FHB Logo Facebook LinkedIn Email Pinterest Twitter Instagram Plus Icon Close Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Main Menu
Subscribe

In every issue you'll find...

  • Expert insights on techniques and principles
  • Unbiased tool reviews
  • Step-by-step details to master the job
  • Field-tested advice and know-how
Subscribe Now!
Subscribe
  • How-To
  • Design
  • Tools & Materials
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
  • Join
  • Log In
Main Menu Subscribe

Fine Homebuilding Project Guides

Framing

Guide Home
Chapter
  • Introduction to Framing
  • Framing Tools, Techniques, and Materials
  • Framing Floors
  • Framing Walls
  • Framing Stairs
  • Framing Roofs
  • Efficient Framing Methods
  • Timber Framing
What's the Difference?

Decoding Framing-Lumber Stamps: Moisture Content, Species, and Grade

Engineers, architects, and builders need to know that the framing lumber they specify and install is strong enough to handle the loads placed on it.

By Don Burgard Issue 222
Article Image

Engineers, architects, and builders need to know that the framing lumber they specify and install is strong enough to handle the loads placed on it. At the same time, they want to build cost-effectively, which involves knowing when a more expensive species or grade of lumber is unnecessary. For these reasons, each piece of framing lumber has a stamp that contains several pieces of information, three of which—moisture content, species, and grade—are essential to know before you start building.

Moisture content

What it says: Moisture content is identified by one of many abbreviations: AD (air-dried to a moisture level at or below 19%); S-DRY (surfaced dry; that is, the board when surfaced at the mill had a moisture level at or below 19%); S-GRN (surfaced green; that is, the moisture level when the board was surfaced was higher than 19%); KD (kiln-dried at or below 19%); and KD-HT (same as KD, although heat-treated as well to kill pests and fungi). KD-15 and MC-15 lumber have moisture levels of 15% or less.

Why it matters: Some builders choose lumber with a higher moisture level for new construction. It’s cheaper, it’s less prone to splitting when nailed, and all the wood will shrink at a similar pace as it dries. Others prefer drier lumber to avoid problems related to shrinkage, such as twisting and nail pops. For remodels, however, go with the drier stuff because it will integrate better with the already dried and shrunken existing lumber. Be aware, however, that moisture content is measured at the mill, not at the lumberyard, so time sitting in rainy weather or hot sun isn’t considered.

Species

What it says: Common wood-species stamps include D Fir (Douglas fir), Hem (hemlock), and PP (Ponderosa pine). Abbreviations are sometimes grouped for species with similar characteristics, such as SPF (spruce, pine, and fir) and Hem-Fir (hemlock and fir).

Why it matters: Species can depend on region, but high-strength lumber often is more expensive. That said, it isn’t always necessary to use the strongest lumber available. Building codes specify maximum allowable spans for each species, so before buying expensive lumber, check local codes to see if a cheaper species could work.

Grade

What it says: There are four categories of framing lumber, most of which have a hierarchy of grades corresponding to their level of weakening characteristics such as knots, splits, or wane.

Structural light framing: These pieces have the highest strength values and are suitable for use in engineered applications such as trusses, rafters, and joists. They are broken down into four subcategories: select structural, No. 1, No. 2, and No. 3.

Light framing: These pieces can be used as plates, cripples, blocking, and in other areas where high strength isn’t crucial. They break down as construction, standard, and utility.

Stud: These pieces are strong enough to handle vertical loads, but they aren’t approved for other uses. No subcategories here.

Structural joists and planks: These larger boards have the same grades as structural light framing.

Why it matters: The farther down the hierarchy you go for each category of lumber, the lower the quality and performance of the wood. Because different species have different strength values, grade must be considered hand-in-hand with species. For example, a 10-ft. Douglas-fir 2×4 of a certain grade will have a different strength value than a Ponderosa-pine 2×4 of the same size and grade. The most important thing to remember here is that within the same species, you can always use a piece of lumber graded above what is required for a particular application, but not one that is graded below.

Photo: Rodney Diaz

From Fine Homebuilding #222

Sign up for eletters today and get the latest how-to from Fine Homebuilding, plus special offers.

Sign Up
X
X
Previous: Remove One Wall and Join Two Rooms Next: Structural Composite Lumber

Guide

Framing

Chapter

Framing Tools, Techniques, and Materials

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

Framing

Framing

Trusted, in-depth guidance from the pros for framing a durable, code-compliant house

View Project Guide

View All Project Guides »

Become a member and get unlimited site access, including the Framing Project Guide.

Start Free Trial

Introduction to Framing
  • House Framing Concepts, Tips, and More
Framing Tools, Techniques, and Materials
  • Tools
  • Techniques
  • Framing Lumber
  • Steel
Framing Floors
  • Floor Framing
  • Engineered Floors
  • Floor Sheathing
Framing Walls
  • Wall Framing Basics
  • Layout
  • Wall Assembly
  • Raising and Straightening Walls
  • Framing Rough Openings
  • Blocking
Framing Stairs
  • Stair Layout
  • Building Stairs
Framing Roofs
  • Roof-Framing Basics
  • Roof Design
  • Laying Out and Cutting Rafters
  • Framing Valleys
  • Working with Trusses
  • Dormers
  • Special Situations
Efficient Framing Methods
  • Advanced Framing
  • Double-Stud Walls
Timber Framing
  • Timber-Frame Construction
  • Timber-Frame Design

Fine Homebuilding

Follow

Newsletter

Get home building tips, offers, and expert advice in your inbox

Sign Up See all newsletters

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Manage Preferences

Taunton Network

  • Green Building Advisor
  • Fine Woodworking
  • Fine Gardening
  • Threads
  • About
  • Contact
  • Advertise
  • Privacy Policy
  • Careers
  • Copyright
  • Terms of Use
  • Accessibility
  • CA Privacy Rights

© 2021 The Taunton Press, Inc. All rights reserved.

    Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Reader Projects
  • Magazine
  • Members
  • FHB House
  • Podcasts

  • FHB Podcast
  • ProTalk
  • Account

  • Log In
  • Join

    Podcasts

  • FHB Podcast
  • ProTalk
  • Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

    Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

    All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

    Shop the Store

  • Books
  • DVDs
  • Taunton Workshops

    More

  • FHB Ambassadors
  • Reader Projects
  • Podcast
  • Customer Support

    Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Sign Up See all newsletters

Follow

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 52%

Subscribe

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in