SINGLE PANE WINDOWS. Although all-season sunroom sales are growing, most sunrooms sold today are actually 3 Season Rooms. If you are looking for a maintenance-free room addition to your home, this structure can be built in just a few days. Most windows we install are single pane glass and there is no HVAC installed in the space. We use an interlocking roof panel connection system that allows for structural integrity, longevity and is leak resistant. The corners have welded seams and the material is backed by a Limited Lifetime Transferable Warranty from our manufacturer.