- Rafter
Spacing,
Blocking Placement
for Proper Load Support of Polycarbonate
- Chart for Cap
& Trim. Our
Base
& Cap has
different spacing requirements.
- - Blocking is framing
member that fits between rafters or studs.
- ( Purlins sit on top
of rafters, run perpendicular & require Base
& Cap.
)
-
- See Structural
Load page for further
explanation of snow and wind load. Also see Lexan Tech Data.
- -
- See Poly
Position & Attach for mid-sheet attachment of roof & wall
sheets.
- 25mm
ok for 80-100 lb. load
-
|
Sheet
Thickness
|
Rafter
Spacing
|
35 lb.
load
|
45 lb.
load
|
60 lb.
load
|
|
6mm
|
24-1/8"
|
every 8
ft.
|
every 6
ft.
|
every 4
ft.
|
|
6mm
|
48-1/4"
|
every 2
ft.
|
every 1.5
ft.
|
do not
use
|
|
8mm
|
24-1/8"
|
not
needed
|
every 8
ft.
|
every 6
ft.
|
|
8mm
|
48-1/4"
|
every 2.5
ft.
|
every 2
ft.
|
do not
use
|
|
10mm
|
24-1/8"
|
not
needed
|
every 10
ft.
|
every 8
ft.
|
|
10mm
|
48-1/4"
|
every 3
ft.
|
every 2.5
ft.
|
every 2
ft.
|
|
16mm
|
24-1/8"
|
not
needed
|
not
needed
|
not
needed
|
|
16mm
|
48-1/4"
|
every 4
ft.
|
every 3
ft.
|
every 2.5
ft.
|
Mfg. specs for
selecting sheet thickness, rafter spacing & blocking placement
support load on roof or wall.
- -Load
in lbs./sq. ft. Roof slope over 7/12 snow slides off. Spacing may
be relaxed. No specs available.
-
- Bldg. dept. has snow &
wind load for your area. Supporting load is factor of frame
strength and poly. sheet rigidity. Follow chart and poly. will
support load. For frame member size see Spans
for Rafters. Get bldg.
dept. approval.
-
- To allow for movement of
condensation past blocking, set blocking 3/8" back from outer
surface of frame, see Blocking.
When using 48-1/4"
on-center rafter spacing, a neoprene spacer is placed at
center of blocking. This eliminates bowing of sheet, see
Spacer
Install.
-
- Note: The sheet must be
supported on all 4 edges with a minimum of 1/2" of sheet bearing
on the frame. When using sheets that have been cut along the
width, and no longer have a rib at the edge, position so first rib
is supported by a minimum of 1/2" of frame.
- -
- Framing
Guide & Install
Manual Crucial read for successful
install.----Reload
Sundance Supply Site
-
- Using rafter framing &
desire minimal shadow, low profile design? See "Let
In" Purlin Design.