The distances bellow, will result in the
rafter, including the pergola end, cantilevering past the beam about 18” for the
6’, 8’, 10’, and 12’ models and about 16” for the 16’ model when using 5 x 5
posts. For 4 x 4 posts, 8”, and 10” columns, there will be an additional 1” of
cantilever, and for 6 ½ x 6 ½ posts there will be 1 ½” less cantilever. You can
cantilever up to 2’ (not including the pergola end); simply deduct the
additional cantilever distance from the post distances in the diagram. If the
pergola has stringers, keep in mind that the stringers are installed to the
outside 2 x 8 beam according to the measurements in the table above; if the post
is moved, the stringers may not line up with the beam.
Ensure that the mounting surface is level. If not, the
post will end up shorter than the ledger board, making the rafters not level.
Beams and ledger will extend the width 12” out from the center of each post.
16’ and 18’ wide pergola’s require a post set in the center of the two posts
pictured above.
All measurements
are from center of post to center of post.
| Pergola Projection |
6' |
8' |
10' |
12' |
16' |
| Post Distance |
5' |
7' |
9' |
11' |
15' 2" |
| Pergola Width |
8' |
12' |
14' |
16' |
18' |
| Distance Between Posts |
4' |
8' |
10' |
12' |
14' |
Potomac Pergola - Freestanding
The distances bellow, including the pergola
end, will result in the rafters cantilevering past the beam about 18” for the
6’, 8’, 10’, and 12’ models; about 16” for the 16’ model; when using 5 x 5
posts. For 4 x 4 posts, 8”, or 10” columns, there will be an additional 1”
cantilever, and for 6 ½ x 6 ½ posts there will be 1 ½” less cantilever. You can
cantilever the rafters up to 2’ (including the pergola end); simply deduct the
additional cantilever distance from the post distances in the diagram. If the
pergola has stringers, keep in mind that the stringers are installed to the
outside 2 x 8 beam according to the measurements in the table above; if the post
is moved, the stringers may not line up with the beam.
Ensure that the
mounting surface is level. If not, the posts will end up at different heights,
making the beams not level.
Beams will extend the width 12” out from the center of each post.
16’ and 18’ wide pergola’s require an extra post set in the center of the two
posts going the width of the pergola.
All measurements
are from center of post to center of post.
| Pergola Projection |
6' |
8' |
10' |
12' |
16' |
| Post Distance |
4' |
6' |
8' |
10' |
14' |
| Pergola Width |
8' |
12' |
14' |
16' |
18' |
| Distance Between Posts |
4' |
8' |
10' |
12' |
14' |
To ensure the
posts are set equal distances apart and square to each other, use the following
formula:
a2 + b2 = c2
Where a is equal to the post width distance, b is equal
to the post projection distance, and c is equal to the distance
diagonally from post to post.
a
2 + b
2 = c
2
8
2 + 6
2 = c
2
64 + 36 = 100
√100 = 10
Dogwood Pergola -
Attached
|
Pergola Projection |
8’ |
10’ |
12’ |
14’ |
16’ |
|
Post Distance from Wall |
89” |
113” |
137” |
161” |
185” |
The distances above will result in
the rafters cantilevering past the beam about 15.5”. You can
cantilever up to 2’; simply deduct the additional cantilever
distance from the post distances in the table. The first support
post should be located behind the mark you just made (the structure
side of the mark.)
The remaining support post(s)
is/are located the same distance from the structure as the first
post. Use the table below to determine the distance between each of
the posts. For 12’, 14’, and 18’ wide pergolas, three posts will be
spaced out at the specified distances. For 20’ and 22’ wide
pergolas, four posts will be spaced out at the given distances. THE
MEASUREMENTS ARE FROM CENTER OF POST TO CENTER OF POST.
|
Pergola Width |
12’ |
14’ |
18’ |
20’ |
22’ |
|
Post Distance |
50 ½” |
62 ½” |
86 ½” |
65 ¾” |
73 ¾” |
Dogwood Pergola -
Freestanding
Before assembling the pergola you
should have the support posts in place and securely attached. For
freestanding units the posts need to be attached to the framing of
the structure or the posts should extend 30” into the ground.
Use the following table to ensure
that your posts are spaced correctly for the width (the direction
the beam runs) of the pergola. For 12’, 14’, and 18’ wide pergolas,
three posts will be spaced out at the specified distances. For 20’
and 22’ wide pergolas, four posts will be spaced out at the given
distances. THE MEASUREMENTS ARE FROM CENTER OF POST TO CENTER OF
POST.
|
Pergola Width |
12’ |
14’ |
18’ |
20’ |
22’ |
|
Post Distance |
50 ½” |
62 ½” |
86 ½” |
65 ¾” |
73 ¾” |
Find the projection for your
pergola on the chart below and locate the next post. (This post will
be in the direction that the rafters are running.) Repeat with
the remaining posts. THE MEASUREMENTS ARE FROM OUTSIDE OF POST
TO OUTSIDE OF POST.
|
Pergola Projection |
8’ |
10’ |
12’ |
14' |
16’ |
|
Post Distance |
82" |
106" |
130" |
154" |
178" |
