Weather seal system for double hung window

A window for reducing moisture entry due to pressure differentials, the window having an interior side for facing toward an interior of a structure in which the window is installed and an exterior side for facing toward an exterior of a structure in which the window is installed, the window comprising:

• a window frame including a first jamb, a second jamb, a header, and a sill, the sill defining a bottom surface for placement on or adjacent a bottom frame member of a rough opening and defining a maximum sill height as measured from the bottom surface of the sill to a top surface of the sill, the sill forming a transition channel at least partially defined by a front surface, a bottom surface, and a back surface, wherein the bottom surface includes a sloped portion that slopes downwardly towards the front surface, and wherein the front surface is configured to transmit moisture out of the channel;
• an active sash that is moveable with respect to the window frame between an open position and a closed position, the active sash having a first side, a second side, a top, and a bottom;
• a primary sill seal configured to contact the sill and the sash when the sash is in the closed position to form a substantially water-proof and substantially air-tight seal;
• and
• a secondary sill seal configured to contact the sill and the sash when the sash is in the closed position to form an air-permeable water barrier, the primary sill seal and the secondary sill seal being arranged about the transition channel such that the transition channel exhibits a pressure substantially corresponding to an exterior of a structure in which the window is installed even when an interior of the structure and the exterior of the structure exhibit a pressure differential, wherein, when the sash is in the closed position with respect to the sill, the secondary sill seal contacts the front surface of the transition channel at a contact point that is closer to the active sash than a contact point between the primary sill seal and the back surface of the transition channel.

A window for reducing moisture entry due to pressure differentials, the window having an interior side for facing toward an interior of a structure in which the window is installed and an exterior side for facing toward an exterior of a structure in which the window is installed, the window comprising:

• a window frame including a first jamb, a second jamb, a header, and a sill, the sill defining a bottom surface for placement on or adjacent a bottom frame member of a rough opening and defining a maximum sill height as measured from the bottom surface of the sill to a top surface of the sill, the sill forming a transition channel at least partially defined by a front surface, a bottom surface, and a back surface, wherein the bottom surface includes a sloped portion that slopes downwardly towards the front surface, and wherein the front surface is configured to transmit moisture out of the channel;
• an active sash that is moveable with respect to the window frame between an open position and a closed position, the active sash having a first side, a second side, a top, and a bottom;
• a primary sill seal configured to contact the sill and the sash when the sash is in the closed position to form a substantially water-proof and substantially air-tight seal;
• and
• a secondary sill seal configured to contact the sill and the sash when the sash is in the closed position to form an air-permeable water barrier, the primary sill seal and the secondary sill seal being arranged about the transition channel such that the transition channel exhibits a pressure substantially corresponding to an exterior of a structure in which the window is installed even when an interior of the structure and the exterior of the structure exhibit a pressure differential, wherein the first jamb defines an first surface and the active sash defines a first side, the window further comprising:
• a primary jamb seal configured to contact the first surface of the first jamb and the first side of the active sash to form a substantially water-proof and substantially air-tight seal;
• and
• a secondary jamb seal configured to contact the first surface of the first jamb and the first side of the active sash to form an air-permeable water barrier,
• the primary jamb seal, the secondary jamb seal, the first side of the active sash, and the first surface of the first jamb defining a drain cavity in fluid communication with the transition channel of the sill and configured such that the drain cavity exhibits a pressure substantially corresponding to an exterior of a structure in which the window is installed even when an interior of the structure and the exterior of the structure exhibit a pressure differential.

A method of forming a window, the method comprising:

• coupling a sash to a window frame with a sill, the sash moveably coupled to the window frame, the sill having a first chamber in a first portion of the sill, the first chamber defined by a front side and a back side;
• attaching a first material to a bottom surface of the sash, the first material configured to form a substantially water-proof and substantially air-tight seal with the sash near the back side of the first chamber when the sash is in a closed position with respect to the sill;
• attaching a second material to the sash, the second material configured to form an air-permeable water barrier between the sash and the sill near the front side of the first chamber when the sash is in the closed position;
• and
• attaching a third material to the sash, the third material configured to form an air-permeable water barrier between the sash and the sill near an interior facing side of the window when the sash is in the closed position.