Actually, the more common term is “lumber dimensions“, which I have written about before, but people often ask about “lumber sizes” so that is how I am explaining it here. Your choice of search terms is probably why you found this article.

Lumber Sizes

Here is a chart to clear up the confusion about 1x, 2x, and 4x nominal lumber sizes versus actual lumber sizes including the equivalent metric lumber sizes. This lumber sizes chart applies to treated and untreated pine construction grade lumber.

This chart applies to the lumber sizes of “quarter” measurements. The nominal lumber sizes are said as “five-quarter by four” or “six-quarter by six” etc. These are not all that common but you can usually find “five-quarter” decking whose actual dimension is 1″x5.5″. You might hear the 1/4 sizes used more commonly among more mature - no, more experienced - builders and lumbermen.

Timber Sizes

Lumber cut 5 inches or thicker is generally classified as timbers. Timbers are usually “rough cut” to actual sizes. In other words, what you see is what you get. A 6×6 is 6″x6″, a 10×10 is 10″x10″ and so forth. When you buy timbers in smooth, or S4S (Smooth 4 Sides) the sizes are usually 1/2″ smaller. In this case, a 6×6 would be 5.5″x5.5″.

Post Sizes

Round stock sizes can get a little complicated but we will keep it as simple as possible here. A thorough discussion including large poles requires getting into the differences between poles and pilings and classes of utility poles and what you are using them for and it goes on and on so…so for the purpose of this article, I will stick to small post sizes.

Small posts are usually measured by the top size (the little end). So, if you want a 4″ top x 8′ long fence post, you would ask for a “four inch – eight” post. The line between post sizes and poles is a fuzzy one but after about ten or twelve feet long, whatever it is that you want usually becomes a pole. If you are using it in water to support a structure it is probably a piling, which is used upside down and measured by the butt (the big end)… and see how it easy it is to get complicated when discussing poles?

If you want square posts make sure you are clear about that when you ask for “posts” as “posts” are usually considered to be round.

Lumber Sizes Questions?

If you have any questions about lumber sizes, let me know with a comment.

So, to answer the question: How long will my treated posts last?

According to the Southern Pine Council you can expect properly treated posts to last many decades. They site a study by USDA Forest Service’s Forest Products Laboratory saying:

Test stakes of treated wood have been buried in the ground at various locations, stretching from the Mississippi Delta to the Canadian border. Data analysis indicates that CCA-treated Southern Pine stakes in place since 1938 have shown no failures at chemical retention levels of 0.29 pounds of preservative per cubic foot of wood, or higher.

Most treated posts are treated to a retention of .40 but you should always ask – just to be safe.

Here’s a great pdf from the USDA with expected life spans for various species of treated posts including a comparison of the life spans of treated and untreated posts (see page two).

If you want a guarantee that your posts will last you can get treated posts coated at the ground line from American Pole and Timber. I mentioned these posts before in How to Build a Fence that Lasts because I have seen them up close and they are tough. They claim that posts coated at the ground line with their poly coating will last fifty years.? In reality, the posts should last 150 years because the ground line is the source of infestations and the place where decay begins.? If that is protected, you don’t have much else to worry about.

The bottom line is that the life span of properly treated posts should be at least 20 years and can be easily extended to 50+ when installed and used in normal conditions (not in water or along the coast, for instance) .? If you choose the right materials, your grandchildren won’t even have to deal with building another fence.

Poles come in numerous sizes, species, grades, and treatment levels. Each of those factors affects price. The biggest factor affecting the delivered price of a pole (treated or untreated) is size – mostly length – and that can be broken into two main reasons.

1. Supply: Trees take a long time to grow and BIG trees are getting scarce.
2. Freight: Permits and special equipment are probably required for long lengths.

In fact, if you order an 80′ long pole today it is likely the tree you will receive is still in the forest today. Crazy, huh?

The chart does not appear clearly in the video. Here it is (below) so you can get a better look.

Don’t use this chart to bid your next project or anything. I simply wanted to make the point that around the 50′ length mark, the pole prices curve turns sharply north. Also notice that the incremental pole prices on the left get larger as well. Yes, it is certainly possible that you might pay $5,000 (delivered) for a 90′ pole. Don’t even ask about poles beyond 100′.

You should always design based on the needs of the structure (as opposed to what materials are cheapest) but “value engineering” is always important to keep budgets in check and projects affordable. With that, if you are building a structure that requires poles longer than about 50 feet, you might consider brainstorming ideas to design the structure so it can use shorter, less expensive, poles.

Basic Take Away about Pole Prices (in a rhyme): Under 20 feet, poles are cheap, beyond fifty, prices are ‘iffy.

Wood Utility Pole Treatments

Utility poles are usually treated with either pentachlorophenol, chromated copper arsenate, copper napthenate, or creosote. Whichever preservative treatment is used, the main goal of the treatment is to extend the life of the pole by rendering the wood useless as a food source for termites and other wood boring pests and to reduce the effects of decay caused by rot and decay. All of the treatments listed above provide excellent life spans for poles. They are usually chosen based on factors including climate where the poles will be installed, environmental impacts of the chemicals used, concerns around how the poles will be handled, and even individuals’ preferences.

The Biggest Problems for Wood Utility Poles

Most decay of wood utility poles happens at the ground line where the poles are often in contact with moisture which causes rot and decay. Wood utility poles do not have many other natural enemies other than the occasional fire, woodpecker, or car wreck. Wood utility poles are quite resilient and can withstand many natural conditions including high winds, acidic soils, and salty air – conditions steel and concrete poles may not withstand as well.

Increasing the Life of Wood Utility Poles

Properly treated wood utility poles are nearly guaranteed to last about 35 years without any inspections, maintenance, or preventative measures. However, the life span of utility poles can be drastically increased (easily doubled) through a regimen of periodic inspections and maintenance such as pole wrapping, which requires digging around the pole and literally wrapping the pole with a protective barrier. An excellent preventative measure is to coat the pole with the polymer wood coating from American Pole and Timber. The polymer coating must be applied before the pole is installed but provides a protective barrier that will prevent the need for labor intensive pole-wrapping in the future.

The study I mentioned at the beginning of this report actually suggests that utility poles can last more than 135 years (up to 260 years – yes, two, six, zero) but that over time other “degradation mechanisms” take their tolls. Typical maintenance programs are not geared towards correcting those issues which include pole top decay, pole splitting, decay at connections, and excessive weathering so the reasonable estimate of a wood utility pole should probably remain in the neighborhood of 75 years.

Applying Your New Knowledge of Wood Pole Life Spans

There is a great chance you are not in the utility business and just want to know how long your barn poles will last.? While there are no hard numbers on that – at least not that I have found YET – this study reveals that the life is probably longer than you might have even hoped.? Barn poles, fence posts, and small electric poles are treated with the same chemicals as utility poles and usually to the same retention levels using the same methods.? Though utility poles are held to higher standings of structural grading and specifications than your average barn pole you can probably expect the life spans to be similar. Again, the extended life span requires some periodic checks and maintenance.

If you are using treated poles or pilings around a marine environment, the rules are a little different since the surroundings are wetter and generally more dynamic and harsh (waves, changing tides, different organisms, constant contact with water).? Properly treated poles or pilings for freshwater applications can probably be made to last 30 years with proper preventative measures and maintenance.

Here’s some solid logic.? Think of all those old barns and fences that were built by your grandfather’s grandfather practically forever ago. While “they don’t make ‘em like they used to”, the treatments have improved.? You can expect your treated wood poles to last a lifetime.

Here is their list of roof truss terms.? You can also read them on their site.

Allowable Stress: The amount of force per unit of area permitted in structural member. Values for allowable stresses of wood can be found in “National Design Specification Supplement Design Values for Wood Construction.”

Allowable Stress Increase or Duration of Load Factor: A percentage increase in the stress permitted in a member, based on the length of time that the load causing the stress acts on the member. The shorter the duration of the load, the higher, the higher the percentage increases in the allowable stress.

Axial Force: A push (compression) or pull (tension) acting along the length of a member. Usually measured in pounds, kips (1000 lb.), tons (2000 lb.) or the metric equivalents.

Axial Stress: The axial force acting at a point along the length of a member, divided by the cross-sectional area of the member (usually measured in pounds per square inch).

Beam Pocket: A void or cutout built into truss to allow beam support.

Bearing: A structural support, usually a wall or beam, that occurs at the top or bottom chord of a roof or floor truss.

Bending Moment: A measure of the bending effect due tot he live load and dead load on a given truss chord member.

Bending Stress: The force per square inch of area acting at a point along the length of a member resulting from the bending moment applied at that point. Usually measured in pounds per square inch or metric equivalent.

Bottom Chord: A horizontal or inclined (e.g., scissors truss) member that establishes the lower edge of a truss, usually carrying combined tension and bending stresses.

Built-up Beam: A single member composed of two wood members stacked on top of each other and fastened together with connector plates, for the purpose of crating additional strength and stiffness.

Butt Cut or Nub Cut: Slight vertical cut at outside edge of truss bottom chord made to ensure uniform nominal span (usually ¼ inch).

Camber: An upward vertical displacement built into a truss bottom chord to compensate for deflection due to dead load.

Cantilever: The condition where both top and bottom chords extend beyond a support with no bearing at the extended end.

Chase Opening: An open panel in a floor truss for the purpose of running utilities through it, such as heating and air conditioning ducts.

Clear Span: Horizontal distance between interior edges or supports.

Combined Stress: The combination of axial and bending stresses acting on a member simultaneously, such as occurs in the top chord (compression + bending) or bottom chord (tension + bending) of a truss.

Compression: Force exerted on truss member that has a compressive or pushing effect on the member and its respective end joint.

Concentrated Load: Superimposed load centered at a given point (e.g., roof-mounted air conditioners).

Dead Load: Any permanent load such as the weight of the truss itself, purlins, sheathing, roofing, ceiling, etc…

Deflection: Movement of a truss (when in place) due to dead and live loads.

Design Loads: The dead and live loads, which a truss is designed to support.

Dual Pitch Truss: A truss that has two different pitches on its top chord.

Facia: Trim board applied to ends of overhang.

Force Diagram: Graphical solution of axial forces as they interact within the members of a truss.

Heel: Point on truss at which the top and bottom chords intersect.

Heel Cut: See Butt Cut.

Interior Bearing Truss: Truss with structural support in the interior truss span as well as at end points.

Lateral Brace: A member placed and connected at right angles to a chord or web of a truss for the purpose of providing lateral support.

Level Return: Lumber filler placed horizontally from the end of an overhang to the outside wall to for a soffit.

Live Load: Any loading which is not of a permanent nature, such as snow, wind, temporary construction loads, etc…

Nominal Span: The horizontal projection of the bottom chord of the truss.

Overhang: The extension of the top chord of a truss beyond the bearing support.

Panel Length: The center line distance between joints measured along the chords.

Panel: The chord segment defined by two succeeding joints.

Panel Point: The point of intersection where a web (or webs) meets a chord.

Peak: Point on truss where the sloped top chords meet. The highest point of the truss.

Plumb Cut: Top chord cut to provide for vertical (plumb) installation of facia.

Purlin: A horizontal framing member used to support sheathing or decking between two main load carrying structural members.

Reaction: Total load transmitted to its support by a given truss.

Saddle: An area where an additional roof slope and a ridge are created to facilitate drainage. Usually found behind vertical obstructions in the roof.

Stress Rated Lumber: Lumber that has been graded either visually or by machine by an approved grading agency and assigned allowable working stress values. All lumber used in engineered wood products such as trusses must be stress rated.

Scupper: An opening in a roof or parapet usually faced with metal flashing to drain water from the roof at a given point.

Sealed Drawings: Drawings prepared, checked, and/or approved by and having the seal of a registered professional architect or engineer.

Slope: (Pitch). The inches of vertical rise in 12 inches of horizontal run for inclined members (generally expressed as 3/12, 4/12, 5/12, etc…).

Splice Point: (Top & Bottom chord splice). The point at which two chord members are joined together to form a single member. It may occur at a panel point or between panel points.

Split Truss: Trusses used where fireplace intersects the truss span, parallel or perpendicular to the truss in the middle or inside of the house. A split truss can be defined also as a stub truss if it is longer than one-half the span or as a monopitch truss if less than one-half the span.

Square Cut: End of top chord cut perpendicular to the slope of member.

Tension: Forces being exerted on a truss member that creates a pulling apart of elongating effect.

Top Chord: An inclined or horizontal member that establishes the upper edge of a truss. Usually carrying compression and bending stresses.

Truss: An engineered pre-built structural component designed to carry superimposed dead and live loads. The truss members are coplanar and are usually assembled such that the members form triangles.

Uniform Load: A total load that is equally distributed over a given length, Usually expressed in pounds per lineal foot (plf).

Valley: A depression in a roof where two roof slopes meet.

Webs: Members that join the top and bottom chords to form the triangular patterns that give truss action, usually carrying tension or compression stresses (no bending).

You can learn more about the parts of structural timber truss on WoodScience (the old LumberTalk.com).

Lumber Dimensions

Here is a simple chart to clear up the confusion about 1x, 2x, and 4x nominal lumber dimensions versus actual lumber dimensions. The chart also includes the equivalent metric lumber dimensions. This chart applies to treated and untreated pine construction grade lumber.

This chart applies to the lumber dimensions of “quarter” measurements. The nominal dimensions are said as “five-quarter by four” or “six-quarter by six” etc. These are not all that common but you can usually find “five-quarter” decking whose actual dimension is 1″x5.5″.

Timber Dimensions

Lumber cut 5 inches or thicker is generally classified as timbers. Timbers are usually cut “rough” to actual dimensions. In other words, what you see is what you get. A 6×6 is 6″x6″, a 10×10 is 10″x10″ and so forth.

Post Dimensions

Round stock dimensions can get a little complicated but we will keep it simple here. A thorough discussion including large poles requires getting into the differences between poles and pilings and classes of utility poles and what you are using them for and it goes on and on so…so for the purpose of this article, I will stick to small posts.

Small posts are usually measured by the top size (the little end). So, if you want a 4″ top x 8′ long fence post, you would ask for a “four inch – eight” post. The line between posts and poles is a fuzzy one but after about ten or twelve feet long, whatever it is that you want usually become a pole. If you are using it in water to support a structure it is probably a piling, which is used upside down and measured by the butt (the big end)… and see how it easy it is to get complicated when discussing poles?

If you want square posts make sure you are clear about that when you ask for “posts”.

Lumber Dimensions Questions?

If you have any questions about lumber dimensions, let me know with a comment. I am always happy to help.

Finding building codes and construction permits in your state can be difficult as evidenced by the numerous requests for help I get so here is a list of building codes resources by state to help you find the building code and construction permit information you need.

Before you run off to build with a copy of your state building codes in hand, check your local building codes as well and look into whether you need building permits or approval from your HOA.

If you know of other resources for building code or permit information for your state, please add a link to it in a comment.

Alabama

Alabama Building Commission

Alaska

Alaska DPS Building Codes and Permits

Alaska Building Codes

Arizona

Department of Fire, Building, and Life Safety

Arizona Building Energy Codes

Arkansas

Arkansas Building Authority

California

Division of the State Architect

Building Standards Commission

Building Standards Code Development and Adoption Project

Colorado

Construction Permit Links

Office of the State Architect

Information for Developers in Colorado

Connecticut

Office of State Building Inspector

or Another Page in the Office of State Building Inspector

Delaware

Construction Weblinks Delaware Licensing

District of Columbia (Washing D.C.)

Washington DC Permits

Department of Consumer & Regulatory Affairs

Florida

Florida Building Codes

Florida Building Permits by County and City

Georgia

Georgia DCA Building Codes

Building Permits

Hawaii

How to Obtain a Building Permit

Idaho

Idaho Building Code Information

Idaho Building Codes

Illinois

Building Commission

Division of Professional Regulation – Engineers

Indiana

Residential Building Permit Statistics

Environmental Permits

Iowa

Building Code Bureau

State Fire Marshall Division

State Architect Professional Building Codes

Kansas

Division of Facilities Management

Kentucky

Office of Housing, Buildings, and Construction

Building Codes and Construction Licensing

Louisiana

Permit Place Building Code Resources

Office of State Fire Marshall

Maine

Main Model Building Code

Maryland

Permits and Development Management

Maryland Codes Administration

Massachusetts

Department of Public Safety

Lexington Construction Regulations

Michigan

State Construction Codes

Bureau of Construction Codes

Minnesota

Building Codes and Standards

State Building Codes

Mississippi

State Agencies

Missouri

Facilities Management, Design, & Construction

Montana

Bureau of Building and Measurement Standards

Building Standards Program

Energy Building Codes

Nebraska

State Fire Marshall’s Office

Nebraska Business Online Resources

Nevada

Nevada Public Safety

Building Codes Internet Resource Directory

New Hampshire

State Building Code Review Board

New Jersey

Division of Codes and Standards

New Mexico

Construction Industries Division

Environment Department

New York

Division of Code Enforcement and Management

North Carolina

State Fire Marshall

NC Building Inspector’s Association

North Dakota

ND Builders’ Association

Department of Commerce

Ohio

Board of Building Standards

Division of Industrial Compliance

Oklahoma

Office of the State Fire Marshall

Building Permits

Oregon

Building Codes Division

Pennsylvania

State Building Codes

Association of Building Code Officials

Puerto Rico

Puerto Rico Building Codes

Rhode Island

Building Codes and Fire Codes

Construction Permit Links

South Carolina

Building Codes Council

Office of State Fire Marshall

South Dakota

Fire Marshall Office

Tennessee

Fire Prevention Division

Texas

Texas Department of Licensing and Registration

Texas Online Construction & Housing

Utah

Utah Chapter of ICC

Uniform Building Codes

Vermont

State Resources (Building Codes Included)

Building Energy Codes Program

Virginia

Virginia Building and Code Officials Association

Department of Housing and Community Development

Washington

Washington State Building Code Council

West Virginia

Division of Energy

Construction Contractor Licensing Board

Wisconsin

Online Business Services

Safety & Buildings List of Administrative Codes

Wyoming

Fire Marshall’s Office

OSHA

Another great resource to check for building codes and compliance is OSHA. Always make sure you and your clients are in compliance with OSHA guidelines. Their fines are big and ugly.

Keep your customers compliant with building codes and OSHA regulations. In addition to keeping yourself out of trouble, it is a great service to them and is a great way to sell a few additional improvement jobs from time to time.

I often get asked by engineers, architects, and designers (and farmers) about the span tables for dimensional lumber. So, I have compiled a list of many places with various span tables for your reading enjoyment and project fulfillment. The idea here is to create a one-stop shop for span tables so let me know if I am missing something.

Roof Truss Span Tables: This is a great find for roof truss span tables. It is easy to use and breaks down the span tables by truss type, pitch, and length. Here’s a list of roof truss manufacturers, too.

Maximum Span Tables for Joists & Rafters: The MSR Lumber Producers Council created and published these span tables floor joists, ceiling joists, and roof rafters. The pdf is 12 pages long and the span tables start on page 3.

Span Tables for Structural-Use Panels: Free pdf download from the APA Engineered Wood Association for Structural-Use Panel Span Tables.

Floor Joist Span Tables: Southernpine.com probably has the best publications – like this one showing floor joist span tables.

Residential Steel Beam & Column Span Tables: This is a pretty specific span table (warning: 29 page pdf) developed by the American Iron & Steel Institute. The span tables start appearing on page 12. If you are having trouble sleeping, start at the beginning. Otherwise, stick to the span tables.

Lumber Span Tables: This is a span table for U.S. Spans for Canadian Species from the Strober Organization, Inc. a supplier for contractors in the eastern U.S.

Header and Beam Span Tables: These span tables are a great find if you are trying to build with beams and/or engineered lumber. The pdf is free from The Southern Pine Council.

Deck Joist Span Tables: Their is a good span table tool in here for deck joists but I cannot link directly to it so go here and click on “Joist Calculator” about halfway down the page. You might have to sign up/in.

Span Table Pocket Card: This is like a cheat sheet from The Souther Pine Council. Every wood professional should have a copy of this around somewhere. The pdf is free or you can order the real thing (laminated) for $0.50 each.

Beam Span Tables: The American Institute of Timber Construction has a nice list of tools and span tables for timber construction.

Bridge Span Tables: This is just interesting and offers no actual value. It is a chart of the longest bridge spans around the world. By “span” they are referring to the distance between the two farthest-apart supports on the bridge (the longest spans). The lengths, which are in meters, are not referring to the total lengths of the bridges.

Tell me what I missed. I know there are a million other span tables out there and I would like to list them here. If you know of something, add it yourself as a comment and I will add it to the list.

This board foot calculator from the University of Missouri is the most straightforward and simple to use board foot calculator I have seen. The calculator even includes spaces for quantity and price/board foot to calculate your total price for you.

Calculate Total Weight Using Board Foot

To calculate weight, you can use the wood weights chart at WoodScience (the old home of Lumber Talk) and multiply the weight per board foot of the species of wood by the total board feet given by the board foot calculator.

That is, total weight = pounds/bdft X total bdft

Calculate Board Feet in Logs and Poles

I do not have a board foot calculator for round stock but here is a fairly simple way to calculate board feet of logs and poles. Use the average diameter of the pole or log to find the radius (r, or half the diameter) and use that to calculate the volume of the log or pole in board feet. Remember radius is simply half of diameter. To find the average diameter of a log or pole use:

Average diameter = (tip diameter + butt diameter)/2

Keeping the length in feet, use the average diameter in the equation for the volume of a cylinder to calculate the total board feet. Calculate board feet of logs and poles using:

Board feet of a log or pole = ((pi (r^2)) X length ) / 12

That looks uglier than it is. Once you have the average diameter of the pole, you can treat the pole as a simple cylinder. If you find a good board foot calculator for a pole, please comment on where it is. I will be happy to post it here and link to you for finding it.