2.
Cut (13) thirteen 2x4-12' floor joist to 11'-9". Treated lumber may be thicker than 1-1/2". Take
this into account when cutting the length of floor joists. Shorten the joist measurements if
necessary to obtain 12'-0" building width.
3.
Place 4x4-10' treated timbers on the ground. Cut (2) two 2x4-8' boards into 2' long blocks to
secure the 4x4s where they butt together.
Assembly Instructions for Rear Floor Section
X
X
X
X
X
X
X
X
X
X
4.
Install the floor joists cut above between the 12' joist headers. Secure with 16d galv. deck nails.
5.
Place floor sections over the 4x4s. Square floor. Measure the floor diagonally (corner to corner).
These measurements will be the same if the floor is square (203-5/8"). To keep the 2x4 frame
from moving, toenail frame to the 4x4 runners.
4x4-12' Treated
Runner
4x8 Flooring
2x4-12' Joist Header
4x4-10' Treated
Runner
Foundation size is 12'-0" x 20'-0". Check local building codes in your area, the construction may
have to change. For a concrete slab, install sill sealer as a moisture barrier between the concrete and
the wall plates. Foam sill sealer can be purchased at home centers in rolls 3-1/2" or wider.
1.
Cut (2) two 2x4-12' to a length of 12' -0". They
will be used for the joist headers. Layout, from
the left, for 12" on center joist spacing. The 'X'
marks where floor joist will be placed.
Details for Optional Sturdy-Built Floor System
Material Description
12' x 20'
2x4 Treated
4 pcs.
8'
2x4 Treated
24 pcs.
12'
4x4 Treated Runners
8 pcs.
10'
Flooring 3/4"
8 pcs. 4x8
Screw Floor Nails
5 lb.
8d
Galv. Box Nails
5 lb.
16d
2x4-2' Treated
Blocks
Front Floor Section
6.
Cut (2) two 2x4-8' to a length of 8' -0". Layout for
12" joist spacing, see above.
7.
Cut (7) seven 2x4-12' floor joist to 11'-9". Install
floor joists between the joist headers. Install this
section against the section assembled above.
8.
Square floor (173"). Install 4x8 flooring over the
2x4s. Use 8d galv. spiral nails.
11-1/4"
12"
12"
