Keep the heat off the roof
Attic Insulation & Ice Dam Prevention in Oshkosh, WI
Air sealing, baffles and loose fill to depth, in that order.
- Free on-site estimates
- Written quote by area with R-values
- Damp basements and roof leaks flagged before work
Why Ice Dams Form
Attic insulation and ice dam prevention go together because ice dams are an attic problem showing up on the roof. Warm air leaks from the living space into the attic through holes in the ceiling. That air warms the roof deck and melts the snow on it. The meltwater runs down to the eaves, which hang out past the warm walls and stay cold, and it refreezes there. Over a few days the ice builds into a ridge that backs water up under the shingles and into the house.
Seal, then insulate
The fix is to keep the roof deck cold. We seal the bypasses through the attic floor first: plumbing stacks, wiring holes, light fixtures, the chimney chase, duct boots and the tops of interior walls. We weatherstrip and insulate the hatch, and we put baffles at the eaves so air can flow from the soffits to the roof vents without being blocked by the new insulation.
How much insulation
The Insulation Institute's summary of Wisconsin's code lists R-49 for ceilings in Zone 6, which includes Winnebago County. HomeGuide rates loose cellulose at R-3.1 to R-3.8 per inch and blown fiberglass at R-2.2 to R-2.9, so R-49 is well over a foot deep. Most attics in older Oshkosh homes have far less than that.
Bath fans and moisture
Bath fans that dump into the attic, rather than outdoors, add moisture that frosts on nails and roof sheathing in winter and drips in a thaw. We check where every fan and dryer vent ends up and point out any that need to be rerouted.
What the Attic Work Includes
Each step keeps heat and moisture out of the attic.
Ceiling bypass sealing
Holes and gaps in the attic floor sealed with foam, caulk and blocking.
Hatch and stairs
Weatherstripped and insulated.
Eave baffles
Keep soffit vents clear so the deck stays cold.
Loose fill to depth
Cellulose or fiberglass to the R-value on the quote.
Foam in slopes and kneewalls
Where loose fill cannot reach full depth.
Published Attic Insulation Costs
| Job | Range and source |
|---|---|
| Attic insulation, average 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 attic guide) |
| Spray foam on the attic floor | $1,100 to $6,800 (HomeGuide) |
| Spray foam on the roof deck | $1,500 to $9,000 (HomeGuide) |
| Spray foam, attic (existing home) | $2,500 to $12,000 (Fixr) |
| Old insulation removal | $1 to $2 per sq ft (HomeGuide) |
National figures from HomeGuide's attic guide (January 2026) and Fixr's spray foam guide (2025). The amount of air sealing, target depth, access and any removal set your price. We inspect the attic and the written estimate is what you pay.
How the Attic Job Goes
1. Inspect
Depth, bypasses, frost, mold and fan exhaust checked.
2. Quote
Sealing, baffles, depth and R-value listed.
3. Seal
Bypasses sealed and hatch insulated.
4. Insulate
Loose fill blown level to depth, with markers.
Why Choose Us for Attic Insulation & Ice Dam Prevention
Sealing listed separately
You can see it is part of the job.
Vents protected
Baffles at every eave bay that needs one.
Depth you can check
Rulers on the trusses.
Attic Insulation & Ice Dam Prevention Questions
Will attic insulation stop my ice dams?
Sealing and insulating removes the main cause, heat reaching the roof deck. Roof design and gutters also play a part, and we look at those.
How much does attic insulation cost?
HomeGuide puts a typical attic job at $1,000 to $2,700, about $1,800 on average, with air sealing at $350 to $3,000.
Should I use heat cables instead?
Heat cables treat the symptom at the eaves. Sealing and insulating the attic deals with the cause.
Do I need to remove my old insulation?
Only if it is wet, moldy, soiled or blocking the sealing work.
Attic Insulation & Ice Dam Prevention Service Areas
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Get an Attic Insulation & Ice Dam Prevention Estimate
Had ice dams last winter? Call before the snow comes back.