Cedar Deck




Introduction: Cedar Deck

About: Furniture hacker. Author of Guerilla Furniture Design, out now. Find me on Twitter and Instagram @objectguerilla.

Summer proper has arrived, and it deserves an appropriate platform. A few weeks ago, I finished this cedar-clad deck, with broad capitol steps at both ends and a built-in bench on the open side. The footprint for this deck is about 16' x 24', good for big parties or outdoor dinners. The steps, which have a deep run and a shallow rise, are a mega-stoop, designed for lounging. One might build a small cabin or 3-sided Adirondack-style shelter on a platform this size -- just buy 12-16' posts instead of 8-footers and use them to support a simple roof. 

While made for a specific site, the structural strategies and construction techniques illustrated here are broadly applicable. We built this with basic hand tools -- just a hammer, a circular saw, and a screw gun, nothing too fancy. Adapt, tweak, and twist this Instructable to your own ends. Also, keep in mind that there are dozens of different ways to build a deck; this is merely one method, explained with the amateur carpenter in mind.

And, if you find this Instructable helpful, please throw me a vote in the Great Outdoors Contest! Thanks!

You will need these materials:

200' stringline
6 8' PT (pressure-treated) 6x6s  (9 if the deck is free-standing)
7 8' PT 4x4s
Approx. 6 80 lb bags Quickcrete per 6x6 and 3 per 4x4
4 12' PT 2x12s
14 8' PT 2x12s
4 12' PT 2x10s
38 8' PT 2x10s
8 12' PT 2x4s
30 8' PT 2x4s
Assorted random 2x4s for stakes and batter boards
Approx. 65 16' x 5/4 cedar deck boards
15 lbs. 2-1/2" deck screws
5 lbs. 3" deck screws
5 lbs galvanized joist hanger nails
5 libs galvanized 3" ring-shank 16D sinkers
50 4-1/2" LedgerLok lag bolts
14 corner brackets
72 2x10 joist hangers
Box of 25 Red Head masonry anchors, if attaching to masonry building

You will need these tools:

Tape measure
Line level
4'-6' level
Speed square
Framing square
Ratchet set
Posthole digger
Circular saw
Masonry drill 

Step 1: Layout

The first step in any building project is to create a structural grid. Lacking advanced survey equipment, we will use string lines and a line level to establish an imaginary plane over the building site that represents the surface of the future deck. This plane will then become a continuing reference throughout construction, keeping the disparate elements coherent to one another.

We wanted our deck to be centered on the door in the side of the adjoining building. I established a level ilne by measuring 1-1/2" down from the underside of the lintel beneath the door (to accomodate the deck boards), setting the level, and tracing a line. We bolted two 12' 2x10s (cut to 141") to the wall, aligning the top of the boards with that level line and one end with the center of the doorway. Adapt these measurements to match whatever building you may be attaching to; if attaching into masonry, use expanding-sleeve masonry bolts (RedHeads) every 12" to secure the 2x10s. If attaching to wood framing, use a pair of 1/2" lag bolts every 16", connecting with studs whenever possible. 

At one end of the 2x10s, pound in a 3" nail. Tie a string line to it and stretch it out, roughly square, about 20'. On either side of the string, pound in two 2x4 stakes, about three feet apart. Put the line level on the string line and pull taut against one of the uprights. When the line level bubble is dead in the middle, trace the string's location onto the stake. Screw a piece of 2x4 level across the pair of stakes, with the top of the board aligned with the pencil mark.

The resultant H-shaped arrangement is called a batter board. The top of the cross bar should, theoretically, be level with the top of the 2x10 rim joist attached to the building. Pull the string line tight again, with a helper holding the framing square against the rim joist. Once the string seems square to the building, make a mark on the 2x4 cross bar on the batter board. Put in a screw and tie off the string.

Repeat at the other end of the rim joist. Measure along the strings to make sure they are an even 23'6" apart, all the way along their length. Make a mark on each string at 186" out from the wall. Measure from that mark to the opposite corner, where the other string meets the rim joist. If the strings are square and parallel, those diagonal measurements should match. 

Establish the outer string line at the 186" mark, measure diagonals to ensure it is parallel to the wall. Pull two centerlines, shifted 5-1/2" off of perfect center to accomodate the width of the 6x6s. You should now have a grid of strings, all level, with six points of intersection. 

Step 2: Foundations

At each intersection, drop a plumb bob, make a mark, and dig a hole at least 3' deep (4' in colder climes, like here in Chicago). Drop an 8' 6x6 into the hole. Align it so it just kisses the string line on two faces and it is also plumb on both faces. Brace out with stakes, diagonals, and screws as shown. 

Mix up some bagged concrete mix in a wheelbarrow, aiming for a fairly dry consistency, like thick oatmeal. Feel free to save a little on concrete by throwing in old chunks of brick, rock, concrete, or masonry. Shovel into the holes, poking periodically with a rod or pipe to force out the air bubbles and make sure it flows into all voids. 

Let cure at least 48 hours. 

Step 3: Framing

Remove the bracing from all the posts. Trace the string line's position on each. Take down the string lines. 

Around the perimeter of the deck, attach 2x10s with at least 2 lag bolts to the posts and into the ends of the rim joists, checking for level religiously. Add a second layer of 2x10s, attaching it to the first with 3" galvanized sinkers. Stagger the joints in the boards by 48" and add another set of lags wherever the joist crosses a post. I use and prefer (not a paid endorsement!) a new product called LedgerLok, structurally rated and easy to install with just an impact driver and no pre-drilling. Add an 8" galvanized metal corner bracket at every post-beam intersection with joist hanger nails, backing up the lag-bolt connection. 

Run a doubled 2x12 down the center as shown in the photo. Run joists between the rim 2x10s and the center girder every 16" on center, securing them with joist hangers and checking the level on each one. At the halfway (48" or so) point in each run of joists, run a  line of blocking to rigidify the frame and keep the joists straight. 

Trim the center posts flush with the top of the joists with a Sawzall.

Step 4: Cladding

Clad the deck in the cedar boards, putting in two screws wherever the board crosses a joist. Stagger the running seams so that there is no continuous line of breaks through the deck surface. Use some 16D nails as spacers to the boards end up about an 1/8" apart, allowing for rain to drain off of the surface. 

To keep the screws aligned, neat, and even without tediously measuring out every screw, make a simple jig. Cut a notch, 1-5/16" deep and 5-1/2" long, out of a chunk of 2x4. Screw a plywood plate to the top of the 2x4, with 2 v-shaped notches where the screws should go. To use, register the 2x4 against the side of the joist and slide the notch over the deck board and start a screw in each notch. Remove the jig and drive the screws home. 

Let all the deck boards run long, then trim them all at once by snapping a chalk line and cutting it with a circular saw with the blade set shallow. 

We left the cedar untreated, so it would weather to a natural gray. If you want, treat it with a rub-on, oil-based product, thinned by at least 20% to allow grain penetration. Apply, allow to soak in for about 20 minutes, then rub the excess off. Do not use un-thinned or water-based sealers on a naturally oily wood like cedar; the finish will peel and flake off, especially in the sun. 

Step 5: Stairs

To make stair stringers, first measure from the top of the deck to the ground. Divide that height by 7-1/2. If the result is a fraction, tweak the divisor until you end up with a whole number of steps; the divisor is the rise of each step. We ended up with a 7-1/4" rise and a 13" run. Most steps are not so deep, but these are meant to be used as seating. Code usually allows for between 7-9" risers, with no more than an 1/8" difference in rise between any adjoining steps and 1/4" of difference over the whole run.

Align the framing square with the edge of a 2x12, as shown, so that the square hits the edge at 7-1/2" and 13", and trace. Repeat until you have the number of steps you need. Keep in mind that the last (bottom) step should be 1-1/4" less (6") than the rest of the steps. Cut out with a circular saw. 

Secure the stringers to the rim joists every two feet, using a 2x4 block at between each. Screw a lag bolt through the stringer and into the 2x4 on either side, creating criss-crossing lags, side-grain-to-side-grain, for best strength. Use the framing square to make sure each stringer is coming perpendicular off of the deck structure, and check the steps for alignment with one another with a level. 

Support the other end of each stringer by sinking a 24" 4x4 in a little bit of concrete. 

Clad in cedar. The treads, at 13" equal 2.5 deck boards in width. Split a board on the table saw to make the center piece, or use the T-bar guide on the circular saw to make an even rip.

Step 6: Bench

The bench on the long edge of the deck is optional; we added it in lieu of a railing there. If not adding a bench, make sure to have a railing at least 36" high (if the deck is less than 30" high) or 42" high (if the deck is more than 30" high). The rail should have some sort of balusters or horizontals spaced no more that 4" apart to keep children from falling through. 

We framed the bench as a set of stud walls -- one to the height of the back (approx .27"), and one to the height of the seat ( approx. 17"). The back was secured into the foundation posts poking through the deck for maximum strength. The slope of the back is simply made with cripples, cut to a 5-degree angle. Add a hinged seat or back to store items underneath, but keep in mind it won't be water-tight in there due to the gaps in the deck boards, for drainage. 

I capped it off with a handrail against the wall, made by cutting down a piece of Douglas Fir into an octagonal cross-section on the table saw and fitting it into some notched brackets. Many off-the-shelf options exist for handrails. Aim to mount it about 36" off of the stairs, parallel to the slope of an imaginary line connecting the nose on each step. 

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    9 years ago on Introduction

    Beautiful, I love it!

    I'm just concerned by your wooden posts seating directly into the concrete, I'm afraid the wood will rot after a few years... And wouldn't the contraction/expansion of the wood crack the concrete?
    I would have used metallic plates to bolt the posts on the concrete after it had dried, or at least put a couple of layers of tar coating on the bottom of the posts if I was to sink them in concrete.
    Well, just my 2 cents, I'm saving a link to this instructable for ater use! Great job! :)


    9 years ago on Step 6

    Isn't life soooo much easier with impact drivers and ledger locks. They are super expensive but worth the cost if you're in business trying to make time!
    Nice instructable!


    9 years ago on Step 6

    Five things:

    The scre jig is a great idea.

    Why didn't you use cedar for the framing, too?

    Great work on layout and assembly.

    You should have a handrail on both ends of the stairs.

    The handrail should be graspable from the top to the bottom fo the stair, and should extend one tread plus one foot past the top of the stair. Fully graspable means that the support should be on the bottom. Such support brackets are readily and cheaply available at all big box stores.

    Oversized aggregate in the concrete will lead to cracking and possibly disinigration of the footing. I know this is done by residential home builders, but it's still a bad practice.


    Reply 9 years ago on Step 6

    Price check cedar 2x10's and you'll see why it's almost never used on the framing! Also it's just not necessary. The structure is almost completely concealed as far as aesthetics go. Pressure treated lumber lasts a long time albeit with more chemicals but not as much as years past. You'd be hard pressed to find a deck that's not built with pressure treated lumber.
    Having said that, it sure would be cool to build with just cedar though!

    The Rambler
    The Rambler

    9 years ago on Introduction

    Very nice. I'll have to revisit this one when I have the money to put a deck on my house.


    9 years ago