The new window frames required a "thermal break," a gap, between the inside and outside edges.
In this case plastic spacers should be used to create thermal breaks between the inner and outer sections of the frame.
Modern aluminium window frames are typically separated by a thermal break made of a polyamide.
There are several ways to compensate for this heat loss, the most common way being the addition of thermal breaks.
Wood is a good insulator, thereby reducing heat transfer at the widely spaced thermal breaks in post-frame systems.
Condensation accumulation on the inside wall surfaces at thermal breaks is practically eliminated.
The frame should have thermal breaks built to help with energy conservation and heat retention.
Furthermore, IFAs have an optional thermal break for cold- and hot-weather climates.
Another method is using insulated lumber framing for a thermal break inside the wall.
One is a lack of the proper thermal break between the outside window and inside frame.