Garrison Style House

The characteristic overhang on a Garrison Colonial may have come about to provide a vantage point from which to fight off intruders. Or it may have been copied from the town houses built in Europe’s crowded cities to provide more living space on the second floor. 

Either way, this soffit-like overhang created a potential for cold air to migrate into the space between the first and second floors. This air infiltration will make the whole house more difficult to heat, as it pulls warmth into the first floor ceiling and second story floor.

Some modern Garrison colonials actually have ventilated coverings on the overhanging soffit, as if inviting cold air up between the floor joists. The overhang should be sealed air tight and insulated to keep heat from escaping. In retrofitting existing houses the soffit is sealed using 2” insulation board that is screwed into place then sealed using expanding foam and covered with the siding material.

The mistake of ventilating the overhang is made by assuming that the overhanging space is like the soffit at the roofline. The roof soffit material should generally be perforated to provide ventilation to the attic, but ventilating the overhang serves only to make the floor and ceiling cold.

Attics are not heated and should be sealed off from the living spaces of the home and then ventilated from the outdoors so that the inside and outside of the roof remain the same temperature – if the roof is warmer in some places than others due to air leaking into the attic from the house, winter snow will melt and then refreeze causing the dreaded “ice dam” that can get under the shingles and ruin the roof.  Of course, it also makes the beautiful icicles that hang down and sparkle in the cold sunlight.  

And if marauders do come…you’re ready!