The short answer
Our free freestanding designs cost $2,423 to $8,234 in materials, the required safety surfacing included: $2,423 for a low deck, $2,898 for the open tree fort, $6,104 for the 10x12. Home Depot prices read October 2026.
Treehouse cost is the structure plus the safety surfacing under it. For the freestanding forts we draw, that runs from $2,423 for a low deck to $6,104 for the big 10x12, in materials you buy and build yourself. The surfacing is in every total, because a raised deck is not safe without it. Home Depot prices read October 2026.
This guide is about the do-it-yourself number: a fort on its own posts, no tree to carry it, built with lumber from a home center. It is not a price for a luxury treehouse or a quote from a builder, because we do not have one and will not make one up. Every figure below comes from the materials list our designer builds for each plan.
What our free plans cost
| Free design | Deck | Sq ft | Materials, about | Of it, safety surfacing | Build time |
|---|---|---|---|---|---|
| Low deck for little ones | 2 ft 6 in | 36 | $2,423 | $1,050 | 36 to 52 h |
| Open tree fort | 5 ft | 64 | $2,898 | $1,120 | 36 to 52 h |
| A-frame tree fort | 4 ft | 64 | $4,116 | $1,190 | 46 to 68 h |
| Half-wall tree fort with a roof | 5 ft | 64 | $4,450 | $1,190 | 46 to 68 h |
| Open fort with a swing set | 5 ft | 64 | $5,635 | $3,080 | 46 to 68 h |
| Raised playhouse | 6 ft | 80 | $5,832 | $1,540 | 58 to 86 h |
| Big six-post tree fort | 6 ft | 120 | $6,104 | $1,820 | 60 to 88 h |
| Tree fort with a swing set | 5 ft | 64 | $7,243 | $3,010 | 58 to 86 h |
| Playhouse with a swing set | 5 ft | 80 | $8,234 | $3,360 | 66 to 98 h |
Read across a row and you see what you pay for. Read down the table and you see what changes the price. Four things do most of the work.
Height and the number of posts
A taller deck needs longer posts and a longer ladder or stairs. The low deck sits 2 ft 6 in off the ground, the open tree fort at 5 ft and the big fort at 6 ft. The big fort also stands on 6 posts, where the open fort uses 4. More posts mean more holes, more concrete and more treated lumber in the ground.
Roof and walls
Adding a roof to the same 8x8 deck is a clear step up. Compare the structure of the open tree fort at $1,778 with the half-wall fort with a roof at $3,260. The roof brings rafters, panels, a ridge cap, drip edge and screws, the half walls bring more framing and boards, and the wind on a roof calls for bigger footings.
Ladder, stairs or rungs
A rung ladder is the cheapest way up and takes the least space. Stairs and a porch, as on the raised playhouse at $4,292 for the structure, cost more in lumber and more in cutting time.
Play equipment
The fort with a swing set, at $7,243, includes a two-seat swing on its own frame, set 9 ft away so the swing never loads the fort. The frame, the seats, the hardware and the surfacing for the swing zone are part of that price, and the swing zone is the biggest single area to cover.
Where the money goes
The materials list for the open tree fort is sorted into groups, and each group appears as its own set of lines in the designer:
- Lumber. The posts, beams, joists, deck boards, guard and ladder. The posts use pressure-treated wood.
- Roofing. Panels, ridge cap, drip edge and screws. The open tree fort has none, so this group is empty until you add a roof.
- Hardware. Cast-in post bases, structural screws, bolts and the small parts that hold the frame together.
- Play equipment. Anything a child uses beyond the deck itself, such as a swing.
- Safety surfacing. The loose fill under the fort and 6 ft around it.
The designer shows each line with a quantity and a price from the Home Depot table we read in October 2026. An item we could not find on the shelf, such as a post cap for a three-ply beam, says “price not read yet” instead of guessing, and the total names it. Open the free designer and change the size to see every group move.
The safety surfacing line
Under any raised play structure the ground has to be soft, so the surfacing is a required line and it is in the total. The CPSC1 guides set the depth by the fall height: 9 in of loose fill kept up all the time, which means putting in about 12 in because it packs down by a quarter. Wood mulch is rated to 7 ft, and wood chips, engineered wood fiber and shredded rubber to 8 ft.
For the open tree fort, playground wood mulch delivered in bulk over the fort and 6 ft around it costs $1,120. Bagged landscape mulch costs less, but its bag does not say it is free of wood treated with CCA, which the CPSC1 says to avoid, so we do not price it.
- 1U.S. Consumer Product Safety Commission Safety Tips for Home Playground Equipment, publication 324
Cost per square foot
You will see treehouse cost per square foot quoted online. We do not repeat other sites’ numbers, because they usually mean a finished treehouse with labor. The figures below are our own, for the structure materials only, calculated from our presets.
- Open tree fort, 64 sq ft: $27.78 per square foot of deck.
- Half-wall fort with a roof, 64 sq ft: $50.94 per square foot.
- Big fort, 120 sq ft: $35.70 per square foot.
Per-square-foot figures mislead on forts. A small deck carries the same posts, ladder and hardware as a larger one, so it costs more per foot, and a roof lifts the number again. Use the full row in the table above, not a rate multiplied by an area.
Your time
Labor is the part of the budget that is not in the total. The open tree fort takes about 36 to 52 working hours, roughly 2 to 4 days. The big 10x12 takes about 60 to 88 hours, roughly 4 to 6 days.
We do not put a price on hired labor. We have no source for what contractors charge for a fort, and a made-up rate would be worse than none. If you plan to hire help, get quotes locally and add them to the materials total yourself.
What is not in the total
The materials total leaves out sales tax, delivery, permits, site work, engineering and equipment rental. An auger or a lift for the posts, if you need one, is a rental on top.
Depends on where you build
Ask your building department first
Local approval not checked here. Many US jurisdictions exempt small play structures up to a size limit, but thresholds, setbacks, HOA rules and zoning vary. Confirm with your local building department before you buy materials. If you build in Canada, the designer has a Canada mode based on NBC 2020.
Get your own number
Open the treehouse designer and pick a fort. The designer is free and draws it in 3D on four or six posts, with no tree needed. It gives you the materials list with prices as you change the size, the height, the roof and the ladder. When the design is right, the full build plan is $29.
If you want to compare before you design, browse the free plans or the tree fort plans. Weighing a ready-made kit against building? The kit versus plans guide covers it, and the playhouse cost guide covers the enclosed, playhouse-style build.
Sources
Every number in this guide that does not come from our own treehouse designer or our own price reads was checked against these 1 documents, numbered in the order the text first cites them and read on Oct 25, 2026. 1 is a playground guide or code.
Our own data, not an outside source: the treehouse designer's materials list and our store price reads. Each line names its store, its product and the day we read it. The required safety surfacing under the play area is in every total, and no labor price is quoted.
- 1U.S. Consumer Product Safety CommissionSafety Tips for Home Playground Equipment, publication 324
