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C R O S S C O U N T R Y F I V E - W A L L S E R I E S S T R A I G H T L E A N T O • G R E E N H O U S E I N S T R U C T I O N S
Foundations
Check your local building codes for foundation requirements in your area.
CONCRETE FOUNDATIONS
When you prepare the concrete foundation, the size should be the same as the greenhouse’s
outside dimensions. One option is to fasten a treated 4” x 4” wooden sill on top of the foundation.
PLEASE NOTE: Especially with concrete, double check all sizes and ensure the forms as square and level
prior to pouring.
PRE-TREATED WOOD FOUNDATIONS
A greenhouse that is 6’, 8’ & 10’ wide can be fastened to a 4” x 4” pre-treated wood timber
foundation. For larger greenhouses, a 6” x 6” wood timber foundation is recommended. These
timbers are placed on a 4” (10 cm) deep and 8” (20 cm) wide gravel bed. Wood timbers can be
stacked to increase the height of the greenhouse.
One advantage of the wood foundation is that it is not
classified as a permanent structure. Therefore, if you move, the greenhouse can be dismantled and moved to
another location.
IMPORTANT: Please see page 6 regarding treated wood information.
A SQUARE AND LEVEL FOUNDATION
Check the width and length of the foundation’s outside dimensions. Then, square the foundation
by measuring diagonally from opposite corners in the form of an “X”. Next, use a
long
carpenter’s
level to check and adjust the foundation until it is level. Finally, measure where the door will be
placed (in most cases it is 34
1
/
2
” wide). Mark these measurements on your foundation.
PRE-TREATED WOOD FOUNDATION
Foundation Styles
Pressure Treated
Wood
4x4, 4x6, 6x6
Concrete Wall or
Concrete Block
with Pressure
Treated Wood
Plate
Concrete Wall
with
Footing
Concrete Wall
with
Footing and
Brick Facing
Gravel
Pre-cast
Concrete Pier
Block
Pressure
Treated
Wood
Pressure
Treated
Wood
Truss on
Models over
13’ Long
Truss on
Models over
13’ Long
Truss on
Models over
13’ Long
Truss on
Models over
13’ Long
NOTE:
8” Concrete
Wall on Gable
Ends, models
over 16’ wide
(see detail)
Flashing by
Others
Flashing by
Others
IMPORTANT NOTE: If pressure treated timbers are used, a 10mm polyethylene barrier must be used between the
wood and the aluminum (see page 6)