Garage Construction Project

Utilities Planning - Air, Vacuum, and Fume Extraction

4 min read

🏗️ Garage Utilities Planning — Air, Vacuum, and Fume Extraction

Summary for future research and pre-drywall planning

1. Compressed Air System (Pre-Drywall Stub)

Purpose

  • Future use of air tools, cleaning, or powering small equipment upstairs.

Recommendations

  • Use PEX-AL-PEX or RapidAir Maxline (rated for compressed air).
  • Install a vertical riser from the main air manifold to the loft.
  • Terminate upstairs with a capped NPT fitting behind a blank wall plate.
  • Add a drip leg + ball valve at the base of the riser to prevent moisture traveling upward.
  • Clearly label both ends before drywall.

2. Central Vacuum (Shop Dust System) — Separate From Fume Extraction

Purpose

  • Woodworking dust collection (table saw, miter saw, etc.)
  • General shop cleanup via retractable hose stations
  • Floor sweep inlet near garage doors
  • Light debris (NOT fumes)

System Design (Planned)

Motor Unit: RIDGID HD1400 shop vac repurposed as central vac motor (upgradeable later) Location: Mechanical room on main floor Piping: 2” thin-wall central vacuum PVC throughout garage

Access Points:

  • 3 retractable hose stations — locations TBD when interior layout finalized
  • 1 floor sweep inlet — near garage doors for quick broom cleanup
  • Tool station inlets — at table saw, miter saw, and other stationary tools

Recommendations

  • Use standard central vac 2” thin-wall PVC (NOT schedule 40 plumbing PVC).
  • Install a vertical riser to the loft for upstairs inlet access.
  • Pull a low-voltage control wire alongside the pipe (inlet activation signals).
  • Pre-drywall: Install backing/blocking for retractable hose stations, floor sweep rough-in.
  • Label all pipe stubs at both ends.
  • Keep totally separate from fume extraction system.

Detailed Documentation: Workshop Dust Collection System

3. Fume Extraction — Must Be a Completely Separate System

A central vacuum cannot handle fumes or vapors. Reasons:

  • Motor sparks → ignition risk
  • PVC causes static → ignition risk
  • Filters clog with solvent and paint
  • Cannot move enough CFM
  • Not explosion-proof

Fumes that require separate extraction

  • Resin 3D printer vapors
  • IPA wash station fumes
  • Soldering smoke
  • Laser cutter smoke
  • Airbrush overspray
  • Automotive solvent fumes (paint and cleaners)

4. It Is Possible to Build a Centralized Fume Extraction System

This is not a vacuum system — it is an industrial-style negative-pressure ventilation system.

System A — Main Fume Extraction (Upstairs + Light Workstations)

Handles:

  • Resin printers
  • Soldering
  • Laser cutter
  • Airbrushing (small)
  • Fume hood for general chemical use

Specifications

  • 6” spiral steel duct trunk line
  • 4–6” branches to each workstation
  • Outdoor-rated inline blower or sealed mechanical closet blower
  • Blast gates or dampers at each branch
  • Metal ducting only (no PVC)
  • Short 3–6 ft section of anti-static flex hose at each workstation
  • System exhausts directly outside
  • Perfect for a hobby-level but future-proof setup

System B — Heavy-duty Paint Booth Extraction (Downstairs Only)

Handles:

  • Automotive painting
  • Solvent-rich work
  • Large airbrush operations
  • Temporary paint booth for Corvette restoration

Specifications

  • Separate from System A
  • 12–24” metal duct
  • Explosion-proof blower (C1D1 or C1D2 rated)
  • Intake and exhaust filters
  • Dedicated high-CFM system (2,000–4,000+ CFM)

5. Optimal Duct Type for Fume Extraction

Best Choice:

  • 26–30 gauge Spiral Steel Duct (“spiral pipe”)

Why

  • Anti-static
  • Fire-safe
  • Smooth airflow
  • Industrial standard
  • Easy to branch and seal

Avoid

  • PVC
  • Dryer duct
  • Long sections of flex-only hose

6. Creating Branches

Preferred: Wye Fittings

  • Best airflow
  • Lowest turbulence
  • Ideal for laser and resin extraction

Acceptable When Necessary: T-Fittings

  • More compact
  • Slightly higher turbulence
  • OK for soldering or resin printer branches

7. Permanent, Airtight Sealing Method (Before Drywall)

Use the industrial triple-seal method:

  1. Slip-fit / crimped duct joint
  2. UL 181 Foil HVAC tape (3M 3340 or 3381)
  3. Duct mastic (RCD #6 or Hardcast 181) over seams and screw heads

Once cured, the system is airtight, permanent, and safe for concealed or exposed use.

8. Should Ducting Be Hidden or Exposed?

Behind Drywall (Hidden)

Pros:

  • Clean aesthetics
  • Quiet Cons:
  • Hard to modify later
  • All sealing must be perfect Best For:
  • Permanent upstairs stations

Exposed / Surface-mounted

Pros:

  • Easy to modify
  • Easy to inspect
  • Ideal for industrial look
  • Easiest future expansion Cons:
  • Visible Best For:
  • Downstairs workstations
  • Laser cutter
  • Airbrush & paint booth
  • Automotive areas
  • Upstairs: Vertical riser hidden, horizontal branches exposed
  • Downstairs: Entire fume trunk exposed for maximum flexibility

9. Pre-Drywall Items to Add Now

  • 6” vertical fume duct riser (capped for future)
  • Dedicated 20A circuit for fume blower
  • Optional 1–2 empty conduits for sensors and future automation
  • Compressed air riser with drip leg
  • Central vacuum riser
  • Ceiling-mounted outlets for future paint booth fans
  • Label every stub clearly

10. General Design Principles

  • All fume systems must exhaust outdoors, not recirculate
  • Use blast gates to isolate stations
  • Keep paint booth extraction separate
  • Avoid any PVC in fume-handling paths
  • Inline or rooftop blowers must be outside the vapor path

Graph View

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