Energy Efficiency in Basement Insulation Overview

Chapter 6: Basement Insulation: Floors, Walls, and Crawl Spaces

Introduction

  • Basements can contribute up to 20% of a building’s heat loss.
  • Air leakage can occur through:
  • Windows
  • Foundation sill plate
  • Cracks
  • Insulation deficiencies often exacerbate heat loss.
  • Soil itself is not an effective insulator.

Types of Basement Construction

Full Foundation

  • Most common construction type.
  • Below-grade foundation walls support the house structure.

Crawl Space

  • Partial depth foundation walls create accessible spaces under houses.
  • Older structures may be built on posts/ piers, leaving the underside exposed.

Slab on Grade

  • Houses built directly on a concrete slab with no basement or crawl space.

Types of Full Foundations

  • Rubble
  • Brick
  • Poured concrete
  • Concrete block

Foundation Characteristics

Poured/Concrete Block Foundations

  • Common since 1920s, often with:
  • Parging
  • Waterproofing
  • Drain tiles
  • Older structures may need repair before insulation installation post drying phase.

Rubble, Brick, or Stone Foundations

  • Uneven structure, rarely damp-proofed.
  • Best insulated externally unless specific conditions (i.e., moisture problems) demand otherwise.

Preserved Wood Foundations

  • Typically insulated and damp-proofed.

Assessing the Basement

Water Leaks

  • Major leaks require correction through excavation, waterproofing, drainage addition, and exterior insulation.
  • Minor leaks may be fixed by grading and patching.

Dampness Indicators

  • Symptoms include:
  • Mould growth
  • Staining
  • Peeling paint
  • Condensation can also form on cool surfaces in humid conditions.

Cracks

  • Active cracks necessitate professional evaluation for structural issues.
  • Radon testing and prevention important for safety.

Insulation Options

Exterior Insulation

  • Best for energy efficiency. Involves:
  • Excavating foundation
  • Waterproofing
  • Installing insulation
  • Pros:
  • Can address any moisture issues readily.
  • No disruption to indoor spaces.
  • Cons:
  • Higher costs and structural concerns.

Interior Insulation

  • Methods include:
  • Rigid board installation
  • Drywall over wooden frame
  • Pros:
  • Seasonal job flexibility
  • Easier DIY approach
  • Cons:
  • Potential for cold wall condensation if moisture is not controlled.

Safety Considerations in Excavation

  • Identify utilities before excavation.
  • Excavation safety protocols for deep digs.

Insulation from the Outside

Steps for External Insulation

  1. Trench Digging
  • Ensuring the trench does not go below foundation footings.
  1. Surface Preparation
  • Cleaning, sealing, and waterproofing foundation.
  1. Insulation Application
  • Use types like rigid mineral wool or polystyrene.
  1. Flashing Installation
  • Prevents water from getting behind insulation.
  1. Environmental Protection
  • Cover the insulation to prevent damage.
  1. Refilling Excavation
  • Proper slope and settling considerations needed.
  1. Finish Details
  • Insulating header areas and ensuring no air gaps.

Interior Insulation Technique

Rigid Board Insulation

  • Best for even vertical walls.
  • Air sealing before insulation installation is crucial.

Frame Wall With Batt Insulation

  1. Framing Installation
  • Include considerations for moisture barriers.
  1. Insulating and Sealing
  • Fill gaps rigorously to prevent heat loss.
  1. Vapour Barrier Integration
  • Ensuring proper moisture flow management.

Crawl Spaces

  • Insulation can occur either on walls or floors, with recommendations based on moisture levels and construction type.
  • Implementing moisture barriers is critical in any crawl space.

Conclusion

  • Proper insulation of basements, crawl spaces, and associated structures increases energy efficiency and reduces heat loss while addressing moisture issues effectively.