How to Price a Deck Build: The 50% Markup Rule for Treated Lumber

To accurately price a deck, stop using square-foot averages and build your estimate from the ground up using a strict material takeoff and your true labor burden. You must apply a minimum 50% markup on pressure-treated framing lumber to account for waste, and itemize every piece of structural hardware. A standard 16x20 deck should be priced by calculating your exact material costs, adding your fully burdened labor hours, and dividing the total by your target gross margin percentage.

Bidding decks by the square foot is how you end up working for free. When you use a flat $45 per square foot rate, you are guessing. You are assuming the footings will be easy to dig, the elevation is standard, and the client won't want hidden fasteners or a complex stair layout.

This guide breaks down exactly how to price a deck build so you actually make your 20% net profit on every single job.

The Square-Foot Pricing Trap

If you take one thing away from this guide, it's this: Never price a deck by the square foot.

Let's look at two 320-square-foot decks (16x20).

Deck A is two feet off the ground. It requires standard 4x4 posts, no cross-bracing, basic 36-inch stairs, and the soil is easy digging.

Deck B is ten feet off the ground on a sloped grade. It requires 6x6 posts, engineered cross-bracing, massive 24-inch concrete footings to pass code, scaffolding to frame, and a custom stair system with a mid-span landing.

If you charge $45 per square foot for both, you will make a killing on Deck A and you will lose thousands of dollars on Deck B. Square-foot pricing ignores elevation, soil conditions, access (can you get a machine in the backyard or are you hand-digging?), and structural engineering requirements. You have to price the components, not the footprint.

Most Contractors Get This Wrong: The Hardware Bleed

Here is the biggest leak in a deck builder's estimate: Hardware and fasteners.

Most guys will do a meticulous takeoff of their joists, beams, decking boards, and posts. Then, when they get to the end of the estimate, they type in "Screws and hangers: $150" and send the bid.

Hardware accounts for 15% to 20% of your total material cost on a modern, code-compliant deck. Let's look at the real numbers for a standard 16x20 deck:

• Joist Hangers (LUS28Z): 34 hangers @ $1.85 each = $62.90
• Hanger Screws (Simpson SD9): 3 boxes @ $45 each = $135.00
• Ledger Fasteners (LedgerLoks or similar): 40 screws = $65.00
• Post Bases (ABA66Z): 6 bases @ $22 each = $132.00
• Post-to-Beam Connectors: 6 brackets @ $18 = $108.00
• Joist Tape (to protect the framing): 6 rolls @ $25 = $150.00
• Decking Fasteners (Hidden fastener clips): 2 boxes @ $90 = $180.00
• Structural Screws (for beam assembly/blocking): 1 bucket = $110.00

True Hardware Cost: $942.90.

If you guessed $150, you just paid $792 out of your own pocket to build the client's deck. You must line-item your hardware.

The 50% Markup Rule for Treated Lumber

When figuring out how to price a deck, your framing materials need special attention. You must apply a strict 50% markup on all pressure-treated framing lumber.

If your cost for posts, beams, joists, and ledger boards is $1,500, you charge the client $2,250. Here is exactly why you need that 50% buffer:

1. The Cull Rate: Pressure-treated lumber is notoriously terrible. If you order forty 2x8x12 joists, at least six of them will look like hockey sticks. You will have to cut around massive knots and severe checking. You are paying for that waste.
2. Shrinkage and Spoilage: Treated wood shrinks. If it sits on the job site in the sun for four days because it rained on Tuesday, it will warp before you can frame it.
3. The Home Depot Run: When you inevitably need three more 2x8s because of bad cuts or warped wood, you have to pay a guy $35 an hour to drive to the lumber yard, load the truck, and drive back. That is a $100 trip for $40 worth of wood.

Do not feel bad about marking up treated lumber by 50%. It is the cost of doing business with an unstable material. (Note: For high-end composite decking like Trex or TimberTech, a standard 30% to 35% markup is acceptable because there is zero cull rate—every board is perfect).

Step 1: Calculating Your True Labor Burden

You cannot estimate labor costs until you know your true labor burden. If you pay your lead carpenter $30 an hour, he does not cost you $30 an hour.

To figure out your burden, you must add up the employer-side taxes and insurances. Here is a real-world breakdown of a $30/hour employee:

• Base Wage: $30.00
• FICA (Social Security & Medicare @ 7.65%): $2.30
• FUTA / SUTA (Unemployment taxes, roughly 2%): $0.60
• Workers' Compensation (Carpentry rate, roughly 15%): $4.50
• General Liability Insurance (roughly 2%): $0.60
• Non-Billable Time (Setup, cleanup, shop meetings @ 10%): $3.00

True Labor Cost: $41.00 per hour.

When you build your estimate, you calculate your labor at $41.00 per hour, then you add your company overhead and profit margin on top of that.

Understanding this exact math is critical not just for estimating, but for knowing how much to pay a contractor helper without bleeding your profit margins dry.

Step 2: The Phase-by-Phase Takeoff

To price the deck accurately, break the job down into five phases. Assign material costs and labor hours to each phase.

Phase 1: Mobilization, Demo, and Prep

Don't forget to charge for getting the job started. Are you tearing down an old deck?

• Materials: Dumpster rental ($450), dump fees ($150).
• Labor: 2 guys, 1 day = 16 hours.
• Hidden Trap: Patching the siding where the old ledger board was attached. Just like knowing how much to charge for drywall repair, you can't just throw a flat $100 at siding repair. If you have to weave in new vinyl or Hardie plank, that's a 4-hour job. Charge for it.

Phase 2: Footings and Posts

This is where you make or lose your money based on soil and elevation.

• Materials: Concrete (calculate bags per hole—a 12" diameter hole, 36" deep takes about six 80lb bags), Sonotubes, post bases, 6x6 treated posts.
• Labor: Hand digging vs. auger. If you are hand digging six holes in rocky clay, budget 2 hours per hole.
• Admin: Time spent waiting for the open-hole footing inspection.

Phase 3: Framing

• Materials: Ledger board, flashing (Z-flashing and ice/water shield), joists, drop beams, blocking, joist tape, and all structural hardware.
• Labor: Attaching the ledger is the most critical and time-consuming part. Budget heavily for removing siding, flashing correctly, and driving LedgerLoks. Framing a standard 16x20 deck should take two experienced carpenters about 1.5 to 2 days (24-32 man-hours).

Phase 4: Decking

• Materials: Deck boards, picture-frame border boards, fascia boards, fasteners.
• Labor: Are you face-screwing treated lumber or using hidden fasteners on grooved composite? Hidden fasteners take about 30% longer to install than face-screwing. A picture-frame border requires extensive blocking during the framing phase and precise miter cuts. Add 8 man-hours for a picture-frame border.

Phase 5: Stairs and Railings

Stairs are the most mathematically complex part of the build.

• Materials: Pre-cut stringers (or 2x12s to cut your own), stair treads, risers, railing posts, rail kits (aluminum or composite).
• Labor: Do not underestimate stairs. Cutting and setting stringers, installing risers, treads, and custom railing angles easily takes two guys a full day (16 man-hours).

Step 3: Margin vs. Markup (The Math That Saves Your Business)

Once you have your total cost for materials (with the 50% treated markup) and your fully burdened labor, you have your Cost of Goods Sold (COGS).

Now you need to add your Overhead and Profit (O&P).

Let's say your company needs 15% to cover overhead (trucks, insurance, office, marketing) and you want a 20% net profit. Your target Gross Margin is 35%.

Most contractors do this (The Wrong Way): They take their $10,000 cost and multiply it by 1.35. $10,000 x 1.35 = $13,500 Selling Price. Let's check the math: $13,500 - $10,000 (costs) = $3,500 gross profit. $3,500 divided by $13,500 = 25.9% margin. You missed your 35% target by almost 10%. You just lost $1,884 because you used markup instead of margin.

The Right Way to Calculate Margin: To achieve a 35% gross margin, you subtract 35% from 100%, which leaves 65% (or 0.65). You divide your costs by 0.65. $10,000 / 0.65 = $15,384 Selling Price. Let's check the math: $15,384 - $10,000 (costs) = $5,384 gross profit. $5,384 divided by $15,384 = 35% margin.

Always divide your costs by your margin divisor. Never multiply.

What This Looks Like on a Job: Real-World Example

Let's price a 16x20 composite deck (320 sq ft) with a picture frame border, basic aluminum railings, and standard 4-step stairs.

1. Materials (After 50% Treated Markup & 30% Composite Markup):

• Footings/Concrete: $350
• Treated Framing & Posts: $1,800
• Hardware, Tape & Fasteners: $1,150
• Composite Decking & Fascia: $3,200
• Aluminum Railings: $1,900
• Dumpster/Permit Fees: $650
• Total Billable Materials: $9,050

2. Labor (Fully Burdened @ $45/hr):

• Demo/Prep: 8 hours = $360
• Footings: 12 hours = $540
• Framing: 32 hours = $1,440
• Decking/Fascia: 24 hours = $1,080
• Stairs/Railings: 24 hours = $1,080
• Total Burdened Labor: $4,500

3. The Final Calculation: Total COGS (Materials + Labor) = $13,550

We want a 35% Gross Margin (15% Overhead, 20% Profit). $13,550 / 0.65 = $20,846

Your final selling price to the client is $20,846.

(Notice that if we had used the lazy square-foot method at $45/sq ft, the bid would have been $14,400. You would have made exactly $850 in gross profit to cover your overhead and your family. That is how deck builders go bankrupt).

Your Next Step

Tomorrow morning, call your local lumber yard and get an updated price sheet for 2x8s, 2x10s, 6x6 posts, and your preferred decking line. Build a simple spreadsheet that automatically applies a 50% markup to the treated framing and a 30% markup to the composites.

Stop guessing on hardware, stop multiplying to find your margin, and stop giving away your labor for free. Price the components, protect your margins, and let the guys doing square-foot bids race each other to the bottom.