1.
Cut (16) sixteen 2x4-12' treated boards to 11' 8-7/8". These will be the floor joists.
2.
Cut (2) two 2x4-8' treated boards into 2' long blocks to secure the 4x4s where the they butt
together. Stagger the 4x4 timbers as shown below.
Assembly Instructions for Rear Floor Section
2x4 Blocks
4x4-8' Treated
Runner
4x8 Flooring
2x4-8' Joist Header
4x4-10' Treated
Runner
4x4-8' Runner
4x4-10' Runner
4x4-10' Runner
Front Floor Section
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4x4 Flooring
Material Description
12' x 18'
2x4 Treated Joist Headers
2 pcs.
8'
2x4 Treated Blocking
2 pcs.
8'
2x4 Treated Joist Headers
2 pcs.
10'
2x4 Treated Floor Joist
16 pcs.
12'
4x4 Treated Runners
4 pcs.
8'
4x4 Treated Runners
4 pcs.
10'
Flooring 3/4"
7 pcs.
4x8
Galv. Spiral Floor Nails
3 lb.
8d
Galvanized Deck Nails
3 lb.
16d
4.
Install the floor joists cut above between the 8' joist headers. Secure with 16d galv. deck nails.
5.
Place floor assembly over the 4x4s. Square floor assembly by measuring the floor diagonally
(corner to corner), then measure the opposite corners. The measurements will be equal when
the floor is square.
3.
Cut (2) two 2x4-8' treated boards to a length of
8' -0"; they will be used for the joist headers.
Layout, from left, for 16" on center joist spacing.
'X' marks where floor joist will be placed.
6.
Cut (2) two 2x4-10' treated boards to a
length of 10' -0". Layout for 16" joist
spacing; see above.
7.
Install floor joists between the joist headers.
Square the floor section. Install this section
against the section assembled above.
8.
Install 4x8 flooring over the 2x4s. Use 8d
galvanized spiral floor nails spaced 8" apart.
Foundation size is 12'-0" x 18'-0". Check local building codes
in your area, the construction may have to change.
Construction Details for Optional 12'x18' Floor System
X
X
X
X
X
X
X
X
X
X
15-1/4"
16"
16"