Gypsum plasterboard (drywall)

What is gypsum plasterboard and how does partition performance work?

Gypsum plasterboard is a paper-faced gypsum-core panel lining interior partitions, ceilings, and wall surfaces. The core (typically 9.5–15 mm) sandwiched between kraft paper skins provides a clean, dust-free surface and supports finishes. Unlike solid walls, a plasterboard partition does not support structural loads; its performance (acoustic, fire, thermal, moisture) depends almost entirely on the assembly system, not the board itself. The assembly includes metal-stud framing, stud spacing and type, board layers, cavity insulation, resilient fixings, and perimeter sealing. Plasterboard is a component of a tested system, not a standalone product.

How does gypsum plasterboard differ from gypsum fibreboard?

Gypsum fibreboard is homogeneous, with cellulose fibre throughout the gypsum matrix and no paper facing. Plasterboard has a gypsum core between paper skins. Fibreboard holds screws directly into its full thickness without backing; plasterboard relies on cavity anchors for loads over 10 kg. Fibreboard's mass per millimetre typically outperforms plasterboard in sound isolation at equal thickness. In humid environments, plasterboard's paper can delaminate if wet; fibreboard has no paper to fail but still needs a moisture barrier. Fibreboard costs 20–40% more. Plasterboard is standard for cost and speed; gypsum fibreboard is chosen where acoustic performance or durability in damp areas justify the premium.

Why does acoustic performance depend almost entirely on the assembly?

A tested acoustic result (e.g. Rw 52 dB) applies only to that exact build-up: stud type, spacing, board layers, cavity insulation, resilient fixings, and perimeter sealing all included. Plasterboard alone at 12.5 mm offers only Rw 28 dB. In a metal-stud partition, a single board layer on one face offers modest performance because sound flanks through the cavity. Double layers with staggered joints (upper layer offset 600 mm) break the load path and improve airborne sound insulation significantly. Resilient fixings (rubber washers or channels) isolate the board from studs. Mineral wool at 50–80 kg/m3 absorbs sound; compressed wool loses benefit. Every unsealed penetration, whether an electrical socket cut through both leaves, a duct running through the full thickness, or a partition stopped at the suspended ceiling instead of the slab, creates a direct acoustic path and can reduce isolation by 5–15 dB, destroying the specification.

What plasterboard types are standard in Slovak practice?

Per EN 520, Slovak projects use Type A (grey, standard, dry areas); Type D (pink/red, fire-resistant, required for staircases and between dwellings, achieves EI90 in tested assemblies); Type D-FH (greenish-grey, fire and moisture resistant, above kitchens and utility rooms); Type F (green, moisture-resistant, behind tiling or in laundry rooms, always with tanking in bathrooms); and Type G (reinforced, impact-resistant, rare in residential work). Typical residential choices: Type A for ceilings and non-critical partitions, Type D between dwellings, Type D-FH above kitchens. Thickness ranges from 9.5 mm (non-structural ceilings) to 12.5 mm (partitions) to 15 mm (acoustic applications).

How are acoustic penetrations sealed and what mistakes destroy performance?

Site discipline is absolute. Perimeter sealing requires gypsum tape and joint compound continuous all the way around the partition at the slab boundary; any gap allows sound to bypass the assembly. Electrical and plumbing penetrations must be sealed with sealant-backed plates; rigid passages are acoustic failures. Socket boxes must not be positioned opposite each other on the two partition faces; sound passes straight through. Every resilient fixing must be installed correctly; mixed rigid and resilient fixings compromise benefit. Partitions ending at a dropped ceiling instead of continuing to the structural slab allow sound to travel over the partition through the plenum, reducing isolation by 5–15 dB and rendering the specification meaningless.

What joint finishing levels apply to different spaces?

EN 13964 defines five levels. Level 0 is no treatment; not suitable for visible areas. Level 1 (tape plus one coat) is acceptable behind wardrobes or covered surfaces. Level 2 (tape, one full coat, one finish coat, sanded) is adequate for low-light corridors or walls to be wallpapered. Level 3 (two full coats, finish, block sanded) suits standard eggshell or silk paint in living rooms. Level 4 (three coats with block sand between, final sand, primer) is required for bright spaces with raking daylight or high-gloss paint. Level 5 (Level 4 plus filler over fasteners) is for premium feature walls under intense light. Under-specifying results in visible imperfections and costly rework under daylight.

How are heavy loads fixed into a plasterboard partition?

Plasterboard cannot support permanent loads on its own. For shelves, kitchen units, radiators, or wall-hung toilets, a noggin (horizontal CW stud or timber) is installed between main studs at fixture height, creating solid backing for bolts or screws. Without a noggin, cavity spring toggles or toggle anchors rated for the load are used; these typically support 20–30 kg per fixing. Every load pathway must be documented and verified on site. Relying on plasterboard alone results in tearing, fixture failure, and safety hazards.

Is plasterboard suitable for wet areas?

Plasterboard alone is not a wet-area finish. In bathrooms, a complete tanking membrane (fluid-applied, sheet-based, or spray) bonded continuously over the plasterboard blocks water ingress. Moisture-resistant Type F or D-FH extends survival if a small leak occurs but never substitutes for tanking. The board is substrate; the membrane is the barrier. In kitchens, Type D-FH with proper sealant and ventilation may be used behind splashbacks. Shower enclosures must have full tanking over the board. Without tanking, water penetrates, the board deteriorates, joints fail, and mould develops.