Free Deck Designer vs a Permit Drawing Set: What the Free Output Leaves Out

Most people start with a free deck designer. You drag out a rectangle, set the height, pick the railing and watch a 3D deck appear. That is a fair way to start. The trouble comes when the building department asks for drawings and you find the free output stops short of what the reviewer needs.

This guide compares what free deck designers give you with what a permit drawing set contains. It is neutral on purpose. We named each tool, we say what it does well, and every statement about a tool is dated: as of November 2026, from the tool itself, its sample or test export, or the maker’s own page. Tools change, so check before you decide.

What a Free Deck Designer Does Well

Free tools have solved the visual half of the job. If you want to know what a deck will look like and roughly what it takes to build, they are very good.

The 3D view

Most of the tools we tested draw a 3D deck you can turn around. That helps you judge size against the house, the stairs against the yard and the railing against the view. Nothing here needs a code table, so it is the part free tools do best.

Sizes and material lists

Several tools turn the design into a material list. One gives a cut list with a connector count. Another gives a table of maximum spans and cantilevers. A third gives scaled plan sheets with elevations and a staking plan. Those are real aids, and they cost nothing.

Good at, tool by tool

Each tool earns its place. Here is what we found each one does well, as of November 2026.

• Trex deck designer. Good at shapes. It draws rectangles, T and L shapes, cut corners, multi-level decks, stairs, railing and walls, and you can design without an account. Its sample PDF shows spans, joist spacing and where the footings go.
• Simpson deck planner. Good at sizing numbers. Its report has a table of maximum joist spans, cantilevers and beam spans, a cut list, and a full connector count with part numbers.
• Decks.com deck designer. Good at a scaled plan. Its export for a custom size has four sheets at 1/4 in to the foot: a plan, two elevations and a footing and staking plan with a squaring diagonal.
• Lowe’s deck designer. Good at the store link. It lets you draw templates or freehand, add stairs, railing and walls, and it ties the design to the store you pick.
• Our designer. Good at the permit sheets. It draws a full set for your size, with the DCA6 table rows it used. It is also free to try with no account.

A caution for all of them: these are statements about our November 2026 exports, and each maker updates its tool.

What “free” can cost you

Free often has a catch. Some tools ask you to create an account before you can export. Some fill the material list with the maker’s own products, and one states in its report that it is meant to be used only with that maker’s connectors. Several say on their pages that they run on a desktop or laptop only. None of that makes a tool bad. It means you should read the sign-in step and the disclaimer before you spend an evening on a design.

Which is the best free deck designer?

It depends on what you need. If you want a quick 3D picture with no sign-in, a tool that lets you design before logging in is enough. If you want scaled sheets and a footing plan, pick one that exports them. If you want a permit set, no free tool we tested produced a full one. The next two sections show why.

What a Permit Reviewer Asks For

A reviewer does not judge the picture. A reviewer checks whether the deck, as drawn, meets the code your jurisdiction uses. For a typical deck handout based on the AWC¹ DCA6 guide, that means a short checklist.

The checklist

The short version: a site plan, a framing plan with a size on every member, a footing plan, a ledger and flashing detail, a lateral load detail, an elevation, a guard detail and a stair detail. We describe each sheet, with real sample sheets you can open, in deck drawings for permit. Your department may add items or drop some, so ask for its handout.

Why the code basis matters

A reviewer wants to see which table a number came from. The prescriptive tables in DCA6¹ give a joist span for a size, species and spacing, for example 11’-10” for a southern pine 2x8 at 16 in on center. A drawing that names the table row lets the reviewer check it in seconds. A drawing with a size and no source makes the reviewer do the work, or ask you to.

How reviewers read a set

Reviewers usually go in the same order. They check the site plan first, because a deck that breaks a setback fails before the framing matters. Next they read the framing and footing sheets against the table. Then they look at the connections: ledger, lateral ties, guard posts and stair stringers. These are the details that fail, and they are the ones free output most often leaves out. A set that answers these questions in the order they are asked gets through in one pass, and a set that does not gets a letter asking for more.

Mistakes a free export can hide

A 3D picture cannot show that a note contradicts the plan, or that a unit is wrong. Both turned up in our November 2026 test exports. We list them with the other common return reasons in deck drawings for permit. Read every note against the drawing before you submit.

Free Deck Designer vs Permit Set, Side by Side

This table lists what we found in each tool’s output as of November 2026. We opened the tools and read sample exports. Where we could not verify a line, it says so. We did not test any tool on a phone, so the phone row uses what each maker says on its own pages.

How to read the table

Read it by row, not by column. A tool can be strong on one row and silent on another. The tool with elevations and a staking plan is the one that suits a simple freestanding deck. The tool with the span table is the one that tells you whether your joist size is in range. Neither is a full set.

Each maker also states the limit of its output. As of November 2026, the Simpson report calls itself “a product selection guide” and “not a finished building plan.” The Trex sample blueprint says it is “not a complete building plan.” The Decks.com plan says it is not considered complete unless approved by your building inspector or structural engineer. Those are the makers’ words, not ours.

What we could not verify

We did not confirm every cell. The ledger detail in one retailer’s tool and its elevations could not be checked, and the phone row comes from the makers’ own statements. If a row matters to you, open the tool and test it. Our own set is $49, and we describe it the same way: prepared to DCA6¹ and IRC R507 prescriptive tables, not engineer-stamped, so check with your building department.

When the Free Output Is Enough

Plenty of decks never need a permit set, and for those a free tool is all you need.

Ground-level, exempt decks

The 2021 IRC text, as adopted by Grant County², Washington, lists decks up to 200 sq ft that are not more than 30 in above grade and not attached to a house among the work that does not need a permit. Your town may set a lower limit or none at all. Local approval is not checked here, and thresholds, setbacks, HOA and zoning vary, so confirm with your local building department. If you are exempt, you still want the deck to be safe, but you do not need a reviewer to read your drawings.

Planning and budgeting

Free tools are also ideal before you commit. Use one to compare shapes, count boards and set a budget. Our deck material calculator turns a size into a board and hardware count in a minute. A good habit is to design in a free tool first, price the lumber, and only then decide whether your project needs a permit set. That order keeps the cost of drawings in proportion to the size of the job, and it lets you change the deck’s footprint for free before any sheet is printed.

When You Need a Full Set

Once the deck attaches to your house or rises off the ground, a reviewer reads the drawings. This is where the free output runs out.

Attached decks

An attached deck needs a ledger detail. DCA6¹ wants a ledger at least 2x8 pressure-treated, continuous flashing with a drip edge, and staggered fasteners. It prohibits a ledger on brick or stone veneer, hollow masonry and a few other walls. A reviewer expects those details on a sheet, not in a note that points elsewhere.

Decks higher than 30 in

A deck more than 30 in above grade needs guards, and usually a stair detail too. An attached deck needs the DCA6¹ hold-down devices. DCA6 treats a freestanding deck as outside the guide, because it assumes the house resists lateral load. Our designer allows a freestanding deck up to 8 ft high with knee braces, and that is our choice, not a code table.

What a set adds

A set puts every one of those details on a sheet, tied to your size and height. If you want to see what that looks like, read deck drawings for permit, then check the rules for your state in the deck permit requirements guide.