Air Seal & Fireblocking

1. Air Sealing a Home

Definition:
Air sealing is the process of closing gaps, cracks, and other openings within the building envelope (walls, ceilings, floors, doors, windows, attics, and foundations) to prevent uncontrolled air movement into and out of a home.

Goals:

• Improve energy efficiency and reduce heating/cooling costs

• Enhance comfort by eliminating drafts

• Minimize moisture intrusion that can cause mold and structural damage

• Improve indoor air quality by controlling airflow, preventing outside pollutants and allergens from entering

Common Air Sealing Methods & Materials:

• Caulking around windows, doors, and framing joints

• Weather stripping around doors and windows

• Spray foam insulation around plumbing, wiring penetrations, and other gaps

• Sealing electrical and plumbing penetrations between living spaces and unconditioned areas (attics, crawl spaces, basements)

• Taping or sealing joints in HVAC ductwork

Typical Locations for Air Sealing:

• Attic and roof penetrations

• Rim joists

• Exterior walls (especially around windows and doors)

• Chimney, flue, or vent penetrations

• Electrical outlets and recessed lighting fixtures

• Ductwork and plumbing penetrations

2. Fire Blocking (Fire Stop) a Home

Definition:
Fire blocking (also called fire stop or draft stopping in certain contexts) involves placing building materials at strategic locations within a wall, floor, or ceiling cavity to impede or slow down the spread of fire, smoke, and gases through concealed spaces.

Goals:

• Slow the spread of fire within walls and concealed spaces

• Allow residents additional time to escape in case of fire

• Help firefighters contain and extinguish the fire more effectively

• Comply with building codes and regulations that require fire blocking for safety

Common Fire Blocking Methods & Materials:

• Solid wood lumber (minimum thickness as specified by code, typically 2×4 or thicker)

• Fire-rated plywood or oriented strand board (OSB)

• Mineral wool insulation (noncombustible)

• Fire-rated caulks and foam (intumescent sealants designed specifically for fire stopping)

Typical Locations for Fire Blocking:

• Horizontal blocking between wall studs at intervals (usually every 10 feet vertically, per building codes)

• Top and bottom plates of wall assemblies

• Intersections between vertical and horizontal cavities (like soffits or dropped ceilings)

• Around pipes, ducts, cables, or conduits that penetrate wall or ceiling assemblies

• Connections between garage and living spaces, stairway framing, and chimney chases

Summary & Comparison

Both air sealing and fire blocking are crucial steps in building or remodeling a home. Although they address different issues, combining both techniques effectively enhances your home’s comfort, efficiency, and safety.