Today we’re talking blocking, as in deck blocking.
Deck blocking is to decking what a fou-rman, 1,200 pound offensive line is to protecting the quarterback. It’s what solid defence and goaltending is to winning playoff hockey. Blocking is the five sugar sticks Honey Boo Boo gulps down before hitting the stage at yet another Toddlers in Tiaras competition.
In essence, blocking is the game changer, and the ultimate stabilizer.
Once you’ve dug the holes, poured the piers, leveled the supporting beams, and completed the framework, or basically all the fun stuff, you’re going to want to move on to installing the deck boards.
After all, and by this point, you’re almost home. And, with the decking planks installed, your deck will actually look somewhat complete. So, let’s get those deck boards installed, and we’ll concern ourselves with the newel posts and railing system afterwards, right? Wrong!
Installing the decking planks will be the final piece of the puzzle. Before the planks, before the railing, and before the stairs get installed, we do the blocking.
First, we establish the position of the newel posts. In order to achieve a straighter, super strong railing perimeter, space the posts no further than six feet apart.
Railing systems are only necessary, by code, if your deck is 24 inches or more, above grade (grass level). Realistically though, I think a railing should be installed if your deck is any more than 12 inches off the ground.
A two foot drop doesn’t seem like much if you’re between the ages of 10 and 20 years old, participate in step aerobics, or are a former highland dancer. But I tell ya, if you’re a toddler, elderly person, or have had knee surgery, looking down at that two foot drop is like staring death right in the face.
Blocking means simply wrapping lumber around the newel posts after they’ve been sunken into the joist system, or providing solid lumber for the anchoring plate of your chosen vinyl, aluminum, or composite post.
If possible, always extend your wooden newel into the joists, it’s a superior strategy to surface mounting. Once you’ve established the railing height, cut your newel post to the proper length (be sure to add the deck board thickness and joist depth to this measure).
Then, cut a ½ inch by 7-1/4 inch (depth of your 2×8 joist) notch into the 4×4 post. This notch will allow you to conveniently set the 4×4 newel on the edge of the perimeter joist, along with perhaps one screw to hold it in position, while you add the blocking.
Blocking should consist of 2×8 lumber (two layers deep) on either side of the post, with a third piece of 2×8 spanning from joist to joist. Lock the blocking into position using PL glue and screws. Then, drive two carriage bolts through the whole assembly.
Basically, the newel posts ought to be able to stop traffic. And, don’t kid yourself, the integrity of this post will be tested.
First by the local inspector, who’ll tug away at this newel like not prying it loose meant they weren’t going to eat that day. Then of course by every visitor, in-law, and good buddy, who’ll want to christen the deck by giving that first newel a little shake, along with the blessing “Yep, this looks pretty good”.
Most aluminum and vinyl railing newels have bottom plates that allow only for surface mounting. When this is the case, plan your blocking so that each and every lag screw gets drilled into solid 2×8 lumber, and not simply the decking boards.
Plus, if your aluminum post system comes with 2-1/2 to 3 inch long screws, toss them in a jar for future, unrelated use.
Then, invest in a series of 4-5 inch, heavier lag screws, and use them instead. There’s no such thing as overkill when it comes to securing a newel posts.