How to Build a Gazebo
Brushes, rollers (for finish)
Drills and bits
Hoe and hose (to mix concrete)
Post hole digger
Shims or spacers
Stakes or batterboards
Two foot level
Octagonal Gazebo: For purposes of illustration, we will demonstrate the layout and construction of a 12'
diameter gazebo. Specific layout and measurements should be adjusted to your gazebo. This gazebo, with its
decorative rails and high, steep-pitched roof, will enhance almost any yard. Build it as a focal point or tuck it into a cluster
The generous floor deck, approximately 12' in diameter, provides ample room for tables, chairs, a
portable barbecue or even a comfortable chaise lounge.
Be sure to review the entire plan carefully before starting construction. The plan for this gazebo is courtesy
of the Western Wood Products Association.
Step 1: Determine Location
Determine the location for the gazebo and drive a stake (No. 1)
into the center of the proposed site. (See Fig. 1). Drive a nail into the
top of the stake and, with a tape or string, mark a circle (with powdered
chalk or lime) with a radius of 6' (12' diameter).
Decide where you want to locate the gazebo entrance and drive
a stake (No. 2) on a line adjacent to the entry opening; place it about 2'
outside the circle you have marked. Drive a third stake (No. 3) opposite the
first, so a string tied between them will cross the center stake.
Drive two more stakes (Nos. 4 & 5) at right angles to
the first. String a line between the stakes; making sure the string crosses
the center stake. (So far, the exact length of the strings doesn't matter.)
To make sure the second string is at a true right angle,
use the 3-4-5 method. Measure out 3' from the center stake on the first string
and 4' from the center on the second string. Mark both strings and measure
the distance between the two points. Adjust the stakes until the diagonal
line measures 5' (See Fig. 1).
Divide remaining quadrants with stakes and string, as shown,
to create eight equal spaces.
Drive a second row of stakes at the point where each string
crosses the circle. (These should be 6' out from stake No. 1.) The space between
stakes on this inner row should measure 4'6" on-center. These stakes
need to be exactly right as they mark the centers for each footing and post.
Step 2: Install Footings
Dig a hole for each footing that is at least 1' deep and
15" diameter. Install forms where needed. Pour footings, using a marker
or board to make sure tops of footings are all at the same level. Accurately
mark point where string crosses the circle and install post anchor before
concrete sets. (Remember the post anchors must be set so that the center of
your posts will all be 6' out from the center of the gazebo, and the on-center
distance between posts will be 4'6".) Recheck measurements and make adjustments
as necessary. Check to make sure all post anchors are level with one another.
This is critical. If you do not have access to a transit, use a long board
with a level placed on top. Getting the post anchors level and at the correct
angle will ease construction on the rest of the project, and will allow you
to follow our dimensions and cutting instructions with minimal site-specific
variation. (Refer to Fig. 3A and check that your post anchors are at the correct
angle for future connections.)
Allow concrete to set for two days. Recheck all measurements
and make certain post anchors are all still level with one another and the
on-center 6' and 4'6" spacing is exactly right.
Step 3: Install Posts
Posts are made using two 2x6s on the outside with a shorter
2x4 sandwiched in the center to support the rafters. (See Figs 3A, 4 &
Before you cut all of the sixteen 2x6s and eight 2x4s required
to make the eight posts, make one post as your sample and cutting pattern
for the others.
Take two 12' lengths of 2x6 and cut a 45-degree angle at
one end so the piece measures 11' 4 " at the long side of the angle cut.
Lay a scrap length of 2x6 (pretend this is a rafter) across the angled end
of one of the cut 2x6s. Position a 12' 2x4 over the top of both of these so
that the 2x4 is aligned with the 2x6. Mark the angle at the top of the 2x4
and cut. Sandwich and center (side-to-side) the 2x4 between the 2x6s (see
Figs. 3A & 4A); lay the scrap piece of 2x6 in position (to check how the
rafters are going to be sitting later on); trim the bottom of the 2x4 flush
with the bottom of the 2x6s. This is your first post. Use it as the pattern
for the other seven. Cut remaining 2x6s and 2x4s. Nail posts together using
pairs of 12d casing nails every 16" or less from both sides.
Set posts in post anchors (refer to Figs. 2, 3A & 4)
using a composition shingle as a moisture barrier. Shim posts in position
using pressure treated lumber (anchor will be 1" larger than post) and
temporarily brace with scrap lumber. Check distances between posts. (Posts
should be 4'6" on-center and 6' out from the center stake.) Distances
should not vary more than 1/2". Check level at top of posts and adjust
if necessary. Fasten all posts to post anchors, using nails or bolts appropriate
to the specific post anchor.
Step 4: Building the Gazebo Decking
Measure out 3' on either side of center stake and set 14"
pier pads in place. (See Fig. 5.) Pier pads are 6' apart, on-center.
Note: When positioning pier pads, remember that the bearing
point of the pad will be 12 " lower than the finished surface of the
Nail two 2x6s together to form beam. Lay beam across pier
pads so ends are equidistant from the center of the gazebo. (See Fig. 5.)
Use a moisture barrier, such as several asphalt shingles, between the pier
and the beam. Check beam for level.
Mark position of 2x10 rim joist on posts, making sure all
marks are level. (Refer to Figs. 3A & 6.)
Tip: To determine position of 2x10 on posts, temporarily
lay a 12' to 14' 2x6 across center beam so both ends of 2x6 are adjacent to
posts. After leveling, make a mark where top of 2x6 touches the post at each
end. Rotate 2x6 90º and mark second set of posts. Repeat for remaining
Cut 2x10 rim joists to length, mitering ends at 22 º;
nail to posts with 12d nails.
Cut 5 " deck support blocks from 2x6s. Predrill and
nail blocks to both sides of posts so top is flush with top of 2x10. Additional
blocking may be required in order to nail decking board securely around posts.
(See Fig. 6A)
Set 2x6 floor joists in place, spaced according to measurements
given in Fig. 6 and flush with top of rim joist. Use general purpose framing
anchors (TECO M-34) at both ends of the center joist. End nail remaining floor
joists to rim joist with three 12d nails, and to posts where possible. (See
Install 2x6 fascia board flush with top of rim joist, mitering
ends at 22 º. (See Figs. 6 & 6B) Use 12d casing nails for more finished
Apply 2x6 decking to floor joists, butt boards tightly. Fit
decking around posts and trim ends of deck boards to a constant 1" overhang.
(See Fig. 6c)
Installing Rafters & Collar Ties
For center block, cut four 2' lengths of 2x6. Using a construction
adhesive, glue/nail to form 6" block. Trim and notch as shown in Fig.
7. Set aside. Place two opposing 12', 2x6 rafters in position as shown in
Fig. 8. Use a plumb line bob to find the center, tack rafters together temporarily.
Mark position for center block, allowing for 12" overhand.
Cut 45º angles on ends next to center block and trim overhanging end
as shown in Figs. 9 and 14. Use as pattern, and cut remaining six rafters.
(Refer to Fig. 8A for an overview of how all eight rafters will attach, but
remember, for now, you are attaching only the first two.)
Temporarily toenail two opposing rafters to the center block
using 12d nails. (Refer to Fig. 7.) Position on posts and check fit. Remove
from posts and firmly toenail these first two rafters to the center block.
Predrill holes to avoid splitting. Refer to Figs. 9 & 10 for an overview
of how the collar tie system will fit together. Position the continuous (8'
of 2x6) collar tie (No. 10 across the first two rafters. Mark angles for trimming
ends. (Pieces should trim to approximately 7'4" on the long side of the
angle cut.) Trim and toenail collar tie into position with 12d nails.
Cut two 2x6 collar tie places as shown in Fig. 11. Notice
that one end is mitered at 45º to match the rafter angle; the other end
is beveled. Use as pattern for the remaining 14 plates required for other
seven collar ties. Cut remaining plates and set aside.
Nail first two plates into position using 12d nails as shown
in Figs. 11 & 9. Predrill holes to avoid splitting.
Set roof truss on posts, making sure center block is centered
and overhand is equal. Nail rafter to post through outer 2x6s using 12d casing
nails. Temporarily brace upper part of posts to keep dimensions rigid and
Anchor remaining rafters to center block and posts, toenailing
to center block with 12d nails and nailing to posts. (See Figs. 8A & 13.)
Following the sequence shown in Fig. 10, cut remaining collar
ties and assemble, toenail into position with 12d nails. Install remaining
collar plates as shown in Fig. 11. Install straps as shown in Fig. 9.
Step 6: Construct the Roof
Start first course of tongue-and-groove roof decking flush
with ends of rafters, tongue up. Put finished face of decking downit
will be seen from below. Miter one end of board and allow a little extra length
at the other end. Face nail the first boards to rafters with 12d nails.
For remaining boards, cut and miter as above; use two 12d
nails per rafterone toenailed through the tongue and one face nailed.
After each triangular section is in place, snap a chalk line down the center
of the rafter and trim other end of decking.
Make sure boards line up between sections to produce the
"coursing" effect of the grooves on the underside.
Apply 2x3 face trim to end of rafters (Fig. 14), flush with
top of decking. Miter ends.
Apply felt roofing paper according to manufacturer's directions,
taking care to seal well around peak.
Apply cedar shakes according to standard roofing methods.
(Refer to Fig. 7 for center top detail.) Install optional decorative finial
on peak. Note: If you plan to install a finial on the peak, attach some blocking
between the top of the center block and underside of the roof peak.
Assemble Rail Sections
Upper railing sections are installed in eight bays; lower
railing is omitted on entry bay. Lower railing is omitted on entry bay. Before
cutting horizontal boards, measure each opening to adjust for any variations
in the widths between posts. When nailing smaller components together, make
certain your nails are an appropriate length so that finished rails have a
Cut horizontal 1x2s and 2x4s to length, mitering ends of
2x4s at 22 º.
Each bay will require 12 vertical 1x2s, each 8 " long.
End nail vertical 1x2s to horizontal 1x2 rails at top and bottom, 3 3/4"
on-center. Nail rail section to 2x4 base and cap, using 6d-casing nails. (Refer
to Figs. 16 & 17.)
Toenail complete railing section to posts, using 12d casing
nails. (See Fig. 17 for position.) Build identical rail sections for remaining
Tip: Temporarily nail a scrap piece of 2x4 to posts at height
of 6'11" to hold your completed railing in place while you nail.
Cut horizontal members to length, mitering ends at 22 º.
(See Figs. 17, 18 & 16.) Toenail 2x4 bottom rail to posts, 1 " above
deck, with the inside 1x4 stop nailed to the 2x4 with 12d casing nails.
End nail 1x2 verticals to horizontal top and bottom 1x4s,
3 3/4" on-center, same as for upper railing section. Toenail to post,
in position, 24" above bottom 2x4.
Cut vertical 1x4 tongue and groove boards 59 23 7/8"
(you will need 14 boards per section); cut 1x2 verticals to 6 2/3" (12
per section). (Refer to Fig. 16.)
Assemble 1x4 verticals for first section on a flat surface,
using a straight edge (such as a 2x4) to keep edges square. Trim last 1x4
to size. Using 3d finish nails, temporarily nail 1x4 bottom stops and 1x1
top stops in place on the panel and check section for fit. Once fitted, secure
position with 6d casing nails.
Build and install six more railing sections in the same manner
for the remaining bays.
Customizing Your Gazebo
The previous gazebo plans showed posts set on concrete piers;
you also have the option of setting posts in the ground. If you install posts
in the ground, your gazebo cannot be moved.
Postholes should be at least 24" deep and can be up
to 4' deep. The actual depth depends on the height of the column and the depth
of the frost line in your area. Posts need to be set deeper than the frost
line to avoid heaving. Check for recommended depth and width of postholes
in your area. Fill the bottom of the hole with gravel and place a treated
wood block on the gravel. Set the posts in the holes, check for level and
brace securely. Fill the hole with concrete or alternating layers of gravel
and earth. Make sure the posts are plumb and in alignment with one another.
Let posts set in concrete overnight.
Reprinted with permission, Osmose Inc.