Fast and True Deck Framing
Forget string and batter boards. Use the deck’s bandboards—and a cantilever beam—for fast layout and framing.
I’m a big fan of anything that saves me time and increases quality. The first backyard decks and front porches I laid out were the standard affair of strings pulled from the foundation, tied to stakes, and criss-crossed all over the place so I could locate and dig post holes before setting them and framing the deck on top. Now I do it reverse order. I make more money and have much more dependable control points for framing.
Frame a “U”
In this system, all the reference points for locating structural deck parts like posts and joist length start with the ledger and band joists. Build three sides of the deck perimeter (ledger and left and right band joists) in the air. Temporarily support them on 2-by-4’s, (strongbacked if the deck is higher than 6 feet). If the project is huge or multi-leveled, I use the same method. I just frame it in smaller, more manageable sections. And, you must remove the siding on the building and flash the penetration properly to prevent leaks.
Ledger, Part 1
It all starts with the ledger. Set it to the right height, cut it the right length, then lay it out for joists. Here’s how:
Determine the ledger’s exact location on the building. I want my finished deck height flush with any doors so egress to and from the house is seamless, so I use the lowest point of the lowest door as my control point for layout. Then, I subtract the thickness of the decking, plus 1/8 inch. In the case of the Lowes ChoiceDek to be used on this project, that’s 1-3/8 inch.
Next, I transfer a level line that indicates the top of the ledger around the building. For short runs a level works, but for longer runs, a laser level is the way to go. Cut the ledger to the overall width of the deck.
Remove the siding just above the ledger layout line. For the aluminum siding here, I used RotoZips’s new metal cutting bit and it blew anything I could do with snips out of the water. Flashing details may vary by area, but the key here is not to skip this part. Many deck failures can be traced back to improperly detailed ledgers that fail, not to mention sill-rotting leaks.
I use a belt-and-suspenders approach to flashing a deck ledger. After the sheathing is exposed, I tuck Grace Ice and Water Shield up under the siding, and then stick it on so there is an impermeable barrier behind the ledger—one that seals around penetrations like lag screws and nails.
Next, I use Phenoseal caulk to seal under any gaps under doors that inegrate with the flashing.
Finally, I install copper flashing. That also gets tucked under the siding, an eventually folded over the ledger. Do not use aluminum. Aluminum does not get along with the copper in the new treated-wood formula, and together they make the recipe for a leak.