Historic Preservation - Technical Procedures
Unsticking A Wood Double-Hung Window Sash
Hspg Prepared For Nps - Sero
Doors And Windows
Unsticking A Wood Double-Hung Window Sash
UNSTICKING A WOOD DOUBLE-HUNG WINDOW SASH
A. This procedure includes guidance and procedures required
to inspect and loosen a wood sash.
B. A wood window sash can bind or stick for many reasons
including: window nailed shut; accumulation of paint
and/or dirt; humidity causing wood expansion; bowed
members; weatherstripping too tight; or building
settlement. NOTE: Some sash were fixed, installed
without operable parts such as single hung sash.
C. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:
1. Safety Precautions
2. Historic Structures Precautions
4. Quality Assurance
5. Delivery, Storage and Handling
6. Project/Site Conditions
7. Sequencing and Scheduling
8. General Protection (Surface and Surrounding)
These guidelines should be reviewed prior to performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).
1.02 SYSTEM DESCRIPTION
A. A window sash in proper working order is freely
sliding, has balancing and moving apparatus in
working order, and has operable sash lock(s) to
deter air infiltration. In addition, operable sash
often have weatherstripping and adjustable interior
stops to allow for seasonal swelling and shrinkage.
A. Replacement stock is available for stop and parting
beads. Be sure replacement is an exact duplicate of the
original. Milling a new piece may be required.
A. A device for cutting paint seals such as "Window zipper"
(Red Devil), or approved equal; available at hardware
B. A rubber mallet and block of wood for jamb and stop
C. Utility knife for cutting paint seals
D. Paint scraper
E. Wide putty knife or "window zipper" to break paint seal
F. Screwdriver and screws to tighten jamb into place
G. Hand soap or household paraffin for waxing the stop and
H. Flat steel pry bar to loosen sash from outside
I. Carpenter's nippers to remove nails
J. 1" chisel to scrape paint in channel
M. Nail to secure sash cord/chain
N. Soap and water
A. Determine if sash is an operable design and not fixed.
3.02 ERECTION, INSTALLATION, APPLICATION
A. The sash may be nailed shut:
1. Check around general area of sash for the
presence of any nails.
2. If sash is nailed shut with finish nails, drive
them completely through with nailset.
3. If large headed nails were used, pull them out with
carpenter's nippers being careful not to damage
B. The sash may be painted shut:
1. Break the paint seal between the stops and the
2. Use a "window zipper" or a wide putty knife with a
3. Do this on the inside and outside of the window.
4. CAREFULLY insert a heavy screwdriver between the
sash rail and jamb at groove for sash cord. TAKE
CARE NOT TO MAR OR DAMAGE FINISH AND/OR SASH.
5. Work at both sides of jambs to loosen sash.
6. If window still will not open, use a pry bar on the
outside of the sash. TAKE CARE TO PROTECT THE SASH
AND SILL FROM DENTS WITH A WIDE PUTTY KNIFE OR WOOD
BLOCKING. INTENSE PRESSURE ON A SMALL AREA SUCH AS
THAT FROM A SMALL SCREWDRIVER OR FLAT PRYBAR CAN
GOUGE OR DENT THE WOOD.
C. If the window has been opened but is difficult to move:
1. Remove any dirt from the channel, stops,
weatherstripping and parting bead.
2. Remove any globs of dried paint from the stops and
parting bead with a 1" chisel and sand edges after
paint is removed.
3. Lubricate stops and parting bead with hand soap or
D. If sash still binds, determine the point of friction:
1. If the friction occurs along the jamb; with a
hammer, tap a wood block approximately 6" long 5 or
6 times against the back of channel to force the
jamb back into place. If this allows the sash to
move more freely, screw the jamb into the jack stud
behind at 3" intervals around the point of
2. If the friction occurs with the stop, use the same
procedure as above, but with less force and do not
drive screws into the stop.
E. Problems such as humidity, paint build-up, or
weatherstripping applied too tightly require more
1. If the window is easily operable during dry times
of the year but will not work properly during humid
times, then humidity is to blame. Repair should
not be attempted until the time of year with
highest humidity. See section 1.02 A; If the
window has adjustable interior stops, it may be
desirable to refurbish and restore them to use.
a. The sash must be carefully planed and should
be done only once.
b. Take off as little of the sash surface as
possible to make the window operable during
all times of the year.
c. Remove the sash as described below with the
problem of paint build-up.
2. If the sash binds because of the build-up of layers
of paint, remove the paint. To remove the paint
properly, first remove the sash:
a. Remove the stop; break the paint seal between
the inside stop and the window frame. Pry the
stop away from the frame with a stiff putty
knife, small pry bar, or wide chisel.
b. Pull one side of sash out to expose the sash
c. Remove cord/chain from both sides of sash.
Temporarily secure the end of cord/chain with
a nail through the cord/chain and across the
pully hole so that it will not fall into the
pocket. Lift out the sash.
d. Remove loose paint from all members by
sanding, and repaint.
e. Reinstall parting bead and sash.
f. When reinstalling inner stop, check
position in relation to the sash one nail
at a time so that sash will fit snugly in
place and will not bind or rattle.
g. To remove the upper sash - lower the sash;
remove the parting bead from the top down; at
midpoint, raise the sash and continue. Follow
the same procedure as above.
3. If weatherstripping applied too tightly is
suspected to be the problem, removal and
reinstallation of weatherstripping will be
END OF SECTION