Arkansas Insulation - Residential Exam

Arkansas Insulation – Residential Exam | 8 questions (27%)

Key Concepts

Heat-transfer mechanisms. Heat always flows from the warmer object to the colder object. The three mechanisms are convection (heat moved by a fluid — gas or liquid — moving from place to place; forced when driven by a fan, register or wind, free when driven by the heated air rising), conduction (molecule-to-molecule transfer in solid matter), and radiation (transfer through space by electromagnetic waves). Mass insulations suppress conduction and convection by entrapping air molecules within their structure; foam insulations work the same way using gas instead of air. (Insulation Handbook (2001), Chapter 3 – Insulation Fundamentals and Principles)

Emittance and reflectance. Emittance (emissivity) is a surface's ability to emit radiant energy; all materials range from 0 to 1. The lower the emittance, the lower the heat radiated from the surface. Emissivity and reflectivity are related: aluminum with an emissivity of 0.03 has a reflectance of 0.97. (Chapter 3) A radiant-barrier material must have reflectivity usually 0.9 or 90 percent or more, emissivity usually 0.1 or less, and must face an open air space. (Carpentry and Building Construction, Section 31 – Radiant-Heat Barriers)

Key Concepts

What "sprayed-in-place" means. Sprayed-in-place insulations (also called self-supported, wet-spray, damp-spray stabilized, spray-on, or dimensionally stable) 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 and sprays the mixture into or over open wall and ceiling cavities. The adhesive is either a liquid that mixes with the insulation at the nozzle or a powder premixed in the insulation. (Ch. 9 — Sprayed-in-Place Insulation)

Wet-spray cellulose application technique. Aim the nozzle at a downward spray angle of approximately 5 to 10 degrees, about 4 feet away from the wall. The angle of the nozzle and the velocity of the material are the two most important factors in reducing falloff. (Ch. 9)

Pump requirement. A diaphragm pump capable of 200 to 300 lb/in² at a flow rate of 2 to 5 gal/min supplies the pressure for wet-spray cellulose application. (Ch. 9 — Application section)

Source: Insulation Handbook (2001), Chapter 8 — Blanket Insulation: Batts and Rolls

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. They come in rolls or batts in standard widths, usually to fit between framing on 16 or 24" centers. (Insulation Handbook (2001), Ch. 8 — Blanket Insulation: Batts and Rolls, p. 137) - 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) - Fiberglass blanket insulation is made from sand (SiO₂), limestone (CaCO₃), and sodium carbonate (Na₂CO₃). Because it is inorganic, it will not rot or absorb moisture, is noncombustible, and does not support mildew, mold, or fungus growth. (Ch. 8, p. 138)

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

Key Concepts

What loose-fill is. Loose-fill insulation is distinguished from other types by the size of the individual unit of material — produced as shreds, granules, or nodules — and is either poured or blown into place depending on the material or application. Pouring-type materials are most commonly sold in bags; pneumatic applications account for about 90 percent of residential installations of loose-fill insulation (Ch. 7, introduction).

Settling (attics). Settling proportions are approximately 20 percent for cellulose, 2 percent for rock wool, and 4 percent for fiberglass. About 20 percent more blown-in cellulose should be installed to offset settling. Installers must refer to the "installed thickness" specifications (Ch. 7, Settling).

Settling (walls). Settling is virtually nil with any cellulose at densities of 3.5 lb/ft³ or higher. Most authorities recommend at least 3.0 lb/ft³ for cellulose in walls; materials with high nominal settled densities should be installed at 3.5 lb/ft³. The general density guideline for walls is roughly 3.5 lb/ft³ for cellulose and 1.5 lb/ft³ for fiberglass or rock wool — roughly two or three times the density of horizontal applications (Ch. 7, Settling).

Source: Insulation Handbook (2001), Chapters 11–12

Key Concepts

Rigid board insulation — general (Insulation Handbook (2001), Chapter 11 – Rigid Board Insulation) - Rigid insulation is made from fibrous materials or cellular plastic foams, pressed, extruded, or molded into boardlike forms. It provides thermal and acoustical insulation, modest strength with low weight, and few heat-loss paths when properly installed. - R-values for rigid board insulation range from 4 to 8 per inch of thickness, depending on composition and method of aging. - Rigid board is used where there are space limitations, where rigidity is critical, or where higher R-values are necessary — though it typically costs more than other insulating materials. - Common low-slope roofing 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.

Source: Insulation Handbook (2001), Chapter 4 — Vapor and Air Retarders

Key Concepts

Definition and purpose. Vapor retarders are materials that 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," the term is inaccurate: vapor retarders only reduce the rate of moisture transfer — they do not stop moisture flow completely. The main reason to retard gaseous water vapor transmission through building envelopes is to prevent it from condensing to liquid water within the structure or insulation. (Insulation Handbook (2001), Chapter 4 — Vapor and Air Retarders)

Technical threshold. A material is technically classified as a vapor diffusion retarder when its permeance is 1.0 perm or less. Materials above 1.0 perm do not qualify. Knowledgeable professionals typically use vapor retarders rated 0.1 perm or less. (Chapter 4)

Vapor retarder vs. air retarder (housewrap). Air retarders (housewraps) are barriers to air and liquid water but not to water vapor. Typical exterior housewraps are not vapor retarders and allow water vapor to diffuse easily through them. (Chapter 4)

Key Concepts

Medical services and first aid (29 CFR §1926.50) - The employer shall insure the availability of medical personnel for advice and consultation on occupational health matters, 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 that is 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 verifiable 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, or a communication system for contacting ambulance service, shall be provided — §1926.50(e). Where 911 service is not available, telephone numbers of…