Building Design and Construction Handbook - Merritt - Ventech!

WALL, FLOOR, AND CEILING SYSTEMS 11.111
or after they enter a doorway. Proper swing of door will not only smooth traffic
flow but also reduce wear and tear on the doors by decreasing impact loading on
the hardware from persons who lean on it to change directions.
Also, selection of entrance doors should take not only esthetics into account but
also traffic volume. The heavier traffic volume will be, the more rugged the doors
should be to withstand wear.
Water Exclusion at Exterior Doors. Exterior doors are subjected to all the effects
of natural forces, as are walls and windows, including solar heat, rain, and wind.
For ordinary installations, closed doors cannot be expected to completely exclude
water or stop air movement under all conditions. One important reason for this is
that clearances must be provided around each door. These are necessary to permit
easy operation and thermal expansion and contraction of doors.
Exterior doors, however, can be made less vulnerable to water penetration by
setting them back from the building face, or by providing overhead protection, such
as a canopy, marquee, or balcony. These measures also will help reduce collection
of snow and ice at door thresholds. In addition, provision of an entrance vestibule
is desirable, because it can serve as a weather barrier. Also, weatherstripping around
doors assists in preventing passage of water and air past closed doors.
At the bottom of a door opening for an exterior door is a sill (Fig. 11.60), which
forms a division between the finished floor on the inside and the outside construction.
The sill generally also serves as a step, for the door opening usually is raised
above exterior grade to prevent rain from entering. The top of the sill is sloped to
drain water away from the interior. Also, it may have a raised section in the plane
of the door or slightly to the rear, so that water dripping from the door will fall on
the slope. The raised section maybe integral with the sill or a separate threshold.
In either case, the rear portion covers the joint between sill and floor. In addition,
all joints should be sealed.
FIGURE 11.60 Typical paneled wood door.