16"
O.C.
23"
46.5"
Fig. 18
2 EACH
CUT 1/4" PLYWOOD TO
PANEL INSIDE OF I-JOISTS
JOIST
46 1/4"
16"
O.C.
22.5"
46.5"
Fig. 19
ANOTHER POSSIBLE FRAMING TECHNIQUE for
I-JOISTS 16” OC:
The procedure is generally the same
as with I-Joists on the prior page, but when the home is a
finished construction (already built and owned) you may
not have extra I-Joist pieces from which to construct
headers. In this case, you may need a way to construct
headers from other available material.
One way to address this problem is to construct headers
from ½”or 3/4” plywood and 2 x 2” rails (Fig. 17). Join the
rails to the plywood with wood glue and nails or screws.
Then attach offset blocking (Fig. 17) as previously
explained. Headers constructed this way will have good
strength and have the advantage of a smooth face
toward the opening. NOTE: The blocking is attached
flush with the ends
of the I-Joist Section when using
constructed headers with a flat inside surface (Fig. 17).
When headers are constructed as described above,
the opening must be framed ½”oversized in only one
dimension to 46 ½” x 23”
(Fig. 18). Next, cut two 1/4”
thick plywood panels (Fig. 19 inset) and nail them to the
two I-Joist faces inside the opening (Fig. 19). The final
opening size will be 23 ½” x 46 ½” (Fig. 19). Please note
that any nail heads in the opening must be set flush or
below the surface and decking and sheet rock must be
cut or installed flush to the opening (Fig. 2b & 19). Finish
the opening by installing the 2 x 2” flashing in the corners
as shown in Fig. 19.
As with solid wood joists, I-Joists that need to be cut
must be supported by some means until they are
connected to headers that tie them to adjacent I-Joists.
CONSTRUCTED
PLYWOOD
HEADERS
SECTION
I-JOIST
USE 2" NAILS
or SCREWS
PLACE BLOCK
INTO INSET TO
MARK OFFSET
INSET
OFFSET
OFFSET LINE
WOOD
GLUE
USE 2" NAILS
or SCREWS
BLOCK
PLYWOOD HEADER
I-JOIST
2 x 2"
WOOD
GLUE
½ or 3/4"
PLYWOOD
2 x 4" or 2 x 6"
2 x 4" or 2 x 6"
2 x 4" or 2 x 6"
BLOCKING
(OFFSET)
BLOCKING
(OFFSET)
BLOCKING
(SET FLUSH)
2 x 2" TOP & BOTTOM RAILS
GLUE AND NAIL TO PLYWOOD
Fig. 17
9
Versa Lift
ATTIC OPENING PREPARATION
INSIDE FINISHED OPENING
INSTALL 2 x 2” FLASHING (4)
Note: I-Joist hangers can be used instead of blocking.
Finish opening with 1/4” paneling to cover hangers
and create a smooth-sided opening (Fig. 16), then
install 2 x 2” flashing in every corner (Fig. 16 & pg. 5).
I-Joist
Hanger
Depending on location
and code requirements,
web stiffeners may be
required for I-Joist when
using hanger brackets.
Web Stiffener
