R-Value Ratings for Insulation

R-Value Ratings

As energy efficiency has become an increasing concern among builders and homeowners, the attributes and performance of building materials and components are being scrutinized more closely. In order to maximize levels of energy efficiency by examining the details of how each individual component of a house performs on its own and as part of a dynamic system, very specific properties are measured and taken into account. This can be especially helpful when trying to select the best building materials for a given application.

R-value is the measurement used when quantifying a specific material’s level of thermal resistance, which is the inverse of U-value, which measures thermal conductance. R-value is often the standard consideration when discussing the effectiveness of insulation. It’s good to be familiar with the specifics of R-value ratings, especially when wanting to understand insulation, energy efficiency, heat transfer and energy audits.

How Does R-Value Relate to Insulation?

Heating and cooling costs account for 50% to 70% of energy used in an average U.S. home. Inadequate insulation can account for a lot of wasted energy, so it is important to be sure that insulation installed is doing its job properly and increase energy efficiency.

The function of insulation is to provide resistance to the flow of heat, and R-value is the measure of exactly this attribute for a given material. A higher R-value equates to higher resistance to heat flow and greater effectiveness in insulating. An insulation material’s R-value, in conjunction with how and where it is installed, will determine its overall thermal resistance and energy efficiency effectiveness. Adding the R-values of each layer of material contained in one building component, such as a wall or ceiling with multiple layers of insulation, will help determine the thermal resistance of the whole component. The way the insulation is installed, as well as other factors, will also affect its thermal resistance, heat transfer and energy efficiency.

Important Factors to Consider When Measuring R-Value Thermal Resistance

When considering R-value as a means to determine the thermal resistance of a building component, there are other factors that must also be taken into account. While R-values are an excellent guide for comparing the attributes of different insulation products, they apply only when the insulation is properly installed. For example, if two layers of insulation are smashed into the thickness intended for one layer, the R value does not double. Likewise, if a single layer of insulation is compressed during installation, it will not be as effective. Stuffing batt insulation sized for 5 inches into a 4-inch wall cavity will actually lower its R-value. Ensuring that insulation is correctly installed will help allow the product’s full benefits to be realized.

Also important to consider is the fact that even when installed correctly, insulation affects heat transfer through the insulation itself but not through other materials, such as glass windows and studs. If there are structural gaps in any building penetrations, even insulation with a high R-value that’s installed properly cannot mitigate heat loss from air leaks. Studs and windows provide a parallel heat transfer conduction path, and insulation between studs in a wall does not restrict heat flow through the studs. This heat flow is called thermal bridging, and the overall R-value of the wall will be different from the R-value of the insulation itself.

Calculating and Converting R-Value

The equation used to calculate R-value may be of interest to some inspectors because if the R-value is known, the equation can also be used to help calculate heat loss. The equation for determining R-value is as follows:

R-value = temperature difference x area x time ÷ heat loss

The temperature difference is expressed in degrees Fahrenheit, the area in square feet, the time in hours, and heat loss in BTUs. Since European R-value uses different units of measure (Celsius, Kelvin, meters, etc.), it may be helpful to know how to convert a European R-value into a U.S. R-value. This is done by multiplying the European value by 0.176 and dividing 1 by the result.

The FTC and DOE on R Value

In the 1970s, the Federal Trade Commission (FTC) created a rule requiring insulation manufacturers to disclose R-values at the point of sale and in some ads. This is intended to protect purchasers from false claims made by manufacturers and to create a standard of comparison for products.

insulation r value1 R Value Ratings For Insulation

The U.S. Department of Energy (DOE) has issued recommendations for insulation R-values in new and existing homes. The recommendations are based on a comparison of the cost for installing insulation versus potential future energy savings. Their recommendations for attics, cathedral ceilings, walls and floors are generally greater due to more heat flow than what is actually required by most current building codes.

R-value ratings are a useful tool, especially when comparing the effectiveness of insulation products for energy efficiency, heat transfer and controlling heat loss. Understanding a bit about how other factors such as heat flow affect a building component’s thermal resistance is important if insulation is to be used to its full benefit.

stumbleupon R Value Ratings For Insulation

delicious R Value Ratings For Insulation

Proper Installation of Insulation

Insulation is to provided as a continuous thermal barrier to minimize heat flow through the walls, ceiling and floors. Insulation acts to keep a home comfortable and helps cut costs for heating and cooling. If insulation is installed incorrectly such as being compressed or installed with gaps or insufficient insulation is installed, your home will not be as comfortable and your energy costs will be increased more than they could be. Remember, it is not difficult to install insulation correctly.

Recent studies have found that over one third of new homes have lower levels of insulation installed than required and/or specified and an additional one fifth have very serious installation problems that will result in significantly decreased effectiveness of the insulation. Additionally, virtually all of the homes studied were found to have numerous insulation installation defects that reduce the performance of the insulation well below its rated R-value. All of these can lead to possible future defect litigation. The following cost-effective procedures will help improve comfort, reduce energy use, and reduce potential defect liability exposure.

Insulation should:

Provide a continuous barrier between the inside conditioned space and the outside,
Be installed to the proper R-value,
Be installed without gaps,
Avoid excessive compression,
Be properly labeled or indicate the proper depth to achieve the specified R-value.

The following steps should be followed in the installation of insulation to ensure efficiency and comfort.

Work with the architect and framer to minimize spaces that are difficult to insulate.
Use materials that meet California quality standards.
Install R-values that meet or exceed design specifications.
Install insulation to completely fill all cavities without gaps and with minimal compression.
Account for special characteristics of the materials used, such as settling, flammability, or water permeability.
Inspect the final job using the accompanying checklist (Attachment I-2) to ensure a quality installation.

Wall Insulation

Unfaced batt insulation installation; batts shall be:

correctly sized to fit snugly at the sides and ends
installed to completely fill the cavity
cut to fit properly — there should be no gaps, nor should the insulation be doubled-over or compressed
non-standard-width cavities shall be filled by batt insulation cut approximately one inch (1″) wider than the space to be filled
cut to butt-fit around wiring and plumbing, or be split (delaminated) so that one layer can fit behind the wiring or plumbing and one layer fit in front

Faced batt insulation installation, where used as a vapor barrier: additional instructions:

facing should be placed toward living spaces
faced insulation must be properly stapled over the face of the studs; it must be continuous with no penetrations
stapling: the batt flange should be stapled to the face of the framing; flanges from adjacent cavities should overlap per manufacturers specifications on facing
each batt should be stapled approximately every eight (8) inches, or according to manufacturers specifications on facing
all tears or breaks in the facing six (6) inches or longer shall be sealed with duct tape or other waterproof tape. Tears and breaks in the facing should be minimal.

Narrow-framed cavities and “chinking:”

non-standard-width cavities shall be filled by batt insulation cut approximately one inch (1″) wider than the space to be filled
narrow spaces (2″ or less) at windows, between studs at the building’s corners, and at the intersections of partitions and walls shall be filled with small pieces of insulation; care should be taken not to compress the insulation

Special situations:

Insulation installations prior to exterior sheathing or lath

all exterior channels (e.g., at wall junctions and corners) must be filled with insulation
all exterior walls adjacent to tubs and showers must be filled with insulation

Obstructions

insulation shall be cut to fit around wiring and plumbing without compression
insulation shall be placed between the sheathing and the rear of electrical boxes
insulation shall be cut to fit around junction boxes
in cold climates water pipes shall have at least two thirds of the insulation between the water pipe and the outside. If the pipe is near the outside, as much insulation as possible shall be placed behind the pipe and no insulation shall be placed between the pipe and the inside.

Rim joists

all rim joists shall be insulated to the same R-value as the walls
as necessary, insulation shall be cut to fit into the rim joist
an alternative to fitting insulation in a web truss located at the rim joist is to completely cover the truss with insulation, snug to the upper and lower floors

Knee walls and Skylight shafts with framing that will support insulation

all knee walls and skylight shafts shall be insulated to a minimum of R-19
the insulation shall be installed without gaps and with minimal compression
for steel-framed knee-walls and skylight shafts, external surfaces of steel studs must be covered with batts or rigid foam unless otherwise specified on the CF-1R and documented by a form 3R generated by EZFRAME

Knee walls and Skylight shafts without framing that will support insulation

for steel-framed knee-walls and skylight shafts, external surfaces of steel studs must be covered with batts or rigid foam unless otherwise specified on the CF-1R and documented by a form 3R generated by EZFRAME
the house side of the insulation shall be in contact with the drywall or other wall finish. The attic side shall be covered with, and supported by a facing rated for attic exposure to stop air intrusion into the insulation.

HVAC/Plumbing closet

insulate all walls of interior closets for HVAC and/or water heating equipment the same R-value as the exterior walls

Batt Ceiling Insulation

Unfaced batt installation:

batts shall be correctly sized to fit snugly at the sides and ends
batts should fill the cavity
where necessary, batts shall be cut to fit properly — there should be no gaps, nor should the insulation be doubled-over or compressed. When batts are cut to fit a non-standard cavity, they should be cut to be one inch (1″) wider than the cavity.
batts should be cut to butt-fit around wiring and plumbing, or be split (delaminated) so that one layer can fit behind the wiring or plumbing and one layer fit in front
for batts that are taller than the trusses, full-width batts should be used so that they expand to touch each other over the trusses
the insulation must cover the wall top plates
hard covers or draft stops should be placed over all deep drops and interior wall cavities to keep insulation in place and stop air movement. If hard covers or draft stops are missing or incomplete, they should be completed before insulation is completed.
required ventilation must be maintained: for eaves or soffit vents, one-inch (1″) of unblocked free air space between the roof sheathing and the insulation is required.
where necessary, use baffles to keep the insulation from blocking the passage of air
insulation shall cover all IC rated lighting fixtures
fixtures that are not IC rated (e.g., halogen lamps, heat lamps) need to be enclosed in an airtight box that meets fire codes, and the box covered with insulation. If fixtures are not IC rated and not enclosed in such a box, they should be replaced or boxed before insulation is completed.

Faced batt installation, where used as a vapor barrier: additional instructions:

facing should be placed toward living spaces
stapling: the batt flange is stapled to the face of the framing; flanges from adjacent cavities should overlap
each batt should be stapled approximately every eight inches (8″) or per manufacturer’s specifications on the facing
all tears or breaks in the facing six inches (6″) or longer shall be sealed with appropriate tape approved by the insulation manufacturer. Tears and breaks in the facing should be minimal.

Special situations:

Insulation at bridging (cross bracing)

batts shall be split lengthwise at the center and packed half into the lower opening and half into the upper opening of bridging (cross bracing) of ceiling and/or floor joists
alternatively, insulation is butted to the bridging and the space is filled with scrap insulation

Rafter ceilings

an inch of air space should be maintained between the insulation and roof sheathing, if necessary to meet local codes
facings and insulation should be kept three inches (3″) away from heated flue pipes or chimneys; follow flue manufacturer’s recommendations

HVAC platform

verify that appropriate batt insulation is placed below any plywood platform or walks for HVAC equipment installation and access

Attic access

permanently attach rigid foam or a batt of insulation to the access cover using adhesive or mechanical fastener

BLOWN-IN CEILING INSULATION

baffles must be placed at eaves or soffit vents to keep insulation from blocking attic ventilation; required ventilation must be maintained: for eaves or soffit vents, one-inch (1″) of unblocked free air space between the roof sheathing and the insulation is required.
hard covers or draft stops must be placed over all deep drops and interior wall cavities to keep insulation in place and stop air movement. If hard covers or draft stops are missing or incomplete, they should be completed before insulation is completed.
small, inaccessible openings shall be hand packed with pieces of batt insulation
attic rulers appropriate to the material installed must be placed around attic to verify depth: 1 ruler for every 250 square feet, evenly distributed around the attic and clearly readable from the attic access
insulation shall be blown to a uniform thickness throughout the attic, with no high or low spots
labels from the insulation bags should be cut out and stapled to a truss vertical near the attic opening
insulation must go underneath and on both sides of obstructions such as cross-bracing and wiring
insulation shall be applied all the way to the outer edge of the wall top plate
insulation shall cover IC rated lighting fixtures
fixtures that are not IC rated (e.g., heat lamps) need to be enclosed in a drywall box and the box covered with insulation. If fixtures are not IC rated and not enclosed in a drywall box, they should be replaced or boxed before insulation is completed.
there shall be no excessive compression of insulation material
clearances around fossil-fuel appliances and heat-exhaust vents shall follow local fire protection codes
no insulation or facing shall be placed in air spaces surrounding metal chimneys or fireplaces; follow manufacturer’s recommendations
batt or rigid foam insulation shall be installed in areas where blown-in insulation has not been applied, such as access panels and doors

Special situations:

HVAC platform

pressure-fill the areas under any plywood platform or walks for HVAC equipment installation and access or verify that appropriate batt insulation has been installed

Attic access

permanently attach rigid foam or a batt of insulation that is equal or exceeds the R-value of the insulation on the attic floor to the access cover using adhesive or mechanical fastener

RAISED FLOORS AND FLOORS OVER GARAGES

batts must be correctly sized to fit snugly at the sides and ends, but not be so large as to buckle — batts should be no more than one inch (1″) wider than the cavity
batts must be cut to fit properly — there should be no gaps, nor should the insulation be doubled-over or compressed
batts should fill the cavity
batts should be cut to butt-fit around wiring and plumbing, or be split (delaminated) so that one layer can fit behind the wiring or plumbing and one layer fit in front
where there is an air space between the insulation and flooring, the headers and band-joists must be insulated
if faced, facing should be placed toward living spaces

Thanks to the California Department of Energy for These Insulation Tips and Installation Pprocedures

tumblr Proper Installation Of Insulation

stumbleupon Proper Installation Of Insulation

delicious Proper Installation Of Insulation

Structural Insulated Concrete Walls

Insulated Concrete for Exterior and Structural Walls

According to the National Association of Home Builders (NAHB) and the Portland Cement Association (PCA), concrete homes account for approximately one-sixth of all new-home construction, and in areas such as Florida and Louisiana, they are particularly favored because of their greater resistance to hurricanes and tornadoes.

Contractors and buyers alike are attracted to their durability, strength, and heat-retention qualities. Let’s take a look at how homes constructed using concrete – in their common application as insulated concrete forms or ICFs – measure up against wood-frame homes.

Does the greater initial cost of insulated concrete forms pay off in the long run?

Proponents of insulated concrete forms claim that the initial higher cost of building with concrete as opposed to the more common wood-frame construction is justified by the savings on lower heating and cooling costs, lower property insurance, and lower maintenance costs.

A variety of factors affects the cost-benefit of insulated concrete forms, including:

the cost of wood compared to concrete for the local area;
the thickness of the walls;
the number and types of windows in the home;
ceiling insulation;
the sizing and efficiency of the heating and cooling equipment; and
the climate in the region where the home is constructed.

The U.S. Department of Housing and Urban Development (HUD) found in 2001 that using insulated concrete forms in construction added about 3% to 5% to the purchase price of a typical wood-frame home. These estimates should be treated with caution, however; a study by the PCA found that additional costs associated with insulated concrete form construction depend on the skill of the crew, and greater savings are found on large-scale projects involving multiple homes, where the method and economy of scale come into play. Simply put, local contractors may take on an insulated concrete form project but may lack the necessary expertise for execution, resulting in added costs.

Additionally, the greater construction costs for a typical insulated concrete form home are not necessarily recouped by the savings on energy and home insurance alone.

Other Values Offered by Insulated Concrete Forms

Resistance to Hazards

The single most significant attribute in favor of concrete construction is its structural safety. Implicit in the average lower insurance cost for insulated concrete form homes is the understanding that ICF homes better withstand natural disasters, such as hurricanes, tornadoes and floods. Insulated concrete form homes typically “recover” from hurricanes far quicker than wood-frame homes, as the exterior walls may withstand a hurricane and only a new roof will be required following such an event. huntsville tornado damage 01 Structural Insulated Concrete Walls In comparison, wood-frame houses in the same areas are usually devastated by hurricanes, meaning
longer rehabilitation times for residents and lengthier processing times for insurance claims. Concrete offers far better compressive strength, and far greater resistance to windborne debris. Insulated concrete form walls have been tested for resistance to tornado conditions by subjecting them to the impact of a 2×4 wood stud traveling at 100 mph. Although it is possible to upgrade the impact resistance of standard wood-frame wall construction to levels suitable for protection against moderate hurricanes and less severe tornadoes, it is impractical to upgrade standard wood-frame wall construction to give comparable performance of ICF walls.

Insulated Concrete Forms and Fire

Concrete walls have superior fire resistance compared to wood-frame houses. Solid concrete insulated concrete form walls can generally sustain as much as four hours of extreme fire exposure, whereas typical wood-frame walls in houses generally do not exceed a one-hour fire rating. For housing, building codes typically require a minimum 15-minute rating, with the exception of special fire separation requirements for multi-family construction, apartments, and townhouse units, where a minimum one- to two-hour fire rating is required for walls between dwelling units.

Furthermore, concrete is not a fuel source that can contribute to fire growth and spread in a building. However, it is also important to realize that doors, windows, and other cavities can mean lower resistance to fire spread if not similarly fire-rated, in comparison to the walls. Regardless, fire resistance is a recognized benefit of insulated concrete form construction and can result in reduced fire insurance premiums.

Durability of Insulated Concrete Forms

In Ireland, where housing ownership is relatively high and the cost of wood compared to concrete is also relatively high, concrete housing is the preferred material for construction. An added appeal for those wishing to go with concrete is the perceived notion that concrete houses will last hundreds of years and thereby provide a legacy to future generations. While it is difficult to exactly quantify durability benefits in the varying use-conditions of building materials, concrete offers added resistance to moisture and other environmental factors. While wood is protected within the walls of the home, it is susceptible to rot in areas where water often penetrates the exterior weather-resistant barrier of a home.

Insulated Concrete Forms and Noise

A study conducted by the Public-Private Partnership for Advancing Housing Technology, or PATH, rated concrete’s sound-absorption qualities as “excellent,” while wood homes scored “average” to “good.” In order for a wood-frame home to obtain similar performance ratings, it is necessary to make certain modifications, such as using thicker gypsum board layers, resilient channels, or acoustic insulation. These enhancements can add about $0.70 per gross square foot of wall area, which accounts for an increase of about 20% in the cost difference between insulated concrete forms and standard wood-frame construction (see the table below). In addition, concrete’s dampening quality limits the vibration to exterior walls when doors or windows are slammed, for example.

Windows and Doors Used Insulated Concrete Forms

In traditional wood-framed homes, there is an added cost associated with installing the windows and doors. Additional material is required to support them, often with expensive micro-laminated headers or additional stud support. In comparison, the overall cost per square foot of fenestration and door construction decreases with concrete, as the concrete bonds better around the cavity and maintains structural support. However, a study of thermographic testing by the NAHB found that houses constructed with insulated concrete form walls have up to a 50% decrease in the required capacity of HVAC equipment because the greater insulative capacity of concrete allows for smaller heating and cooling systems. Finally, once the concrete is set, it is comparatively difficult and costly to saw through the concrete to create additional cavities or modifications for HVAC units or windows.

Cost Comparison Based on Performance

Another way of assessing the cost-benefit of insulated concrete form housing is to measure the cost of upgrading a wood-frame home to perform in a manner similar to a concrete home, shown in the following table.

Performance Characteristic	Increase in cost to upgrade or retrofit a typical wood-frame home to ICF standards
Fire protection	Not feasible or considered impractical
Sound-proofing	20%
Durability	20%
Energy efficiency	33%
Safety and hazard mitigation	50%

As seen above, the added costs of upgrading a wood-frame home to meet comparable performance levels of an insulated concrete form home show that concrete homes may offer greater value, depending on the consumer’s needs.

While it is commonly agreed that insulated concrete is a more expensive technique for home construction, it is generally incorrect to presume that the greater initial cost will be recouped by energy savings alone. The single biggest attribute in favor of insulated concrete is its structural integrity and ability to withstand severe environmental hazards. Rather than looking at any single element of the cost-benefit scenario, the greater all-round performance attributes of insulated concrete provide a compelling argument for its choice as a construction material in exterior walls.