So much for 'treated' lumber

[Sawyer Rob]

I've heard that you should only buy pt lumber rated for ground contact. That appears to be relatively new advice so probably not well known when you built.

There's the right answer right there...

SR

 

[MacLawn]

Yep, tag says "above ground." It should be below grade treated for 6x6 posts, even used above ground.

 

[mcfarmall]

The only good treated lumber nowdays is the stuff that's treated with creosote and it's only available to municipalities for use on bridges, trestles, etc..

 

[teejk]

Yep, tag says "above ground." It should be below grade treated for 6x6 posts, even used above ground.

Wasn't long ago that you bought pt lumber without any designation, just "pt". I wonder where the non ground contact stuff will have any use at all. The whole industry changed after CCA was outlawed.

 

[Fossil Farm]

Residential pressure treated lumber does not last very long. It will last longer than untreated, but does not last a lifetime. Most of it has to be painted, stained or creosoted to have much of a durable life anymore, especially when it is cut and the cut ends are not retreated before installation. I have seen several 4x4's rot from the center out since the treatment only goes in an inch or two and the cut end was not retreated. Hopefully they come up with a better treatment without having to reapply onsite.

 

[TnAndy]

I've heard that you should only buy pt lumber rated for ground contact. That appears to be relatively new advice so probably not well known when you built.

Yeah, in studying the types, apparently "above ground" should have (and who really knows) 0.1lb/cuft.....ground contact is 0.2, and below ground is 0.4.

I can tell ya the 0.1 I used (according to the tag) is a waste of money and effort to put it in. IF I can find below ground in the sizes I need, that is what is going back.

There is about a foot of clearance under the deck at that point...not a lot, but the ground slopes away from the house at a few inches clearance to a foot or so at the point these rotted. Water is just normal rain runoff....they don't sit in water.

 

[ovrszd]

The right answer is oosik's second paragraph.

I asked earlier where the water is coming from but didn't hear an answer.

Edit: Whoops, hadn't read the last response.

So no water other than normal rainfall is landing on this wood?

Why did it only rot in that area? Why didn't the entire wood portion of the deck rot?

 

[Sawyer Rob]

Yeah, in studying the types, apparently "above ground" should have (and who really knows) 0.1lb/cuft.....ground contact is 0.2, and below ground is 0.4.

I can tell ya the 0.1 I used (according to the tag) is a waste of money and effort to put it in. IF I can find below ground in the sizes I need, that is what is going back.

There is about a foot of clearance under the deck at that point...not a lot, but the ground slopes away from the house at a few inches clearance to a foot or so at the point these rotted. Water is just normal rain runoff....they don't sit in water.

NOT around here!

.40 is NOT ground rated, .60 is the in ground rating and what I buy when I buy poles...

IF it touches the ground, buy .60 or it will not last real long...at least around here it won't.

SR

 

[cqaigy2]

Here in the wet PNW, i try to use concrete in and on the ground with stand off where wood will attach. The idea being reducing contact to ground and trying to keep the wood as dry as possible.

 

[300UGUY]

NOT around here!

.40 is NOT ground rated, .60 is the in ground rating and what I buy when I buy poles...

IF it touches the ground, buy .60 or it will not last real long...at least around here it won't.

SR

I used .6 treated posts for a barn, fences and a deck, 30 years ago, and nothing has rotted off yet. But you need to be careful, the stuff is pretty nasty. I've got splinters in my hands, and my whole hand swelled up, like a catchers mitt. Docs said it was a toxic reaction. I wear gloves and a mask cutting it.