Deck Wood Types: Treated, Cedar, Redwood, Ipe Compared

The main deck wood types are pressure-treated lumber, redwood and cedar, and tropical hardwoods such as ipe, with composite and vinyl boards as the non-wood alternatives. Costs, lifespans and upkeep below are This Old House's figures (page read 2026-09-25); decay classes are from the USDA Wood Handbook, Table 14-1.

• Pressure-treated lumber - about 15 years, $8 to $20 per square foot, water repellent every 2 years. Economical, but it can crack, split and warp. The wood itself is usually a pine or fir that the Handbook rates slightly or moderately decay resistant, which is why it is treated.
• Redwood and cedar - 20+ years, $3 to $30 per square foot depending on grade, regular maintenance to prevent graying. This Old House notes heartwood is far more durable than sapwood; the Handbook puts western red cedar and old-growth redwood heartwood in its resistant group and young-growth redwood in its moderately resistant group.
• Tropical hardwood (ipe) - 40+ years and up to 100 above ground, one UV-blocking treatment, almost knot-free, but expensive and it must be predrilled. The Handbook rates ipe very resistant, and its side hardness of 3,680 lbf is about 3.7 times teak's 1,000 lbf.
• Composite - 20+ years, $12 to $45 per square foot, soap-and-water cleaning; warranties often do not cover fading or scratches.
• Vinyl - 20+ years, $5 to $13 per square foot, never needs sealing, fewer color options.

This Old House does not say whether its per-square-foot figures include labor, so treat them as a way to compare materials, not as a quote.

The American Wood Council's DCA 6, a prescriptive deck guide based on the 2015 International Residential Code, lists the species it covers in Table 1. Preservative-treated Southern pine, Douglas fir-larch and hem-fir are listed for above-ground and ground-contact use; treated spruce-pine-fir (SPF) for above ground only. Redwood and western cedars appear as naturally durable species, and a footnote says pieces with 90% heartwood in width on each side need not be treated.

In other words, a cedar or redwood deck is allowed without treatment only when the boards are essentially all heartwood. Anything with a sapwood edge should be treated or kept out of the structure.

DCA 6 Table 2 gives maximum joist spans for No. 2 lumber, 40 psf live load, 10 psf dead load and wet service. For Southern pine:

• 2x6 - 9 ft 11 in at 12 in on center, 9 ft 0 in at 16 in, 7 ft 7 in at 24 in
• 2x8 - 13 ft 1 in, 11 ft 10 in and 9 ft 8 in
• 2x10 - 16 ft 2 in, 14 ft 0 in and 11 ft 5 in

For Douglas fir-larch, hem-fir and SPF a 2x8 at 16 in spans 11 ft 1 in; for redwood, western cedars, ponderosa and red pine it spans 10 ft 7 in. Softer species span less at every size.

The guide also sets minimums that settle most 2x6 versus 2x8 debates: the ledger must be at least 2x8, and joists and rim joists that carry guard posts must be at least 2x8. Overhangs are capped at a quarter of the joist span. A 2x6 is only an option for short spans where no guard posts attach to the joists.

DCA 6 says all decking must be dimension lumber (2 in nominal) or span-rated decking under the American Lumber Standard Committee policy, attached to each joist with two 8d threaded nails or two #8 screws, spaced about 1/8 in apart, and each board must bear on at least three joists. Boards can run anywhere from perpendicular to 45 degrees to the joists.

The Wood Handbook describes the thinner option: radius-edged decking is made 5/4 or 2 in nominal (1 or 1-1/2 in actual) by 4 to 6 in nominal, in 8 to 16 ft lengths, with a 1/4 in edge radius on the thinner boards and 3/8 in on the thicker, usually in Premium and Standard grades. If you use 5/4 boards, check that they carry a span rating for your joist spacing.

A 20 by 20 ft deck is 400 square feet. Multiplying This Old House's per-square-foot ranges:

• Pressure-treated: $3,200 to $8,000
• Redwood or cedar: $1,200 to $12,000, depending heavily on grade
• Composite: $4,800 to $18,000
• Vinyl: $2,000 to $5,200

This is simple arithmetic on published ranges, not an estimate for your site. Railings, stairs, footings, permits and labor can change the total, so get local quotes. DCA 6 also requires a final inspection before a deck is used.

Replacing a few boards on an old deck starts with knowing what they are. Treated pine, cedar and redwood weather to similar grays, but the end grain still differs. Compare against our western red cedar, redwood, southern yellow pine and ipe pages, or photograph a fresh cut with WoodLens. For older treated decks and CCA, see treated wood for decks.