Double-Hung Windows

Our luxury double-hung hardwood windows feature two operable sashes or a custom operation based on your specification. Both the lower sash and the upper sash can be opened for efficient ventilation. Beautifully crafted with rich wood species, hardwood double-hung windows deliver versatile styling and optimal performance for your unique design.

Double-Hung Windows Data Sheet


Meeting Rail Latch

Oxidized bronze alloy. Located at the center of the meeting rail, the latch’s cam action manually draws the sash into a locked position.

Finishes: Oil-rubbed Bronze (US10B), Lacquered Red Bronze (US20A), White Bronze (US26D).


Standard: Ultralift 88L series 670 heavy duty tube / spring balances, Heavy Duty BSI, or Amesbury Group fully concealed block and tackle balances mortised into the stiles of the operable sash.

Custom: Traditional weight and chain or clock spring balance systems are available on a custom basis. Contact factory for more information

Sash Locks (Included for oversized units)

Oxidized bronze alloy at midpoint of sash stiles. Turning the side latch compresses the weather-strip and locks the sash at each jamb.

Finishes: Oil-rubbed Bronze (US10B), Lacquered Red Bronze (US20A), White Bronze (US26D).

Egress: Properly-sized units meet egress requirements using standard hardware configuration.

Optional Hardware

Custodial locks, sash restrictors.

Insect Screens

1" x 1/4" tubular extruded frames in anodized bronze, mill finish aluminum or custom color painted aluminum. Mesh of 18 x 16 screen cloth held with vinyl spline, available in charcoal finished aluminum, mill finish aluminum, stainless steel or bright brass. Maximum width of screen mesh is 72". Wood-framed screens are available.


All glazing is per project specifications. Duratherm can accommodate most configurations and make-ups from 1/8" single glazed to a maximum of 1 3/4" security glass.

Clear glass opening: Unit height minus 7 3/4", unit width minus 6 3/4".


Double continuous extruded silicone flap gasket set in rebate around the perimeter of the sash. Engaging the lever handle compresses the weather-strip to ensure a tight seal.


The minimums and maximums shown are intended as guidelines. For applications that exceed these ranges, please contact the factory for assistance.


Minimum: 18”

Maximum: 72"


Minimum: 36”

Maximum: 96"


Based on:

20" clear width

24" clear height

5.7 sq ft clear opening

Minimum unit width: 25"

Minimum unit height: 68"

To meet egress requirements:

At minimum unit width of: 25", height must be at least: 68"

At minimum unit height of: 68", width must be at least: 25"

Frame Depths

Standard: 6 1/4”

Minimum*: 6 1/4”

Maximum: 10”

Static Air Infiltration:
ASTM E283 cfm/ft2 @ 1.57 psf

Allowed 0.10 Test Result 0.007

Water Infiltration:
ASTM E547-cyclic ASTM E331-static at 8 psf

Allowed 0.0 Test Result 0.0

Load Deflection:
ASTM E330 10 sec at +60 and -60 psf


Sash Torsion:
AAMA/WDMA/CSA 101 / I.S.2 / A440


Vertical Deflection:
AAMA/WDMA/CSA 101 / I.S.2 / A440


Forced Entry:


Thermal TransmissionResults

Center of Glass:

ASTM C-236 U-value using Viracon VE1-2M Low E glass and Lawrence Berkeley Laboratories Winow 5.2 analysis program.

1": 0.29 with Argon: 0.24

Total Unit:

1": 0.34 with Argon: 0.30

Hurricane ImpactResults

Large Missile Impact and Cyclical Air Pressure:

- ASTM E1996-05, ASTM E1886-05

- Tested at 42 psf

- Wind Zone 3, not including Dade County, FL

- Missile Level D

Note: Contact factory for size limitations

and detail modification required for

hurricane certified units.


Exterior Wood Species

  • Cypress

  • Honduran Mahogany

  • Jarrah

  • Redwood

  • Sapele Mahogany

  • Spanish Cedar

  • Teak

Interior Wood Species

  • Ash

  • Cherry

  • Douglas Fir

  • Maple

  • Red Oak

  • Cypress

  • Honduran Mahogany

  • Sapele Mahogany

  • Spanish Cedar

  • Teak

  • White Oak


Dry Glazing

Specially developed extruded silicone gasket sets the glass by compression. Our proprietary system is long-lived, low maintenance and water resistant.

Wet Glazing

Our special silicone wet glazing compound bonds to the glass for long-lived sealing. Plus, our continuous extruded silicone weatherstrip runs around the frame perimeter and the seal is not compromised by seasonal expansion and contractions of the sash and frame.