Glossary of Building and Construction Terms

Welcome to our handy Glossary page. Here we cover terms common used to describe our industry and products.

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ADA Access: ADA is also known as the American Disabilities Act. This is a specific set of codes established by federal and state agencies for handicap accessibility. The code applies within the modular building and also for egress to the structure. Our design team will ensure your facility meets the ADA regulations and criteria for your use and occupancy.


Built Up Roofing: This type of roof covering has multiple levels of quality and warranty. The most common is a two ply (two layer) hot applied system. The surfacing for a built up roofing system consist of a cap sheet with granules or gravel. The hot asphalt is used to seal the roofing surface. This type of roofing system has varied warranties based on the number of layers and materials utilized.


Clear Span Steel Beam: This type of modular roof beam is used when long open spans are desired in a floorplan design. Most modular structures can span up to 66’ with this type of beam. The steel allows for open span without supplemental posting being required.

Complex Roof: In the modular industry this generally refers to a roof with a low slope such as a ½”:12” slope. The roofline will typically peak at the center of a modular section based on the length of a structure. As an example, with a 60’ long structure the roof would have the highest peak at 30’ and slope both directions toward the ends of the building.


Design-Build: The process of providing all design and construction services with one contractor. This is inclusive of the design and preconstruction phase, the manufacturing process, and the site work required for a complete and seamless project. The advantage to design-build construction is that you are also building budgets as you progress forward. Having your construction team in place helps streamline the decision making process as you go, helping you prioritize your wants and needs list. Often times when other methods of construction are selected the architect may over-design a scope of work or feature and not know that the project is off budget until all the bids come in several weeks later.


EPDM Roofing: Ethylene propylene diene terpolymer or EPDM roofing is very common in the modular industry due to our complex roof design. This type of roof covering is a synthetic rubberized roof covering that is applied as a glue down or mechanically fastened roofing system. The EPDM comes in black or white and is also available in varied thicknesses for warranty and life cycle.


Fire Alarm System: A fire alarm system is often required by the local jurisdiction. A commercial fire alarm system will include hard wired devices and lighting and audible alarms to indicate a heat or fire situation. If your location has an existing fire alarm system the new modular building will have to include compatible devices and be able to communicate with your main fire control panel.

Floor Joist: A joist is a horizontal structural member used in framing to span an open space, often between beams that subsequently transfer loads to vertical members. When incorporated into a floor framing system, joists serve to provide stiffness to the subfloor sheathing, allowing it to function as a horizontal diaphragm. A typical modular building will have floor joist framing at 8” – 16” on center depending on the use and occupancy of the area floor load.


Gable Roof: A gable roof is one that has two roofing sections sloping in opposite directions. In the modular industry this type of roof is used on smaller structures of 1800 square ft or less. The reason a gable roof is not common on larger structures is that the pitch increase makes the building sections too tall to transport over standard roadways without special permits. If a gable roof is requested on a larger structure Modular Solutions, Ltd will usually install site built trusses. Consult our sales team for more details on this type of structural request.

Glu-Lam Beam: Also know as glue laminated timber is a structural engineered roof beam for modular buildings. The beam will range in size based on the structural requirements and the floorplan design. When a glu-lam beam is used in modular construction the typical span will be 20-30’ between posts. A post is required to help support the roof load, but can be concealed in an interior wall.

GSA Contract: GSA Stands for General Services Administration. The federal government allows GSA to solicit vendors for various products and services so that vendors are preapproved and ready to provide proposals and competitive offers. Modular Solutions, Ltd has held a GSA contract since 2000. Our contract is for modular buildings, installation services, and modular leases. Our GSA Contract Number is GS-07F-0199L.


Heat Pump: A heat pump is a device used for heating/cooling in modular buildings. A heat pump absorbs heat from a cold space and releases it into a warmer one. A heat pump is much more cost effective to operate in heat mode than a traditional heat strip or resistance heater but will only work in mild climates. Our design team can make recommendations as there are many types of heating and cooling systems available in the marketplace today.


LED Lighting: LED stands for Light Emitting Diode. There are many benefits in choosing LED lighting instead of the of the industry standard fluorescent lay in lighting packages. The key benefit is less operational cost. LED lights also directional light source. LED lights used to be extremely expensive, but with new materials and more manufacturers making the LED lighting, we are able to almost match the costing of a fluorescent light package. Consult your sales team for options and creative lighting solutions.

LVT: LVT is used to refer to luxury vinyl tile. LVT is a hard surface product that is non-porous. It is made from 100% vinyl. LVT uses photo finish so there are a greater number of colors and options available that simulate wood, stone or other flooring products. LVT requires no waxing or additional maintenance this is required of some flooring products. above the finished floor. The typical tile and grid system is based on a 2’ x 4’ design. There are other options available with this type of acoustic ceiling system, consult your sales team for options.


MESC Contract: MESC is for Mohave Educational Services Cooperative. MESC is an Arizona based contract for school districts, local, and state agencies to purchase modular and prefabricated buildings and associated site work as required. MESC has a competitive proposal process and award the contract based on factors such as experience, qualifications, past performance, financial strength, and competitive cost analysis. Modular Solutions, Ltd has been a contract holder since 2007. Our contract number is 15H-MSL-1005.

Mobile Office: A modular building that is generally meant to be used for temporary purposes for a lease or short term occupancy.

Modular Building: Any building or facility fabricated off-site for installation at a defined location. This building can be a single section or can be made up of multiple sections that are bolted or welded together to make a single structure.


PCA Contract: PCA Stands for Purchasing Cooperative of America. PCA is a nationwide contract for local and state agencies to purchase modular and prefabricated buildings, and associated site work as required. PCA has a competitive proposal process and awards the contract based on factors such as experience, qualifications, past performance, financial strength, and competitive cost analysis. Modular Solutions, Ltd has been a PCA contract holder since 2014. Our PCA contract number is PCA-3-208-18.

Perimeter Frame Modular: The flooring system in a perimeter frame modular is all steel construction. Using I-beam and C-channel construction the all steel floor system is constructed with a chassis and frame and is intended to be installed on a concrete or block stemwall foundation system.


Rafter: The structural members that support the roof load and decking. A Rafter will generally have a low slope such as ½”:12” slope to improve water drainage off the roof.


Siding: The exterior finish of the modular building. There are many options available in prefinished siding, ask your sales consultant for a full list of options. The most common are wood siding with groves, lightweight siding that looks like wood, steel, or aluminum.

STC Rating: This is short for sound transmission class, which is just a rating of how sound will flow through an interior partition, ceilings/floors, doors, windows, or exterior wall. The higher the rating the better the soundproofing.


T-Grid: T-Grid ceilings are a suspended ceiling system that provides a way for tiles to be suspended in a grid system and installed in squares. A typical modular T-Grid ceiling system is set at 7’10”.

True Modular: A building referred to as a true modular generally is constructed with large 10” or 12” floor joist system, and constructed to be set on a block or concrete stemwall. This type of modular structure is built with no frame or carrying chassis. The building sections are transported via a special low boy hauling system and then craned onto the permanent foundation and welded in place on site.

Truss: The structural members that support the roof load & decking. A truss will generally have a higher pitch slope such as 3”:12” or higher to implement water drainage off the roof.


VCG: Refers to vinyl covered gypsum. This is a traditional gypsum wall board that is covered with a thin vinyl material. The vinyl covered gypsum comes in a few colors, and is available in 8’-10’ wall heights. This product can also be used in fire rated areas as required with some additional installation materials. This material will have a joint every 4’, and is a little less expensive than traditional tape, texture, and painted drywall systems because it can be installed quicker.

VCT: VCT is used to refer to vinyl composition tile. This is typically a 12” x 12” square tile that glues down to the subfloor and is available in multiple colors. This type of floor covering does require proper maintenance, wax, polish, and attention to get the expected life cycle out of the product.


Wall Mount Mechanical Unit: This type of mechanical unit is very common in the modular industry. A wall mount unit can be gas, electric heat strip, or heat pump. A wall mount unit is mounted to a sidewall of the modular building and is currently one of the most cost-effective methods of installing an HVAC unit to a modular building. The wall mount units are however not as energy efficient as other types of mechanical systems, so sometimes we recommend you look at all options for your mechanical requirements.