Insulation · Attic loose fill
Attic insulation that starts with the attic you have.
A vented attic performs best when the ceiling plane is sealed, ventilation paths stay open and loose-fill insulation is installed evenly to the specified depth. Thermal Shop first looks at accessible conditions, then recommends fiberglass or cellulose based on the existing material, required performance, access and project goals.
At a glance
- Where
- Vented attic floors, over the ceiling
- Materials
- Loose-fill fiberglass or cellulose
- Comes first
- Air sealing and open ventilation paths
- Installed to
- The depth the product and the specification call for
What it is
Loose-fill insulation is blown through a hose from a machine in the truck and spread across the attic floor, over and between the ceiling framing, to an even depth.
In a vented attic, the ceiling is the line between the house and the outdoors. The insulation sits on that line, so the air leaks, penetrations and eave details at the ceiling matter as much as how deep the insulation goes.
Before more insulation goes in
More depth is not the first answer in every attic. Existing insulation should be clean, dry and suitable to remain. Accessible air leaks, bath-fan terminations, recessed lights, flues, attic hatches and soffit ventilation all deserve attention before a top-off or re-blow is scoped.
Some conditions call for the appropriate specialist before insulation work continues:
- Mold or moisture damage
- Active pests
- Roof leaks
- Unsafe wiring
- Suspected asbestos or vermiculite
- Structural defects
We can assess the insulation work once those are addressed.
How it is installed
Look at the attic
Check the existing material and its depth, the accessible air leaks, the ventilation at the eaves, and anything that needs another trade first.
Seal and prepare
Seal the accessible gaps and penetrations in the ceiling, keep safe clearances at flues and fixtures, and set baffles where the soffit airflow needs protecting.
Blow to the specified depth
Install the loose fill evenly across the floor to the depth the product's bag chart and the job specification call for.
Check and mark
Check coverage and depth before leaving the attic, and mark the installed depth.
Where it fits
- Vented attics over finished ceilings
- Attics with thin, settled, or uneven insulation
- Attics re-blown after the old material comes out
- New homes, once the ceilings are hung
Fiberglass or cellulose?
Both are loose-fill materials we recommend, depending on the attic. Neither is the right choice everywhere.
| Consideration | Loose-fill fiberglass | Cellulose |
|---|---|---|
| What it is | Lightweight fiberglass blown as loose fibers | A denser loose fill made primarily from treated recycled paper fiber |
| How it goes in | Blown evenly across open attic floors | Blown across the floor, where it settles into irregular areas |
| Depth and coverage | Set by the exact product's bag chart and the project specification | Also product-specific: depth, coverage and preparation come from its bag chart and the specification |
| What it does not replace | Deliberate air sealing, safe clearances, ventilation detailing, or a sound roof | Deliberate air sealing, safe clearances, ventilation detailing, or a sound roof |
The installed target comes from the selected product's documentation and the job specification, and we set it once the exact product is known.
A complete attic system
Each part depends on the others. Deep insulation still underperforms over an open air path or a blocked vent.
- Ceiling air barrier
- The ceiling and its seals separate the house from the attic. Air leaking through it carries heat and moisture past the insulation.
- Top plates and penetrations
- Gaps at the tops of walls, wiring and plumbing holes, and chases are sealed where they can be reached, before insulation covers them.
- Insulation depth
- An even layer at the specified depth, without thin spots at the edges or around obstructions.
- Baffles and soffit airflow
- Baffles keep insulation out of the intake vents at the eaves, so air can move under the roof deck.
- Attic access
- The hatch is part of the ceiling, so it is sealed and insulated with the rest of it.
- Flues and fixtures
- Chimneys, flues, and some recessed lights need a safe clearance or an approved dam, not insulation packed against them.
Built to the assembly. Installed for local inspection.
Thermal Shop works from the approved plans, the selected product documentation and the requirements adopted for the project's jurisdiction. We document installed depth or assembly details and coordinate questions before finishes cover the work.
Photos from our installers
Start your insulation project
Homeowners
Request a Free EstimateHow it works for homeowners
- Request a free estimate and tell us what you're working on and where.
- We look at the attic, the house, or the concern first, then recommend the material and give you options.
- We install the work you approve and clear the work area when the install is done.
Contractors
Request a BidHow it works for contractors
- Request a bid with your plans, specs, and the work you want priced.
- Insulation is priced on its own bid, separate from gutters and shelving.
- We schedule around site readiness and inspections, and clean up the work area when the install is done.