• Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by first logging in then clicking here: Upgrades

Maximum Moisture Content

classicT

classicT

Moderator
Staff member
Joined
Aug 2, 2017
Messages
3,253
Location
AZ, USA
What is the maximum moisture content allowed for IRC framing elements?

Per R602.2 Grade - Studs shall be a minimum No. 3, standard or stud grade lumber.
Per R602.1.1 Sawn Lumber - Sawn lumber shall be identified by a grade mark of an accredited lumber grading or inspection agency...that complies with DOC PS 20.

After reading though PS 20 (http://www.alsc.org/greenbook collection/ps20.pdf), I can not find anything that spec's out the max moisture for No. 3/stud grade. If greater that 15/19% it is considered green, but can green lumber receive a No. 3/stud grade stamp?

 
2012 R802.1.2.8 Fire retardant wood shall be dried to a moisture content of 19% or less for lumber 15% for wood structural panels. Only percent I find
 
McShan said:
2012 R802.1.2.8 Fire retardant wood shall be dried to a moisture content of 19% or less for lumber 15% for wood structural panels. Only percent I find
Click to expand...
I've found that reference, and the same for pressure treated....but for framing members (stud grade), nothing
 
ANSI/AWC NDS-2015 National Design Specification (NDS) for Wood Construction, defines it per reference standards in both the IRC and The IBC
A lot of the technical stuff is now in the standards and references not in the code books....
 
Last edited:
Ty J. said:
What is the maximum moisture content allowed for IRC framing elements?

After reading though PS 20 (http://www.alsc.org/greenbook collection/ps20.pdf), I can not find anything that spec's out the max moisture for No. 3/stud grade. If greater that 15/19% it is considered green, but can green lumber receive a No. 3/stud grade stamp?
Click to expand...

We built with all green lumber until sometime in the 80s, I didn't see the switch because by that time all my work was engineered and engineers' standard spec sheets always said 19% or less, I asked why and was told that direr lumber held fasteners better.

We can still buy S-Green and it is supposed to be 19% or less so I'd say the control is at the mill level, as far as the prescriptive code is concerened all you can do is look at the grade stamp, if the mill has screwed up that's somebody else's problem.
 
When we built with green DF, we had so many customer complaints because of the black mold on the side of the lumber, you could write your name on the FJ's. We eventually switched to I-joist to meet the spans needed. Other than the learning curve the switch over to I-joist cost us more but it eliminated a lot of complaints.
 
Pcinspector1 said:
When we built with green DF, we had so many customer complaints because of the black mold on the side of the lumber, you could write your name on the FJ's. We eventually switched to I-joist to meet the spans needed. Other than the learning curve the switch over to I-joist cost us more but it eliminated a lot of complaints.
Click to expand...

Over the years we never had mold complaints on wet lumber, some time in the 80s we started seeing it and were told it was because the environmentalists were making them use junk lumber from the forest floor, we switched to KD for a small amount of money more. I would never use I Joists, they are made with that crappy OSB that is full of formaldehyde and other chemicals, they collapse in fires and if they get wet. A few years ago California finally made them take the formaldehyde out and now we are getting mold on all OSB, if it rains I am now even getting mold on regular plywood, apparently the formaldehyde was inhibiting mold growth. We have ordinances in many AHJs requiring buildings with I Joists to be placaraded on the front so firemen won't go in or on them in the event there are fires.

Truss and TJI Placards
 
Conarb, have not seen the placards here yet.

The I-joist issue with firefighter's prompted a code changes in the IRC 2012 code requiring drywall on the underneath side of the I-joist to give a firefighter a bit more time before the floor goes out from under them. Not sure if that requirement kicked in any earlier code or not?
 
Pcinspector1 said:
Conarb, have not seen the placards here yet.

The I-joist issue with firefighter's prompted a code changes in the IRC 2012 code requiring drywall on the underneath side of the I-joist to give a firefighter a bit more time before the floor goes out from under them. Not sure if that requirement kicked in any earlier code or not?
Click to expand...
Florida and various jurisdictions across US. By ordinance, Not required everywhere and not in fire code.
 
Last edited:
You must log in or register to reply here.
Top