Air sealing

[Drew]

When our home was built in 1989, the builder placed insulation in the garage ceiling, saying it would help if we ever planned to convert the attic to a bedroom.

A few years ago we had the attic finished but the room seems to be cool and the floors are even colder.

Do you have any ideas why this room is cooler than the other bedrooms and what we can do to change it?

[home improvement guy]

The room above the garage as well as the walls and ceilings of the rest of the home are most likely insulated to the minimum allowed by code at that time. Over the years as energy costs have increased, the standards for insulating and air sealing a home have changed and are now a priority for both builders and buyers.

In the early 1970s and '80s, energy conservation was low on the builder's priority lists and air sealing was most likely never considered. Why is air sealing important? If the walls and ceiling are insulated to codes and then cold or hot air passes through or around the insulation, the furnace and air conditioner will work harder and longer to accommodate for the unconditioned air in the indoor environment.

Air sealing should be performed after the home is framed and insulated and then inspected by a third party before the hanging of the drywall. Some of the products that are used to stop airflow are cardboard, drywall, house wrap, expanding foam insulation, etc. What I think has happened to your house is that the insulation in the garage ceiling was installed before the garage ceiling was covered with drywall.

The installers simply stapled the insulation to the bottom of the ceiling joists, leaving a large air gap between the top of the insulation and the bottom of the attic's flooring. Airflow from the soffits to the attic now enters each gap and cools or warms the bedroom's floors.

If accessible, the gaps at the ends of the garage's ceiling joists can be blocked with additional insulation and cardboard or any type of air barrier.

A preferred improvement would be to fill the gap above the insulation with loose fill, blown-in insulation by either drilling through the bedroom floors or by running a long blower hose in between each joist and filling the gap as the hose is slowly removed.

In addition to being exposed to unconditioned air, a heat register may have been added to the room from the existing ductwork. The ductwork is designed for the cubic feet of the existing living area. By adding a heat register, the furnace blower may not be able to move enough air for the additional room. Have the furnace inspected further by a qualified HVAC (heating venting air conditioning) technician.