We just sweep our deck with a push broom after a rain to keep water from pooling.

 

[ponytug]

I wouldn't drill holes. In my experience, that is just another channel for rot to start from. I'd either recess the fasteners, and sand the cupping down, or flip the cupped boards. Neither is a quick fix. Keeping the deck oiled annually will help some. Keeping water off by brushing or blowing off is not exactly zero effort, but it depends a bit on the size of the deck.

All the best,

Peter

 

[Larry Caldwell]

Not all treated wood is really treated. I installed "ground contact rated" guardrail posts on a tree bridge 8 years ago, lag bolted to custom ordered 4x10 stringers. The posts rotted, the stringers did not. Some treated wood is junk. I have no idea how to tell the difference.

 

[ponytug]

Not all treated wood is really suitable for soil contact. I installed "ground contact rated" guardrail posts on a tree bridge 8 years ago, lag bolted to custom ordered 4x10 stringers. The posts rotted, the stringers did not. Some treated wood is junk. I have no idea how to tell the difference.

There are a series of ratings, and unfortunately, much of the "ground contact" lumber sold in my local box stores is only suitable for "incidental ground contact", I.e. not in contact with soil.

Preservative Use Categories – Preserved Wood

preservedwood.org

While UC4A is rated for actual ground contact, around here I have found that I need ratings UC4B, or better, if I am putting lumber on the ground, or underground, and it is a requirement to treat any cut ends with copper naphthenate if you don't use lumber as is. I treat every drilled hole with copper naphthenate, and the in ground up 12" of every fence post with at least two coats of 17% copper naphthenate, (equivalent to 2% copper by weight). I have been using the Tenino brand for years.

All the best,

Peter

 

[5030]

If the sub structure is good, replace the deck with synthetic dimensional decking and forget about it forever or until the substructure fails. No upkeep other than a pressure wash infrequently. We did ours and all 3 rentals 3 years ago and everyone looks like new. We used Trex and stailless steel square drive deck screws. Is it cheap? Certainly not but it will outlast you.

 

[ponytug]

If the sub structure is good, replace the deck with synthetic dimensional decking and forget about it forever or until the substructure fails. No upkeep other than a pressure wash infrequently. We did ours and all 3 rentals 3 years ago and everyone looks like new. We used Trex and stailless steel square drive deck screws. Is it cheap? Certainly not but it will outlast you.

After what I thought was a fair amount of research and comparison shopping, we redid our deck in Timbertech (Vintage, hidden fastener), and I'm not impressed, but I have friends who used Trex, who were even less impressed with theirs. Both companies make a variety of grades and types of materials, so I don't know that there is an apples to apples comparison to be made. The Timbertech material appears not to be uniform, and some boards have bowed, while adjacent boards are stable. Only non-uniformities in the extrusion could cause that. Not worth trying to cash in on a warranty replacement of a few boards, as replacing the problem boards requires removing a lot of the deck to get to them. If I have to do that, the Timbertech is gone permanently.

We also used hidden fasteners that were supposed to be better for the composite (purportedly less water intrusion and freeze/thaw damage), but with our temperature cycles, the boards are moving laterally in the fasteners, with no obvious way to inch them back into their original position. So we have gaps, and are close to needing to screw down some boards to keep them from being trip hazards. When we get there, I plan to try loosening some fasteners, and try a demolition hammer and some angle iron to move the boards back into position, but I'm open to a different/better way.

It might be that here with the solar heating in the summertime, the deck gets warmer than typical, but I don't see how that's any worse that a lot of the country. It might also be that there is more under deck wood expansion and contraction than areas that get summertime rains. (Trying to be generous here.)

If I were doing it again, I would not use wood or composite, and just go with concrete boards. After we purchased our boards, I noticed that Timbertech revised their claims of fire resistance to claims of smoke rating, which is not even close to the same thing in my book. Frankly, if the deck is not in a confined space, who cares about smoke ratings? I haven't tried to see what the fire/smoke rating on ours actually is, as I'm hoping not to rip out. My bottom line is that the material isn't stable in this installation. Caveat emptor.

All the best,

Peter

 

[ultrarunner]

What about the aluminum deck material?

 

[ponytug]

What about the aluminum deck material?

I did look into that, and the general consensus seemed to be that aluminum deck materials made great fresh water dock materials as it was very resistant to water and weather. The downside was the reflected and conducted heat, and thermal conductivity. Supposedly the recommendation was shoes only, and not for sitting above as the reflected solar energy was huge. As most of our deck is in direct sun for much of the day, it did not seem like a match made in heaven, for us.

Here in California, I wouldn't install an aluminum deck these days for fire reasons as the melting point is so low.

When we originally put in our new deck, I did look into using lightweight prefabricated concrete sections as well, a la light weight parking structures, but locally, the installers wanted an amount of money that made pouring in place much cheaper. Much cheaper. Basically, I think that they didn't want my business, and I can understand that. Overall, a concrete deck was 3-4X price of a more standard new concrete footings, pressure treated supports, and Timbertech. Actually, it was so expensive, it would have been cheaper to put in a 15' high retaining wall, truck in fill, compact it, and then put down some pavers. And don't get me started on the seismic report ($$$) we had to file for replacing an existing deck, nor the request for an archeological survey. I fought the latter pointing out that this was replacement of a pre-existing deck, with no further archaeological disturbances. I hate to think what the hoops would have been for a concrete retaining wall, though post LA fires they may, may, be changing their tune.

Lots of ways to skin a cat as they say...

All the best,

Peter