Attic Too Hot? Why It Happens and How to Fix It
A hot attic is normal. A hot house is not. Here is how attic heat gets into your rooms and what actually stops it.
Why attics get so hot
On a sunny day the roof deck heats up and radiates heat into the attic. That is normal. The problem is when that heat gets into your living space or the attic cannot shed it. The usual causes:
- Too little insulation on the attic floor, so heat moves down into the rooms below. See how much insulation you need.
- Air leaks between the house and the attic (around lights, fans, plumbing and wiring holes, and the attic hatch) that let hot attic air in and cooled air out.
- Poor attic ventilation: blocked soffit vents, too few or mismatched intake and exhaust vents.
- Ducts in the attic that are leaky or poorly insulated, heating your cooled air before it reaches the rooms.
Signs your hot attic is costing you
- Upstairs rooms much hotter than downstairs
- AC running constantly in summer
- Ceilings that feel warm to the touch
- Rising summer energy bills
What actually helps
- Air seal first, then add insulation. ENERGY STAR recommends sealing air leaks and insulating together for the best results.
- Bring insulation up to the recommended R-value for your climate.
- Make sure intake and exhaust vents work and that insulation is not blocking the soffits (baffles help).
- Seal and insulate attic ducts.
A radiant barrier can help in hot, sunny climates, but it is not a substitute for insulation and air sealing. An insulation pro can measure what you have and recommend what is worth doing.
Common questions
Is it normal for an attic to be hot?
Yes. Attics in summer are often much hotter than outdoors. The issue is whether that heat reaches your living space, which insulation and air sealing control.
Will an attic fan fix a hot attic?
Sometimes it helps, but a powered fan can pull cooled air out of the house through leaks in the ceiling. Air sealing and insulation usually come first.
Does more insulation keep the house cooler in summer?
Yes. Insulation slows heat flow both ways, so it keeps summer attic heat out of the rooms below as well as winter heat in.
General information summarized from the public sources listed below. It isn't professional, medical or legal advice. A licensed professional who inspects your home can tell you what it needs.