Internal dry partition

A non-load-bearing partition built dry: a frame of metal studs, clad on both faces with boards and filled with mineral wool in the cavity. Light, fast, inspectable and easy to modify, it gets its acoustic insulation and fire resistance from layering, not from mass.

The dry partition reverses the logic of masonry: instead of entrusting performance to the mass of a single material, it builds it by layering lightweight elements. A metal frame holds the boards; the cavity houses mineral wool and the services; the number and type of boards tune fire and acoustics. It is a system designed «in layers», where each performance is added without loading the building structure.

The secret of dry-system sound insulation is not mass but decoupling. The two board faces (mass) are separated by the mineral-wool cavity (spring): the sound energy that vibrates the first board is largely dissipated and not transmitted to the second. With a few centimetres and a few kilograms one reaches performance that masonry would only achieve with great thickness. The performance is lost, however, through acoustic «short circuits»: unsealed joints, back-to-back electrical boxes, overly rigid studs.

The fire resistance (EI class) of a dry partition comes from the boards, not the frame. The boards — gypsum, gypsum-fibre or calcium silicate — contain crystallisation water which, by evaporating, keeps the board cool until it is consumed, delaying the passage of heat. By increasing the number of layers and using specific boards (type F, high-resistance) one reaches EI 60, 90 or 120. Staggered joints between layers and correct jointing are an integral part of the certified performance.

Building dry means assembling components, not mixing and waiting for curing. The advantages are speed, the absence of water and drying times, the low weight (a tenth of an equivalent masonry) that loads the structure less, and reversibility: the wall can be dismantled, moved and recycled. In return it demands assembly precision and care for the details — fixings, seals, resilient perimeter strips — because that, and not mass, is where the performance lies.