A ground-level deck — a freestanding platform, typically under 30 in. above grade — is the most achievable substantial build a competent DIYer can take on. It has no ledger board bolted to the house, which is where a large share of deck failures originate, and in most jurisdictions no guardrail is required at that height. What is left is careful layout and honest structure.
Check before you dig
Call your national underground utility locating service (811 in the United States) several working days before digging anything. It is free, it is required in most states, and hitting a gas or fibre line is a very expensive way to learn this.
Permits and the questions to ask first
Rules vary enormously by state, county and city, so ring your local building department rather than relying on a general article — including this one. The five questions worth asking:
- At what height or square footage does a deck require a permit here?
- What is the local frost depth for footings?
- Are there setback requirements from property lines and septic fields?
- Does a freestanding deck still require inspection?
- Are there homeowners' association rules that apply on top of code?
Many jurisdictions exempt freestanding decks below a certain height and area from permits entirely, which is a large part of why this design is so popular.
Layout and sizing
Design around furniture, not around lumber. A dining set for six needs roughly a 12 × 12 ft clear area once chairs are pulled out; a pair of loungers wants about 10 × 10 ft. Then round to standard lumber lengths so you are not cutting a foot off every board.
Stake the corners
Batter boards and mason's line beyond each corner let you adjust without re-driving stakes.
Square it with the 3-4-5 method
Measure 3 ft along one line, 4 ft along the other; the diagonal between those marks must be exactly 5 ft. Scale it up — 6-8-10 or 9-12-15 — for better accuracy on a large deck.
Check both diagonals
On a rectangle, the two corner-to-corner diagonals must match. This single check catches nearly every layout error.
Slope for drainage
Grade the ground beneath away from the house at roughly ¼ in. per foot. Keep the frame itself level.
Footing options
| Type | How it works | Good for | Notes |
|---|---|---|---|
| Precast deck blocks | Pyramid blocks set on compacted gravel | Low freestanding decks in mild climates | Fast and cheap; can move with frost heave |
| Poured concrete piers | Holes dug below frost line, filled, with post bases set in | Anywhere with real winters | The durable standard; more labour |
| Helical / screw piles | Steel piles driven mechanically to depth | Poor soil, no-dig sites | Installed by contractors; premium cost |
| Concrete tube forms | Cardboard tube in a dug hole, poured flush | Consistent pier height | Combine with an expanded base in cold zones |
Frost depth is the deciding factor. In a region with a 36 in. frost line, a deck on surface blocks will move seasonally; whether that matters depends on whether it touches the house. Freestanding and low, a little movement is tolerable — which is another reason this design forgives beginners.
Space beams and footings to keep spans within limits. As a general guide for pressure-treated softwood, a doubled 2×8 beam spans roughly 6–8 ft between supports, and a doubled 2×10 roughly 7–9 ft, but you must confirm against your local code's span tables rather than a rule of thumb.
Framing the platform
- Use ground-contact rated pressure-treated lumber for everything within 6 in. of soil. The rating stamp on the board tells you; "above ground" treatment is not adequate here.
- Joist spacing: 16 in. on centre is standard. Drop to 12 in. for composite decking or for boards laid diagonally.
- Crown the joists. Sight along each board and install with the slight upward curve facing up.
- Blocking or bridging at mid-span stops joists twisting and stiffens the whole platform noticeably underfoot.
- Joist hangers, correctly nailed. Use the structural connector nails specified by the hanger manufacturer, in every hole. Deck screws are not a substitute — they are not rated for shear in that application.
- Protect the joist tops. Self-adhesive butyl joist tape over every joist and beam keeps water out of the fastener holes and adds years to the frame for a small cost.
Tool check
An impact driver is close to essential for the fastener volume here — a 12 × 12 ft deck swallows several hundred screws. See our cordless drill and impact driver guide for the difference and why the combo kit is the right buy.
Decking and fasteners
| Decking | Relative cost | Maintenance | Life |
|---|---|---|---|
| Pressure-treated pine | Low | Clean and re-seal every 2–3 years | 15–20 yrs |
| Cedar / redwood | Medium | Annual wash, seal every 2–3 years | 15–25 yrs |
| Composite | High | Wash only | 25–30 yrs |
| PVC | Highest | Wash only | 30 yrs+ |
| Hardwood (ipe etc.) | High | Oil annually or let it silver | 40 yrs+ |
Fastener chemistry matters more than people expect. Modern copper-based pressure-treated lumber corrodes ordinary steel quickly, so use fasteners and connectors specifically rated for contact with treated wood — hot-dip galvanised or stainless. Mixing a stainless screw with a plain galvanised hanger also invites galvanic corrosion; keep the system consistent.
Leave a gap between boards for drainage — typically the thickness of an 8d nail for wet-treated lumber that will shrink, or the manufacturer's stated gap for composite, which expands and contracts with temperature instead.
Finishing and maintenance
Let new pressure-treated lumber dry before sealing — sprinkle water on it, and if it beads rather than soaks in, it is not ready. Depending on climate and how wet the stock was, that can be anywhere from a few weeks to several months.
After that, an annual routine: sweep debris out of the board gaps, wash with a deck cleaner rather than a high-pressure washer at close range (which shreds softwood fibres), check every fastener for lifting, and inspect the frame where it meets the ground. Hauling materials for all of this is the unglamorous half of the job — our truck rental checklist covers getting 16 ft joists home without damaging anything.
Frequently asked questions
Do I need a permit for a ground-level deck?
It depends entirely on your jurisdiction. Many exempt freestanding decks below a set height — often around 30 inches — and below a set area, but the thresholds vary by city and county. Call your local building department before you buy materials.
How deep should deck footings be?
Below the local frost line, which ranges from essentially zero in the far south to four feet or more in northern states. Your building department publishes the figure for your area, and it is the single most important number in the whole build.
Can I use deck screws in joist hangers?
No. Joist hangers must be fastened with the structural connector nails or screws specified by the hanger manufacturer. Standard deck screws are not rated for shear loading in that connection.
What spacing should I use between deck boards?
For wet pressure-treated lumber that will shrink, roughly the thickness of an 8d nail. For composite and kiln-dried material, follow the manufacturer's stated gap — those products move with temperature rather than moisture.
