CUT THE TIMBER FRAME
FOUNDATION
Start by crosscutting two pressure-
treated 4x6 timbers to 8 ft. long, and
two other 4x6s to 6 ft. long. Mark both
ends of all four timbers for a 1¾-in.-
deep x 5½-in.-wide half-lap joint. Set
the depth of cut on your circular saw
to 1¾ in., and make a shoulder cut
across the timber precisely 5½ in.
from each end of the four 4x6s. Then
set the saw to its maximum depth of
cut and make the cheek cut in from
the end of the timber [ 1 ].
Flip the timber over and make
another cheek cut into the opposite
edge. To complete the half-lap joint,
trim away the last bit of waste wood
with a reciprocating saw or hand-
saw. Repeat to cut half-laps into both
ends of all four 4x6 timbers. Lay out
the 6x8-ft. timber frame founda-
tion, overlapping the half-lap joints
at each corner. Measure the opposing
diagonals to check that the foun-
dation frame is square and make
adjustments as needed; then secure
each half-lap joint with two 3½-in.-
long structural screws [ 2 ].BUILD THE ROOF TRUSSES
In this build, you’ll prefabricate the
roof trusses that frame the green-
house roof to simplify the framing
process. Each truss is composed of
two angled roof rafters and a horizon-
tal collar tie. There are five trusses in
all: front and rear gable-end trusses,
and three intermediate trusses. Begin
by cutting ten 2x4 rafters to 52½ in.
long. Miter-cut the top end of each raf-
ter to 40 degrees; leave the bottom
end square. Next, measure up 2½ in.
from the bottom of the rafters and cut
a small notch known as a bird’s-mouth
cut. These notches allow the lower end
of the rafters to sit f lush on top of the
sidewalls. (See the photos on page 52
for more information.)
Also, measure down 25½ in. from
the upper end of each rafter and cut a
¾-in.-deep x 1½-in.-wide notch into
the top edge of each rafter. Cut the
¾-in.-deep sides of the notches with
a jigsaw, and then chop out the block
of waste wood with a hammer and
1½-in.-wide chisel. These notches will
accept a 1x2 strap after you install
the trusses.
To assemble the trusses, butt
together the 40-degree-mitered ends
of two rafters. Then glue and screw a
½-in. plywood gusset plate over the
joint between the rafters [ 3 ]. (We
used yellow decking glue throughout
this project.) Fasten the gussets with
1¼-in. decking screws. Repeat for the
remaining four pairs of rafters.
For each of the three intermedi-
ate trusses, cut a 1x4 collar tie to 60
in. Miter-cut each end of the collar312Part Qty. Size and Description
A 10 1⁄2" x 18" reinforcing bar
B 2 4" x 6" x 72" timber frame
foundation
C 2 4" x 6" x 96" timber frame
foundation
D 10 2" x 4" x 52
½" rafter
E 3 1" x 4" x 60" intermediate truss
collar tie
F 2 2"x 4" x 56" gable-end truss collar tie
G 2 2"x 4" x 13
5⁄8" front truss vertical
blocking
H 1 2" x 4" x 8
½" rear truss top block
I 2 2" x 4" x 7
1⁄8" rear truss side blockJ 10 2" x 4" x 69
¼" sidewall stud
K 2 2" x 4" x 96" sidewall top plate
L 2 2" x 4" x 96" sidewall sole plate
M 4 2" x 4" x 69
¼" rear wall stud
N 1 2" x 4" x 65" rear top plate
O 1 2" x 4" x 65" rear sole plate
P 2 2" x 4" x 69
¼" front wall stud
Q 2 2" x 4" x 75
¾" front wall trimmer
stud
R 2 2" x 4" x 17
¾" front wall top plate
S 2 2" x 4" x 18
5⁄8" front wall top plate
T 8 2" x 4" x 23" eave blocking
(Trim eave blocking to finished length on-site)
U 10 1" x 2" roof battens
V 10 1" x 2" sidewall battens
W 2 1" x 2" x 96" rafter strapping
X 1 ¾" x 7¼" x 99" ridge cap
Y 1 ¾" x 8" x 99" ridge capZ 1 1" x 3" x 8
¼" vent frame top
AA 2 1" x 3" x 17
1⁄8" vent frame side
BB 2 1" x 3" x 4
1⁄8" vent frame end
CC 1 1" x 3" x 36
3⁄8" vent frame bottom
DD 1 3
5⁄16" x 16
¼" vent top plywood
gusset
EE 2 2½" x 7" vent side plywood gussetFF 2 1" x 3" x 76
¾" door stile
GG 1 1" x 3" x 19
5⁄16" door head rail
HH 1 1" x 3" x 19
5⁄16" door midrail
II 1 1" x 4" x 19
5⁄16" door bottom rail
JJ 1 1" x 4" x 32" door head casing
KK 2 1" x 4" x 77" door side casingLL Polycarbonate roof panel
MM Polycarbonate sidewall panelNN 6 1" x 4" x 21
¼" potting bench
support
OO 3 2" x 4" x 25
¾" potting bench brace
PP 4 1" x 4" x 96" potting bench slat
QQ 1 ½"-diameter x 94" conduit for
hanging plants
RR 2 1" x 4" x 20" cleat
SS 4 5⁄4" x 6" x 72" decking
TT 5 2" x 4" x 20
½" deck floor joist
UU 2 2" x 4" x 72" deck band joist