Your home is always exchanging heat and air
Comfort problems follow pathways
Heat naturally moves from warmer areas toward cooler areas. Air moves because of pressure differences. Moisture can travel with moving air. Comfort improves when insulation, air barrier, ventilation, and mechanical systems work together.
Three ways heat moves
1
Conduction
Heat moves through solid materials such as framing, drywall, metal, and glass.
Openings like these — around pipes, wires and light fixtures — let heated air leave the rooms below.
2
Convection
Heat moves with air. Warm indoor air escapes near the top of the home, drawing colder air into lower areas.
Why one room may be different
A hot or cold room may be influenced by low insulation, air leakage, blocked attic ventilation, duct leakage, limited HVAC airflow, sun exposure, a garage or addition below or beside the room, or several conditions occurring together.
Why an inspection matters
If the cause is uncontrolled airflow, insulation alone may not solve it. If the insulation is wet or contaminated, covering it is not a responsible solution. If ventilation is blocked, adding material can make the condition worse.
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You will hear the term R-value. It is simply a measure of how much a layer slows heat moving through it — a higher number means more resistance. Here is roughly what those numbers look like as depth in an attic.
Depth varies with the attic and the installation. Depth alone does not tell you how the attic performs.
Controlled ventilation is different from air leakage
Ventilation is intentional. Air leakage is uncontrolled. We reduce unwanted leakage while preserving the ventilation the assembly needs.
3
Radiation
Heat travels in waves. Sunlight heats the roof, and hot roof materials radiate heat into the attic.