Lately it seems that half the jobs I get are upgrades to decks originally built 20 to 30 years ago. Usually the clients are just looking for an aesthetic upgrade, such as new railings and decking. But oftentimes a thorough deck inspection reveals problems caused by lax building practices—ones that probably didn't meet building codes enforced at the time and that certainly wouldn't meet today's codes. After my inspection, I present my recommendations to the owners, emphasizing how these structural upgrades will address safety and liability issues and improve the future resale value of the house (noting the rigorous home inspectors in our area).
While some contractors recommend that the entire deck be demolished and built new from scratch, it’s rare that the decks I encounter need to be reframed (unless the owner wants a major design change). Old CCA-treated SYP joists, beams, and posts are almost always in great condition; the main deficiencies are in the hardware and connection details, which can be corrected.
A project we recently completed provides a good example of the kinds of deck frames we typically find in our area, and the fixes we employ. Even though it's a grade-level deck and the stakes aren't as high as they would be for an elevated deck in the event of a catastrophic failure, we still followed all the same measures.
Decking and Railing Overdue for Replacement
Though the owners routinely maintained the pressure-treated decking and railing by cleaning and re-staining it regularly, the wood showed its age. The splitting and splintering deck surface was unsafe for bare feet. The shanks of the nails holding the boards down had rusted through, so the decking had come loose in places and was cupping and lifting.
On the guardrails, the baluster spacing was almost 8 inches, much greater than allowed even at the time the deck was originally built (current railing codes require spaces between balusters to be less than 4 inches). The balusters were fastened through the top and bottom rails with single 8d finish nails, and the rails were merely toe-nailed—again with finish nails—into the posts. Those inadequate connections became even weaker over time as the joints opened up.
Finally, the structural railing posts were notched around the rim beam and double-notched at the corners and only nailed or toe-screwed in place. A hardy push was all it took to either snap off the posts at the notch or pry the fasteners out.
Start With the Ledger
The ledger was mounted over the 1x8 skirt board and secured to the house with only a couple of 12d nails in each joist bay and a single 3/8-inch-diameter lag screw into the rim joist every 4 to 6 feet. The bigger problem, though, was that there was no ledger flashing. With the ledger simply fastened over the skirt board and siding, debris had accumulated in the gap, a condition that we knew from experience could lead to significant rot.
When we pressure-washed the gunk out and carefully checked the condition of the siding and framing, however, we discovered that the siding, skirt board, and rim joist were still in good condition, possibly because the owner pressure-washed the deck every couple of years. Another factor that probably limited damage is the fact that the red cedar and redwood siding and skirt board were protected with a good coat of paint.
Still, we wanted to install proper flashing and prevent future problems, so we carefully pried the first course of clapboards above the deck frame away from the wall and snagged out the siding nails. Next, we applied self-adhering flashing tape to the wall, over the top lap of the siding course that dropped behind the ledger, and out onto the top of the ledger. We also removed the riser boards beneath the doors and covered the entire area with more flashing tape, tucking it as far behind the adjacent siding butts as possible.
We fabricated aluminum L-flashing with a 5 ½-inch-tall wall leg—the tallest possible without bumping up against the nails on the overlying siding course—and a 3-inch-wide joist leg. Along the edge of the joist leg, we bent a reverse hem to stiffen the metal and make it easier to handle when slipping it into place. With the riser boards out of the way, it was easy to slide the flashing pieces behind the siding and along the ledger. Finally, after the flashing was installed, we renailed the clapboards that we had pried away from the wall.
Ledger Attachment. To secure the ledger more robustly to the wall framing, we supplemented the existing lag bolts with 5-inch-long LedgerLOK screws. While the LedgerLOK spacing table called for screws to be spaced 10 inches apart, we simply installed two screws per joist bay in a staggered pattern, rather than measure out a precise layout.
With the multi-level deck’s two ledgers dropped 7 inches below the floor levels inside the house, aligning our top row of screws about 2 inches down from the tops of the ledgers meant that the screws penetrated the rim joist about 2 inches up from its bottom edge. We carefully located the bottom row of screws so that we drove them into the mudsill. This isn't a detail found in the FastenMaster installation guide for LedgerLok screws, but one that is acceptable provided 3/16-inch-diameter pilot holes are bored into the center of the mudsill to prevent splitting.
Lateral load connections were not a code issue 20 years ago when the deck was built, so no special hardware existed back then. And even though most local building officials don't require this measure on existing decks, I always add lateral load anchors when upgrading a deck. This is an easy upgrade that adds a measure of safety, as well as being one less thing for a home inspector to note as a deficiency when the home is resold.
Installing two 1,500-lb. lateral load anchors can be a challenge with a finished basement ceiling inside, but the new 4 X 750-lb. lateral load detail in the 2015 IRC simplifies the process in a retrofit situation like this. We used Simpson Strong-tie’s new DTT1 connectors, locating two within 2 feet of the ends of the deck, and two more evenly spaced along the ledger on each deck level, for a total of eight connectors (four on each deck level).
DTT1 connectors can be installed using either 3/8-inch-diameter lag screws or Simpson Strong-Tie SDWH Timber-Hex screws driven into the center of the mudsill. On this project, the original joist hangers had a cutout on the side flange that aligned with the mudsill and closely matched the screw offset from the deck joist side. We found the easiest way to install the anchors was to slip the DTT1 onto the shank of the Timber-Hex screw and drive it through the ledger into the mudsill first, then mount the connector to the side of the joist with 1 ½-inch-long SST SD structural screws.
Strengthening the Load Path
We dug alongside two of the eight footings to gauge their size and depth. Luckily they were adequate for our calculated deck loads, and we assumed the others were too, since the deck showed no signs of settling. Otherwise, we would have temporarily supported the deck frame in order to dig and install new properly-sized footings.
The original 4x4 posts were cast into the concrete footings and showed no signs of decay. But they were notched, so only one ply of the double rim beam was fully supported. To strengthen the load path, we installed short 2x4 support blocks between the top of the footings (which were about an inch below grade) and the outside beam ply. Since most new PT 2x4s—including those that are stocked locally—are only treated for "above-ground" use, we repurposed some of the old CCA-treated 2x4s for the blocks.
The original hangers along the ledger and the rim beam were in good condition with no rust. However, it's hard to imagine why the original workers even bothered to install them, since most were only fastened with two or three nails. And the nails they did use—roofing nails and 4d box nails—were inadequate (we’ve found that this is a very common defect). So we removed all of the old nails—they pulled out quite easily—and replaced them with structural metal connector screws, filling every hole in the hangers with a fastener.
The end joists were just toe-nailed into the ledger and rim beam. On new deck jobs, we typically install concealed-flange hangers and drop the end joists into them. On retrofits like this, we reinforce the connection with large angle brackets with 12d spikes into the ledger and beam.
Because the posts were just toe-nailed into the rim beam, we reinforced those connections with suitable retrofit metal hardware.
Guard Posts for New Rails
The new TimberTech composite rail system required new structural 4x4 guardrail posts. We located them following the span recommendations of the rail manufacturer, and secured them to the deck frame using SST DTT2Z tension ties for rock-solid support (for more on installing code-compliant guard posts, click here).
Because the new decking—TimberTech Earthwoods Evolutions Terrain—would be installed with HIDFast stainless fasteners, we installed extra nailing blocks alongside joists where the butt joints would fall so that the fasteners could be held back from the plank ends.
And since the stair treads would also be composed of the same decking (which has a different span rating than the original PT decking), we added additional support to the stringers. TimberTech requires solid blocking between stringers for support when this particular decking is used for treads. So we installed extra stringers spaced about 12 inches apart, along with 2-by blocking between the stringers.
Finally, though the original joists were in good condition, there were loads of holes and splits on the tops. To ward off future decay, we installed YorkWrap staple-on joist cap strips to help shed water and keep debris out of the joists' cores. Then we were ready to install the new decking and rails.
Is It Cost Effective?
Half the labor on a deck refitting job is in the prep—removing the old decking, tuning up the old frame, and prepping for the border board and railing. The balance of the work is the same as on an entirely new deck—installing the decking, railing, and other finish details. So is it cost-effective to save and upgrade an old deck frame? I think so, provided the joists are in good condition and there are no structural issues like undersized joists that can’t be remedied with the straight-forward retrofit measures described above.
On the material side of the ledger, we saved the cost of the new deck framing and most of the hardware—on this job I estimate that at about $1,100. On the labor side, we saved the cost to demolish and dispose of the old deck frame, the labor to handle new materials, and the labor to build a new frame. On this job, the labor could be valued at about $2,500.
Many of the improvements end up being a wash between the old frame upgrades and work needed on a new deck frame—ledger flashing, structural guard posts, lateral load connections, fastening the ledger, and border blocking—so they don’t factor into the net cost or savings when comparing an upgrade to a new frame.
The net materials and labor needed to improve the old deck frame—pressure-wash behind the ledger, de-nail the joists, add hardware where needed, install missing fasteners, install joist cap material, and add post blocks—totaled about $450. So when tallied up, we saved $3,150 by saving the old deck frame. Sure, I could sell a homeowner on an entirely new deck frame and earn a profit doing that. But I’d rather devote my clients’ budget to upgrades like better decking, railing, and other features and finish details they will appreciate more—and earn a profit on that end.