Types And Characteristics Of Insulation

When considering insulation for your house, it helps to know about the types of products available, the characteristics of each type, and the rating system used to determine the insulating values of these products.

The "R" value of insulation is the measure of its resistance to heat flow. As it increases, the resistance to heat flow becomes greater. The R value of an insulating material varies as conditions change. It also varies depending on how and where you use it. For instance, when fiberglass insulation becomes wet, its R value decreases dramatically. When there are voids in insulation in wall cavities, the value is lower than when installed properly. The voids allow for air infiltration, which decreases the R value of the insulation.

Foamboard insulation is closed cell insulation, because the cells trap air and gas bubbles in it. As moisture and air infiltrate these cells as the foamboard ages, its R value decreases from its original rating.

Although there are many types available, you will probably only need to know about three or four, as you will not be using all the insulation materials in his house. You do need to be familiar with fiberglass, rock wool, and cellulose insulation as well as with the polystyrene and polyisocyanurate types.

Fiberglass Insulation

Fiberglass insulation is the most common. It consists of blend of soda ash, ground sand, and boron, and it is available as batt insulation with a vapor barrier, or blanket insulation, which is unfaced so that a separate vapor barrier can be installed only when it is needed. The R value varies greatly. It can be as high as R38. Blanket insulation comes in 4-foot and 8-foot lengths, and both the batt and blanket types are available in 16-inch and 24-inch widths. Typically, 3 1/2 inch batt insulation with an R11 or R13 rating is used to insulate in wall cavities and 6-inch insulation with an R20 rating is used in ceilings and attics.

The fire-resistance of fiberglass insulation is lower than the other types. Its R value also decreases significantly when it gets wet. Loose fill fiberglass insulation also is available for use in houses. It is blown into wall and ceiling cavities as well as into attics.

The thickness of the fiberglass insulation used in a house depends on where it is going in that house. For instance, when the walls have 2" x 4" wall studs, the thickness of the batt insulation can only be 3 1/2 inches, the thickest size that will fit in that space. It is not a good idea to install insulation thicker than 3 1/2 inches in this wall cavity because as you compress the insulation you lower its R value. In many houses being built today, the size of the wall studs are 2" x 6" to accommodate 6-inch thick batt insulation, which has a higher R value and therefore more effective.

Rock Wool Insulation

We frequently find rock wool insulation in a house as well. It comes from slag, a byproduct in the manufacture of steel. Its melting point is twice that of fiberglass. Rock wool is very dense, and this characteristic makes it more sound-retardant than fiberglass insulation. Rock wool insulation is an appropriate choice in sound deadening applications. You blow rock wool into wall cavities and attics as is fiberglass or cellulose insulation.

Cellulose Insulation

Cellulose insulation is recycled paper and is used in wall and ceiling cavities. Before used, however, it is treated chemically to make it fire and insect resistant. Cellulose insulation has excellent sound-proofing qualities, as does rock wool, and its R value decreases significantly after it gets wet, like fiberglass insulation. After it dries, the texture of cellulose insulation is like tissue paper, and, it becomes ineffective as an insulating material.

Other Insulation Materials

We use extruded polystyrene and polyisocyanurate insulation materials in both exterior and interior applications. They apply as panels to the surfaces. Extruded polystyrene insulates foundation walls below grade. You also find it under a concrete slab to prevent the cold air from entering the house through the slab. Extruded polystyrene consists of benzine and ethylene or Freon gas. Polyisocyanurate insulation consists of a foil face and works as a sheathing material. It is very strong and has a very high R value. Since not fireproof, polyisocyanurate insulation must have a fire retardant sheeting material [drywall] on the interior side.



Vapour Barriers

A vapor barrier cannot function properly if not installed correctly. It causes more harm than good when placed incorrectly in an insulated space. A vapor barrier slows down the heat transfer process from a warm space to a cold one and, therefore, it limits the amount of condensation that takes place.

For example, during the heating season, the moist, heated air in the house penetrates the wall cavities, where its moisture condenses. While a vapor barrier installed in the wall cavities cannot eliminate this process altogether, it can slow the process down, limiting the amount of moisture that collects in the wall cavities. This is significant for if much moisture collects there, it could lower the R value of the insulation in the wall cavities. Also, if moisture collects in the wall cavities for an extended time, it could damage the wood framing.

In most cases, the vapor barrier should face the interior or warm surface of the walls, ceilings, and floors. If you are in an area where temperatures remain warm all year, however, this should not be the case. Commonly, these houses have a central air conditioning system. Under these circumstances, the hot air outside travels into the house instead of a reverse flow as is common in houses located in areas where there are four seasonal temperature changes. When placing the vapour barrier towards the living area in a house in a warm climate, the hot exterior air can condense in the wall cavities, where it could damage the wood framing and the insulation. This also could lead to the growth of mildew and fungus in the walls as well as to peeling and blistering paint on the interior surfaces. When installing insulation without a vapor barrier, install a polyethylene film over the studs and insulation to serve as a vapor barrier.



Sealing Your House Against Drafts

The air in your house is in constant movement. Inside air moves out and outside air moves in.The rate at which air does this is the Infiltration Rate.

A well sealed home will see it's total air replaced about once an hour. A poorly sealed home can loose its total air about 3 or 4 times that rate. The difference in heating bills can be staggering. Filling the gaps can and will dramatically lower your energy costs.

What You'll Need

To fill the gaps, get yourself a few batts of fibreglass insulation, silicone caulking, duct tape, weather-stripping and a pair of work gloves.

How And Where

While there may be thousands of tiny openings through the exterior of older homes, it is several large openings that account for most of the air infiltration. Plugging them is usually very easy.

ATTICS: Most attics do not have enough insulation, therefore, much heat loss happens there. Inspect around the fireplace chimney, above bathrooms and closets, and over kitchens and stairs. Upgrade the deficient places with the fibreglass batts up to the recommended levels. Don't forget to include the attic side of the access hatch. The insulation can be stapled to the cover to keep it in place.

HEATING DUCTS: Seal all the joints of both return and supply ducts with the duct tape. Consider insulating all duct work that runs through uninsulated attics and crawl spaces. The return ducts create a partial vacuum thus pulling cold air into them from these spaces. Without the tape, you lose about 10% of the heat produced by the furnace before it reaches the living space.

FIREPLACES: Look up inside your fireplace with a flashlight to check your damper. It should seal tightly around all its edges. Clean out any debris or mortar that prevents a tight fit. Keep the damper closed when not using the fireplace. While checking this damper, also check the dampers on bathroom exhaust fans. Do this by feeling around the fan for drafts on a cold windy day. Clean the lint from the flapper on the dryer vent to make sure it closes properly.

BASEMENTS AND CRAWLSPACES: Caulk the space between the bottom of the sill plate and the top of the foundation. Stuff insulation between joist ends where they meet the outside wall. Stuff fibreglass batt insulation into cantilevered floor cavities that overhang the foundation wall. Be sure to fill the entire cavity.

DOORS: Place weatherstripping around the top and sides of exterior doors. There are several kinds that work well. Make sure the threshold has a tight fit at the bottom of the door. Several types of threshold weather-stripping are readily available. A sweep attached to the bottom inside door will aid poor sealing thresholds.

WINDOWS: Install "V" type weather-stripping to windows to take up the space on window parts that fit poorly. Be sure that the locking mechanisms still work to pull the sashes together when finished. A clear, removable caulk is available that cannot be made to fit tightly. It is especially effective on double hung windows.

SWITCHES AND PLUGS: Install foam gaskets behind switch & plug face plates on exterior walls. Childproof protectors inserted in unused outlets will further reduce air infiltration.

OPENINGS IN CEILINGS: Lighting fixtures, and other openings through ceilings should be sealed to prevent falling air drafts. REMEMBER! Light fixtures that recess into ceilings require at least three inches of space between them and any insulation to prevent fire.

Allowing for this will set up holes through your insulation and will account for drafts. This can be addressed by use of a gasket under the rim of the lens cover or by changing the fixture to a flush mount type.

A Final Word

It can be overdone. All houses should have kitchen and bath power exhaust fans that have vents through the attic space to prevent condensation problems. Almost all older homes will respond will respond very well to tightening up measures.



Types of Weatherstripping

You can weatherstrip your doors even if you're not an experienced handyman. There are several types of weatherstripping for doors, each with its own level of effectiveness, durability and degree of installation difficulty. Select, among the options given, the one you feel is best for you.

Metal

Seals by spring tension. Nearly invisible with proper installation. A good value.

very effective

lasts 10-20 years

moderately easy to install; measure, cut and nail

used on most wood window channels

used on door frame top and sides

installation requires tin snips, hammer, nails, tape measure

Foam-filled Vinyl Tube

Unsightly in some places. Reinforced flange is very durable. Do not paint the tube gasket.

very effective

lasts 5-10 years

easy to install; measure, cut and nail

used on window frames

used on door frame top and sides

installation requires knife or shears, hammer and nails or staple gun, tape measure

Hollow Vinyl Tube

Unsightly in some places. Reinforced flange is very durable. Do not paint the tube gasket.

effective

lasts 2-7 years

easy to install; measure, cut and nail or staple

used on window frames

used on door frame top and sides

installation requires knife or shears, hammer and nails or staple gun, tape measure

Foam Rubber Tape

Many widths and thicknesses available. Will not stick to dirty surface. Clean and dry surfaces before installing.

effective

lasts 1-5 years

easy installation; measure, cut, peel and stick

used on window top and bottom

used on door frame top and sides but not where surfaces slide against each other

installation requires knife or shear, tape measure

Rigid Metal Strip Tube Gasket

Metal strips with slots rather than holes for fasteners can later be adjusted. Do not paint tube gasket.

very effective

lasts 5-10 years

moderately easy to install; measure, cut, screw or nail in place

used on window frames

used on door frame top and sides

installation requires hack saw, hammer and nails or screwdriver and screws, tape measure

Wood Strip Foam Gasket

Wood strip can be finished to match door frame. Not good for warped doors. Do not paint the foam.

effective

lasts 1-3 years

moderately easy to install; measure, cut and nail in place

used on door frame top and sides

installation requires hand saw, hammer, nails, tape measure

Felt Strips

Only good for narrow and even gaps. Comes apart where rubbing occurs. Do not paint. Not effective when wet.

least effective

lasts 1-2 years

easy to install; measure, cut, nail or staple

used on wood window top and bottom

used on door frame top and sides

installation requires knife or shears, hammer and nails or staple gun, tape measure

Vinyl/Plastic/Mylar 'V'

This works like the spring metal. It's installed flat and then bent to a 'V' shape, the open end of the 'V' to the outside of the doors which open inward.

very effective

lasts 2-20 years

easy to install; measure, cut, peel and stick

used on window channels, sides, top and bottom

used on door frame top and sides

installation requires knife or shears, tape measure
Glass Fiber

 Glass fiber, best known by its trade name fiberglass, is one of the most common insulation materials and is standard in newly constructed wood-frame homes. It is made of long, spun glass fibers coated with resins to create bonding between the fibers.

Fiberglass has the advantages of being relatively inexpensive, easy to install, resistant to moisture damage while being relatively nonflammable. In batt or blanket form, it has the advantage of not settling and creating gaps after installation. In its rigid board form, it offers the advantages of high R per inch and some structural stability.

Glass fibers can be irritating, therefore installing it requires some special handling. Masks, gloves, long sleeves and other protective apparel should be worn when handling this type of insulation.

Cellulose Insulation

 Cellulose insulation is made from paper products, primarily recycled newsprint. The paper is shredded and milled to produce a fluffy low-density material. Large amounts of chemicals, primarily boric acid, are added to provide flame resistance. The great advantages of cellulose are its relative low cost, ease of installation and high R per inch, roughly 25 percent higher than glass fiber. Its disadvantages are it can absorb moisture which may alter its physical and chemical properties and it may settle if not applied at the correct density.

Where Products Can Be Found

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CIMA Cellulose Insulation Manufacturers Association - In-depth answers to all your insulation questions on Cellulose Insulation.

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STYROFOAM* Brand Insulation is preferred by more architects, designers, specifiers, builders, contractors, building and home owners than any other brand of extruded polystyrene foam. In fact, it's the most widely used extruded polystyrene foam insulation in residential, commercial and industrial buildings throughout the world – in both new construction and retrofit applications. Because of its excellent water resistance, high insulation value and superior compressive strength, STYROFOAM Brand Insulation is used in basement wall insulation and foundation drainage, slab-on-grade insulation, waterproofing/damproofing protection, radiant floor heating applications. It's also used in insulation applications for a wide variety of roofs and ceilings, and for all kinds of walls.

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