Correct Answer: B. Sub-floor and Floor Covering
Solution:
A floor is generally composed of two main parts. The sub-floor is the underlying structural layer that supports the load, which could be a concrete slab or timber joists with sheathing. The floor covering is the top finish layer that you see and walk on, like tiles, wood, or carpet.
Correct Answer: C. To prevent lateral buckling and distribute load
Solution:
Bridging (or strutting) consists of small pieces of wood or metal fixed in a criss-cross pattern between floor joists. Their main function is to hold the joists in a vertical position, preventing them from twisting or buckling under load. This also helps to distribute a concentrated load on one joist to the adjacent ones, increasing the floor's overall stiffness.
Correct Answer: B. Decoupling the floor surface from the main structure
Solution:
While mass and rigidity play a role, the most effective soundproofing technique is decoupling. This involves creating a separation (e.g., with a resilient underlayment) between the finished floor surface and the structural sub-floor. This break prevents sound vibrations (especially impact noise like footsteps) from traveling directly through the structure, significantly reducing noise transmission.
Correct Answer: C. The joists have an insufficient depth for the span
Solution:
Floor vibration is primarily a matter of stiffness, not strength. A floor can be strong enough to not collapse but still feel bouncy. The stiffness of a joist is directly related to its depth (height). If the joists are too shallow for the distance they need to span, they will deflect more under load, leading to noticeable vibration and a bouncy feeling.
Correct Answer: B. To prevent moisture from rising from the ground
Solution:
A Damp-Proof Membrane is a sheet of impervious material, typically polythene, laid under a concrete slab. Its sole purpose is to act as a barrier to stop ground moisture from rising through the concrete via capillary action, which could otherwise cause dampness, damage to floor coverings, and mould growth inside the building.
Correct Answer: A. It allows for natural expansion and contraction of the flooring
Solution:
A floating floor is not nailed or glued to the sub-floor. The planks are joined to each other, creating a single, continuous mat that "floats" on an underlayment. This method is crucial for materials like laminate and wood, which expand and contract with changes in humidity and temperature. Floating installation allows this movement without causing the floor to buckle or warp.
Correct Answer: C. A hard, dense, and smooth surface
Solution:
Power floating, or power troweling, uses a machine with rotating blades to smooth and compact the surface of fresh concrete. This process is performed after the concrete has started to stiffen. It removes imperfections, closes surface voids, and creates a very dense, durable, and smooth finish, which is often required for industrial and commercial floors.
Correct Answer: A. Granolithic flooring
Solution:
Granolithic flooring consists of a topping made from a rich mix of cement and fine aggregate (often granite chips), which is applied over a fresh concrete base. It cures to become a single, solid (monolithic) floor with the slab. This creates an exceptionally hard-wearing, dust-free, and abrasion-resistant surface suitable for factories, workshops, and garages.
Correct Answer: B. To cover the expansion gap and protect the wall base
Solution:
Most floor coverings, especially wood and laminate, require an expansion gap around the perimeter to allow for movement. The skirting board neatly covers this unsightly gap. Additionally, it protects the bottom of the wall from scuffs, kicks, and damage from furniture or vacuum cleaners.
Correct Answer: C. Linoleum
Solution:
Unlike vinyl flooring, which is a synthetic product made from petroleum-based chemicals, linoleum is manufactured from natural and renewable resources. Its primary components are solidified linseed oil, pine resin, ground cork dust, wood flour, and mineral fillers, all pressed onto a jute backing. It is valued for its durability and eco-friendly properties.
Correct Answer: C. Filling the joints between the tiles with mortar
Solution:
Grouting is the process of filling the spaces or joints between tiles with a special mortar called grout. This locks the tiles in place, prevents dirt and water from getting between them, and gives the finished floor a clean, continuous appearance. The grout itself comes in various colors to match or contrast with the tiles.
Correct Answer: B. Jack arch floor
Solution:
Jack arch flooring is a traditional construction method where shallow arches are built between the lower flanges of parallel steel joists (I-beams). The space above the arches is then filled with lean concrete to create a level surface. This system was common in the late 19th and early 20th centuries for its strength and fire resistance.
Correct Answer: B. Double joist floors use intermediate beams to support the joists for longer spans
Solution:
In a single joist floor, the joists span directly from one wall to another. This is suitable for shorter spans. For larger rooms, a double joist floor is used, which introduces larger intermediate beams called binders. The common joists then span a shorter distance between these binders, allowing the overall floor to cover a much larger area without needing excessively deep joists.
Correct Answer: A. Rubber flooring
Solution:
Rubber flooring, often manufactured from recycled vehicle tires, is highly valued for its resilience, durability, and shock-absorbing qualities. This makes it an ideal choice for high-impact environments like weight rooms, gymnasiums, and children's play areas to provide comfort and safety.
Correct Answer: C. A thin layer of material laid over a sub-floor to create a smooth, level surface
Solution:
A screed is a precisely levelled layer, typically of a sand and cement mixture, that is applied on top of a concrete sub-floor or slab. Its purpose is not structural; rather, it is to create a perfectly flat and smooth surface upon which the final floor covering (tiles, wood, vinyl, etc.) can be laid correctly.