(1)
most
squeaks in a wood floor come from movement between this type of joist and the
subflooring
(2)
care
must be taken to insure that the wood is kiln dried to lessen the chances for
warping
(3)
with
older floors, especially of plank over joists, special attention should be paid
to the nailing pattern [every 6" - 8"], to leveling as much as
possible and to sanding the subflooring flat
b.
“Glu-lam”
are joists in which strips of fir, spruce, pine, etc. are “laid-up” i.e. glued together to form a single wood beam
similar in appearance to a solid wood joist. They have greater structural integrity, little warping, can
be engineered for larger spans and are more expensive.
c.
Wood
I-beam is similar in look to a standard steel I-beam. It is the strongest, most structurally stable wood joist,
best for longer spans and can be expensive.
d.
Steel
I-beam is the strongest, most stable and should be used for very long
spans. However, if the span is too
long, even though the I-beam will support the floor, there may be excessive
flexing which will cause problems with any kind of flooring except rug.
2.
Subfloor
Material
a.
Plywood;
(1)
should
be five score 3/4" or better
(2)
an
excellent subfloor consists of two layers of ½" , or ½" and 3/8", laid so no seam lies directly over a parallel
seam
(3)
½"
should not be used unless the joist spacing is 14" on center or less
(4)
chip
board, oriented strand board, MDF, or other composite forms of plywood should
not be used unless the material has been specifically approved by the National
Wood Flooring Association
(5)
in any
case, wood flooring should not be installed if the moisture content of the
subfloor is over 12%
(6)
the
floor should be clean of any lumps or bumps of extraneous materials, plasterers
and masons are especially prone to leaving their droppings
3.
Fastening;
a.
Nails, staples, screws, or etc. must be put in less than 8" apart
along all joists
b.
Applying
a bead of contractors cement to the top of the joist before putting down the
subflooring will give a stronger, more stabile floor
4.
Paper
was traditionally laid down between the subfloor and wood flooring. In most cases, with a properly
installed plywood subfloor, no paper is needed between the subfloor and wood
flooring. The exceptions might be;
a.
Resin
or rosin paper has no practical value and can even act as a blotter to hold
water and pull it across a greater expanse of floor.
b.
Polyethylene
can provide excellent moisture protection but deteriorates and can become
worthless within a few years.
c.
15#
felt paper can be used as a moisture barrier over a moderately damp basement or
other such situation.
d.
30#
felt paper is good to use when there is a very damp area under the floor such
as a wet basement or a dirt crawl space.
B.
Installation
of wood flooring over plywood/joist system
1.
All
flooring should be milled tongue and grooved and “end matched” [tongue and
groove on the ends].
2.
Expansion
space; At one time quarter and rift sawn flooring was used almost exclusively,
which is why many old homes had their wood floors installed tight to the
molding with no problems. Today, most
flooring is of mixed cut wood, with relatively little quarter or rift
sawn. If not installed properly,
such floors may suffer cupping or buckling to the point of raising off the
subfloor or pushing out walls. To
allow for this natural movement of wood;
a.
A
minimum of ½" of expansion space should be allowed at the perimeter of the
average room.
b.
A
larger area should have a greater expansion space.
c.
This
expansion space is then covered by the base molding and shoemold, which can
total 1 ½" across.
d.
When a
wood floor directly abuts a solid surface or floor such as stone or tile, a
1/4" or better buffer should be used. Silicone caulking is excellent for this purpose and it can
be tinted to match caulking or mortar.
3.
The
method of fastening the wood flooring to the subfloor is contingent upon the
amount of movement which is apt to occur after installation, as determined by
the width and type of wood. For
optimum fastening;
a.
4"
face width and less, should be toe nailed in to the tongue using standard
flooring nails or staples, spaced every 8" to 10".
b.
When
the face measurement is over 4", planks should still be toe nailed but a
bead of flooring or contractors adhesive should be applied 3" apart, the
full length, on the back of every plank.
c.
With
planks over 10" in width, serious consideration should be given to face
nailing or “pegging” [screwing with a matching or complementing wood cap] and
for extra wide plank or large areas of floor using butterfly keys to reduce
separation.
C.
Installation
of wood flooring over slab systems, i.e. concrete, gypsum, etc.
1.
Moisture
issues arising from temperature differences and concrete’s tendency to “wick”,
give rise to special requirements when installing wood flooring over these
materials, with special requirements
when installing at, or below grade.
2.
Above
grade, a layer of 30# felt or moisture resistant sound proofing should be laid
on the slab with a minimum of a 3" overlap at seams.
3.
When
installing below grade, an impermeable, self-sealing membrane such as one-ply
roofing should be installed.
a.
The
membrane should be fastened down with mastic type adhesive.
b.
The
membrane should extend in one piece at least 10" up all contiguous walls.
c.
Subflooring
should be two courses of 5 score plywood, ½" and ½" are best, ½"
and 3/8" are acceptable.
d.
If
elevations are an issue, and the type of slab will allow it, a single course of
½" plywood may be installed.
e.
This
should be fastened to the slab through an impermeable, self-sealing moisture
proof barrier [one ply roofing].
f.
This
system should not be installed over radiant heat.
4.
A 1/4" expansion space should left between sheets of
plywood, on all sides.
5.
Each
layer should be oriented perpendicular to each other and sheets staggered so
that no seam lies on a parallel seam.
6.
Leave a
minimum ½" expansion space at walls and where butting to stone,
tile, concrete, etc.
7.
A
“floating floor” should be made by
glueing and nailing, stapling, or screwing the two layers of plywood to
each other.
8.
Nothing
should extend through the bottom of the plywood which might puncture the
moisture barrier Plywood should not to be fastened to
the concrete.
9.
Fasten
wood flooring as described above, use nails, etc, which will not penetrate
below the bottom of the plywood.
10.
Dimension
A, in the diagram below, is the total thickness of a carpet and pad when
compressed, or the thickness
of tile or other floor covering.
Adjustments can be made to bring that dimension to the height of the
wood flooring.
D.
Proper
layout of flooring
1.
It is
critical that the wood flooring be in the best possible visual alignment with
surrounding area.
a.
Straight
laid flooring is generally laid parallel with the long axis of the area
although it may be laid perpendicular to a major doorway or other architectural
element.
b.
Because
walls are not always parallel, the center line should be established
visually. This is particularly
important when the floor runs off a major entryway to an area. The flooring should appear to run
straight off the center of the entry.
c.
If
there is any question of the best location for the center line, have a line
snapped off the entryway. If
possibly, have a few courses of flooring laid out.
d.
To
assure a properly centered floor, have the flooring start at the established
centerline and extend in both directions
e.
With
parquet, herringbone, etc, a
layout should be snapped to assure the proper orientation to the area.
2.
No one
loves an ugly butt. Attention
should be paid to the relationships of the ends [butt ends] of the planks, When the ends of planks are too close
together it can be disconcerting.
This can be prevented by attention to detail during layout.
a.
The
general rule-of-thumb is that no butt end should be placed closer than twice
the width of a plank to another end
b.
The
randomness of plank length means being a bit too close occasionally occurs and
if there are a lot of short pieces [under 30"] it is absolutely
unavoidable.
