Home Insulation

INTRODUCTION TO INSULATION AND HEAT FLOW

Heat naturally flows from warm areas to cooler areas, regardless of direction. In winter, heat flows from the inside of the house to the outside. This flow of heat can never be stopped entirely, but the rate at which it flows can be reduced by using materials which have a high resistance to heat flow.

Heat is transferred in three distinct ways, any or all of which may be occurring at any given time:

• Conduction - Conduction is the transfer of heat through a solid object. When one part of an object is heated, the molecules within it begin to move faster and more vigorously, these molecules then hit other molecules within the object causing the heat to be transferred through the entire object.
  
  
  
  
• Convection - Convection is the transfer of heat by the movement of a fluid (water, air, etc.). In an uninsulated wall cavity, air removes heat from the warm interior wall, then circulates to the colder exterior wall where it loses the heat.
  
  
  
  
• Radiation - Any object will radiate heat to cooler objects around it by giving off 'heat waves'. This is a direct transfer of heat from one object to another, without heating the air in between. This is the same process in which the Earth receives heat from the Sun or a wood stove supplies heat to its surroundings.
  
  
  
  

Obviously an important step in the construction of an energy efficient house is to control this heat loss, which can account for up to 70% of the total energy loss of a home. As was previously stated, heat will flow in any direction where a temperature difference occurs. Therefore all areas which separate the interior of a house from the exterior or heated spaces from unheated spaces need to have a high resistance to heat flow, in other words, they should be insulated.

How Does Insulation Work?

Insulation is any material which slows the rate of heat flow from a warm area to a cooler one. The more the rate is slowed, the better the insulative qualities of the material. Its ability to resist heat flow is measured as an R or RSI (metric) value, the higher the R-value, the more the material will resist the flow of heat. In order to be effective, insulation materials must be able to reduce the transfer of heat by conduction, convection and radiation, this is determined by both its physical properties and installation.

• Conduction - Since conduction is the transfer of heat through solid objects, most insulations usually contain tiny 'pockets' of still air. The air pockets reduce the conductive heat loss by minimizing the amount of 'solid' material within a wall or ceiling cavity.
  
  
  
  
• Convection - In large air spaces, such as a wall cavity, large amounts of heat can be lost through convection (and radiation). As long as the insulation is carefully installed to completely fill the cavity, there should be no air spaces in which convective heat loss can occur.
  
  
  
  
• Radiation - Most insulations have a cellular structure which block the flow of heat by radiation. If the cavity is completely filled with insulation, radiant heat loss from the inside finish to the outside sheathing is virtually eliminated.
  
  

Choosing An Insulation

The R-value is not the only consideration when choosing insulation, other factors which deserve consideration are the materials fire, mold, insect, vermin and moisture resistant properties, as well as its cost and ease of application. There are many different types of insulation materials, each with properties which make it suitable for certain applications while being unsuitable for others. The insulation summary on the next page lists the advantages and disadvantages of the insulation types most commonly used.

INSULATION MATERIALS SUMMARY

Batt Insulation

Glass Fibre

Glass Fibre Batts are manufactured from glass which is spun into long fibres, then woven and
coated with a binding agent. Batts are light weight, fit standard joist and stud spaces and if
installed carefully will not slump or settle. They do not, however, readily fit into irregular spaces
and can leave 'insulation voids' around obstructions (nails, electrical wires, trusses, etc.). During
installation glass fibre can cause eye, skin and respiratory irritation and manufacturer's safety
recommendations should be followed. Average R-value is 3.2 per inch (RSI 0.022/mm).

Advantages

• Manufactured for standard joist and stud spacings
  
• Relatively easy to install
  
• Fire and mold resistant
  
• Small amounts of moisture have little effect on R-value
  

Disadvantages

• Can cause eye, skin and respiratory irritation during installation
  
• Does not readily fit into irregular spaces
  
• Can leave 'insulation voids' around obstructions if care is not taken during installation
  
• Air movement around the insulation can significantly degrade R-value
  
• Should not be covered with heavier insulation or other materials which may compress it
  

Mineral Wool (Slag and Rock Wool)

Mineral Wool is manufactured from melted industrial slag, which is fiberized and treated with
oil and binders to suppress dust and maintain shape. It is similar to glass fibre in texture and
appearance. Rock Wool is manufactured in a similar manner except that natural rock is used instead of slag.
These materials have a high fire resistance but can cause eye, skin and respiratory irritation during installation.

The average R-value for both slag and rock wool is 3.3 per inch (RSI 0.023).

Advantages

• Manufactured for standard joist and stud spacings
  
• Relatively easy to install
  
• Good material for insulating around chimneys, since it doesn't support combustion
  
• Small amounts of moisture have little effect on R-value
  

Disadvantages

• Can cause eye, skin and respiratory irritation during installation
  
• Should not be covered with heavier insulation or other materials which may compress it
  
• Does not readily fit into irregular spaces
  
• Can leave 'insulation voids' around obstructions if care is not taken during installation
  

Loose Fill Insulation

Cellulose Fibre

Cellulose fibre insulation is made from finely shredded newsprint which is chemically treated
to resist fire and fungal growth. Due to the small size of the particles, cellulose can 'flow' around
obstructions (nails, electrical wires, trusses, etc.) to give a uniform fill.

Blown Cellulose has an average R-value of 3.6 per inch (RSI
0.025/mm) which is dependant on the chemical mix, paper type and it's blown density. If the insulation is not blown to manufacturer's recommended density it can settle over time, and the intended R-value will not be obtained.

Blown cellulose can be installed in vertical wall cavities using a variety of specially designed, reinforced interior sheeting products.

Poured Cellulose has an average R-value of 3.4 per inch (RSI
0.024/mm) and must be applied to the manufacturer's recommendations to achieve desired density and R-value.

Advantages

• Fills irregular horizontal spaces
  
• Blown-In Cellulose can be installed with rented equipment or hand poured
  
• Chemical additives provide fire, corrosion, vermin and fungal growth resistance
  
• Small amounts of moisture have little effect on the materials R-value
  

Disadvantages

• Should not be covered with heavier insulation or other materials which may compress it
  
• Will settle over time, manufacturer's recommendations should be followed to achieve desired
  R-value
  

Glass Fibre

Blown Glass Fibre is a similar material to glass fibre batts, except that the material is 'chopped
up'. It has an R-value of 2.9 per inch (RSI 0.02/mm), which is reduced if not blown to the proper density. The particles in glass fibre tend to be larger than those in cellulose, therefore it doesn't always flow as freely around obstructions and can leave insulation voids. As with the batts, during installation glass fibre can cause eye, skin and respiratory irritation and manufacturer's safety recommendations should be followed.

Poured Glass Fibre has basically the same properties as the blown product except its R-value
is usually slightly higher, R-3 per inch (RSI 0.021/mm).

Advantages

• Fills irregular horizontal spaces
  
• Fire and mold resistant
  
• Small amounts of moisture have little effect on the materials R-value
  

Disadvantages

• Can cause eye, skin and respiratory irritation during installation
  
• Should not be covered with heavier insulation or other materials which may compress it
  
• Can settle over time if not blown properly, (manufacturer's recommendations should be
  followed)
  

Mineral Wool (Slag and Rock Wool)

Mineral Wool is manufactured from melted industrial slag, which is fiberized and treated with
oil and binders to suppress dust and maintain shape. It is similar to glass fibre in texture and
appearance. Rock Wool is manufactured in a similar manner except that natural rock is used instead of slag.

The properties listed below refer to both types of insulation.

The blown material has an R-value of 2.7 per inch (RSI 0.019), and as with all blown materials
this will vary depending upon the installed density. These types of materials have a high fire resistance
but can cause eye, skin and respiratory irritation during installation.

The poured material has the same characteristics as the blown material, but with a slightly
higher R-value, R-3.0 per inch (RSI 0.021). Manufacturer's recommendations should be followed for
installation techniques.

Advantages

• Good material for insulating around chimneys, since it doesn't support combustion
  
• Fills irregular horizontal spaces
  
• Small amounts of moisture have little effect on the materials R-value
  

Disadvantages

• Can cause eye, skin and respiratory irritation during installation
  
• Should not be covered with heavier insulation or other materials which may compress it
  
• Can settle over time if not blown properly, (manufacturer's recommendations should be
  followed)
  

Vermiculite

Vermiculite is a mineral closely related to mica, which when heated expands to form a light
weight material with insulating properties. There are two types of vermiculite: untreated and
treated. The treated material is coated with asphalt to make it water-repellent for use in high
moisture areas. Untreated vermiculite absorbs water, and once wet dries very slowly.

Untreated vermiculite has an R-value of 2.3 per inch (RSI 0.016/mm) compared to R-2.5 per inch
(RSI 0.017/mm) for the treated material. Vermiculite is usually hand-installed, and is suitable for both
horizontal and vertical applications. It is non-combustible, odourless and non-irritating, although
due to its high density it is not usually the material of choice where a high R-value is desired.

Advantages

• Pours easily into irregular spaces
  
• Non-combustible
  
• Non-abrasive, odourless and non-irritating
  

Disadvantages

• Dries very slowly after absorbing moisture
  
• Not usually used where a high R-value is desired
  

Wood Shavings

Wood shavings, although rarely used today, were once a very popular insulation product
due to their wide availability and low cost. Shavings were often treated with lime or other chemicals, to increase
resistance to water absorption, fire and fungal growth. This insulation product is still a common
sight in older homes across North America.

Wood shavings have an average R-value of 2.44 per inch (RSI 0.0169/mm). They tend to absorb
moisture and dry very slowly. Over time the material may settle and is hard to effectively treat against fire, vermin and fungal growth.

Advantages

• Readily available and inexpensive
  

Disadvantages

• Low R-value
  
• Dries very slowly after absorbing moisture
  
• Hard to effectively treat against fire, vermin and fungal growth
  
• Can settle over time
  

Rigid Insulation

Glass Fibre - Above Grade

The above-grade rigid glass fibre is designed to be used as an exterior sheathing and is faced on one side with an air/moisture barrier, to prevent water and wind intrusion from lowering its R-value.

The above grade glass fibre has an R-value of 4.4 per inch (RSI 0.031/mm).

Advantages

• Relatively non-combustible
  
• Allows a higher R-value to be achieved on exterior walls
  

Disadvantages

• No known disadvantages
  

Glass Fibre - Below Grade

The below-grade rigid glass fibre is unfaced and has a higher density than the above grade version. It is designed to act as a drainage layer between the foundation wall and the surrounding soil.

The below-grade glass fibre board has an R-value of 4.2 per inch (RSI 0.029/mm).

Advantages

• Relatively non-combustible
  
• Can provide drainage next to the foundation
  

Disadvantages

• Can not sit in water, should be connected to a good drainage system
  

Expanded Polystyrene

Expanded polystyrene is produced by expanding polystyrene beads which are then bonded together to form rigid boards. 'Bead Board' as it is often called is manufactured in two densities. The high density board is more moisture resistant and can be used on the exterior of a foundation providing the surrounding soil is dry and sandy. Polystyrene will 'break-down' if left exposed to sunlight for prolonged periods. It must also be protected from solvents and only compatible sealants should be used. If the insulation is to be used in the interior of a house, it needs to be covered with a fire-resistant material, such as drywall.

Low density expanded polystyrene has an R-value of 3.7 per inch (RSI 0.026/mm) while the high density has an R-value of 4.0 per inch (RSI 0.028/mm).

Advantages

• Can be installed either on the interior or exterior where space is limited (cathedral ceiling, flat roof, exterior walls, etc.)
  
• Lightweight
  
• Less expensive than extruded polystyrene or most other rigid insulations
  
• Doesn't cause skin irritation
  

Disadvantages

• Must be protected from sunlight, solvents and non-compatible sealants
  
• When used on the interior a fire-resistant covering is required
  
• Low-density board can only be used above grade.
  

Extruded Polystyrene

Extruded polystyrene is a closed cell foam plastic board, which is manufactured in two densities. Both the low and high density board are suitable for below grade applications, however the high density board should be used where the material will be exposed to relatively high pressures, such as below a concrete slab or in built-up roofing. Polystyrene will 'break-down' if left exposed to sunlight for prolonged periods and must also be protected from solvents. If the insulation is to be used in the interior of a house, it needs to be covered with a fire-resistant material, such as drywall.

The low density extruded polystyrene has an R-value of 4.7 per inch (RSI 0.033/mm) while the high density has an R-value of 5.0 per inch (RSI 0.035/mm).

Advantages

• Can be installed either on the interior or exterior where space is limited (cathedral ceiling, flat roof, exterior walls, etc.)
  
• Lightweight
  
• High-density board can handle relatively high pressures, under concrete slabs, etc.
  
• Doesn't cause skin irritation
  
• When joints are properly sealed, extruded polystyrene can act as an air barrier
  

Disadvantages

• Must be protected from sunlight and solvents
  
• When used on the interior a fire-resistant covering is required
  
• More expensive than expanded polystyrene
  

Polyurethane and Polyisocyanurate

Polyurethane and polyisocyanurate insulations are manufactured by chemical reactions between poly-alcohols and isocyanurates. They are a closed cell board, the cells contain refrigerant gases (fluorocarbons) instead of air. The boards are usually double-faced with foil, or sometimes come bonded with an interior or exterior finishing material. The boards must be protected from prolonged exposure to water and sunlight, and if used on the interior must be covered with a fire-resistant material, such as drywall. Due to the relatively high cost of these insulations, use is generally limited to areas which require a high R-value but where space is very limited.

The faced boards have a typical R-value of 5.8 per inch (RSI 0.040) to 7.2 per inch (RSI 0.050).

Advantages

• Can be installed on the interior or exterior where space is very limited but a high R-value is needed
  
• When joints are properly sealed it can act as both an air and vapour barrier
  
• Very high R-value per inch
  

Disadvantages

• Must be protected from prolonged exposure to sunlight and water
  
• When used on the interior a fire-resistant covering is required
  
• More expensive than most other types of insulation
  

Phenolic Foam

Phenolic foam is manufactured from phenol formaldehyde resin, and is available as either an open or closed cell product. The boards usually come with a foil facing on one or both sides. It is much less combustible than other rigid insulations. It should be protected from prolonged exposure to sunlight and water. It is suitable for wall sheathing, and for use on the interior, both above and below grade. Use is generally limited to areas which require a high R-value but where space is very limited.

Open cell insulations have a typical R-value of 4.2 per inch (RSI 0.029) while closed cell insulations have a typical R-value of 8.3 per inch (RSI 0.058).

Advantages

• Can be installed where space is very limited but a high R-value is required
  
• Very high R-value per inch
  
• Less combustible than other types of rigid insulation
  

Disadvantages

• Must be protected from prolonged exposure to sunlight and water
  
• Currently the most expensive rigid insulation product
  
• When used on the interior a fire-resistant covering is usually required
  

Spray Foam Insulations

Polyurethane Foam

Polyurethane is a closed cell foam which is usually pale yellow in colour, and can be used for a variety of spray applications. The material is mixed on site with special equipment for large applications. For small applications, single component foam is available in spray cans, for sealing around windows, doors, etc. The foam will act as an air barrier, but not a vapour barrier and should be protected from prolonged exposure to sunlight. When the foam is used in the interior of a house it must be covered with a fire-resistant material, such as drywall.

Polyurethane foam has an R-value of 6.0 per inch (RSI 0.042/mm) which takes into account the loss of refrigerant gases over time.

Advantages

• Acts as an air barrier
  
• Ideal for use with irregular shaped surfaces and narrow openings, eg: shim spaces around doors and windows
  

Disadvantages

• When used on the interior a fire-resistant covering is usually required
  
• Large applications require specially trained contractors
  
• Must be protected from prolonged exposure to sunlight
  

Isocyanurate Plastic Foam

Isocyanurate foam is a two component material, and is made from a combination of isocyanurate, resins and catalysts which create an open-celled semi-flexible plastic foam insulation. It is best suited for use in exterior stud wall cavities, perimeter joist spaces and in small areas such as the shim spaces around doors and windows. Special applicators are used on site to mix the chemicals in the proper proportions, and trained contractors should be used to ensure correct installation. The material can be used as an air barrier, but when installed on the interior of the house it should be covered with a fire-resistant material, such as drywall.

Isocyanurate plastic foam has an R-value of 4.3 per inch (RSI 0.030/mm).

Advantages

• Good for irregular shapes and spaces
  
• Acts as an air barrier
  

Disadvantages

• When used on the interior a fire-resistant covering is required
  
• Requires specially trained contractors
  
• There are some limitations on the thickness of the material which can be applied
  

Sprayed-In-Place Insulations

Sprayed-in-place insulations are loose fill products which are blown in to wall cavities. During the blow-in stage the insulation is mixed with an adhesive, usually water-based, which binds the insulation together to form a seamless batt. This type of insulation, when properly installed resists settling and shifting and allows the cavity to be completely filled, leaving no air gaps, thereby greatly reducing air leakage. The three most common types of insulation installed in this way are cellulose, glass fibre blowing wool and mineral or rockwool.

Cellulose

Spray cellulose is the same material as loose fill insulation, except that it is applied using special applicators which mix the material with an adhesive, allowing it to adhere to the surface it is applied to.

Spray cellulose has an R-value of 3.5 per inch (RSI 0.024/mm).

Advantages

• Non-settling
  
• Resistant to air flow
  
• Can offer complete filling of wall cavities
  

Disadvantages

• Requires trained contractors for installation
  

Glass Fibre

Blown Glass Fibre is the same material as glass fibre batts, except that the material is 'chopped
up'. It has an R-value of 2.9 per inch (RSI 0.02/mm), when blown to the proper density.

Advantages

• Non-settling
  
• Can offer complete filling of wall cavities
  
• Small amounts of moisture have little effect on the materials R-value
  

Disadvantages

• Can cause eye, skin and respiratory irritation during installation
  
• Requires trained contractors for installation
  

Mineral Wool (Slag and Rock Wool)

Sprayed-In-Place mineral wool is the same material used in loose fill insulation, except that it is 'chopped up' and mixed with an adhesive.

Both slag and rock wool have an R-value of 3 per inch (RSI 0.021).

Advantages

• Non-settling
  
• Can offer complete filling of wall cavities
  
• Good material for insulating around chimneys, since it doesn't support combustion
  
• Small amounts of moisture have little effect on the materials R-value
  

Disadvantages

• Can cause eye, skin and respiratory irritation during installation
  
• Requires trained contractors for installation
  

RECOMMENDED INSULATION LEVELS

When deciding on insulation levels, the house should be viewed as a whole and a balanced
approach should be used. It makes very little sense to add a high level of insulation in the attic
when the exterior walls have low insulation values, or the basement is uninsulated. Since heat
loss occurs through all areas of a house, each part of the building envelope which separates the
heated interior from the outside needs to be insulated. In new construction this is a fairly simple
process. In an existing home it is more difficult, but usually not impossible. For example, small
holes can be drilled into exterior or interior walls, and new insulation blown in, or rigid
insulation can be applied to the exterior of the house under a new exterior finish.

The list below gives recommended levels of insulation for the main areas of the home.
Values are shown in both imperial 'R' and metric ('RSI') units.

Minimum Recommended Insulation Levels For Cold Climate Housing

Basement Floors

R-10 (RSI-1.8)

Basement Walls

R-12 (RSI-2.1)

Above Grade Walls

R-20 (RSI-3.5)

Ceiling

R-40 (RSI-7.0)

Floors over unheated spaces

R-20 (RSI-3.5)

Exposed Cantilevers

R-28 (RSI-4.9)

Recommended Insulation Levels For Energy Efficient Homes

Basement Floors

R-10 (RSI-1.8)

Basement Walls

R-20 (RSI-3.5)

Above Grade Walls

R-40 (RSI-7.0)

Ceiling

R-60 (RSI-10.6)

Floors over unheated spaces

R-40 (RSI-7.0)

Exposed Cantilevers

R-40 (RSI-7.0)

Note: R-1 = 0.1761 RSI

INSULATION VALUES

The following charts provide the thermal resistance (insulation value) of various materials used in house construction.

INSULATION MATERIALS

Building Material	R-value/inch (RSI/mm)	R-value (RSI) for Thickness Listed
Batt Insulation
Mineral fibre, batt	3.3 (0.023)
Glass fibre, batt	3.2 (0.022)
Loose Fill Insulations
Cellulose fibre, blown (settled thickness)	3.6 (0.025)
Mineral fibre, loose fill	3.0 (0.021)
Glass fibre, loose fill (poured)	2.9 (0.020)
Glass fibre, loose fill (blown)	3.0 (0.021)
Expanded mica (vermiculite)	2.3 (0.016)
Spray Foam Insulations
Polyurethane (foamed in place)	6.0 (0.042)
Isocyanurate, sprayed	5.0 (0.034)
Sprayed-In-Place Insulations
Cellulose fibre, sprayed (settled thickness)	3.5 (0.024)
Glass fibre, sprayed	2.9 (0.020)
Mineral fibre, sprayed	3.0 (0.021)
Rigid Insulations
Polyurethane boardstock	6.06 (0.0420)
Extruded polystyrene boardstock	5.0 (0.0347)
Semi-rigid glass fibre sheathing	4.4 (0.0305)
Expanded polystyrene boardstock	3.71 (0.0257) - 4.3 (0.0298)
Glass fibre roof board	3.99 (0.0277)
Fibreboard	2.80 (0.0194)
Mineral aggregate board	2.62 (0.0182)
Other Materials
Cork	3.71 (0.0257)
Wood fibre	3.33 (0.0231)
Wood shavings	2.44 (0.0169)

STRUCTURAL MATERIALS

Building Material	R-value/inch (RSI/mm)	R-value (RSI) for Thickness Listed
Cedar logs and lumber	1.33 (0.0092)
Softwood lumber (except cedar)	1.25 (0.0087)
Concrete (30-150 lb per cubic foot)	0.06 (0.0069) - 1.0 (0.00045)
Concrete block (3 oval core) sand and gravel aggregate 4-12 inches (100-300 mm)		0.71 (0.12) - 1.28 (0.22)
Concrete block (3 oval core) cinder aggregate 4-12 inches (100-300 mm)		0.71 (0.12) - 1.28 (0.22)
Concrete block (3 oval core) lightweight aggregate 4-12 inches (100-300 mm)		1.50 (0.26) - 2.27 (0.40)
Common brick Clay or shale 4 inches (100 mm)		0.4 (0.07)
Common brick Concrete mix 4 inches (100 mm)		0.3 (0.05)
Stone (lime or sand)	0.087 (0.00060)
Steel	0.003 (0.000022)
Aluminum	0.0007 (0.0000049)
Glass (no air films) 1/8 - 1/4 inch (3-6 mm)		0.06 (0.01)

AIR

Building Material	R-value/inch (RSI/mm)	R-value (RSI) for Thickness Listed
Enclosed Air Space (non-reflective)
Horizontal space - heat flow up		0.85 (0.150)
Horizontal space - heat flow down		1.02 (0.180)
Vertical space - heat flow horizontal		0.97 (0.171)
Air spaces less than 1/2 inch (12 mm) minimum dimension		0
Enclosed Air Space (reflective)
Horizontal space - faced one side heat flow up		1.84 (0.324)
Horizontal space - faced two sides heat flow up		1.89 (0.322)
Horizontal space - faced one side heat flow down		5.56 (0.980)
Horizontal space - faced two sides heat flow down		5.87 (1.034)
Vertical space - faced one side heat flow horizontal		2.64 (0.465)
Vertical space - faced two sides heat flow horizontal		2.73 (0.480)
Air spaces less than 1/2 inch (12 mm) minimum dimension		0
Air surface films
Outside air film (moving air)		0.17 (0.03)
Inside air film (still air) Horizontal, heat flow down		0.92 (0.162)
Inside air film (still air) Vertical, heat flow horizontal		0.68 (0.12)
Inside air film (still air) Horizontal, heat flow up		0.61 (0.105)
Inside air film (still air) Sloping 45 degrees, heat flow up		0.61 (0.105)
Other
Attic air film		0.5 (0.08)

ROOFING MATERIALS

Building Material	R-value/inch (RSI/mm)	R-value (RSI) for Average Thickness
Asphalt roll roofing		0.15 (0.026)
Asphalt shingles		0.44 (0.078)
Wood shingles (cedar shakes)		0.94 (0.165)
Built-up membrane (hot mopped)		0.33 (0.058)
Crushed Stone (not dried)	0.09 (0.0006)

SHEATHING MATERIALS

Building Material	R-value/inch (RSI/mm)	R-value (RSI) for Thickness Listed
Softwood plywood	1.25 (0.0087)
Mat-formed particleboard	1.25 (0.0087)
Insulating fibreboard sheathing	2.38 (0.0165)
Gypsum sheathing	0.89 (0.0062)
Sheathing paper	0.062 (0.0004)
Asphalt-coated kraft paper vapour barrier	negligible
Polyethylene vapour barrier	negligible

CLADDING MATERIALS

Building Material	R-value/inch (RSI/mm)	R-value (RSI) for Thickness Listed
Fibreboard siding Medium-density hardboard		0.578 (0.10)
Fibreboard siding 3/8 inch (9.5 mm) High-density hardboard		0.5 (0.08)
Softwood siding (lapped) Drop, 1x8 inch (18x184 mm)		0.79 (0.139)
Softwood siding (lapped) Bevel, 1/2x8 inch (12x184 mm)		0.81 (0.143)
Softwood siding (lapped) Bevel, 1x10 inch (19x235 mm)		1.05 (0.185)
Softwood siding (lapped) Plywood, 1/8 inch (9 mm)		0.58 (0.103)
Wood shingles		1.0 (0.17)
Brick (clay or shale) 4 inches (100 mm)		0.42 (0.074)
Brick (concrete and sand [lime]) 4 inches (100 mm)		0.3 (0.053)
Stucco 1 inch (25 mm)	0.20 (0.0014)	0.20 (0.0356)
Metal siding Horizontal clapboard profile		0.7 (0.123)
Metal siding Horizontal clapboard profile with backing		1.40 (0.246)
Metal siding Vertical V-groove profile		0.70 (0.123)
Metal siding Vertical board and batten profile		negligible

INTERIOR FINISH

Building Material	R-value/inch (RSI/mm)	R-value (RSI) for Thickness Listed
Gypsum board, gypsum lath 1/2 inch (12.7 mm)	0.89 (0.0062)	0.445 (0.0787)
Gypsum plaster 1/2 inch (12.7 mm) Sand aggregate	0.20 (0.0014)	0.1 (0.01778)
Gypsum plaster 1/2 inch (12.7 mm) Lightweight aggregate	0.63 (0.0044)	0.315 (0.05588)
Plywood 5/16 inch (7.5 mm)	1.25 (0.0087)	0.391 (0.0653)
Hardboard (standard) 1/4 inch (6 mm)	0.72 (0.0050)	0.18 (0.03)
Insulating fibreboard 1 inch (25 mm)	2.38 (0.0165)	2.38 (0.4191)
Drywall, gypsum board 1/2 inch (12.7 mm)	0.88 (0.0061)	0.44 (0.0775)

FLOORING

Building Material	R-value/inch (RSI/mm)	R-value (RSI) for Thickness Listed
Maple or Oak (hardwood) 3/4 inch (19 mm)	0.91 (0.0063)	0.7 (0.12)
Pine or Fir (softwood) 3/4 inch (19 mm)	1.28 (0.0089)	1.0 (0.17)
Plywood 5/8 inch (16 mm)	1.25 (0.0087)	0.781 (0.1392)
Mat-formed particleboard 5/8 inch (16 mm)	1.2 (0.0087)	0.781 (0.1392)
Wood fibre tiles 1/2 inch (12.7 mm)	2.38 (0.0165)	1.19 (0.209)
Linoleum or tile (resilient) 1/8 inch (3 mm)	0.08 (0.014)
Terrazzo 1 inch (25 mm)	0.08 (0.00055)	0.08 (0.014)
Carpet with fibrous underlay		2.08 (0.366)
Carpet with rubber underlay		1.28 (0.226)

Insulation

Insulating Energy Efficient Houses

Two common framing methods and key structural points are detailed for insulating energy efficient wall systems for new housing. Exterior finishes as well as foundation and roof framing is varied to show different finishing and applications. Exterior weather barrier details are not shown but its installation is very important. Some details are also provided for insulating cantilevered floors and attic spaces.

• Frame Wall with Exterior Insulation
  
  
  • Floor Joist Detail
    
  • Roof Construction Detail
    
  • Exterior Corner Detail
    
  • Window Details
  
  
  
  
• Frame Wall with Interior Horizontal Strapping
  
  
  • Floor Joist Detail
    
  • Roof Construction Detail
    
  • Exterior Corner Detail
    
  • Window Detail
  
  
  
  
• Cantilever Floor Detail
  
  
• Insulating the Attic Space
  
• Installing Batt Insulation
  
  

Frame Wall with Exterior Insulation

A simple 2 x 6 inch (38 x 140mm) single stud wall, 24 inch (600mm) on centre, uses rigid or semi-rigid insulating sheathing, applied to the outside to achieve an energy efficient wall system. This construction method can achieve R28 (RSI 4.9) or higher using standard framing practices. Exterior board insulations reduce the thermal bridging heat loss through framing components while reducing convection heat loss from outside air penetration.

Floor Joist Detail

The floor joist and headers are set in to allow for extra board insulation. This is required to maintain two-thirds of the insulation outside the air/vapour barrier. The 2 x 4 inch (38 x 89mm) bottom plate allows the board insulation to extend above and seal the header.

A foam gasket will provide the seal between the mud sill and the concrete, while providing protection for the polyethylene air/vapour barrier.

Roof Construction Detail

Air movement from the soffit into the highly insulated attic space is maintained using insulation stops.
Horizontal strapping at the top (centre and bottom) of the wall provides a means of securing the exterior sheathing and can provide the firm backing required for a stucco type finish.

The ceiling air/vapour barrier is caulked and stapled to the wall vapour barrier against the solid backing. If possible join them so that the ceiling air/vapour barrier is outside the wall air/vapour barrier.

Exterior Corner Detail

This method provides solid backing for the drywall at exterior corners.

Air/vapour barrier joints should be sealed with acoustical sealant and stapled into solid backing (studs). Allow a little slack but do not bunch up or join the air/vapour barriers in the corners as this creates difficulties when drywalling.

Blocking is also required in the exterior corners to permit siding or other exterior finishes to be properly attached.

Window Details

A 12 to 18 inches (300 to 450mm) strip of 6 mil polyethylene is caulked and stapled around the window frame prior to installation. The corners need to be overlapped so they can be folded back after installation. The strip of polyethylene is than caulked and stapled to the wall air/vapour barrier.

Horizontal strapping around the outside edge of the window frame provides secure fastening for the plywood sheathing and exterior finish. Remember to insulate the box lintel above the window before installing the window unit.

Frame Wall with Interior Horizontal Strapping

Standard 2 x 4 or 2 x 6 inch (38 x 89mm or 38 x 140mm) framing is used for the main walls. The wall is then insulated and a continuous air/vapour barrier is applied. Interior 2 x 2 or 2 x 3 inch (38 x 38 or 38 x 64mm) strapping is then applied horizontally on 24 inch (600mm) centres. The strapping separates and helps to protect the air/vapour barrier from being damaged due to plumbing, electrical or drywall installation. Electrical and other services are installed on the inside of the air/vapour barrier.

As shown single stud walls can also be built with insulated sheathing on the exterior. Make sure two-thirds of the insulation value is on the outside of the air/vapour barrier.

Floor Joist Detail

Wrap the air vapour barrier from inside the foundation and drape around the outside. After the floor joists and sheathing are installed the polyethylene can be wrapped around the floor joists as shown. Once the exterior walls are completed the polyethylene is then caulked and stapled to the basement and first floor polyethylene air/vapour barriers. This detail shows the air/vapour barrier secured and protected between the top plates of a preserved wood foundation.

The inset header and floor joists allows a reasonable level of insulation using a board type insulation on the outside. This allows for one-third of the value of the insulation to be placed on the inside the header.

Roof Construction Detail

High heel trusses are used to obtain a high level of insulation in the attic directly over the exterior walls while still allowing for adequate ventilation flows.

Wall and ceiling air/vapour barriers are caulked and stapled into the top plates of the wall and then secured by the interior strapping.

Exterior Corner Detail

Studs are used in the interior corners of inside walls to provide solid backing for drywall or wallboard.

The air/vapour barrier joints should be caulked and stapled to solid backing (studs). The polyethylene should not be joined or bunched into corners as it causes difficulties with drywalling.

Window Detail

A 12 to 18 inches (300 to 450mm) strip of 6 mil polyethylene is caulked and stapled around the window frame prior to installation. The corners need to be overlapped so they can be folded back after installation. The strip of polyethylene is then caulked and stapled to the wall air/vapour barrier between the horizontal strapping and the drywall or wallboard.

Cantilever Floor Detail

All seams in the cantilever subfloor must be sealed to act as an air barrier. Insulation must fill the entire cavity to the inside face of the wall. Rigid polystyrene or wood blocking installed between the floor joists should be sealed with caulking to the joists and subfloor surfaces. Additional rigid insulation may be added to the underside prior to installing the exterior sheathing and weather barrier.

Insulating The Attic Space

Heavy polyethylene is placed over and between the ceiling joists (if no air/vapour barrier is present), being sure that it fits snugly into the spaces and that all joints are overlapped and caulked using acoustical sealant.

The batts are fitted tightly together between the joists, with care taken to extend the insulation as far as possible over the top of the exterior wall without cutting off the air flow from the soffit vents (insulation stops can be installed between the rafters to keep the vents open). Subsequent layers of batt insulation should be run in opposite directions, to help reduce heat loss through the joists and joist spaces.

If loose-fill insulation is used, it can be poured or blown into place, and a rake or screed board used to level it off.

Installing Batt Insulation

Batt insulation is relatively simple to install, and is effective if care is taken and a few simple rules are followed.

• Butt the ends of the batts together as snugly as possible.
  
• The first layer of insulation should fill the joist space completely, so that the second layer can run perpendicular to the first, preventing heat loss through the joists.
  
• Ensure that subsequent insulation layers sit tightly together, and that no air gaps exist between them.
  
• The insulation should be extended over the top plates of exterior walls, and insulation stops used to prevent it from blocking air flow from soffit vents.
  
• Irregular shaped spaces/gaps should be insulated with custom cut pieces or loose fill insulation.