What Caused This Wood Deck Failure?

[ultrarunner]

California climate may have helped? I've heard your cars don't rust out.

unless there are some underground utilities to contend with, one thing I'd do is to add an underground drain to the gutter downspout so rainwater isn't being dumped out to just run back under your house.

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Mild climate here… few with A/C and older homes had heaters optional.

Decks still fail but the old Green Treated Wood has exceeded my expectations.

The replacement stuff sold when the green pulled from the consumer market simply a waste of time and money.

At the folks home the deck circa 1965 is heavy galvanized steel girders supporting concrete with inset 12x12 tile and railings of heavy galvanized steel.

60 years and no issues.

Couldn’t hazard a guess what it what cost today.

The original owner had a steel fabrication company that built bridges and pedestrian walks around marinas among other things.

 

[dodge man]

I can remember a treated wood called Wolmanized (sp?) but I think it had cyanide in it or some other toxic substance. That seemed to be the downfall of the good treated lumber.

 

[oosik]

I would say - trapped moisture. I have two small decks - 10x16. Both are raised well off the ground - 40 inches or more.. Both were built along with the house in 1982. They are as solid as the day they were built. Neither has any type of skirting.

There is 3/8 inch gap between each of the deck boards. The local winds can blow up thru the decking.

Another factor - our area is semi-arid. Annual rainfall ~ 12 inches.

 

[Rustyiron]

It was about 20 years ago when they started f ing with the proven treatment chemistry. (CCA)
IIRC the first rendition was corrosive to common fasteners and aluminum flashing. I'm not sure how many changes since then but I don't think the current version is (or maybe as) that was.
In my little bit of checking I was told or read that "timbers" were still allowed to use CCA. What dimension constitutes a timber I don't know.

 

[ponytug]

I can remember a treated wood called Wolmanized (sp?) but I think it had cyanide in it or some other toxic substance. That seemed to be the downfall of the good treated lumber.

Yes, it is banned in many areas due to the hexavalent chromium in it (close to 50%). ("CCA-C")

http://www.americanpoleandtimber.com/wp-content/uploads/2015/06/treated_wood_specguide.pdf

There was another commonly used product that was pentachlorophenol. Also not very healthy for humans, and quite persistent.

Pentachlorophenol | US EPA

Pentachlorophenol (PCP) is an industrial, wood preservative used mainly to treat utility poles and cross arms.

www.epa.gov

All the best,

Peter

 

[jyoutz]

I would say - trapped moisture. I have two small decks - 10x16. Both are raised well off the ground - 40 inches or more.. Both were built along with the house in 1982. They are as solid as the day they were built. Neither has any type of skirting.

There is 3/8 inch gap between each of the deck boards. The local winds can blow up thru the decking.

Another factor - our area is semi-arid. Annual rainfall ~ 12 inches.

I’m surprised that your annual precipitation is so low. Typically ponderosa pine grows in areas with 18-30” annual precipitation. Above 30” Douglas fir becomes dominant. Below 18” is typically woodland species like junipers.

 

[ponytug]

I’m surprised that your annual precipitation is so low. Typically ponderosa pine grows in areas with 18-30” annual precipitation. Above 30” Douglas fir becomes dominant. Below 18” is typically woodland species like junipers.

Perhaps grey pine or stone pine?

 

[dstig1]

Wolman is a company that is big in pressure treated wood. One of the first, I believe. Wolmanized was just their brand name for it. The industry reformulated all PT to get away from the arsenic compounds close to 20 yrs ago. It wasn't just them. They cranked up the amount of copper which costs a lot and was what made all the regular galvanized fasteners disappear in no time due to galvanic corrosion. Developments since then have allowed them to reduce the copper content quite a bit but it is still pretty corrosive thus the need for triple dipped galvanized or SS stuff.

There are still some arsenic based treatments available but they are specialized and not easy to get.

 

[jyoutz]

Perhaps grey pine or stone pine?

Not in Washington. His photos show nice stands of ponderosa pine, which makes me think they get a bit more precipitation than 12”.

 

[kenmac]

I doubt you actually did anything that caused it. Treated wood today just doesn't last. I'm finding yellow wood doesn't last as long as other brands of treated wood.
I have some yellow treated wood on my deck that has rotted, while treated wood of a different brand (from Lowes) is still good and it's right next to each other