Drafty Rooms? A DIY Checklist: Seal First, Then Insulate

The Short Answer

A drafty room is usually an air-leakage problem first and an insulation problem second. Cold air coming in around windows, doors, outlets and the attic hatch makes a room feel colder than its thermostat reading, and thick insulation does little if air moves straight through it.

So the order matters: find the leaks, seal them, then add insulation where it is thin. The EPA estimates that air sealing plus insulation can save an average of 15% on heating and cooling costs (11% of total energy costs). Most of the sealing is cheap, DIY work.

Step 1: Find the Leaks

ENERGY STAR’s DIY guide points out that in most homes the most significant air leaks are hidden in the attic and basement. The drafts you feel in a room are often the other end of those leaks. Check both the room and the house:

• In the room: window sashes and frames, exterior doors, baseboards, outlets and switches on exterior walls, and any recessed lights.
• In the attic (ENERGY STAR’s list): behind and under kneewalls, the attic hatch, wiring and plumbing holes, dropped soffits open to the attic, recessed lights and the furnace flue or duct chase.
• How: on a windy day, move a lit incense stick around the edges of each suspect spot. Smoke that is pushed sideways marks a leak.

Step 2: Seal the Room

• Window and door frames: caulk fixed cracks around trim; weatherstrip the parts that move. Our door weatherstripping guide covers which seal goes where.
• Outlets and switches on exterior walls: foam gaskets fit behind the cover plates. The Department of Energy’s Building America guide says they may provide some air sealing and sound insulation benefit. Turn the circuit off first and verify power is off with a tester before you remove a plate.
• The attic hatch: weatherstrip its edges and add rigid foam on top. See how to seal an attic hatch.

Step 3: Film the Worst Windows for Winter

Old single-pane or loose windows are prime draft sources, and replacing them is expensive. A shrink-film kit is the cheap stopgap: ENERGY STAR says these covers are inexpensive, reduce drafts, help the house feel warmer during winter months. You stick double-sided tape to the frame, apply the film and use a hair dryer to tighten it. It comes off in spring. Our kit picks are in best window insulation kits.

No authoritative source puts a percentage on the energy saving, so treat it as a comfort fix for the worst windows rather than a whole-house strategy. More in our windows guide.

Step 4: Check the Attic Insulation

Once the attic floor is sealed, check how much insulation is up there. ENERGY STAR’s quick test: if it is just level with or below your floor joists, so you can easily see them, you should add more. Its recommended levels:

Source: ENERGY STAR recommended insulation levels. ENERGY STAR’s project guide recommends you complete an attic sealing project before doing this project.

If You Add Insulation Yourself

• Blown-in insulation needs a blowing machine; ENERGY STAR notes some home improvement stores offer rentals.
• Wear safety glasses, gloves and a mask. ENERGY STAR’s DIY guide recommends an OSHA-approved particulate respirator or a double-strap dust mask.
• Keep all insulation at least 3 inches away from recessed “can” lights unless they are rated IC (insulation contact).
• Never cover soffit vents; keep a clear path for air at the eaves.
• Stop and call a professional if you find vermiculite, knob-and-tube wiring, or damp or moldy materials. Our attic air sealing guide covers when to hire out and what it costs.

What This Costs

ENERGY STAR rates sealing and film projects at the low end of its cost scale ($ means under $100), and DIY attic insulation in the middle. Caulk, foam tape, outlet gaskets and a couple of window kits typically fit in a modest budget; a full attic top-up is the expensive part. If your state or utility runs an insulation program, check it before buying materials, because some cover most of the cost.

What We’d Buy

We may earn a commission if you buy through these links, at no extra cost to you. Products are chosen on published specifications; we do not test them in-house (how we choose).

Frost King V443/4 Vinyl Foam Tape (4-pack)

Self-adhesive foam for window sashes, door frames and the attic hatch.

Check price on Amazon

Outlet Insulator Foam Gaskets 50-Pack

Fit behind outlet and switch plates on exterior walls. Turn the power off first.

Check price on Amazon

3M Indoor Window Insulator Kit

Shrink film for the draftiest windows over winter.

Check price on Amazon

Frequently Asked Questions

Why are some rooms in my house so drafty?

Usually air leakage: gaps around windows, doors, outlets and the attic hatch, often connected to bigger leaks in the attic and basement. Rooms over garages or under attics are especially prone.

Should I air seal or insulate first?

Air seal first. ENERGY STAR recommends completing attic air sealing before adding insulation, because insulation does not stop air moving through gaps.

Do outlet gaskets really help?

A little. The Department of Energy's Building America guide says foam gaskets may provide some air sealing benefit. They are cheap and quick, but bigger leaks are usually elsewhere.

How much attic insulation do I need?

ENERGY STAR recommends R49 in climate zones 2 and 3 and R60 in zones 4 to 8 for an uninsulated attic. If you can easily see the tops of the floor joists, you need more.

Does window shrink film work?

ENERGY STAR says it is inexpensive, reduces drafts and helps the house feel warmer in winter. There is no reliable figure for the energy saved, so use it on the worst windows.

Related Guides

• Electric blanket vs space heater — the cheaper way to stay warm at night
• Attic air sealing cost — when to hire a pro
• Door weatherstripping — sealing exterior doors
• Drafty basement — the bottom of the stack
• Home energy audit checklist — a two-page printable
• Space heater cost calculator — what one costs per hour and per month
• Best window insulation kits and draft stoppers — the products, compared

Sources

• ENERGY STAR: Methodology for estimated savings
• ENERGY STAR: DIY guide to sealing and insulating (PDF)
• ENERGY STAR: Attic air sealing project
• ENERGY STAR: Attic insulation project
• ENERGY STAR: Recommended insulation R-values
• ENERGY STAR: Plastic over windows
• ENERGY STAR: DIY checks and inspections
• Building America Solution Center (DOE): Air seal electric outlets and switches