NAGC FAQs and Tips

SLUMP- is a term used for concrete to express how wet or dry the mix. Slump is determined by
pouring concrete in a cone-shaped metal container and letting sit for a specified period of time, then lifting the cone. The distance in which the concrete drops from the original height once the cone is removed is considered the slump. The greater the distance, in which the concrete drops, the higher the slump and the wetter the concrete mix.

BACKER ROD In glazing, a polyethylene or polyurethane foam material installed under compression and used to control sealant joint depth, provide a surface for sealant tooling, serve as a bond breaker to prevent three-sided adhesion, and provide an hour-glass contour of the finished bead

BULLFLOAT - A tool used to finish and flatten a slab. After screeding, the first stage in the final finish of concrete, smoothes and levels hills and voids left after screeding. Sometimes substituted for darbying. A large flat or tool usually of wood, aluminum or magnesium with a handle.

CALCIUM CHLORIDE - A chemical used to speed up curing of concrete during damp conditions

CFM (Cubic Feet per Minute) - The measure of volume of air. When testing systems, find the CFM by multiplying the face velocity times the free area in square feet. The face velocity is the amount of air passing through the face of an outlet or return. Free area is the total area of the openings in the outlet or inlet through which air can pass.

COPPER PIPE TYPES - Type K has the heaviest or thickest wall and is generally used underground. It has a green stripe. (Kelly Green). Type L has a medium wall thickness and is most commonly used for water service and for general interior water piping. It has a blue stripe (Lavender Blue). Type M has a thin wall and many codes permit its use in general water piping installation. It has a red stripe. (Mad Red)

CURING In concrete application, the process in which mortar and concrete harden. The length of time is dependent upon the type of cement, mix proportion, required strength, size and shape of the concrete section, weather and future exposure conditions. The period may be 3 weeks or longer for lean concrete mixtures used in structures such as dams or it may be only a few days for richer mixes. Favorable curing temperatures range from 50 to 70 degrees F. Design strength is achieved in 28 days

DEAD LOAD - The constant, design-weight (of the roof) and any permanent fixtures attached above or below.

DRIP EDGE - A device designed to prevent water from running back or under an overhang

EPDM - Ethylene Propylene Diene Monomer. A single ply membrane consisting of synthetic rubber; usually 45 or 60 mils. Application can be ballasted, fully adhered or mechanically attached.

EXPANSION COEFFICIENT - The amount that a specific material will vary in any one dimension with a change of temperature

EXPANSION JOINT - A device used to permit a structure to expand or contract without breakage

FIRE WALL - Any wall built for the purpose of restricting or preventing the spread of fire in a building. Such walls of solid masonry or concrete generally sub-divide a building from the foundations to two or more feet above the plane of the roof.

GIRDER - A main beam upon which floor joists rest, usually made of steel or wood

GLAZING BEAD In glazing, a strip surrounding the edge of the glass in a window or door which holds the glass in place

HARDWARE - Metal accessories such as door knobs, towel bars, toilet paper holders, etc

HIGH EARLY CEMENT - A portland cement sold as Type III sets up to its full strength faster than other types.

HVAC - Heating Ventilation and Air Conditioning

LAMINATED GLASS Two or more lites of glass permanently bonded together with one or more inter-layers

MIL THICKNESS - Measurement used to determine thickness of a coating. 1 mil =.001 inch (1/1000).

MORTAR TYPES - Type M is suitable for general use and is recommended specifically for masonry below grade and in contact with earth, such as foundations, retaining walls and walks. Type M is the strongest type. Type S is suitable for general use and is recommended where high resistance to lateral forces is required. Type N is suitable for general use in exposed masonry above grade and is recommended specifically for exterior walls subject to severe exposures. Type 0 is recommended for load-bearing walls of solid units where the compressive stresses do not exceed 100 lbs. per square inch and the masonry wall not be subjected to freezing and thawing in the presence of excessive moisture.

OIL-CANNING - The term describing distortion of thin-gauge metal panels which are fastened in a manner restricting normal thermal movement.

PURLINS - A horizontal structural member spanning between beams or trusses to support a roof deck. In slope glazing, purlins are the horizontal framing members

Slump is a term used for concrete to express how wet or dry the mix. Slump is determined by
pouring concrete in a cone-shaped metal container and letting sit for a specified period of time, then lifting the cone. The distance in which the concrete drops from the original height once the cone is removed is considered the slump. The greater the distance, in which the concrete drops, the higher the slump and the wetter the concrete mix.

Tips

Allow all concrete used for structural purposes to cure for 28 days before it is loaded or used
Make sure that when pouring concrete in cold weather the air temperature is 32 degrees and rising. Cover concrete with insulating blankets immediately

Do not add any additional water to the designed strength of the concrete as this will weaken the compressive strength

When planning an expansion or new construction allow a minimum of 6 months to secure engineering and obtaining permits

Make sure that when you receive multiple quotes for work to be done that your scope of work is clearly defined and that the prospective bidders list all exclusions and qualifications. ASK a lot of questions!

In the process of selecting a contractor make sure that they have all of the proper insurances including general liability and more importantly workers compensation insurance. If the contractor does not carry workers compensation and his employee is injured at your facility you will become liable.
Ask for references, a contractor who is reputable will gladly offer them.

 
North American General Contractors
6640 Quad Avenue
Baltimore, MD 21237
(410) 485-7757
www.nagcmd.com
info@nagcmd.com