The right lumber is key to a successful deck-building project.
Well walk you through how to select lumber, examine the quality, and more.
Selecting the best wood for decks is a balancing act between budget, beauty, and quality.
Credit: John Bessler
This quality is most characteristic of the heartwoodthe dense, centermost core of the tree.
Rare speciessuch as ipe, cambara, and merantidisplay similar color characteristics.
They are generally more durable but more difficult to work with and more expensive.
Credit: WATERBURY PUBLICATIONS INC
Imported Woods
Imported hardwoods offer a more costly but extremely durable alternative to domestic woods.
On the other hand, ipe is twice as strong as pressure-treated Douglas fir.
Some of each species is cut from sustainable forests.
Credit: Ed Gohlich
These products can be challenging to obtain.
Check with theForest Stewardship Councilfor information on sustainable wood products.
All rare hardwoods are extremely dense and may prove difficult to work with.
Credit: Bob Stefko
Ipe is so dense that it neither needs nor will accept stains or finishes.
Other species can be finished with hardwood stains or oils.
Redwood and cedar look better than PT lumber, but only the heartwood naturally resists rot.
Credit: Matthew Benson
The light-colored sapwood may rot in a few years unless treated regularly with a preservative.
Use these guidelines to select lumber for your decks framing, posts, decking, and railings.
Use lumber rated for ground contact for posts and framing members within 6 inches of the soil.
Look for a grade stamp that says ground contact or indicates a treatment depth of 0.40 or greater.
Some pressure-treated species are less porous than others, so theyre incised before being treated.
These incisions still show after treatment, so place this lumber where it will be less visible.
Wood that has been kiln-dried after treatment (KDAT) is the highest quality.
Posts
Standard-sized deck postsare 4x4s or 6x6s.
Pick pressure-treated lumber with care.
Some boards will be smaller than standard nominal sizes.
An untreated 2x10 will measure 914 inches, while a pressure-treated 2x10 may only be 918 inches wide.
For the deck surface, you could use 2x4s, 2x6s, or 5/4x6s.
Cedar 1x lumber usually has one rough side and one smooth sideput the rough side down.
For structural members, choose a No.
2 grade or lumber graded as standard.
For decking and railings, some grades are free of knots, but expensive.
Choose the best wood for decks your budget will allow.
A lumber-grade stamp indicates the quality of the stock and notes its moisture content.
For framing, air-dried lumber is adequate.
Use S-dry or MC-15 lumber for decking and rails.
Grade stamps differ from species to species, and board markings differ from dimension stamps.
A pressure-treated stamp specifies the treatment chemical, treatment depth, and other data.
Pay special attention to both the grade and the moisture content of untreated lumber.
B-grade redwood has only tiny knots and is all heartwooddesirable, butexpensive for decking.
If you want to retain the brown shade of construction boards, plan tostain themevery year or two.
Otherwise, allow them to weather naturally.
Lumber treated with other chemicals, such as ammoniacal copper quaternary (ACQ), is not considered hazardous.
Afterward, sweep up thoroughly and dispose of scraps.
Do not burn pressure-treated waste.
Call your local environmental agency and ask about proper disposal methods.
Keep children out of the work area.
Posts larger than 4x4 are prone to twists and cracks, so consider sandwiching 2x2s instead.
Measurements of common dimension lumber vary from 34 to 112 inches.
Add 10% to framing quantities and 15% to decking to allow for waste.
Lumber lengths are in even 2-foot intervals.
Most longer stock is slightly longer than stateda 12-foot board might measure 14414 inches, for example.
If you will cut several lengths from a board, remember to allow for the saw kerf when estimating.
Kerf is the width of the wood that is removed by the saw.
Be sure to allow for overhangs.
Buy enough lineal feet of decking to make up the deck area, plus the waste allowance.
Make actual counts of posts, beams, joists, and other framing members.
If the lumber is not kiln-dried, let it dry for several weeks.
The stickers will let air circulate evenly throughout the stack.
Kiln-dried lumber is ready to use, but youll need to protect it from the elements, too.
Square-cut posts and balusters are the most common and will complement almost any architectural style.
you’re free to dress them up with mortises, bevel cuts, and post caps.
If you want something more stylish, look at the supply of milled stock carried by your home center.
You might be surprised at the array of styles in different species.
Turned balusters are available in numerous configurations and go well withVictorianor classic landscape designs.
Add style to the railings by adding milled post caps or finials.
Finials come in many configurations and are proportioned to fit 4x4 or 6x6 posts.
Some come complete with lag screws that only require predrilling the posts.
Other styles need drilling for screws or dowels.
Post caps cover the tops of the posts completely and shed rain from the end grain.
Youll find them fluted, corniced, and chamfered in styles that match any deck design.
Heartwood is typically darker in color than sapwood due to the natural aging process.
Kiln-drying lumber is a faster, more expensive method of drying wood.
Depending on the quality of decking lumber you choose, most wood decks last between 10 and 30 years.
United States Environmental Protection Agency.
