Design Solutions - Fall 2021 - 54

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THREE GRADES
As is consistent with all AWI
Woodwork Standards, wood stair,
handrail, and guard systems aesthetic
requirements are still designated as
Premium, Custom and Economy grades.
Definitions for judging components
color and grain as " well matched " and
" compatible " are designated in the 3.4
Aesthetic Section of the standard as
well as the online Glossary.
STRINGERS AND TREADS
Since the stringer is a major
Stair fabrications vary widely in
prominence and visibility on a huge
array of construction project types.
The entire surface of stairs may end
up completely covered in carpet or
highly designed as a prominent and
unique building feature, expressed
in fine hardwoods with a wonderful
assortment of grain and figure.
The stair standards section 3.2
Material Requirement helps the
designer and specifier know where
the limitations are as they create the
stair. Grade Tables on page 5 state
allowances for sapwood, wormholes,
color streaks, and visible aesthetic
qualities of solid lumber and sheet
products.
What if the owner has chosen
a rustic style and all the wood has
features not usually allowed in the
traditional aesthetic grades? It is stated
in 3.2j that the number of allowable
natural characteristics shall be as
agreed to between the owner/design
professional and the manufacturer/
supplier. If choosing reclaimed lumber
or roundwood, look at the available
materials together and decide what will
be agreeable to the owner's sense of
aesthetic and practical day-to-day use.
54 designsolutions I fall 2021
component of a stair's structural
integrity, attention must be placed on it
looking as well as it performs. On pages
6 and 7, differences in the requirements
for exposed stringers and concealed
stringers are noted. For example, in
Premium Grade for Exposed Stringers,
no more than three staves per 305mm
[12 " ] and 3.2.1.1g, the visible staves
shall be of the same species or
covered with matching veneer when a
transparent finish will be applied.
For concealed stringers, a range of
engineered materials are allowed such
as glued/laminated timber, laminating
veneer or parallel strand lumber.
Stairs can be a large visual
enhancement of a project or hidden
between walls. Either way, they
must perform reliably and are often
considered the workhorse of the
building, a pathway for the movements
of the building's occupants, equipment
and furniture transfer and sometimes
the setting for a grand entrance. The
part that meets with human contact the
most is the treads. Pages 7-9 contain
the requirements for treads that are
wood, hybrid, veneered, plank, and
made to accept carpet, as well as good
information about landings and tread
ends, curved treads and starting steps.
When a tread is curved, the front
edge, the shape of the nosing will no
longer conform to the straight grain of
the wood. An allowance is made in the
standard at 3.2.1.10 for exposed end
grain. In order to maximize the value
of hardwoods in a stair that may be
partially covered in the center hightraffic
portion of the stair, a " hybrid "
tread construction may provide the
most value. Specifics can be found
on page 7, 3.2.1.4 and an illustration
showing the hardwood ends attached
to the edge of the less visible stock is
found on page 33 figure 89. Further
information on stairs that will be
completely concealed by carpet are
found on page 8, 3.2.1.7. This states
how many knots and whether finger
joints are allowed that would otherwise
not have been permitted on exposed
wood stair fabrications.

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Design Solutions - Fall 2021

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