Gymnasium floor products offered by NOFMA mills are
most often made of 3/4in oak, pecan or maple. Some NOFMA
mills make 25/32in maple. Beech and birch are also suitable.
It is most important to have some resiliency built
into these floors, but in most respects installation closely
follows the screeds-in-mastic method recommended
for conventional use, with a plywood or board subfloor
installed over the screeds. Also, 2 layers of 1/2in plywood
cushioned and laid on a 45° angle to each other may be
used as a subfloor.
Acclimate all floor system materials to the established
environment well in advance of installation.
Make sure the slab is dry and level with a good float
finish. Maximum surface variation is 1/4in in 10ft. Grind
down high areas and fill low areas with concrete leveling
compound.
Sweep the slab clean and prime with asphalt primer.
Let dry thoroughly and coat with asphalt mastic, using a
notched trowel designed to apply at a rate of 50 sq. ft.
per gallon. Embed a layer of 15 lb. asphalt felt or building
paper, starting at a wall with a half sheet. Lap seams.
Cover this with another layer of mastic and embed a second
layer of asphalt felt or building paper, starting at the
same wall with a full sheet to cover the seams of the first
layer.
Either hot or cold mastic is satisfactory. If the cold type
is used be sure to allow time (2 hours) for solvents to
evaporate before applying the building paper.
An alternate method for a surface vapor retarder is to
embed a 4 to 6 mil polyethylene film in a cold mastic. Lap film edges 6in.
A suspended concrete slab with a controlled environment below needs no surface vapor retarder.
A suspended slab over exposed earth or an uncontrolled
environment requires a proper vapor retarder over the
slab. In this case cross ventilation below the slab is essential, and, if over exposed earth, a ground covering of 6
mil polyethylene should be provided.
Screeds used and their application are identical to that
previously described, with these exceptions. Place
them on 12in centers, (9in centers with 3rd grade flooring)
unless a subfloor is to be used, then 16in centers are
allowed. Leave 2in space between the ends of the screeds
and the base plate on all walls to allow for expansion.
The strip flooring may be nailed directly to properly
spaced screeds, but a much more sound and satisfactory
floor can be achieved by installing a subfloor of 3/4in minimum
plywood or 3/4in dressed square-edged boards no
wider than 6in. Follow arrangement and nailing schedules
described previously. If boards are used, leave 1/2in
space between them.
Start laying the finish flooring in the middle of the
room and work toward the walls. Engage the first two
courses groove-to-groove with a slip tongue glued into
one groove. Join the strips and face nail as well as blind
nail both courses. Proceed with succeeding courses in
the conventional manner, using either 7d or 8d flooring
nails, 2in flooring cleats or 2in 15 gauge staples with 1/2in
crown.
After an area 3ft or 4ft wide has been laid across the
room, leave a 1/16in expansion space between the last course
laid and the next course. Repeat this expansion space
evenly at 3ft to 4ft intervals across the room. Different
area environmental conditions may require more or less
field expansion.
Nailing is most important. Nail to all screeds and to
both screeds when a strip passes over a lapped screed
joint. All end joints do not need to meet over screeds but
adjacent strips should not break over the same screed
space.
If a subfloor is used, nails must be no more than 10in
to 12in apart with a minimum of 2 nails per board near
the ends (1in-3in) along the length of strips.
Allow 2in expansion space along all walls and at doorways.
This can be covered at the walls with an angle iron
bolted to the wall or a special wood molding, and at doorways
by a metal plate designed for such use.
After installation and through the sanding and finishing
process, the interior environment should be maintained
near to an occupied condition. Extended times with
no HVAC in operation should be avoided. This can promote
a static "green house" effect. These conditions can
allow an abnormal increase in moisture which may
adversely affect flooring.
If problems occur during installation contact the distributor immediately.
Flooring Installation Guide :: Index
1) Installation Introduction
2) Handling & Storage
3) Job Site Conditions
3.1) Installing over Concrete
3.2) Testing Concrete for Excessive Moisture
3.3) Concrete Slab Preparation Prior to Installation
4) Laying & Fastening
5) Plank Flooring
6) Laying a New Strip Floor Over an Old Floor
7) Parquet, Block Herringbone & Similar Flooring
8) Special Construction Situations
9) Tips for Easier & Better Flooring Installations
10) Strip Flooring on Walls & Ceilings
11) Installation of Gymnasium Floors over a Concrete Slab
Installation content courtesy of NOFMA. FloorMall.com is a Proud Member of NWFA.
