The attic floor is the lid on the house
Attic Air Sealing & Insulation in Des Moines, IA
Close the gaps first, then add insulation to depth, so warm air stays downstairs.
- Free on-site estimates across the metro
- Written quote listing material, depth and R-value for each area
- Air leaks, damp spots and old wiring checked before anything is covered
Seal the Lid, Then Fill It
Attic air sealing and insulation is the most common upgrade we do in Des Moines, because the attic floor is where warm air escapes all winter. Heat rises through gaps around plumbing stacks, chimneys, light fixtures, bath fans, wall tops and the attic hatch, and the insulation lying on top does little to stop moving air. Sealing those gaps first, then adding insulation to depth, is what makes upstairs rooms comfortable and cuts the frost and ice that build up on cold roofs.
What the target is
Iowa's code table sets R-49 for ceilings in Climate Zone 5, which covers Polk, Dallas and Warren counties. Existing homes do not have to meet it, since the rule leaves remodels of one- and two-family homes out of scope, but it is the number we aim for. Older metro attics often have a few inches of matted fiberglass or settled cellulose, well short of that. Many newer attics are closer, but we still find thin spots at the eaves, around hatches and over bonus rooms.
Air sealing, spot by spot
We go through the attic and seal the top plates of interior walls, the chases around chimneys and flues (with fire-rated materials where heat is involved), plumbing and wiring holes, recessed light housings, bath fan boxes and the hatch. In houses built before 1940, a quarter of Des Moines' housing according to Point2Homes, we often find open wall cavities that run straight up from the basement; capping those tops is some of the best work we do.
Blown-in or foam?
On a vented attic with an open floor, blown cellulose or fiberglass over the sealed floor is usually the best value. Spray foam belongs on the roof deck when the attic holds ductwork or equipment, in vaulted ceilings with no room to vent, and on kneewalls and the floors behind them in story-and-a-half homes. We often mix the two: foam to seal the hard spots, loose fill for depth.
Ice dams and attic frost
Central Iowa gets real snow, about 36.5 inches in a typical Des Moines season according to Wikipedia. When warm air leaks into the attic, it melts snow on the roof, and the water refreezes at the cold eaves into ice dams. The same moist air can frost the underside of the roof deck. Sealing the attic floor and keeping baffles open at the eaves deals with both.
Ventilation and safety
We keep soffit vents clear with baffles, make sure bath fans vent outside instead of into the attic, keep clearance around chimneys and flues, and dam around the hatch so loose fill stays put. If we find vermiculite, which can contain asbestos, we stop and recommend testing before anyone disturbs it. Get a free estimate
What Attic Work Includes
The pieces of a typical attic job.
Attic floor air sealing
Top plates, chases, stacks, wiring holes and light housings sealed with foam, caulk or fire-rated material.
Blown-in top-up
Cellulose or fiberglass blown over the sealed floor toward R-49.
Baffles and eave work
Vent channels kept open so the roof can breathe and ice dams are less likely.
Hatch and pull-down stairs
Weatherstripped and insulated covers for the attic opening.
Roofline foam
Closed-cell or open-cell under the deck where the attic holds ducts or equipment.
Kneewalls and bonus rooms
Sealing and insulating the walls and floors around finished attic space.
Typical Attic Costs
| Job | Range (source) |
|---|---|
| Average attic insulation job | $1,000 to $2,700, about $1,800 average (HomeGuide) |
| Air sealing | $350 to $3,000 (HomeGuide) |
| Blown-in, attic | $0.90 to $2.40 per sq ft (HomeGuide) |
| Spray foam on the attic floor | $1,100 to $6,800 (HomeGuide) |
| Spray foam on the roof deck | $1,500 to $9,000 (HomeGuide) |
| Old insulation removal | $1 to $2 per sq ft (HomeGuide) |
Figures from HomeGuide's January 2026 attic guide. How much sealing there is, the depth you want, access and any removal change the total; the written estimate we give you is the price.
How an Attic Job Goes
1. Look and measure
We check depth, condition, venting, wiring and any signs of moisture or vermiculite.
2. Written plan
The quote lists sealing work, material, depth, target R-value and price.
3. Seal
Gaps and chases get closed before any new insulation goes down.
4. Insulate
Baffles go in, the hatch is dammed, and insulation is blown or sprayed to depth.
5. Check
We show you the finished depth and clean up.
Why Choose Us for Attic Air Sealing & Insulation
Sealing before filling
Gaps get closed first, not buried.
Depth you can verify
Depth rulers or photos show what was installed.
Vents respected
Soffit vents and bath fans are handled so the attic stays dry.
Attic Air Sealing & Insulation Questions
How much insulation should a Des Moines attic have?
Iowa's code table lists R-49 for Zone 5 ceilings. For blown cellulose or fiberglass that typically means well over a foot of depth, depending on the product.
Will new insulation stop ice dams?
It helps, but air sealing matters more. Ice dams start when warm air leaks into the attic and melts roof snow, so we seal first and keep the eaves vented.
Do I need to remove the old insulation?
Only if it is wet, moldy, contaminated by animals, or blocking air sealing. Dry, clean insulation can usually stay and be topped up.
How long does an attic job take?
Most single-family attics take a day. Older houses with a lot of sealing or removal can take longer.
Attic Air Sealing & Insulation Service Areas
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Get an Attic Air Sealing & Insulation Estimate
We will check your attic and send a written plan with the depth and price.