1.
Cut (17) seventeen 2x4-12' treated boards to 11' 8-7/8". These will be the floor joists.
2.
Stagger the 4x4 timbers as shown below. Cut (2) two 2x4-8' boards into 2' long blocks
to secure the 4x4s where they butt together.
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. Measure the floor diagonally
(corner to corner). These measurements will be the same if the floor is square. It should
measure 173". Tenail frame to the 4x4 runners.
3.
Cut (2) two 2x4-8' 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.
4x4-8' Treated
Runner
4x8 Flooring
2x4-8' Joist Header
4x4-12' Treated
Runner
4x4-8' Runner
4x4-12' Runner
4x4-12' Runner
6.
Cut (2) two 2x4-12' to a length of 12' -0". Layout
for 16" joist spacing, see above.
7.
Install floor joists between the joist headers. Square
floor section. Measurement will be 203-5/8". Install
this section against the section assembled above.
8.
Install 4x8 flooring over the 2x4s. Use 8d galv.
spiral nails.
X
X
X
X
X
X
X
X
15-1/4"
16"
16"
Material Description
12' x 20'
2x4 Joist Headers
2 pcs.
8'
2x4 Blocking
2 pcs.
8'
2x4 Joist Headers
2 pcs.
12'
2x4 Floor Joist
17 pcs.
12'
4x4 Treated Runners
4 pcs.
8'
4x4 Treated Runners
4 pcs.
12'
Flooring 5/8" or 3/4"
8 pcs. 4x8
Screw Floor Nails
4 lb.
8d
Galv. Box Nails
5 lb.
16d
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.
Constructing Details for Deluxe Floor System
Deluxe floors include 4x4 runners, standard floors do not
