If you’re looking for a lot of ventilation, but don’t want to sacrifice performance, take a good look Gerkin double hung windows . Our double hung windows are quite possibly the tightest double hung of any double hung made today.
The 4800 Double Hung features a patented "candy cane" operating jamb stop which seals the ends of the interlock rail and the face of the lower sash with perfection! No other double hung has it. The 4800 is quite possibly the tightest double hung of any double hung made today!
The 5800 Double Hung window was tested to be used in sizes up to 60" x 99". The air infiltration rate is an amazing .03!