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DIY Tips For How To Build A Redwood Deck

Decks, Patios, & Porches
By on May 9, 2014
DIY Tips For How To Build A Redwood Deck

If the fronts of houses are more public and formal, the backs are decidedly private and informal, which explains why backyard decks are so popular in an age of instant access and crowded commutes. A wooden deck can be a kind of sanctuary, hosting only the invited. It can be both a party center and a quiet retreat—a place to repair, to relax, or to conjure empires.

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If your home and lifestyle are still waiting for that backdoor retreat, we have good news and bad news. The bad news is that lumber prices have spiraled out of sight in the past three years. The good news is that you can zero out these increases by building your own deck. The material costs for the simple treated-lumber and redwood deck described here exceeded $2,000, but when finished, the deck is at least a $4,000 improvement. That moves the price back nearly a decade. While there are dozens of deck styles and configurations you might choose, ours would fit a great many of the homes being built today.

We decided to build our superstructure out of pressure-treated pine because of its strength and high resistance to moisture and insects. But, we also wanted the rich look and feel of redwood—to say nothing of its weather resistance—in the finished product, so we came up with this boxlike construction. The concealed pressure-treated lumber does most of the work, while the construction heart-grade redwood does most of the showing off. When stepped in and out to echo the lines of the house and when capped with a simple redwood bench, the deck manages an attractive complement of scale, with a look that is both satisfying and modest.

Getting Started

The first order of business is to lay out the perimeter. Measure out from the house, at each end of your future deck, 13 feet 10 1/2 inches. Then, drive in wooden stakes and stretch a string line between them. This line will give you the exact outer edge of the double rim joist and the posts that will support it. A redwood 2-by-12 trim board will eventually bring the dimension to 14 feet.

Using this line as a guide, dig posthole footings to frost level, usually 24 to 48 inches, depending on climate. Place one footing at each of the outside corners of the deck layout and equally space two more posts between these. Then, to accommodate the step and offset, dig two additional footing holes—one at the outside corner and one at the inside corner of the offset.

Pour these holes to approximately one inch above grade with concrete, and while the mix is still wet, insert metal 4-by-4 brackets into the concrete so that the outer edge of the bracket is aligned with the string line. Then, level each bracket in both directions with a torpedo level. Finally, allow the footings to cure a day or two before building on them.

Because this deck is built at ground level, there will be no getting under it once it's finished. For this reason, it pays to strip the sod and cover the area with landscape fabric. The fabric will keep weeds from growing under the deck. Just roll out the fabric and pin it in place with galvanized nails. Shovel a little sand over the fabric to hold it in place.

The next step is to mount the ledger plate on the house. In our case, the first row of hardboard siding was not shimmed out at the bottom. If yours is, you'll need to either remove the shim or shim the top of the ledger plate. The point is, the ledger plate should be vertical, not canted inward.

To mount the 2-by-10 ledger, block under it or have a helper hold it up, then nail it to the siding-clad rim joist of the house with a few 16d galvanized nails. If your ledger will wrap around a trimmed corner, as ours did, use a circular saw to mortise out the depth of the vertical trim on the back side of the ledger. This need not be a perfect cut, as its only purpose is to allow the ledger to fit flush against the siding. In our case, we also continued the ledger partway around the cantilevered wall, stopping 1 1/2 inches short of the adjoining 45 degree trimpieces.

With the ledger tacked in place, bore a series of pilot holes every 24 to 32 inches along its length and lag the ledger into the rim of the house. Galvanized lagbolts, 1/2-by-5 inches long, will reach through all three layers of material. Back up each with a washer.

Installing Hangers and Posts

Start by laying out and marking all the joists along the ledger. A 14-foot span requires joists set on 16-inch centers. With the layout complete, install a joist hanger at each marked location. To keep from getting a few of them too high or too low, use a short piece of 2-by-10 as a guide, aligning its top with the top of the ledger. When positioned correctly, nail the hangers in place, using proper joist-hanger nails.

With the house side of the deck laid out and fitted with hangers, it's time to determine the height of the 4-by-4-inch posts that will support the double rim joists. Begin by cutting short lengths of 4-by-4s and setting them in their footing brackets. Then, set a precut joist (13 feet 6 inches) into one of the ledger hangers opposite a footing and place a 4-foot level atop the joist. When the joist is level, mark the post and cut it to length, then set the joist on the post and check for level again. When two such posts are marked and trimmed, use their elevations to snap a string line across the remaining posts.

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With all posts cut to length, nail two sets of 2-by-10s together with 16d galvanized nails to create the double rim joist. Alternate the nails, high and low, at 16-inch intervals. Make the outer 2-by-10 of the double rim 3 inches short of the overall length of the deck, to accommodate the redwood trim joist. Then, cut the inner joist 1 1/2 inches short of the outer joist at each end. These stepped ends will allow you to nail the intersecting side joists from both directions.

With the posts cut and the double rim joist nailed together, set the rim on the posts and lay out the hanger locations to match those on the ledger. Then, nail the posts through the footing brackets and join the posts to the rim joist with galvanized truss plates. Nail the remaining floor joist hangers. Then check each joist to determine which side has the crown and set them into the brackets with the crown up. Nail all the joists to the joist hangers.

Building the Corners

Our deck has two corner details that required special attention. The first was the 45-degree-angle extension around a cantilevered dining room wall. To build this section, just frame in a double rim joist to span between ledger and outer double rim. Nail the intersecting corners, in both directions, and add a corner bracket to the inside of the double offset. Then, use 45-degree-angle joist hangers to support the joists set against the angled ledger.

As for the step offset, frame in a double joist on one side—in our case this was alongside our porch post—using a double-width joist hanger. Then, frame the outer edge of the offset conventionally, wrapping it back to the double joist. A second double-width hanger makes this an easy connection. Then, bridge between the return of the double rim joist and the ledger plate on the house with a second double rim. Finally, cut shorter joists to fill in the open spaces and hang them 16 inches on center.

Decking the Framework

Before decking over the pressure-treated undercarriage, thoroughly caulk the joint between the ledger plate and the house siding. This will keep rainwater from entering the joint and rotting the siding. Also, keep in mind that you'll find some warped lumber in every stack you buy. These boards are still usable but should be reserved for cutting into shorter lengths to fit tight spots. Use your straightest boards for the longest sections of exposed deck. To keep the decking running straight, measure out from the house at several points and snap chalklines to establish a straight run across the joists. Every three or four boards, rekey your decking off of these lines.

Starting against the house, lay your first length of 2-by-6 redwood tight against the siding. Then nail or screw it down, with two fasteners in each joist. Though nails work well enough, we used 3 1/2-inch deck screws. They are harder to install, but galvanized screws hold longer and are better at coaxing warped lumber back in line.

For quick gapping of all subsequent decking planks, it pays to make two 1/4-inch spacers. (We made ours from 1/4-inch plywood.) Slide a spacer between the preceding plank and the latest plank and nail or screw the plank in place. Then, slide the spacer down a joist and fasten the plank again. When screwing the end of a plank, always prebore clearance holes to avoid splitting it. When fastening a plank away from the ends, place two screws at every intersecting joist, each 3/4 inches in from the edge of the plank.

With all the decking in place, it's time to install the 2-by-12 rim-joist trim boards. Miter the corners and screw them to the pressure-treated rims so that the top of each 2-by-12 is flush with the top of each decking plank. To keep the top edge of this trim board from warping outward, as it surely will, screw it to the decking planks as well, about every 18 inches.

Building the Benches

The benches we built here are about as simple as they come. To construct the continuous J-shaped bench, start by building two redwood boxes, 16 3/4 inches square, using standard 2-by-4 lumber. Next, miter-cut two sets of 19 3/8-inch crosspieces for each box. Join them back-to-back with galvanized nails. Finally, screw them into the boxes.

Set each box in its corner, just inside the 2-by-12 trim board, and measure for the seat planks. Miter each plank at 45-degree angles, using the positions of the boxes to establish the length of the planks. Finally, screw these planks to the tops of the boxes, preboring clearance holes in the ends. To build the long runs of the bench, boxes won't be necessary. Just lay out 2-by-4 braces (also 16 3/4 inches long) about 32 inches apart and screw three deck planks over them. With all three planks assembled, cut one end at a 45-degree angle.

To build the bench legs, cut 14 1/2-inch-long pieces of 2-by-12 planks and screw one to each 2-by-4 seat support. Do the same with the boxes, placing one leg under the inside edge of each box and one spaced between the boxes. Turn the assemblies upright and set them in position. Then, join the two mitered corners and screw the seat planks in place. Assemble the short end of the J in like fashion, and build the remaining bench without corner boxes. To anchor the bench to the deck, drill the face of each leg and drive 3 1/2-inch screws at an angle into the deck planks.

To trim out the bench, screw mitered 2-by-6 redwood planks to the sides of the seat, anchoring them at each crossmember location and at each mitered corner. Finish the bench by nailing 3-inch uprights to the faces of each 2-by-12 leg. These vertical trimpieces not only bring the legs into a more satisfactory scale, but also hide the anchoring screws.

Finishing Up

All that remains is to conceal the truss plates nailed to the posts with a redwood skirt and to build two box steps. To install the skirt, simply rip a redwood 1-by-8 into two 3-inch strips and nail them to the fronts of the posts.

Because our deck is built so near the ground, we opted for a simple box step, set on concrete. If you prefer, you can rest your steps on concrete cap blocks, set in a bed of gravel. To make the steps, build two rectangular boxes. Set these boxes on their supports and drill the back of each several times with a 1/4-inch bit. Then, screw through these holes into the face of the deck. The oversized screwholes will allow the step to float a bit with the seasons. Finally, screw a 2-by-12-inch tread to the top of each box.

Copyright © Popular Mechanics 2001. Reprinted by permission.

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