Arkansas Insulation - Commercial Exam

Arkansas Insulation — Commercial Exam | 8 questions (27% of exam)

Key Concepts

Heat-transfer mechanisms. Heat (thermal energy) always flows from a warmer object to a colder object. The three mechanisms are convection (transfer by physically moving molecules of a fluid), conduction (molecule-to-molecule transfer in solid matter), and radiation (transfer through electromagnetic waves) — Insulation Handbook (2001), Chapter 3.

R-value. R-value is a measure of a material's ability to resist heat transmission. The higher the R-value, the greater the insulating effectiveness. R-value is cumulative: one type of insulation might have a value of R-5 per inch, and two inches would have a total R-value of R-10 — Carpentry and Building Construction, Section 31.1 — R-Value Basics.

U-value. The U-value is the flow rate of heat (thermal transmittance) through a material. The lower the U-value, the better the insulating value. U = 1/R and R = 1/U — Insulation Handbook (2001), Chapter 3.

Reporting conditions. R-values usually are reported at mean temperatures of 75°F per FTC regulations. The R-value per inch of a specific material is not necessarily always the same; it can be affected by temperature, density, and thickness — Insulation Handbook (2001), Chapter 3.

Arkansas Insulation – Commercial Exam Source: Insulation Handbook (2001), Chapter 9 – Sprayed-in-Place Insulation; Chapter 10 – Foamed-in-Place Insulation

Key Concepts

Sprayed-in-place systems generally (Ch. 9) - Sprayed-in-place insulations are modified loose-fill products blown into wall cavities or attics; cellulose, fiberglass, and rock wool are the most common materials. A special blowing machine combines an adhesive, water, and the insulating material. The adhesive is either a liquid that mixes with the insulation at the nozzle or a powder premixed in the material. - After application, stud faces are scraped clean with a stud scrubber to create a flush blanket. Excess insulation is recycled into the blowing machine for reuse as long as it is free of debris. - Drying: "Most products in use today require no more than 24 hours for drying" — this is a maximum, not a required wait. Sealing the wall too soon can lead to mold and mildew. Vapor retarders, and some paints and vinyl wallcoverings, should not be applied to the inner wall surface until the insulation has dried. - Vapor retarders are required unless proper ventilation is provided; materials used as vapor retarders for blown-in insulations must have a permeance rating of **less…

Arkansas Insulation – Commercial Exam | 5 questions (17%)

Key Concepts

Product definition and composition - Blanket insulations are flexible, bound products made from mineral (glass, rock, and slag) or cotton fibers, available in widths suited to standard spacings of wall studs and attic or floor joists — usually to fit framing on 16" or 24" centers. Continuous rolls can be hand-cut and trimmed to fit; batts come in precut lengths. (Insulation Handbook (2001), Ch. 8 — Blanket Insulation: Batts and Rolls) - Cotton thermal insulation is 75 percent cotton and 25 percent polyester. The polyester improves tear strength and recoil characteristics. It is treated with a flame retardant and insect/rodent repellents. (Ch. 8)

R-values - Typical R-value for fiberglass blanket insulation is 3.2 per inch, though R-values can range from 3.04 to 4.3. (Ch. 8) - Rock wool batt insulation: 3.6 per inch — slightly higher than the typical fiberglass figure. (Ch. 8, Rock and Slag Wool section) - R-values are additive, so greater R-values can be achieved by installing multiple layers where there is adequate space. (Ch. 8)

Source: Insulation Handbook (2001), Chapter 7 – Loose-Fill Insulation

Key Concepts

What loose-fill is. Loose-fill products are produced as shreds, granules, or nodules and are either poured or blown into place. Pneumatic applications account for about 90 percent of residential installations of loose-fill insulation. Materials covered: cellulose, fiberglass, mineral wool (rock wool and slag wool), vermiculite, perlite, wood shavings, and expanded polystyrene. (Ch. 7, pp. 93–94, General Description)

Perlite. Packaged in bags and must be poured into place; it is not suitable for blow-in methods. It is widely used in masonry construction, poured into the cavities of concrete block. (Ch. 7)

Settling. Approximate settling proportions: cellulose ~20 percent, rock wool ~2 percent, fiberglass ~4 percent. About 20 percent more blown-in cellulose should be installed to offset settling. Installers must refer to "installed thickness" specifications. (Ch. 7, Settling, p. 77)

Key Concepts

Rigid board basics (Insulation Handbook (2001), Ch. 11 – Rigid Board Insulation, p. 225) - Rigid insulation is made from fibrous materials or cellular plastic foams, pressed, extruded, or molded into boardlike forms. - R-values range from 4 to 8 per inch depending on composition and method of aging. - Common low-slope roof board types: cellular glass, glass fiber, mineral fiber, perlite, polyisocyanurate, polystyrene (expanded and extruded), wood fiberboard, and composites. - Polyisocyanurate is the most common roof insulation according to 1999 statistics; it is approved for installation directly to a steel roof deck without a thermal barrier.

Product-specific properties (Ch. 11) - XPS: fine, closed cells containing a mixture of air and refrigerant gas; consistent R-value of 5.0 per inch regardless of density. Suitable below grade. - EPS: molded, coarse closed cells containing air; R-value varies with density. Manufactured from less than 1.0 lb/ft³ to over 2.0 lb/ft³. High-density board is more moisture-resistant and can be used on the exterior of a foundation provided the surrounding soil is dry and sandy. Roofing EPS must be of sufficient density to resist foot traffic. Typically costs 40 percent less than XPS (p. 229). - PIR: highest R-value of…

Key Concepts

1. Definition and permeance threshold. A material is technically classified as a vapor diffusion retarder when its permeance rating is 1.0 perm or less. Materials with a perm value greater than 1.0 allow too much water vapor to pass through to qualify. Knowledgeable professionals typically specify vapor retarders rated 0.1 perm or less. (Insulation Handbook (2001), Chapter 4 — Vapor and Air Retarders)

2. What vapor retarders actually do. Vapor retarders "restrict or reduce the rate and volume of water vapor diffusion through a building's ceilings, walls, and floors." They are commonly made of polyethylene sheets, treated papers, and metallic foils. Historically called "vapor barriers," that term is incorrect — they only reduce the rate of moisture transfer; they do not stop moisture flow completely. The main reason to retard water vapor transmission is to prevent it from condensing to liquid water within the structure or insulation. (Chapter 4)

3. Polyethylene film ratings. Polyethylene films have perm ratings in the 0.02 to 0.08 range and are the most popular vapor retarder material. (Chapter 4)

Key Concepts

Medical services and first aid (§ 1926.50) - The employer shall insure the availability of medical personnel for advice and consultation on matters of occupational health, and provisions shall be made prior to commencement of the project for prompt medical attention in case of serious injury — § 1926.50(a), (b). - In the absence of an infirmary, clinic, hospital, or physician reasonably accessible in terms of time and distance to the worksite, a person holding a valid first-aid certificate from the U.S. Bureau of Mines, the American Red Cross, or equivalent training verified by documentary evidence shall be available at the worksite to render first aid — § 1926.50(c). - First aid supplies shall be easily accessible. Kit contents shall be in a weatherproof container with individual sealed packages for each type of item, and shall be checked by the employer before being sent out on each job and at least weekly on each job to ensure expended items are replaced — § 1926.50(d)(1), (d)(2), Page 33. - Proper equipment for prompt transportation of the injured person, or a communication system for contacting ambulance service, shall be provided — § 1926.50(e). Where 911 dispatch services are not…