Garapa vs Ipe vs Cumaru for Backyard Decks, Judged by Frame, Dead Load and Site

The Short Answer, Framed Around Your Deck Frame

Garapa is the right backyard board when the structure underneath it is the limiting factor, and Ipe or Cumaru win when the frame is new, the deck is high, or the surface has to survive heavy traffic and furniture for thirty years without complaint. Most comparisons of these three species stop at hardness and color. That is the easy part. The harder question, and the one that actually decides which board you should order, is what the deck is being built on and how the finished assembly will carry weight, shed water and breathe.

A tropical hardwood deck is a structural decision as much as a finish decision. Garapa runs roughly twenty percent lighter than Ipe. That difference is invisible on a spec sheet and very visible when you are adding several hundred pounds of permanent load to a fifteen year old frame with original footings. Ipe and Cumaru bring the strength and the density that let a board sit over a wider bay, take a stair tread beating, and hold a crisp edge on a picture frame border. Garapa brings a lighter, cooler, friendlier board that a two person crew can install without wearing itself out, at a cost well below Ipe.

None of the three is a bad choice for a backyard. The wrong choice is a species picked without checking joist spacing, ground clearance and dead load first.

Dead Load Decides Whether You Can Re-Deck an Existing Frame

Swapping pressure treated decking for a dense tropical hardwood can nearly double the permanent weight of the walking surface, and that matters most on re-decks, elevated decks and anything over living space. Residential deck framing in the United States is normally designed to the load combination in the American Wood Council's prescriptive deck guidance, which assumes a 40 pound per square foot live load and a 10 pound per square foot dead load. The published tables at awc.org/codes-standards are built on that assumption, and DCA 6 is the document your inspector is most likely to be working from.

Run the arithmetic before you order. Pressure treated southern yellow pine sits around 35 pounds per cubic foot at in service moisture. A nominal 5/4 board finishes near one inch thick, so that decking contributes roughly 2.9 pounds per square foot. Ipe at about 1,050 kilograms per cubic meter, near 65 pounds per cubic foot, contributes roughly 5.4 pounds per square foot in the same thickness. Cumaru at about 1,070 kilograms per cubic meter lands slightly higher. Garapa, near 820 kilograms per cubic meter, comes in around 4.2 pounds per square foot.

On a 16 by 20 foot deck, moving from treated pine to Ipe adds roughly 800 pounds of permanent load. Garapa adds about half that. On a ground level deck with generous footings, nobody will ever notice. On a second story deck hung from a ledger that was installed with the minimum fastener schedule of its era, or a deck framed over a finished basement or a garage, that delta belongs in a conversation with an engineer, not in a lumber order. Wet weight is higher still. Dense tropical decking picks up water fast on the surface after a storm even though it absorbs very little into the core.

This is the single most common reason a homeowner ends up in Garapa on a re-deck. The frame is sound, the footings are adequate for a moderate increase, and the owner wants a real hardwood surface without pulling the deck down to dirt and starting over.

Thickness Availability Is the Quiet Constraint

Only Ipe, Cumaru and Jatoba can be sourced consistently in 2x decking thickness, which quietly removes Garapa from any part of a project that needs a true two inch board. Most backyard decks are built from 5/4x6, and that is the correct default for framing at 16 inches on center. Some designers spec 1x6 for a lighter, tighter look, and that board wants joists at 12 inches on center rather than 16. The step up to 2x is a different world. Commercial boardwalks, piers and plaza decks are specified at 2x thickness to control deflection, and no professional will go first with a thinner board on a public job even where the strength math for a 5/4 board works out.

That rule reaches into residential work more often than people expect. Community docks, HOA boardwalks, shared pool decks and long municipal style walkways attached to a private property all get pulled toward 2x. If any portion of your project falls into that category, Garapa is out for that portion and Ipe, Cumaru or Jatoba is in. Mixing is legitimate. Garapa on the private deck and Ipe on the shared boardwalk is a perfectly defensible split, and the two weather toward a compatible silver if left bare.

For pure backyard work, Garapa and Red Balau both live comfortably in 5/4 and 1x, and both are sound choices where an engineer or the local code official has signed off on the framing. Their absence from the 2x world is a sourcing reality, not a knock on the wood.

Garapa, Ipe and Cumaru Along the Axes That Change a Build

The properties that separate these species on a job site are density, sourceable thickness and stiffness, not the Janka number everyone quotes. Hardness predicts dent resistance under a dropped grill lid. It does not predict how the board behaves over a stretched joist bay, how many fasteners your crew can drive in a day, or whether the deck can be built at all on the frame you already own.

Read the dead load column next to your framing plan, then read the thickness column next to your scope. Those two together eliminate more options than any hardness ranking.

Span, Deflection and Joist Layout

All three species belong on joists at 16 inches on center in 5/4 thickness, and none of them earns you permission to stretch that spacing. Density and stiffness are related but not identical. Ipe and Cumaru are stiffer than Garapa and will bridge a sloppy bay with less visible sag, but a deck that flexes underfoot is a framing problem wearing a decking costume. The fix is blocking and correct spacing, not a harder board.

Three layout rules apply to all three species. A diagonal deck board layout increases the effective span across each bay by roughly forty percent, so tighten joists to 12 inches on center for diagonal work. A picture frame border needs continuous blocking under every perimeter board, doubled where two mitered boards meet, since a border board otherwise lands on nothing at its outer edge. Butt joints inside the field must land on doubled joists or on a joist with a sister, giving each board end its own full bearing and its own fastener line.

Garapa is the species where crews are most tempted to cut corners, since the board is lighter and easier to bend into place. Resist that. A board that can be pushed flat by hand during installation will telegraph every framing irregularity once furniture sits on it. The USDA Forest Products Laboratory Wood Handbook is the reference worth keeping open when you are comparing mechanical properties across species rather than trusting marketing tables.

Ground Clearance, Shade and Drainage Change the Ranking

A shaded, low, poorly drained backyard deck is the one condition where the durability gap between Garapa and the Class 1 species turns into a real service life difference. Ipe and Cumaru are rated EN 350 Class 1, the top durability classification, which is why they show up on municipal boardwalks that never get maintained. Garapa is durable but sits a class below that. In an open, sunny, well ventilated yard with 18 inches of clear air under the joists, that difference is academic across a normal ownership period. In a north facing corner where the deck is 8 inches off wet clay and leaves pile up under it every autumn, it stops being academic.

Fix the site before you argue about species. Keep a minimum of 12 to 18 inches of clearance under the joists wherever the design allows it. Slope the grade away from the structure. Put down gravel or a permeable ground cover instead of letting bare soil pump moisture upward. Skirting should be ventilated, not sealed, and any solid skirt panel should have open area top and bottom so air actually moves. The building enclosure principles behind that are laid out well at buildingscience.com, and they apply to the cavity under a deck exactly as they apply to a crawl space.

If the deck skirt or an adjacent wall gets clad in wood, the profile rules matter. Shiplap takes visible fasteners. Only tongue and groove works with a hidden fastener system. Either way the material goes on furring strips over the framing so the back face can dry, and grooves face down so water drains out rather than collecting in the joint.

Stairs, Pool Surrounds and the Details Where Species Choice Actually Changes

Stair treads and pool coping are the two places on a backyard deck where the harder species pull decisively ahead, and where a lighter colored board pulls ahead for a different reason. Treads take concentrated abrasion at the nosing from every trip up and down, plus the shear from a foot landing at an angle. Ipe and Cumaru hold a crisp nosing edge for decades. Garapa will show wear at the nose sooner, particularly on a heavily used main stair from a kitchen door. Support stair treads at 12 inches maximum between stringers regardless of species, and never let a tread cantilever more than the code allowed nosing projection.

Pool decks invert part of the argument. Ipe reaches genuinely uncomfortable surface temperatures in full afternoon sun, and Cumaru is close behind. Garapa's honey color reflects more and runs measurably cooler underfoot, which is why it keeps winning pool surround jobs in the South and Southwest even from clients who would otherwise default to Ipe. Chlorinated and salt water splash zones both call for 316 stainless fasteners, not 304 and never coated carbon steel. Anywhere near saltwater air, 316 is the only sensible specification for the whole deck.

Two more details. Fascia and riser boards see far less wear than treads, so mixing a Garapa fascia with Ipe treads is a legitimate way to control weight and cost without a visible compromise. And if the deck falls inside a wildland urban interface zone, check the local ignition resistant material requirements against the guidance published by NFPA. Ipe carries an ASTM E84 Class A rating, meaning a flame spread index of 25 or less, which satisfies most such requirements without treatment.

Fastening and On Site Drilling

Every one of these species gets pilot drilled on site, against the frame as it was actually built, and no reputable mill drills fastener holes before shipping. Layout shifts. Joists are not perfectly parallel. Field cuts, stair openings and picture frame miters all move hole positions after delivery, which is why a factory hole pattern would be wrong before the first board landed. Plan the drilling as installation labor and budget it honestly.

The technique is the same across all three, with Ipe demanding the most from your bits. Pilot every hole. Use two fasteners per board at every joist crossing. Hold about three quarter inch edge distance so the fastener does not split out the board edge. Near board ends, pilot the full depth rather than starting the screw into a partial hole. Land butt joints on doubled bearing. A self centering combination bit that counterbores and countersinks in one pass will save more time than any other tool decision on the job. Garapa drives easier and dulls bits slower than Ipe, which is a genuine labor advantage on a large deck.

Hidden fastener systems need a factory machined groove in the board edge, so that profile has to be ordered up front rather than improvised on site. Clip systems set the board gap for you, which is a real benefit in dense hardwoods where consistent spacing is otherwise fussy. Face screwed installations with plugs give a cleaner look than exposed heads and are easier to service later when a single board needs to come out.

Checking, Factory Coating and the First Summer

Surface checking is normal in dense tropical decking and cannot be prevented, only kept small. A check is the wood releasing tension as the surface heats and dries faster than the core. It does not weaken the board. Fine surface checks are a sign that the material seasoned properly rather than evidence of a defect, and any supplier promising a check free tropical deck is either misinformed or telling you what you want to hear.

The meaningful mitigation is a stabilizing oil applied before the board ever reaches the site. J. Gibson McIlvain factory coats tropical decking with Cutek, a penetrating oil wood stabilizer that significantly reduces checking by slowing the moisture exchange at the surface. Site practice does the rest. Take delivery of material at an in service moisture content of 12 to 16 percent, sticker and cover it on flat bearers rather than stacking it on grass under plastic, seal every field cut end, and get the deck installed and ventilated rather than letting bundles sit in July sun for three weeks.

Garapa checks, Ipe checks and Cumaru checks. The difference between a deck where the checking is invisible from standing height and a deck where it bothers the owner is almost entirely handling and detailing.

"The calls we get about checking almost always trace back to how the material was stored between delivery and installation, not to the species. When decking shows up factory coated with Cutek and the crew keeps it stickered, covered and off the ground, checks stay small enough that nobody notices them from a standing position. I would rather talk a client through that in advance than replace boards later." Norm Moton, Director of Sales, J. Gibson McIlvain

Ordering, Grading and Documentation

Decking grade is not lumber grade, and the difference determines how much of what you receive actually goes down on the deck. Tropical decking is selected on both faces and both edges, since either face may end up visible on a stair riser or a fascia return. Hardwood board grading rules published by the National Hardwood Lumber Association govern the lumber side of the business, while decking is sorted against a decking specific standard that assumes the board will be seen from every angle outdoors.

J. Gibson McIlvain mills and stocks Garapa, Ipe, Cumaru and Jatoba decking in 1x and 5/4 profiles, holds Ipe in a vast inventory across every standard and custom dimension including 2x, and ships nationwide to job sites from the mid Atlantic to California. Orders come out of a commercial and contractor volume operation rather than a retail counter, so bring your framing plan and your board footage to the conversation. Call 800-638-9100 for a quote, or start with the Ipe decking material detail and the wider hardwood and decking program.

On the documentation side, ask two questions of any supplier. First, whether the material is available FSC certified, which matters on projects chasing points under a green building program. The chain of custody framework is described at fsc.org and the credit structure at usgbc.org. Second, when using a CITES listed species, documentation is required to move the material legally, and your supplier should be able to produce it without hesitation. The current appendices are published at cites.org. None of the three species in this comparison is a difficult import, but the habit of asking is what keeps a project out of trouble.

If you want a wood that carries a manufacturer warranty, that conversation moves to modified products. Accoya, Thermory and Abodo Vulcan all come with published warranties, and all three top out around 16 feet in length because of kiln size, with the metric products landing just under 16 feet. Solid unmodified tropical hardwood carries no such warranty from anyone, and a supplier offering one on Ipe should prompt a follow up question. Species level property data for cross checking any of this is easy to find at The Wood Database.

How J. Gibson McIlvain Would Specify This

Start with the frame, then the exposure, then the species, and write the order so the crew never has to improvise. Here is the sequence that produces a deck nobody calls about in year three.

• Confirm the framing first. Joists at 16 inches on center for 5/4 decking, 12 inches on center for 1x or for any diagonal layout, continuous blocking under picture frame borders, doubled bearing at every butt joint.
• Check dead load before switching a re-deck to tropical hardwood. If the deck is elevated, hung from an older ledger, or sits over conditioned space, have an engineer confirm the frame before adding roughly 2.5 pounds per square foot with Ipe or Cumaru. Garapa cuts that increase close to half.
• Pick the species by exposure. Full sun pool surround or a large open deck where barefoot comfort matters, Garapa. Main stairs, heavy traffic, or a surface that has to look sharp for decades with minimal attention, Ipe or Cumaru. A shared boardwalk or dock element in the same project, 2x Ipe, Cumaru or Jatoba only.
• Order the profile you actually need. Grooved edges if a hidden clip system is going in. Square edge for face screwing with plugs. Add fascia, riser and stair stock to the same order so the color and the coating schedule match across the whole deck.
• Specify factory Cutek coating on the decking and order end sealer for field cuts. Take delivery at 12 to 16 percent moisture content, sticker and cover on site, and install into a ventilated cavity with 12 to 18 inches of clearance under the joists where the design permits.
• Use 316 stainless fasteners on any coastal or pool project, two per board per joist, pilot drilled with a self centering combination bit at about three quarter inch edge distance.
• Plan the finish schedule before the first board goes down. Bare boards on all three species weather to silver gray. Holding the original honey, olive brown or amber color means a penetrating oil refresh on a regular cycle, and that decision should be made while the deck is still easy to coat.

Deck framing and guard requirements are code driven, so verify the current provisions in your jurisdiction through iccsafe.org before finalizing anything. Bring the framing plan, the square footage and the exposure conditions to 800-638-9100 and the species question tends to answer itself in about ten minutes.