DCA6 Explained: the Free Deck Code Guide in Plain English, Table by Table

DCA6¹ is the name you see on county deck handouts and permit checklists, often with no explanation. Here is the plain version. DCA6 is a free guide that gives you ready-made sizes for the parts of a wood deck, so you read a table instead of calculating. This guide explains what the DCA6 PDF is, how it compares with the IRC, which decks it covers, and how to read its tables with one worked row each.

We read the PDF itself, page by page. We quote single rows and link the source, and we do not reproduce its tables, which belong to the American Wood Council¹.

What DCA6 Is

DCA6¹ stands for Design for Code Acceptance No. 6. The full title is Prescriptive Residential Wood Deck Construction Guide. The American Wood Council (AWC) publishes it, and it is free.

Who wrote it and which edition we read

The edition we read is DCA 6¹-2015, “based on the 2015 IRC,” copyright 2018. We downloaded it again on November 4, 2026 from the AWC link, and it matched our earlier copy byte for byte. You can open the DCA6 PDF on the AWC site and compare the tables below with the pages.

Is there a newer DCA6?

As of November 4, 2026 we found no 2018 or 2021 DCA6¹ edition on the AWC site. If you see a newer-looking copy, check the cover for the edition and the code year. Some copies online are older editions, such as a 2012 version, so read the edition before you trust a table.

DCA6 PDF: where to get it

Download the DCA6¹ PDF from the AWC page and not from a file-sharing copy. The AWC file is free, and you get the commentary pages that explain each rule. Save it, because county handouts often cite its page numbers.

DCA6 vs IRC R507

The IRC is the model code. Its section R507 covers exterior decks. DCA6¹ is a prescriptive guide, which means it turns the code’s rules into tables a builder can follow without an engineer.

Why counties hand out DCA6

Building departments like prescriptive guides because they make plan review fast. If your deck matches the table, the reviewer ticks the box. Many counties copy DCA6¹ tables into their own handouts, sometimes with local changes. Your county adopts the code, and the county’s text wins.

Where the 2021 IRC differs

Counties that have moved to the 2021 IRC print slightly different tables. Two county deck guides we read show these differences for southern pine:

• Beams. The 2021 spans run a little longer than DCA6. For a 2-2x8 beam under 6 ft joists, the county guides show 8’-9”, and DCA6 shows 8’-6”.
• Footings. The 2021 table sizes footings by the area they carry, at a soil bearing of 2,000 psf, where DCA6 uses 1,500 psf. At 20 sq ft the 2021 footing is 11 in round, and at 160 sq ft it is 30 in round.
• Lateral ties. The 2021 alternative uses four hold-down devices rated 750 lb, instead of the two rated 1,500 lb in DCA6.

We only have the southern pine rows for the 2021 tables. We did not read the 2021 rows for Douglas fir-larch, hem-fir or spruce-pine-fir.

Why our designer follows DCA6

DCA6¹ is complete for all four species groups it lists. Where the 2021 southern pine spans are longer, DCA6 is the more cautious choice. So our designer uses the DCA6 tables everywhere. That is a design choice. It is not a claim that your county requires DCA6.

Which Decks DCA6 Covers

DCA6¹ is a prescriptive guide for standard residential decks. It works only if your deck fits inside its limits. Check each one before you read a table.

The limits

• Snow load. Not for snow above 40 psf.
• Hot tubs. The guide does not cover them.
• Shape. The deck’s length, measured out from the house, must not be more than its width, measured along the house.
• Spans. Joist span tops out at 18’-0”, measured face to face with the overhang left out. Beam span also tops out at 18’-0”.
• Load. The tables assume 40 psf live load and 10 psf dead load.

Attached decks and non-ledger decks

DCA6¹ handles a deck with a ledger on the house. It also handles what it calls a non-ledger deck, which stands on its own posts beside the house. The guide still assumes the house resists the lateral load in both cases, so a non-ledger deck is still tied to the house.

A five-step check for your own deck

Run your deck through this list before you open a table.

1. Confirm the snow load for your address is 40 psf or less, and that there is no hot tub.
2. Measure how far the deck sticks out from the house and how wide it runs along the house. The first number must not be larger than the second.
3. Pick a species group. If you are not sure your lumber is southern pine, use the Douglas fir-larch, hem-fir and spruce-pine-fir row, which has shorter spans than southern pine.
4. Pick joist size and spacing, and check the span against Table 2.
5. Work through the beam, post, footing and ledger tables in that order, because each table’s input comes from the one before it.

Levels and unusual shapes

Our designer draws single-level rectangular decks. A deck with more than one level, curves or an unusual plan takes more than one row from each table, so ask your building department what it accepts.

Reading the DCA6 Tables, With a Worked Row

Every table works the same way: pick your species, find your size and spacing, read the span. Here is one worked row for each of the four tables most decks use.

Joists (Table 2)

Joist spans are listed by species group, size and spacing at 12, 16 and 24 in on center. For southern pine, a 2x8 at 16 in on center spans 11’-10”, and a 2x10 at 16 in spans 14’-0”. For Douglas fir-larch, hem-fir and spruce-pine-fir, which share one row, the 2x8 at 16 in spans 11’-1”.

Say your deck sits 12 ft out from the house. A southern pine 2x8 at 16 in tops out at 11’-10”, so it is too short by 2 in. A 2x10 at 16 in passes with room to spare. A 2x8 at 12 in spans 13’-1” and also passes. The table gives you three ways to fix the same deck.

The overhang is listed separately. A 2x8 southern pine joist at 16 in may overhang 2’-0”, and the overhang never exceeds one quarter of the span. DCA6¹ also asks for a ledger at least 2x8.

Beams (Table 3A)

Beam spans depend on the beam makeup and on the joist span it carries. For southern pine with joists spanning 12 ft, a 2-2x10 beam may span 7’-1” between posts, and a 3-2x10 beam may span 8’-9”. A taller or wider beam buys you fewer posts. The guide caps beam span at 18’-0” and lets a beam extend one quarter of its span past the post.

Joists must sit on the beam in one of three ways: blocking, a clip rated at least 100 lb for uplift and lateral load, or hangers. Joists never frame in from opposite sides of one beam.

Posts and footings (Table 4)

Table 4 gives the tallest 6x6 post you can use for a given beam span and joist span, measured from grade, or the top of the footing, to the underside of the beam. For a 12 ft beam span with joists up to 14 ft, a southern pine post can stand 13 ft and a Douglas fir-larch post can stand 12 ft. An 8x8 post may replace a 6x6 anywhere, up to 14’-0”.

The same table sizes the footing for a soil bearing of 1,500 psf and 2,500 psi concrete. For that 12 ft beam span with joists up to 14 ft, the footing is 30 in round, or 26 by 26 in square, and 13 in thick. DCA6¹ lets corner posts use 90% of that size. We keep the full size in our designer.

Depth is a separate rule: the bottom of the footing sits at least 12 in below grade or below the frost line, whichever is deeper. Soil weaker than 1,500 psf needs a soils investigation. For other soils, DCA6¹ gives a commentary table and formula, and our designer does not use them. Our deck footings guide reads the table and the frost line question in full.

Ledger fasteners (Table 5)

Table 5 gives the fastener spacing for a ledger on the house band, by joist span. Take joists spanning 10 ft and a 1-1/2 in lumber band with up to 15/32 in sheathing:

Fasteners are staggered top and bottom. If the band is a 2x8 with bolts, the commentary tightens the spacing to 19 in for 10 ft joists. The full row set, the flashing and the walls where a ledger is not allowed are in our ledger board guide.

What DCA6 Does Not Cover

Knowing the edge of the guide matters as much as knowing the tables. Here is where DCA6¹ stops.

Freestanding lateral bracing

DCA6¹ assumes the house resists lateral load, and it says the IRC gives no lateral table for decks. So a freestanding deck’s bracing is outside the guide. Our designer allows a freestanding deck up to 8 ft with knee braces both ways at the corner posts, and blocks anything above that. The designer flags this with an amber check because the bracing is our choice, not a code table.

For attached decks, DCA6¹ does give a lateral rule: two hold-down devices rated at least 1,500 lb within 2 ft of the deck edges. It also asks for a knee brace parallel to the beam at each corner post taller than 2’-0”, and it prohibits braces on center posts.

Heavy loads and tall posts

A hot tub, a snow load above 40 psf and posts taller than the Table 4 limit all fall outside DCA6¹. Each of those needs a calculated design.

When to call an engineer

If any limit above does not fit, a reviewer may ask for an engineer. Our designer is built to block the paid plan when a deck falls outside the tables and to tell you to get one. We prepare plans to DCA6¹ and IRC R507 prescriptive tables, not engineer-stamped, so check with your building department. If you want the full list of sheets a reviewer expects, read deck drawings for permit, and for the ledger rules read the ledger board guide.