FAQ Knowledge Articles

Ultimate Double Hung Round Top Picture G2 (UDHRTPG2) and Ultimate Double Hung Round Top Transom G2 (UDHRTTRG2) products have minimum springline height dimension limitations due to how the bottom rail connects to the stile and manufacturing safety concerns. 

Therefore, certain round top shapes which do not have a springline height dimension are not available in these product types (i.e. RT1, RT7-8, RT17-18, RT29, RT31-32,and RT42-43 shapes). 

Available Picture and Transom shapes for these product types include RT2, RT6, RT9-10, RT21-26, RT30, RT33-34, and RT45-46.

However, there are minimum springline height limitations depending on round top shape and product type. 

For UDHRTPG2 units:
  • shapes with a continuous springline (i.e. RT2) have a minimum springline height of 4 55/64", and
  • shapes with a non-continuous springline (i.e. RT6) have a minimum springline height of 7 5/8". 
For UDHRTTRG2 units:  
  • shapes with a continuous springline have a minimum springline height of 3 23/32", and
  • shapes with a non-continuous springline have a minimum springline height of 6 1/2". 
The UDHRTPG2 unit uses a taller bottom rail than the UDHRTTRG2, per the Architectural Detail Manual.

For existing openings in which round top shapes are needed but not available in CUDHRTP-NG and UDHRTTRG2, Marvin recommends UCART product as an In-Sash alternative which is available in many of these shapes.  The UCART daylight openings are unlikely to align with UDHG2 product as these products are made with different frame and sash parts, but they are fairly close and accessories such as SDL bars can be aligned across these product types.