The Theory Behind Thermal Break Aluminum Extrusion Shapes
Step 1	A low thermal conductive material (polyurethane) is poured into a special pocket in the aluminum extrusion. This hardens to form a strong, hard, high density, durable thermal break.
Step 2	The underside of the pocket containing the connected aluminum wall is then removed leaving the hardened low conductive polyurethane as the only bond between the outside and inside walls of the frame member. Heat and cold transmission is virtually stopped at this point. This polyurethane in no way adversely affects the structural integrity of the aluminum extrusion.
Step 3	Since aluminum is a conductor of heat flow, thermal break now stands alone as a barrier against heat flow, dramatically reducing the buildup of condensation on the interior frame. This barrier works effectively to help keep cold out in the winter and heat out in the summer.
Step 4	Recently some extruders have adopted a different technique called " Skip Debridging". Skip Debridging refers to the method of not removing (skipping) at certain points, sections of the aluminum bridging from the underside after the polyurethane has been poured and cured. This pattern usually leaves behind approximately 1"-2" of aluminum bridging for every 18"-20" of full de-bridging. This was developed to allay some fears in the market if a catastrophic fire were to destroy the thermal barrier product; some level of structural integrity in the frame structure would remain. The heat conductivity and condensation resistance loss incurred in a skip de-bridged product is believed to be quite small in relation to a fully de-bridged product, thus having very little effect on the thermal performance or condesation resistance. Either method constitutes a "Thermally Broken Product".