Understanding the structure of a building may help you to diagnose issues with energy efficiency. Air leakage and thermal bridges might be happening in load bearing assemblies or clusters of framing materials.

A working knowledge of HOW buildings are constructed may help in determining problem areas for insulation, air leakage or potential moisture issues. Wherever there are clusters of framing, corners, bump-outs or large sections of hard materials, there is potential for heat loss and air leakage.

MAIN PARTS OF RESIDENTIAL STRUCTURES:

FOUNDATIONS:

• The foundation is a buildings anchor to the ground.
  
• Materials may be stone, brick, concrete block, poured concrete or wood.
  
• Often, the older the foundation, the more issues you'll find with air leakage and water infiltration.
  
• Concrete and masonry are poor insulators and will require added layers of insulation.
  
• Floor slabs, footings and foundation walls in older buildings may not have insulation on exterior or interior surfaces. This can create large heat loss surfaces.
  

FRAMING:

• In Canada, most homes built after 1940 use 'platform' or 'Western Style' framing - dimensional lumber, engineered sheet goods and steel I-beams, arranged in wall, floor and roof systems that sit on top of one another.

• Insulation, air tight and vapour control layers are often incorporated into the skeleton frame of residential buildings. Maintaining continuity of these layers may be challenging with complex frames.
• Cavity insulation - layers of insulation between framed components - may not be sufficient to stop heat loss due to thermal bridging. Application of continuous insulation may be required.

ROOFS:

• The shape of a roof can define the architectural style of a building - but it may also add complex intersections that are difficult to insulate and air seal.
  
• Wall and roof intersections on older buildings are a common area for heat loss, reduced insulation and potential for ice-damming.
  
• Older buildings may use lumber, timber or log pole rafters. These roof types must be inspected for structural integrity, passive attic ventilation and insulation levels.
  
• Modern residential construction mostly uses engineered roof trusses, made from dimensional lumber and steel connectors. Trusses will swell and shrink like regular lumber, which may lead to a condition called truss 'uplift', where ceilings and walls will move and warp slightly. This may crack interior finishes and open up pathways for air leakage.
  
• A roof structure may include living space, which may make for challenging insulation and air sealing.
  
• Dormers, chimneys and other roof penetrations are common areas for heat loss, air leakage and reduced insulation.
  

PORCHES and DECKS:

Porches and deck structures may be original to the building or later additions. Inspect the connections to the house for signs of movement or pulling. If an exterior structure is pulling away from the building, it may open cracks for potential air and moisture infiltration.

• A deck may be a separate structure OR may be attached to the main house. In either case, the deck will require its own foundation and structural stability. Municipal building offices will have guidelines for decks as part of their information for builders and renovators.
• Columns and structural elements that have been exposed to years of weathering must be inspected for structural integrity.
• Maintaining the continuity of air tight and insulation layers must be considered if decks or porches are being added or altered.