Money and materials
The arch in this article was built from rough-sawn cedar, but it can also be built from pressure-treated lumber for about half the cost.
Depending on where you live, you may have
other choices of rot-resistant lumber available,
such as cypress or redwood. If you choose treated
lumber, you'll find everything you need for
this project at home centers. If you choose
another wood species, you may have to special-order
lumber or visit a traditional lumberyard.
You'll need only standard tools like a drill, a
circular saw and a jigsaw. Make sure your framing
square is a standard model (16 x 24 in., with
a longer leg that's 2 in. wide). If yours is an oddball,
buy a standard version so you can
easily mark out the brackets (see Photo 2). A
few days before you dig the postholes, call 811 to
have underground utility lines marked.
Figure A: Garden Arch
Cut the pieces to these dimensions to create the arch. All measurements given on Figure A are for standard “surfaced”
lumber. If you choose “rough-sawn”
lumber as we did, some measurements
will change slightly because rough-sawn
lumber dimensions vary.
Cut the parts
To get started, cut notches in the tops of the
beams (Photo 1). If you're using “rough-sawn”
lumber as we did, you may have to change the
length and depth of these notches to suit your 2x8 headers. (The dimensions of rough-sawn
lumber vary.) Set the cutting depth
of your circular saw to 1-1/2 in. to make
the crosscuts for the notches. Then set
your saw to full depth to make the other
Next cut the 2x8 headers to length and
mark arcs at the ends as shown in Figure
A. To mark the curves, use the bottom of
a 5-gallon bucket or any circle that's 10 to
11 in. in diameter. Cut the curves with a
The curved brackets may look complicated,
but they're easy to mark out since
they're based on a standard framing
square. After marking with the square
(Photo 2), set a nail in your sawhorse 20
in. from the edge of the board. Carefully
adjust the position of the board until both
corner marks of the bracket are 24 in.
from the nail. Then, holding your pencil
at the 24-in. mark on the tape, draw an
arc. To draw the second arc, move your
pencil to the 29-in. mark on the tape
(Photo 3). Cut the straight edges of the
brackets with a circular saw and the arcs
with a jigsaw. If the curves turn out a bit
wavy, smooth them with an orbital or belt
sander. Don't be too fussy, though.
Nobody will notice small imperfections.
Put it all together
Mark one header 12 in. from both ends
and lay out the posts, aligned with the
marks. Take measurements at the other
end to make sure the posts are perfectly
parallel. Drive 3-1/2-in. screws through
the posts and into the header. At the tops
of the brackets, drive 3-in. screws at a
slight angle so they won't poke through
the face of the header (Photo 4). Set
1-1/2-in.-thick blocks under the other
ends of the brackets. Then drive screws at
an angle through the sides of the brackets
and into the posts. Be sure to drill 1/8-in.
pilot holes so you don't split the brackets.
Set the second header in place and screw
it to the posts. Note: The brackets are not
centered on the posts, so there's a 1-in.
gap between the second header and the
Back to Top
Set it up
You'll set the arch posts into 10-in.-diameter
holes 30 in. deep. But before you
move the arch into place, screw on a temporary
2x4 “stretcher” 30 in. from the
post bottoms. Then round up a helper or
two and set the posts into the holes.
Patiently level and plumb the arch, using
stakes and 2x4s to brace it (Photo 5). Be
careful not to nudge the posts out of position
as you fill the holes with concrete. Let
the concrete harden for at least four hours
before you finish the wood. We brushed
on two coats of clear penetrating wood
finish to deepen the color of the wood
and repel moisture.