Total Precast Advantages

Lafarge precast and prestressed concrete is widely used in low-rise and mid-rise apartment buildings, hotels, motels, and nursing homes where the repetitive use of standard components manufactured in a factory can be fully utilized. Owners, designers and developers are attracted by precast and prestressed concrete's superior durability, sustainability,  fire resistance and sound-control features.

Two-hour fire containment within each living unit provides safety for adjacent units. Using precast concrete housing of this quality reduces fire insurance rates and increases residence safety and noise privacy, often generating higher incomes for building owners.

Hollow-core slabs are the standard product used in this type of construction. The most common floor and roof elements employed are 203-millimeter (eight-inch) deep hollow-core units. These slabs can span up to nine meters (29.5 feet) or more without intermediate supports. Longer spans can be achieved by using 254-millimeter (10-inch) or 305-millimeter (12-inch) deep hollow core units.

For hotels, motels, and apartment buildings the hollow-core slabs are oriented to span between load-bearing shear walls or to span from the central corridor to an exterior wall. Independent balcony slabs are the preferred solution in total precast construction. It is possible to provide proper thermal and weather separation by using independent balconies supported by the precast wall system.

The use of precast walls speeds the building process. Construction rates of one floor per week and better often can be achieved. Architectural insulated panels used for the exterior of a building can provide a durable, attractive, energy-efficient envelope. Ancillary recreation, parking, and convention facilities are commonly constructed using precast concrete framing with long span roof and floor members.

Wood-frame construction is not always the most economical way to build multi-unit housing. Owners and developers are discovering that for low-rise and mid-rise apartment buildings, hotels, motels, and nursing and retirement homes, precast hollow core concrete floors combined with precast walls can be the true winner for getting projects finished fast, generating revenue sooner, and maintaining quality, value, and fire resistance.

Faster Occupancy 

Precast components can be manufactured and erected by one trade more efficiently and quickly than any other building system. Speedy completion means your building can be occupied and generating revenue sooner. The solid, secure, high-quality look and feel of solid precast construction encourages greater occupancy at higher rents, with better selling and resale values.

Life Comfort
Precast offers some of the lowest sound transmission of any building material used for multi-unit housing. When ceilings and floors are made with precast, noise complaints become a thing of the past. Tenants like the sense of security of a building that is solidly built, fire resistant, and virtually decay-proof. They know their families are safe and their possessions are protected.

Life Safety
Nothing is as solid and secure as a precast building. Tenants sense the structure's quality and permanence as they walk the floors and experience the quiet of the evening. They feel safe during the worst that nature can offer, including hurricanes, tornadoes, earthquakes, and fire. Even their neighbors offer little threat because precast protects them with superior fire resistance that meets or exceeds the fire ratings of their building codes.

Precast and Fire Safety
A major concern when building assisted living/retirement multi-family housing is minimizing the threat of fire on lives and property. An effective approach to this fire containment problem is called Balanced Design, which consists of three elements: containment, detection, and suppression. Containment, the key ingredient in Balanced Design, requires fire-resistant building materials with two-hour or higher fire rating. A multi-unit structure built with precast floors and roofs, combined with precast dividing walls, meets these requirements and can contain a fire to within the unit of origin, leaving surrounding areas virtually undamaged.

Precast does not burn, give off lethal fumes or smoke, and does not fuel a fire. Furthermore, it maintains its structural integrity even in the most intense blaze. Precast stays in place when other safety devices fail, keeping fire contained and occupants safe.

Speed of Construction

Precast components can be manufactured and erected by Lafarge (one supplier) more efficiently and quicker than any other building system. The use of precast walls speeds the erection process. Construction rates of one floor per week and better are often achieved. Architectural insulated wall panels used for the exterior of a building can provide a durable, attractive, energy-efficient envelope. Ancillary recreation, parking, and convention facilities are commonly constructed using precast concrete framing with long span precast roof and floor members

Parking Structures

Lafarge is a Western Canada leader in the design and manufacture of precast, prestressed concrete parking structures. Total precast parking decks are just one of the many product applications we offer.

Lafarge has engineered, manufactured, and erected parking decks for more than 40 years. Our parking systems allow for speedy construction, low-maintenance, and cost-efficiency, not to mention the durability and strength of precast, prestressed concrete compared to other systems. Our parking deck system uses 12-foot-wide double tees that can be topped in the field or pre-topped in the plant eliminating the need for site-cast concrete. We have a "Lite-Wall" forming system that can be used in lieu of columns and beams to accommodate sloping ramps. We can also provide precast stairwells, stairs, and elevator shafts. We offer assistance that includes preliminary designs, accurate schedules, and budget pricing. Engineering services span from the conceptual stage through final construction. The variety of finishes features, and colors that we offer are just some of the ways Lafarge can help you with your next project.

Lafarge knows that creating the best parking structure to fit the site requires a careful balance of all the elements as well as a logical plan from start to finish. Lafarge's early involvement in a project, before key design decisions are made, can make a dramatic difference in the final result. Our expertise and input can minimize the time and cost required to complete a project. Precast parkades offer fast construction, versatility of design, attractive exterior finishes, durability, and economy, making precast, prestressed concrete a popular choice for commercial, municipal, and institutional clients. [CE: clients or projects?]

Exterior Finishes
Precast parking garage exteriors can be delivered with a wide range of shapes and finishes ranging from smooth dense structural units to any number of architectural treatments depending on the budget available.

Loads and Forces
Precast concrete parking structures allow for volume changes from creep, shrinkage, and temperature differences. Components are cured before they are delivered to the site. The connections between members allow the structure to relieve pressures from ordinary expansion and contraction that otherwise could cause cracking in structural elements. Lateral design loads from wind, earthquake or earth can be resisted in a precast concrete structure by transferring loads through the floor diaphragm to shear walls and/or to column beam frames. Care in locating and the isolation of shear walls and isolation (expansion) joints will ensure performance.

Loading walls with framing beams or floor members can minimize connections between shear walls to resist uplift forces. Connections can be designed to prevent beam rotation and absorb bumper loads without undue restraint against volume changes.

Bay Sizes
For maximum economy, bay sizes should be as large as practical and modular with the standard precast concrete floor elements selected. For long span parking, the bay size selected need not be a multiple of the width of the parking stall. Clear spans with fewer columns create an open concept for added security.

Drainage
Sloping of floors to achieve good drainage is essential to quickly remove rain and salt- laden water from the structure. The drainage pattern selected should be repeated on all floors wherever possible to allow for repetition in manufacturing the precast elements. Locate isolation (expansion) joints at high points to minimize possible leakage. Slope the floors away from columns, walls, and spandrels to promote proper drainage.

Durability
High-strength precast concrete components are cast under controlled conditions in the Lafarge plant. When precast concrete elements are prestressed, concrete is cast around highly tensioned pretensioning strands that run through the steel forms. After the concrete has cured, the pretensioning force is released into the beam placing the concrete in compression.

Prestressed slabs and beams are virtually crack-free and highly resistant to attack by chloride ions. Where cast-in-place composite topping is used over precast floor members, wire mesh reinforcement should be incorporated in the topping. A high strength concrete topping having a water/cement ratio of 0.40 or less, 6 percent entrained air, and five days of curing under wet burlap will produce the best results (see CSA S413).

A series of crack control joints should be tooled into the topping above all joints in the precast members below. A V-shaped trowel will produce a 25-millimeter deep by 12 millimeter wide joint. Later these joints are prepared by grinding with a V-shaped abrasive wheel and filled with a polyurethane sealant.

Pretopped double tees are a recommended alternative to field-placed concrete toppings. This system has an excellent 35 to 55 MPa  (5,000 PSI to 8,000 PSI) plant produced wearing surface, broom-finished to provide improved driving traction. Standard details are used for adjacent camber differential, joint treatments, erection stability, and drainage with this system.

Except for column base plates, connections and exposed hardware often use hot dipped galvanized or stainless steel. Where connections are subsequently welded, the welds should be minimal and located where they can be easily maintained. For more information contact for local Lafarge representative.