Pressure Treated Wood for exterior application

[miz0133]

For designing an exterior deck, does the wood need to be specified as pressure treated wood? IBC Section 2304.11.4 only talks about wood in contact with ground to be pressure treated. I would specify regular wood members for tthe entire deck taken into account the wet factor but not the incising factor (non PT). Even for post that have a stand-off, I would think they are not considered to be in contact with the ground (Exposed earth). Any insights would be greatly helpful?

 

[msquared48]

If it is exposed to the elements, it should be. Painting will not guarantee no rot. Any cute or holes in the members heed to be hand treated after the cuts or holes are in place too as the pressure treating only penetrates 1/4 to 1/2" or so into the member. The interior of the PT members is vulnerable to rot.

Mike McCann
MMC Engineering

 

[JAE]

Or use Cedar.

 

[msquared48]

Cedar is OK for the decking, maybe the joists, but I would not use it for main structural members.

Mike McCann
MMC Engineering

 

[dik]

For my wife's ramp, I used PWF stuff... for preserved wood foundations... it will outlast both of us... Depending on the use, I would only use preservative treated lumber, and if I wanted it to last, PWF...

Dik

 

[miz0133]

Thank you for your feedbacks. Does the code require PT for exterior use or just for "in contact with ground". Can someone refer me to the code section that talks about PT wood?

 

[TheMoonlitKnight]

Read IRC 2012 section R317.1.3. Remember the ICC codes are model codes. At times they will be vague, because they are not in the business of enforcing rules. If your client is really concerned about squeaking out a few extra bucks at the expense of a quickly-deteriorating deck, contact the project's building code jurisdiction and get the answer directly.

But, read the whole R317 section - it requires PT for more than direct contact with the ground.

 

[SLTA]

From a practical standpoint, all the wood should be PT, unless you want to rebuild the deck in a few years' time.