How To Lay
Tongue and Groove
You've just finished framing the first floor
deck for a brand new
home and your ready to start putting down the
3/4" tongue and
groove plywood. If you framed it well and got
your 16" centers
laid out right, the process should go smooth as
silk. The key to
success is in the framing of the joists.
The first step in laying plywood over the
floor joists is to snap
a chalk line. This gives you a straight line to
follow. I always
snap this line at 48 1/4" in off the edge of
the rim joist. This
ensures that in the course of installation the
plywood (which is
48" wide) will not hang over the edge of the
rim joist. It
doesn't matter whether you start in the front
or back of the
house. For best results, start where you have
the longest run without a
jog in or out in the foundation.
After you have snapped your line, determine
which joist the first
sheet of plywood will break. If the joists
where laid out 16"
o.c. (on center) from the end of the building,
the edge of the
plywood would split the joist at 8 feet.
Sometimes the roof
layout determines the floor joist layout. This
is ususally the
case when the roof is a hip roof. In this
instance start with the
joist that will allow the tongue and
groove plywood to cover all the joists,
even if it hangs over the edge of the first
joist. This will be cut off later.
After you have determined where to start,
adhesive to the top edge of the joists. Apply
no more than 48"
the width of the plywood. Lay the first sheet
in the glue with
the groove edge on the chalk line. Holding the
sheet to the line,
nail the leading edge of the plywood to the rim
joist so it
splits the joist. You'll be covering 3/4 of an
inch of the joist
with 3/4" exposed. Still holding the plywood to
the chalk line,
put a nail in the rim joist at the first
Now put nails in the rim joist where the floor
joists are nailed
into it. When nailing off the field these nails
can be used as a
guide to find the joists.
Now the groove edge can be nailed. On the
leading edge, move the
joist so the edge of the plywood splits the
joist. Once you have
the joist where you want it, nail the plywood
to it. Now taking
your tape measure, hook the leading edge of the
joist you just
nailed, and pull it along the edge of the
plywood. Mark 16"
centers on the plywood and pull the leading
edge of the joists to
this mark and nail them. This will help keep
the joists in line
and will help make sure future course of
plywood break on 16"
centers no matter which joist you start
Glue up the joists for the next sheet. Butt
the next sheet to the
one previously installed, making sure to hold
it to the chalk
line and nail the groove edge corner. Nail it
to the rim joist
just like the first sheet. Once again move the
joist so the
plywood splits it. Hook that joist with your
tape, mark centers
and move the joists to the lines. Keep laying
the plywood in this
fashion to the other end of the building.
Your now ready for the next course of
plywood. If I've started
with a full 96" sheet on my first course, I
like to start my
second row with a 48" piece. This works great
if the building
length is in increments of 4 feet
(24',28',32',36' etc.). This
isn't always the case. If the building is an
odd length you can
usually use your ending cutoff to start the
next course. Stagger
the joints a minimum of 32" apart.
Start the next course by gluing the joists.
Do not apply the glue
more than 4' byond the first course of plywood.
Stand the sheet
on its tongue edge next to the groove edge of
the sheet you are
standing on. Make sure its butt edge is lined
up on the joist it
is breaking on and let it fall into the glue.
As it hits the
glued up joists, step on it and try to pull it
in with your foot.
Only under the right conditions will the tongue
into the groove. Sometimes the sheet can be
jumped into the
groove. This involves standing on the sheet and
jump with force
towards the the sheets in the previous row. In
most cases it
takes a sledgehammer and a 4' to 6' 2x4 beater
block to persuade
the sheets together. The block keeps the groove
edge from getting
damaged by the sledge. This is a two person
operation. One stands
on the tongue edge of the plywood to guide the
sheet into the
groove while the swings the sledgehammer. This
will be the
process for the rest of the installation.
Once the piece is in place, nail off the
tongue edge, making sure
the leading edge is breaking on a joist. Move
the joist so the
groove edge breaks on the joist. Pull 16"
centers from that
joist, mark the plywood, move the joists if
necessary, and nail
To keep the joists at the ends of the
building straight, do not
glue or nail them. Ideally we'd like the
plywood to be hanging
over the ends. After all the plywood is in
place, snap a line
from one corner to the other and cut this over
off. Move this joist to the cut edge to make it
straight and nail
Tips:Mike Merisko (c) 2006
-Field can be nailed as you go (recommended to
set sheet in
or after all plywood is in place.
-do not glue more than 4' out from sheet. Keeps
glue off your
when you pull centers.
-When nailing groove edge, nail at least 2"
from edge to keep
-Before installing plywood, check for damaged