Garage Construction Project

Insulation Execution

15 min read

Implementation Plan

Overall Strategy ✅ DECIDED: Complete Building Envelope (Both Levels)

Sequencing Decision: Insulate entire building envelope (main garage + upper level) in one phase before drywalling either level.

Benefits:

  • Single material order with bulk pricing
  • One blower rental for all blown insulation
  • Maximum heating efficiency for winter construction work
  • Complete all messy work before clean finishing work
  • One insulation inspection covering entire building

Timeline: Late Winter/Early Spring 2026 (after all rough-in work complete)

Phase 1: Complete Building Envelope (Main Garage + Upper Level)

Step 1: Planning & Decisions (Before Framing Complete)

  1. Review Insulation Strategy and select approach
  2. Confirm main garage wall insulation: R-21 batts (DIY) ✅ DECIDED
  3. Confirm main garage ceiling insulation: Blown cellulose R-49 ✅ DECIDED
  4. Confirm upper level sloped roof: Blown cellulose R-49 (recommended)
  5. Confirm upper level knee walls (if any): R-21 batts
  6. Determine DIY vs. contractor for blown insulation (both levels)
  7. Calculate total materials needed for BOTH levels
  8. Order materials or schedule contractors

Step 2: Preparation (After Framing, Before Insulation)

  1. Photograph all framing, electrical, plumbing penetrations (BOTH levels)
  2. Verify all electrical boxes and wiring are complete (BOTH levels)
  3. Check for air leaks around rough openings (BOTH levels)
  4. Measure and confirm stud/joist spacing and depth (BOTH levels)
  5. Measure upper level sloped roof area and rafter spacing
  6. Identify any knee walls in upper level that need insulation
  7. Set up work area, PPE, and tools
  8. Set up scaffolding/ladders for upper level access

Step 3: Air Sealing (FIRST - Most Critical)

Main Garage Level:

  1. Rim joists: Spray foam all gaps between sill plate and rim joist
  2. Top plates: Spray foam where walls meet ceiling (before ceiling insulation)
  3. Bottom plates: Spray foam at wall/floor junction
  4. Electrical boxes: Install foam gaskets or putty pads
  5. Penetrations: Spray foam around all pipes, wires, HVAC penetrations
  6. Window/door rough openings: Spray foam gaps (low-expansion foam)

Upper Level: 7. Knee wall backs: Air barrier critical if any knee walls 8. Rafter bays: Spray foam at ridge (if vented assembly with baffles) 9. Top plates of knee walls: Seal before insulation 10. Upper level penetrations: Any skylights, vents, electrical penetrations 11. Attic hatch/access: Weatherstrip and prepare for insulation

  1. Allow to cure: 1-2 hours before insulating

Step 4: Main Garage Wall Insulation (R-21 Batts - DIY)

  1. Start at one corner, work systematically
  2. Measure and cut batts to fit each stud bay
  3. Split batts around electrical boxes and wires (don’t compress behind)
  4. Install with kraft facing toward interior (warm side)
  5. Staple facing flanges to studs (inset, not face)
  6. Use unfaced batts or split faced batts around boxes
  7. Friction-fit pieces in odd-shaped areas
  8. Fill top and bottom of each bay completely
  9. Check for gaps and compressions
  10. Photograph each wall section for records

Step 5: Blown Cellulose Insulation (R-49) - Main Garage Ceiling + Upper Level Sloped Roof

CRITICAL DEPENDENCY: Blown-in cellulose insulation REQUIRES drywall to be installed on the ceiling first! The insulation will be blown into the closed ceiling cavity through drilled holes, then patched.

Drywall Requirements:

  • Main garage ceiling: Fire-rated drywall (Type X, 5/8” thick) required for fire separation between garage and loft above
  • Stairwell walls: Drywall on 2x4 framed stairwell/mechanical room enclosure (provides enclosed stairwell for fire separation)
  • Upper level ceiling: Standard 1/2” drywall acceptable
  • Cost difference: Minimal (~$2-3 more per sheet for Type X), but critical for code compliance

Fire-Rated Door Required

A 20-minute fire-rated, self-closing door is required at the top of the stairwell to complete the fire separation between garage and habitable loft. Standard interior doors are NOT fire-rated. See Structure & Fire Safety for details.

Important: Do BOTH main garage ceiling AND upper level sloped roof in same day with same blower rental!

Option A: DIY Dense-Pack Installation (Both Levels)

Prerequisites (MUST be complete first):

  • Type X fire-rated drywall (5/8”) installed on main garage ceiling
  • Standard drywall (1/2”) installed on upper level ceiling

Main Garage Ceiling Preparation (960 sq ft):

  1. Mark stud locations on drywall with pencil
  2. Mark drilling pattern: 2 holes per joist bay (16” apart)
  3. Calculate hole spacing: ~24” between rows
  4. Cover/protect recessed lights if any

Upper Level Sloped Roof Preparation: 5. Install vent baffles (Raft-R-Mate) in ALL rafter bays BEFORE drywall if vented assembly

  • Baffles maintain 2” air channel from soffit to ridge
  • Critical for preventing moisture problems in vented roof
  1. If unvented assembly: skip baffles, blow full depth to ridge
  2. Mark rafter locations on installed drywall
  3. Mark drilling pattern for each rafter bay

Dense-Pack Blowing Process (Both Levels): 9. Rent insulation blower with dense-pack tube attachment ($45/day, often FREE with 20+ bag purchase) 10. Drill 2” holes in drywall at marked locations 11. Load cellulose bags (~37 bags main + 30-50 bags upper = 67-87 total) 12. Start with main garage ceiling (easier, practice first) 13. Insert dense-pack tube into drilled hole, seal around tube 14. Helper feeds bags continuously while operator controls pressure 15. Fill each cavity until firm resistance felt (3.5 lbs/cubic ft density) 16. Move to upper level sloped roof 17. Work from bottom to top of each rafter bay 18. Check for proper density (should feel firm when pressed) 19. Return blower rental same day 20. Patch all drilled holes with drywall compound 21. Sand patches smooth when dry 22. Prime and paint patches to match ceiling

Time Required: 6-10 hours total for both levels (with helper)

Option B: Professional Dense-Pack Installation (Both Levels)

  1. Prerequisites: Install Type X drywall on main garage ceiling and standard drywall on upper level ceiling BEFORE scheduling insulation
  2. Get 2-3 quotes specifying BOTH levels and dense-pack method (see contractor recommendations)
  3. Verify quote includes: main ceiling (960 sq ft) + upper sloped roof (TBD sq ft)
  4. Confirm quote includes drywall hole patching, sanding, and priming
  5. Verify R-49 specification for both areas in contract (3.5 lbs/cubic ft density)
  6. If vented assembly: confirm contractor will install vent baffles BEFORE drywall
  7. Schedule install after air sealing, wall insulation, and ceiling drywall complete
  8. Be present for install to answer questions
  9. Inspect density (should feel firm) and coverage before final payment
  10. Get documentation (material brand, R-value achieved, square footage, density)

Step 5a: Upper Level Knee Walls (If Applicable - R-21 Batts)

If your upper level has knee walls (short walls where sloped roof meets floor):

  1. Install R-21 batts in knee walls (same as main garage walls)
  2. Kraft facing toward warm side (interior of loft)
  3. Air seal behind knee walls (critical for performance)
  4. Consider rigid foam air barrier on back side of knee walls

Step 6: Quality Checks (Both Levels)

  1. Check for compressed insulation areas (walls and ceilings)
  2. Verify no gaps at top/bottom plates (all levels)
  3. Confirm vapor barrier facing correct direction (if batts)
  4. Verify blown insulation depth meets R-49 (13-14”) at multiple points
  5. Check vent baffles are properly installed (if vented assembly)
  6. Verify no insulation blocking soffit vents or ridge vent
  7. Photograph all completed areas (both levels, multiple angles)
  8. Update building plans with insulation specs for both levels

Step 7: Wall Drywall Preparation (Both Levels)

  1. Ensure all wall insulation (batts) is behind stud face
  2. Trim any excess batt facings that protrude
  3. Verify electrical boxes are accessible and properly set for drywall thickness
  4. Clean up loose insulation debris
  5. Verify ceiling drywall patches (from blown insulation) are sanded smooth and primed
  6. Document all insulation for future reference (photos, R-values, materials used)
  7. Schedule final insulation inspection if required

Construction Sequencing (Complete Project)

Recommended Construction Sequence ✅

Phase 1: All Rough-In Work (Winter 2025-26)

  • Complete all framing (main + upper level)
  • Install all electrical boxes, run all wiring (BOTH levels)
  • Install all plumbing rough-in
  • Install HVAC rough-in (mini-split line sets, radiant manifold)
  • Mark any future penetrations
  • Inspection: Rough-in inspection (electrical, plumbing, mechanical)

Phase 2: Complete Building Envelope Insulation (Late Winter/Early Spring 2026)

  • Air seal entire building (main + upper level)
  • Insulate main garage walls (R-21 batts)
  • Insulate upper level knee walls if any (R-21 batts)
  • Install ceiling drywall (BEFORE blown insulation):
    • Main garage ceiling: Type X fire-rated drywall (5/8” thick)
    • Upper level ceiling: Standard drywall (1/2” thick)
  • Insulate main garage ceiling (R-49 blown cellulose - blown through drywall)
  • Insulate upper level sloped roof (R-49 blown cellulose - blown through drywall)
  • Patch drywall holes from insulation installation
  • Inspection: Insulation inspection if required
  • Result: Fully insulated, heated workspace for finishing work

Phase 3: Finish Main Garage (Spring 2026)

  • Drywall main garage walls (ceiling already installed in Phase 2)
  • Paint walls and ceiling
  • Install electrical finish (outlets, switches, lights)
  • Floor coating (after 90-day concrete cure - late January 2026+)
  • Trim, baseboard
  • Cabinets and storage

Phase 4: Finish Upper Level (Summer 2026 or As Desired)

  • Drywall upper level walls (ceiling already installed in Phase 2)
  • Paint
  • Electrical finish
  • Flooring
  • Trim
  • Built-ins or storage as needed

Benefits of This Sequence:

  • ✅ Work in open walls for electrical/plumbing (easier, no rework)
  • ✅ Complete all messy work (insulation) before clean work (drywall)
  • ✅ Heated workspace for winter finishing (VEVOR heaters much more efficient)
  • ✅ Single material order, one blower rental, one inspection
  • ✅ Maximum heating efficiency for construction and long-term use

Materials & Components

Ceiling Drywall (REQUIRED BEFORE Blown Insulation)

Main Garage Ceiling:

  • Type X fire-rated drywall, 5/8” thick
  • Required for fire separation between garage and living space above
  • Brands: USG Sheetrock, CertainTeed, Georgia-Pacific
  • Quantity: ~960 sq ft ÷ 32 sq ft per sheet = 30 sheets
  • Cost: ~540-660 total
  • Code requirement: Fire-rated assembly for garage ceiling

Upper Level Ceiling:

  • Standard drywall, 1/2” thick
  • Brands: USG Sheetrock, CertainTeed, Georgia-Pacific
  • Quantity: TBD based on upper level area
  • Cost: ~$12-15 per sheet
  • Can use standard drywall since not separating garage from living space

Installation:

  • Must be installed BEFORE blown cellulose insulation
  • Will have holes drilled for dense-pack insulation, then patched

Main Garage Walls (R-21 Batts - Recommended)

Insulation:

  • R-21 kraft-faced fiberglass batts, 6.25” thick for 2×6 walls
  • Brands: Owens Corning, Johns Manville, Knauf
  • Quantity: ~1,100 sq ft ÷ coverage per bag = 15-20 bags
  • Cost: ~$550-770 total
  • Where: Home Depot, Lowe’s, Menards

Example Product:

  • Owens Corning R-21 Faced Fiberglass Batt 15” × 93” (86.67 sq ft per bag)
  • Johns Manville R-21 Kraft-Faced 15.25” × 93”

Garage Ceiling (Blown Cellulose R-49 - Recommended)

Insulation:

  • Loose-fill cellulose insulation
  • Brands: GreenFiber, US GreenFiber, Johns Manville
  • Target: R-49 (13-14” depth)
  • Quantity: ~37 bags for 960 sq ft @ R-49
  • Cost: 370-555 material
  • Where: Home Depot, Lowe’s (often free blower rental with purchase)

Equipment Rental:

  • Insulation blower: $45/day
  • Often FREE with minimum material purchase (check store)
  • Hoses and accessories included

Example Products:

  • GreenFiber Low Dust Cellulose Blown-In Insulation
  • US GreenFiber Cocoon Loose-Fill Cellulose

Upper Level Sloped Roof (Blown Cellulose R-49 - Recommended)

Insulation:

  • Same as garage ceiling: Loose-fill cellulose
  • Target: R-49 (13-14” depth in rafter bays)
  • Quantity: TBD - depends on upper level roof area (estimate 30-50 bags for typical 24’×40’ loft)
  • Cost: $10-15 per bag
  • Note: Measure actual sloped roof area to calculate exact quantity

Vent Baffles (IF Vented Assembly):

  • Required to maintain air channel from soffit to ridge
  • Install in EVERY rafter bay before blowing insulation
  • See vent baffle section below for details

Upper Level Knee Walls (If Applicable - R-21 Batts)

Insulation:

  • Same as main garage walls: R-21 kraft-faced batts
  • Quantity: TBD - depends on knee wall height and length
  • Typical knee wall: 4-6 ft high
  • Cost: Same as main wall batts ($35-42/bag)

Combined Upper Level Estimate:

  • Sloped roof cellulose: 30-50 bags ($300-750)
  • Knee wall batts (if any): 5-10 bags ($175-420)
  • Vent baffles (if vented): 40-80 pieces ($140-280)

Air Sealing (CRITICAL - All Applications)

Spray Foam:

  • Great Stuff Pro Gaps & Cracks (gun-style recommended)
  • Quantity: 6-12 cans
  • Cost: 96-144
  • Foam gun: $30-50 (reusable, worth it)

Alternative/Supplement:

  • Touch ‘n Foam Professional (24 oz cans)
  • Great Stuff Fireblock (for fire-rated penetrations)

Other Sealants:

  • Acoustic sealant or latex caulk for smaller gaps: 3-6 tubes
  • Foam gaskets for electrical boxes (if not using putty pads)
  • Weatherstripping for attic hatch

Total Air Sealing Cost: $150-250

Loft/Sloped Roof (Future)

Tools & Safety Equipment

Safety (Required):

  • N95 respirator or dust mask (cellulose/fiberglass dust)
  • Safety glasses
  • Work gloves
  • Long sleeves and pants
  • Hat or head covering

Tools:

  • Utility knife with extra blades
  • Straight edge or T-square
  • Staple gun + 9/16” staples (for faced batts)
  • Tape measure
  • Shop vacuum (cleanup)
  • Ladder

For Blown Cellulose:

  • Insulation blower (rental)
  • Helper (required for feeding machine)
  • Drop cloths or tarps

Coordination

  • Contractor scheduling and access: see Insulation Contractors
  • Pre-install walk-through to align on details and photos to capture

QA / Documentation

  • Photo log of each bay before close-in
  • Thickness and R-value confirmation from contractor
  • Record locations of unvented sections and any foam-only areas

Checklist (Execution)

Phase 1: Complete Rough-In (Before Insulation)

  • Complete all framing (main + upper level) — stage:: 4
  • Install all electrical boxes and run wiring (BOTH levels) — stage:: 4
  • Complete plumbing rough-in (if any) — stage:: 4
  • Complete HVAC rough-in (mini-split lines, radiant manifold) — stage:: 4
  • Photograph all walls/ceilings showing wire/box locations — stage:: 4
  • Schedule and pass rough-in inspection — stage:: 4

Phase 2: Complete Building Envelope Insulation (Both Levels)

Planning & Ordering:

  • Review Insulation Strategy and confirm approach — stage:: 5 — DECIDED: Option A
  • Measure upper level sloped roof area and rafter count — stage:: 5
  • Calculate total materials for BOTH levels — stage:: 5
  • Order R-21 wall batts (15-20 bags main + 5-10 bags upper if knee walls) — order:: Insulation Order — stage:: 5
  • Order Type X fire-rated drywall (5/8”, ~30 sheets) for main garage ceiling — stage:: 5
  • Order standard drywall (1/2”, TBD sheets) for upper level ceiling — stage:: 5
  • Order cellulose (67-87 bags total for both levels) OR schedule pro installer — order:: Insulation Order — stage:: 5
  • Order vent baffles if vented assembly (40-80 pieces) — order:: Insulation Order — stage:: 5
  • Purchase air sealing materials (spray foam, caulk, gaskets) — stage:: 5
  • Reserve insulation blower with dense-pack tube (FREE with 20+ bag purchase) — stage:: 5

Air Sealing (Both Levels):

  • Air seal main garage: rim joists, top plates, bottom plates, penetrations — stage:: 6
  • Air seal upper level: knee walls, rafters, penetrations, attic access — stage:: 6

Main Garage Insulation:

  • Install R-21 batts in all main garage walls (DIY) — stage:: 6

Upper Level Insulation:

  • Install R-21 batts in upper level knee walls (if any) — stage:: 6

Ceiling Drywall Installation (BEFORE blown insulation):

  • Install Type X fire-rated drywall (5/8”) on main garage ceiling — stage:: 6
  • Install standard drywall (1/2”) on upper level ceiling — stage:: 6

Blown Insulation (AFTER ceiling drywall):

  • Install vent baffles in all rafter bays (if vented assembly) — stage:: 6
  • Blow cellulose main garage ceiling to R-49 through drywall (DIY or contractor) — order:: Insulation Order — stage:: 6
  • Blow cellulose upper level sloped roof to R-49 (same day as main ceiling) — order:: Insulation Order — stage:: 6
  • Patch drywall holes from insulation installation — stage:: 6

Quality Assurance (Both Levels):

  • QA: Check depths, gaps, compression, vapor barrier orientation (all areas) — stage:: 6
  • Verify vent baffles secure and no insulation blocking vents — stage:: 6
  • Photograph all completed insulation areas (both levels, multiple angles) — stage:: 6
  • Document final R-values and materials used — stage:: 6
  • Schedule and pass insulation inspection (if required) — stage:: 6

Phase 3: Finish Work (After Insulation Complete)

  • Drywall main garage — stage:: 7
  • Paint main garage — stage:: 7
  • Electrical finish main garage — stage:: 7
  • Floor coating (after 90-day concrete cure) — stage:: 7
  • Drywall upper level — stage:: 8
  • Finish upper level — stage:: 8

Contractor Selection (If Hiring Ceiling Installation)

When to Hire vs. DIY

DIY Makes Sense:

  • You’re comfortable with physical labor
  • You have a helper available
  • Budget is tight (1,440-1,920 pro)
  • You enjoy learning new skills
  • Time is not a constraint (1 weekend vs. 3-6 hours pro)

Hire Contractor If:

  • You value your time highly
  • You don’t have a helper
  • You prefer guaranteed coverage/quality
  • Physical limitations (climbing, dust sensitivity)
  • Want warranty on installation

Questions to Ask Contractors

Experience:

  1. How many blown cellulose jobs have you completed?
  2. Can you provide 2-3 local references I can call?
  3. Are you licensed and insured? (verify certificate)

Specifications: 4. What R-value will you guarantee? (should be R-49) 5. What brand of cellulose do you use? (GreenFiber, JM, etc.) 6. What depth will be installed? (should be 13-14” for R-49) 7. Do you provide before/after photos? 8. Will you mark depth guides for future reference?

Process: 9. How long will the job take? (should be 3-6 hours for 960 sq ft) 10. What cleanup is included? 11. Do you install vent baffles if needed? 12. What warranty do you provide on installation?

Cost: 13. What’s your cost per square foot? ($1.50-2.00 expected) 14. Any additional fees (travel, setup, disposal)? 15. Payment terms (50% up front typical)?

Red Flags

  • ❌ No license or insurance
  • ❌ Unwilling to provide references
  • ❌ Won’t specify R-value or depth
  • ❌ Price significantly below $1.50/sq ft (cutting corners)
  • ❌ Pushes flash-and-batt when you asked for cellulose
  • ❌ Cash-only payment (no paper trail)

Expected Pricing (960 sq ft Garage Ceiling)

  • Low End: 1,440 total
  • Average: 1,680 total
  • High End: 1,920 total

What’s Included:

  • Material (cellulose insulation)
  • Labor (blowing, coverage verification)
  • Equipment (blower, hoses)
  • Cleanup (bagging waste, vacuuming dust)
  • Depth verification and documentation

Not Included (typically):

  • Air sealing (you should do this first, DIY)
  • Vent baffles (may be extra, ask in quote)
  • Electrical box covers (you provide)
  • Attic access weatherstripping (DIY)

Procurement

References

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