The various attic insulation types can be divided into batt-type, loose-fill, board-stock, and spray-applied insulators and these can be further divided on the basis of the building materials that are utilized. The most common building materials for insulating the attic include fiberglass, mineral wool, cotton, mineral fiber, cellulose fiber, rigid fiberglass, rigid material fiber, Polyisocyanurate, wet-spray cellulose, open-cell light density polyurethane, and closed cell medium density polyurethane.
Pros and Cons
Various attic insulation types have their own unique advantages and disadvantages. Moreover, some attic insulation material is easy to acquire whereas other types of materials are difficult to find. Cotton insulation and rigid fiberglass are hard to find and choosing the correct type usually boils down to availability, price and effectiveness of the insulating material.
The need for attic insulation may arise if you notice that -
The Value of R-value
- The walls are cold
- The air inside is uncomfortably hot in summers
- Cooling costs are high
- Mold is growing on walls or in the basement
- There is uneven heating
- The floors are cold
- The air conditioning is ineffective
The attic insulation types can also be chosen using the R-values of materials that are used for insulation or the R-value derived by specialized type of insulation. The R-value is a measure of thermal resistance and a high R-value implies better thermal resistance. Batt-type insulation can be made by using fiberglass, mineral wool, or cotton and the R-value is higher for fiberglass and cotton. However, cotton batt-type insulators are difficult to find whereas fiberglass insulators are easily available and mineral wool is ideal for soundproofing and fire resistance.
Batt, Loose-fill, Board-stock, and Spray-applied Insulators
Batt-type insulation is usually in the form of blankets of fiber, which are 48 inches long, which is wide enough to fit in between wall studs. Wall studs are upright pieces of wood used to frame a house and support the walls of the structure. Loose-fill type of attic insulators can be affected by air movements in the attic and is ideal if no one is planning to occupy it and also needs a professional installer when it provides almost the same R-value as that of batt-type insulators.
Board-stock and spray applied insulators provide the highest R-value and can be ideal for cold and wet climates since board-stock insulation usually drains away the water content and spray-applied insulators can act as an air barrier and vapor retardant.
Prices and Codes
The building codes in Canada usually require the R-value to be at least R-40 in the attic and this factor can influence your choice of attic insulation types. Fiberglass insulation is used in batt-type insulation as well as in loose-fill.
They can cost anywhere from $ 125 to $200 for the complete house and around half of that for just the attic. This is because the attic needs at least 12 to 15 inch thick fiberglass layer to meet the standards of the Canadian National Building Code.
The price of spray applied insulators is the same as that of batt-type insulators. Spray applied insulators are suitable for wet climates whereas batt type insulation is ideal for providing fire resistance in hotter climates.
Section 9.19.2 of the Canadian National Building Code defines the basic requirements of access to the attic. According to this section, the hatch shall be not less than 550 mm by 900 mm with the exception of cases where the hatch serves a solitary dwelling unit. Furthermore, the hatch may be condensed to 0.32 m2 in area with no dimension less than 545 mm, or 500 mm by 700 mm.