How Much Does a DIY Outdoor Sofa Cost? Build vs Buy a Platform Sofa
A 7 ft 2 in outdoor platform sofa costs about $340 to $490 in lumber and finish to build, against $699 to $3,298 for comparable finished outdoor seating.
A three-seat outdoor platform sofa, 7 ft 2 in wide, costs about $422 in materials to build, with a realistic range of $340 to $490. A loveseat comes to about $343, a lounge chair about $279, and a matching coffee table about $108. Comparable finished outdoor platform sofas and loveseats sold through catalog retailers and showrooms range from about $699 to $3,298, and that range usually does not include the cushions or delivery. Cushions are the one thing the lumber estimate leaves out, and we will get to them below.
All estimates here are at typical US home-center prices and vary by region, so use them to plan rather than to quote.
What the number includes
The figures come from the computed shopping list in our Coastal Platform Sofa plans. The design is a low, boxy platform sofa with a floating plinth base, wide flat arms, tight horizontal slats on the arms and the tall back, and a deck under the seat. Everything is built from 2x4 and 2x6 outdoor lumber. Here is the 3-seat sofa broken down and rounded:
| Category | What is in it | Estimated cost |
|---|---|---|
| Lumber | 11 boards of 2x4 and 2 boards of 2x6, outdoor-rated | $255 |
| Fasteners | Exterior structural and deck screws, exterior wood glue | $62 |
| Hardware | Felt or rubber furniture pads | $1 |
| Finish | About 5 quarts of exterior stain or paint, sandpaper | $104 |
| Total (3-seat sofa) | about $422 |
The other pieces in the same kit scale down the same way:
| Piece | Size | Estimated materials | Range |
|---|---|---|---|
| 3-seat sofa | 7 ft 2 in wide | $422 | $340 to $490 |
| Loveseat | 5 ft 2 in wide | $343 | $270 to $400 |
| Lounge chair | 3 ft 2 in wide | $279 | $220 to $320 |
| Armless middle module | 2 ft 2 in wide | $138 | $110 to $160 |
| Coffee table | 48 x 24 x 14 in | $108 | $90 to $120 |
The armless middle module is worth noticing. It uses the same parts as the sofa and lets you extend a run, so you can build a sectional in stages instead of committing to one length.
The cushions, honestly
The sofa is sized for thick, deep standard cushions: 24 x 24 x 6 in seat cushions and 24 x 18 x 6 in back cushions, one of each per seat. A 3-seat sofa takes three of each, a loveseat two, a lounge chair one. The plans list two optional 18 x 18 in throw pillows as well.
The lumber estimate does not price the cushions, and we will not guess at a price here because outdoor cushions vary enormously with fabric and fill. Search for outdoor seat cushions 24x24x6 and outdoor back cushions 24x18x6 and read the specs for fabric type and drainage. Quick-dry foam and solution-dyed acrylic or polyester covers are the features to look for if the sofa will stay outside. This is the single largest variable in your final bill, and it is the item that most separates a budget outdoor sofa from an expensive one at a showroom.
Build versus buy
The comparison is not apples to apples, so it helps to break down what each path gives you.
What the store version offers. Finished outdoor sofas arrive assembled or nearly so. Many include cushions, a fabric warranty and a frame warranty. Delivery is included or optional. You can sit in one before you buy, and returns are possible. The time cost is close to zero.
What the DIY version offers. You choose the length, the wood and the color. The lumber is common, the joinery is simple, and the plans keep every piece to standard boards. You can build the loveseat this year and add a middle module next year. And the numbers favor building by a clear margin: even the top of the 3-seat range ($490) is below the bottom of the comparable finished range ($699), though that is before cushions.
Where the gap narrows. If you compare against the cheap end of the retail range, the saving is smaller after you add cushions. If you compare against the high end, the saving is large. Comparable teak or eucalyptus-look furniture at the top of the range is priced for the wood and the brand, and you are paying for neither when you build from outdoor-rated pine or cedar.
What you give up. A warranty, delivery, and a finished surface that has been machine-sanded and sealed at a factory. You also give up a weekend.
What moves the price
Wood choice
The plans call for outdoor-rated lumber: cedar, redwood, or pressure-treated lumber rated for above-ground use. The estimate uses about $1.20 per foot for 2x4 and $1.68 per foot for 2x6. Cedar and redwood cost more than pressure-treated in most regions and are lighter, easier to work and better looking. Pressure-treated costs less and is fine for a painted or stained piece, but let it dry as the supplier advises before finishing, and sand it well. If you are going to put the sofa on soil or constantly wet ground, think about ground contact, which is a different rating. This design sits on a plinth with felt or rubber pads, so keep it up on pavers or a patio rather than on bare soil.
Finish
Finish is $104 of the $422, about a quarter of the cost, because every face, edge and end of a slatted sofa needs coating. A tight-slat design has many edges. Use an exterior stain and sealer or exterior primer and paint, and seal the end grain well, because that is where moisture enters. A weathered teak tone is easy to achieve with a gray-brown semi-transparent stain; natural tones also work.
Fasteners
The plans specify coated or stainless exterior screws. Stainless costs more but resists rust streaks. Use exterior deck screws for slats and cladding and #10 exterior structural screws for the frame joints. Exterior waterproof wood glue goes in every joint where it helps.
Quantity of pieces
Going from loveseat to sofa adds about $79. Adding a coffee table adds about $108. The cheapest way to furnish a patio is often a loveseat, two lounge chairs and a table, because each piece shares the same techniques and the same finish.
The hard parts and how the plans handle them
Platform sofas are simple structures: a box, a deck and a back. But there are three places where the details matter.
Cushion fit. If your cushions are not the sizes the plans call for, the proportions will be off. The seat is 15 in high, the back 30 in tall and the depth 29 in, built around 24 x 24 x 6 in and 24 x 18 x 6 in cushions. The plans include a cushions and sizes sheet so you can check before you cut.
Straight slats. The tight horizontal slats on the arms and back look best when the boards are straight, dry and free of large knots. Buy boards individually when you can, and sight down each one. Use the plans’ numbered steps and cut list rather than improvising.
Square assembly. The wide arms are 7 in wide, the same depth as the sofa, flush with the back. A box that is out of square will show along those edges. A speed square or framing square and a pair of bar clamps catch problems before screws go in.
The plans use numbered steps with one clear drawing each, a lettered parts list, a cut list and a shopping list for every piece. If you can follow flat-pack furniture instructions, you can follow these. They are generic DIY plans, not engineered drawings, so they do not replace your own judgment about the load on a particular piece.
Tools and skill level
This is a first-build-friendly project. You need a saw, a drill and a tape measure, plus sandpaper. A pocket-hole jig is optional. If you want one, a pocket hole jig kit speeds up some joints, though the plans do not require it. A random orbit sander makes the finishing step less tedious; a random orbital sander is the tool people tend to wish they had bought first.
The plans describe the sofa as a weekend build and the table as an afternoon. Allow extra time for finish to dry between coats, which depends on weather and product.
Sizes available
The kit covers five pieces. The 3-seat sofa is 7 ft 2 in wide, the loveseat is 5 ft 2 in, the lounge chair is 3 ft 2 in, the armless middle module is 2 ft 2 in and the low slatted coffee table is 48 x 24 x 14 in. All are the same height and depth family, so they work together. The plans say you can finish in weathered teak or natural tones.
Planning a full seating group
Because every piece shares the same parts and proportions, it helps to price the whole group before you buy lumber. A loveseat ($343), two lounge chairs ($558) and a coffee table ($108) come to about $1,009 in materials. A 3-seat sofa, one lounge chair and the table come to about $809. Buying lumber for several pieces at once also lets you pick the straightest boards from a larger pile and often reduces waste, since offcuts from one piece can become the short parts of another. Finish by the gallon rather than the quart if you are building more than one piece, and ask the supplier whether your chosen product is rated for exterior furniture rather than for fences or decks, which are designed for different wear.
Practical notes on outdoor use
Outdoor furniture lives a hard life. Keep the base off wet ground. Rinse cushions and let them dry. Re-coat the finish on a schedule that suits your climate; the plans include a yearly check log and finishing and care guidance. If the sofa will sit under a cover or a pergola, it will last longer than if it sits in open weather.
If you have small children, be aware that a deep platform sofa with tall arms is a seat, not a play structure. Keep the pieces on level ground and avoid stacking.
Is a DIY outdoor sofa worth it?
For most backyards, yes. The lumber and finish for a full 7 ft 2 in sofa come to about $340 to $490, and a loveseat and two lounge chairs together would still come in under the top of the comparable finished range. The exceptions are people who want a warranty, who do not want to finish wood themselves, or who need the set immediately.
You can see how other outdoor builds compare in the build-cost hub, where estimates are listed by project.
Where to go next
The Coastal Platform Sofa plans cost $12.99 and run 82 pages, including all five pieces, a cushions and sizes sheet, a cut list and shopping list for every piece, a budget planner and a yearly check log. If you plan to build more than one project this year, the complete collection bundles every plan for $129. Start by choosing your cushions, because everything else in the design is sized around them. Then open the sofa plans and pick your piece.
