This customer called us because their upstairs were cold in the winter and hot in the summer. They had ice damming every year, and they decided it was finally time to put a stop to it. They had a new baby sleeping in a room over the garage, and they didn't want to deal with a cold nursery this year. First-floor temperatures were okay in rooms with rugs, but the bare floors stayed cold all winter. Cold air fell like a waterfall from an old "whole-house" fan in the ceiling. The house is a West-facing 2100 square foot 4-bedroom split-level ranch in East Irondequoit, and was built in 1960.
We did a thorough evaluation of the house and found several issues contributing to the temperature problems and ice damming. The biggest issue is actually fairly common in split-level homes -- the split-level wall that runs the width of the house right at the stairwell has open wall cavities at the bottom (in the basement) that connect straight up to open wall cavities at the top (in the attic).
The air inside your wall cavities is warm; warm air rises. If that air can escape into the attic, it creates a vacuum, drawing your "paid-for" warm air up and out, pulling basement air up into your home, and sucking cold winter air into your basement from outside. All that extra warm air getting in to the attic was creating the ice damming.
We also found problems with the insulation levels, particularly in the garage ceiling with the bedrooms above it. Fiberglass batts in a floor will settle over time, leaving lots of air space. When air can circulate through insulation, it ceases to insulate.
We found that nothing was wrong with their furnace or thier duct system. There was plenty of heat, and it was being successfully delivered to where it belongs. The problem was in the home's ability to retain the heat.
Insulating without air-sealing should be a crime, and this house needed both. When a house has multi-level attics, we usually recommend sealing and insulating the wall cavity to stop the massive heat-loss. That's exactly what we did here, using rigid foam board. We also insulated and gasketed the attic access door, and installed a "David Lewis" insulated box over the whole-house fan. Pipe, wire, and vent penetrations in the attic-floor were sealed up with spray foam before a layer of insulation was blown in.
Half of this house is over the garage, and half is over a basement.
In the basement, we sealed the rim joists where where most of the outside air was getting in. The rim joist is at the top of the basement wall. It's where the kitchen floor above sits on the top of the cinderblock basement wall. We sealed the leaks with spray foam.
We were able to insulate the garage ceiling by filling the joist cavities with densely packed cellulose insulation. When cellulose is packed tightly into a cavity, it acts as both insulation and an air-barrier, eliminating the "convection loops" of air that steal the heat from the rooms above. As an added benefit, it's a great sound buffer. They can now open the garage door without waking the baby!
Building Expert: Mike Swanson
Problem: Cold Room Over Garage
Problem: Cold Floors
Problem: Upstairs Cold in Winter
Problem: Upstairs Hot in Summer
Problem: Drafty Whole House Fan
Solution: Seal Multi-Level Attic
Solution: Rim Joist Spray Foam
Solution: David Lewis Fan Cover
Solution: Dense-Pack Garage Ceiling