Special offer

But it is pressure treated---what do you mean it is rotted?

By
Home Inspector with Charles Buell Inspections Inc.

 

Some woods are naturally rot resistant---like black locust and the heart wood of redwood and cedar.  Other more readily available woods can be made rot resistant by treating them with creosote---as has historically been done with telephone poles and railroad ties.  Part of the ambiance of fooling around railroad tracks in the summer is the smell of creosote.

We also treat wood with copper in various chemical solutions.

Both of these approaches have their limitations over time depending on how far the treatment goes into the wood.  Railroad ties have to routinely be replaced because of the decay that happens in the center of the ties.  These ties often get re-sold as landscaping timbers where the decay and damage from wood destroying insects can continue until there is virtually nothing left except the exterior shell of the timbers.

At an inspection the other day, I found this retaining wall made of short sections of creosote treated telephone poles. 

Telephone pole retaining wall 

One can easily spot the deterioration of the center of the poles while the outer surface remains in good shape where the creosote was able to more fully penetrate.

Telephone pole retaining wall 

If one goes to the big box stores or any lumber yard, one can buy what is known as “ground contact” pressure treated lumber.  One would think that in buying this stuff you should be able to put it in:  “contact with the ground.”  In my opinion this is an egregious example of either “false advertising” or at the very least not telling the whole truth.  The reality is that most of these “ground contact grade” pressure treated woods WILL decay over time---not the outer treated part---but the center of the wood where the treatment process could not get to.

Now there are grades of pressure treated wood where the treatment is “required” to fully penetrate the entire piece of wood.  These “foundation- grade” pressure treated woods should not be confused with the readily available materials found at the big box stores.

As you can see in the following picture, this “ground contact” pressure treated 6x6 has completely rotted away at the center core leaving a very well defined area that actually got “treated”----the rest is compost.

Ground contact pressure treated lumber 

These ground contact pressure treated materials actually hold up very well long term when they can dry out.  But when buried in wet conditions---like when used for retaining walls---they will decay and or become infested with wood destroying insects.

 

Charles Buell, Real Estate Inspections in Seattle.

Posted by

* * * * * * * * * * * * * * * * * * * * * * * * *

Seattle Home Inspector

 

The Human Rights Campaign   QR code for Charles Buell Inspections Inc  ASHI.org

 

WA State, Home Inspector Advisory Licensing Board

Comments (10)

Atlanta's Home Inspector, David Lelak IHI Home Inspections
IHI Home Inspections 404-788-2581 - Canton, GA
Experience the IHI Difference

Charles, You are always teaching!

I used to love walking down the railroad tracks as a child and, yes, there is a distinctive odor from the creosote. Wow, you brought back memories (and smells). I like that you pointed out the differences between ground contact and foundation grade treated woods. One should always read and understand precisely what they are purchasing.

Mar 29, 2012 03:00 AM
Dick Greenberg
New Paradigm Partners LLC - Fort Collins, CO
Northern Colorado Residential Real Estate

Hi Charles - I got my primer on this subject many years ago when I had to replace a long, wide exterior stairway made of railroad ties, all of which had rotted inside to the point where they weren't structurally sound. That was a hard, ugly job and I wouldn't want to do it ever again.

 

Mar 29, 2012 03:03 AM
Kathryn Maguire
GreatNorfolkHomes.com (757) 560-0881 - Chesapeake, VA
Serving Chesapeake, Norfolk, VA Beach

Awesome post.  The issue with the general public is we don't know the difference and can sometimes be misled by less than forthcoming contractors. 

Mar 29, 2012 06:23 AM
Steven Cook
No Longer Processing Mortgages. - Tacoma, WA

Charles -- thank you for the explanation of why the old railroad ties on the edge of my property are not safe to walk on any longer.

Mar 29, 2012 07:58 AM
Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

David and Bonnie, and of course the fact that it is called "ground contact" I find a bit "unhelpful"

Dick, I know what you mean.  People spend countless hours building these retaining structures only to watch mother nature take them away

Kathryn, I would venture to guess that most builders do not even know there is a difference.

Steven, they do degrade don't they :)

 

Mar 29, 2012 08:17 AM
Donald Hester
NCW Home Inspections, LLC - Wenatchee, WA
NCW Home Inspections, LLC

Charlie, I had hit one railroad tie and a bunch of carpenter ants cam screaming out. I did not have a camera or that would of a great shot.

Mar 29, 2012 09:46 AM
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

So, you're saying that burying enough 6x6" pressure-treated posts can, over time, provide enough compost for the garden?  Excellent!  I bet that's some good stuff!

Ground contact is a bit of a misnomer!

Mar 29, 2012 06:33 PM
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

Labeling can be made to inform and mislead it would seem. That hollowed out 6x6 looks like it would make a nice bowl. 

Mar 30, 2012 07:56 AM
Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

Don, Carpenter Ants love railroad ties

Jay, compost and retain---all in one

Jim, maybe we could do this deliberately---cutting off short sections and making them into planters.

Mar 30, 2012 08:08 AM
Anonymous
Jerry

Charles,

To meet the strict standards of the American Wood Protection Association, western lumber species such as Douglas fir and hem fir which are very dense need to be penetrated with a preservative to a minimum 0.25 inches in the outer shell of the lumber.  In order to accomplish this, western species must be incised (tiny slits on the surface of the lumber) to meet the AWPA requirements for penetration and retention.  Outside the West, the common species that is treated is Southern Yellow Pine.  SYP readily accepts preservative treatment and does not require incising.  Building codes do not require any species to be fully treated.

All materials eventually fail over time, but the most common reason that western species fail before the end of their normal service life is the fact the lumber was not field treated after being cut or drilled.  Building codes require all end cuts in treated western wood species be treated according to AWPA M4 with a Copper Naphthenate solution.  Since SYP lumber is penetrated almost 100%, building codes do not require SYP lumber to be field treated after being cut or drilled.  There are many brands of end cut solution on the market.  You should shop for one with at least a 2% copper solution.

Apr 03, 2012 07:21 AM
#10