Anchoring rail posts at the bottom of deck stairs
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Outdoor stair railing detail
Stiffen up posts at the bottom of outdoor stairs or deck railings by bolting them on three sides.
The bottom post is the toughest
post to make solid when you build outdoor stair railings. The usual technique is to bolt it
to the stair stringers (the frame). But
it'll only be solid if the stringers are
solid. That's the challenging part.
First, build a level landing pad for the
stair stringers. You don't need to pour a
footing. Just dig out and compact a
minimum 4-in. thick gravel base, then
pour a concrete slab or lay paving
Lay out and cut the stringers. (See
How to Build Deck Stairs for more information.) Make
the bottom tread cut 1-1/2 in. shorter
than the others. You'll fill out this space
with a 2-by “subriser” (see photo).
Fasten the top of the stringers to the
deck. Rip a piece of treated 2-by lumber
to match the height of the bottom riser,
then screw this “subriser” to the bottom
ends of all three stringers. The finished
riser (cedar in our case) will cover it.
Cut each post to length, allowing
them to run alongside the stringer to
the ground. Then cut a 1-1/2 in. deep notch into the post so it sits over the
stringer, flush with the outside face.
Tack the post into the framing, making
sure it's tight to the stringer and
subriser. Then cut and nail treated 2-by
blocks between the stringers and tight
to the backside of the posts. Next drill
two 1/2-in. holes through the stringer
and the post. Hold them 1-1/2 in. from
the top and bottom. Drill another
1/2-in. hole through the subriser, the
post and the block behind it. You'll
need either an extra-long drill bit or an
extension bit. Install 1/2-in. galvanized
carriage bolts with washers and nuts.
Tighten them firmly.
Finally, install the risers and treads as
shown in the photo. The post won't be
as rock-solid as one set in concrete.
You'll still feel some give when you lean
on it. But it's strong—it won't move
unless the stairs move.
Note: Confirm the handrail
detail on this post design
with your local building inspector
to make sure it's acceptable
in your region.