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16. Floors A. Platform floor with absorbent blanket. Either a floating layer of timber or wood based board, 18 mm thick, with tongued and grooved edges and all joints glued, spot bonded to substrate of 19 mm plasterboard; or a floating layer of two thicknesses of cement bonded particleboard with joints staggered, glued and screwed together, total thickness 24 mm. Resilient layer of 25 mm mineral fibre, density 60-100 kg/m3. Note that the low figure gives the best insulation but a "soft" floor. Floor base of 12 mm timber boarding or wood-based board nailed to timber joists (size to suit the structure). Ceiling of two layers of plasterboard with joints staggered, total thickness 30 mm, with an absorbent blanket of 100 mm unfaced mineral fibre, density 12-36 kg/m3, laid on the ceiling. B. Heavy ribbed floor with absorbent blanket. Floating layer of timber or wood based board, 18 mm thick with tongued and grooved edges and all joints glued, spot bonded to substrate of 19 mm plasterboard nailed to 45 mm x 45 mm timber battens placed on the joists. Resilient strips of 25 mm mineral fibre, density 80-140 kg/m3, laid on joists. Floor base of 45 mm thick timber joists. Ceiling of two layers of plasterboard
with joints staggered, total thickness 30 mm, with an absorbent blanket
of 100 mm unfaced mineral fibre, density |
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C. Ribbed floor with heavy deafening? Floating layer of timber or wood based board, 18 mm thick with tongued and grooved edges and all joints glued, nailed to 45 mm x 45 mm timber battens placed either on or between joists (for sheet materials, placing on joists is recommended). Resilient strips of 25 mm mineral fibre, density 80-140 kg/m3, laid on joists. Floor base of 45 mm thick timber joists. Ceiling of either 19 mm dense plaster on expanded metal lath or 6 mm plywood fixed under the joists plus two layers of plasterboard with joints staggered, total thickness 25 mm. Both types of ceiling to have deafening of mass 80 kg/m2 laid on a polyethylene layer. † Deafening (pugging) may be of the following types: Traditional ash (75 mm), or 2-10mm limestone chips (60 mm), or 2-10 whin aggregate (60 mm), or Dry sand (50 mm). Figures in brackets show approximate thickness required to achieve 80 kg/m2. Do not use sand in kitchens, bathrooms, shower rooms or watercloset compartments. |
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Junctions for floor type 3 Timber frame wall Seal the gap between wall and floating layer with a resilient strip glued to the wall. Leave a 3 mm gap between skirting and floating layer. A seal is not necessary but if used must be flexible. Block air paths between the floor base and the wall, including the space between joists when joists are at right angles to the wall. Seal the junction of ceiling and wall with tape or caulking. |
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16. Heavy masonry leaf Mass of leaf (including any plaster) Seal the gap between wall and floating layer with a resilient strip glued to the wall. Leave a 3 mm gap between skirting and floating layer. A seal is not necessary but if used must be flexible. Use any normal method of connecting floor base to wall. Seal the junction of ceiling and wall lining with tape or caulking. Light masonry leaf If the mass (including any plaster) is less than 355 kg/m2 a free-standing panel as specified in wall type 3 must be used. Seal the gap between wall and floating layer with a resilient strip glued to the free-standing panel. Leave a 3 mm gap between skirting and floating layer. A seal is not necessary but if used must be flexible. Use any normal method of connecting floor base to wall but block air paths between floor and wall cavities. Take ceiling through to masonry, seal junction with free-standing panel with tape or caulking. Floor penetrations Ducts or pipes penetrating the floor must be in an enclosure both above and below the floor. Either line the enclosure, or wrap the duct or pipe within the enclosure, with 25 mm unfaced mineral fibre. The material of the enclosure must have a mass of 15 kg/m2. Penetrations of a separating wall by ducts and pipes must have fire protection in accordance with Part D. Leave a 3 mm gap between enclosure and floating layer, seal with acrylic caulking or neoprene. Enclosure may go down to the floor base if specification A is used, but keep isolation of enclosure from floating layer. Where permitted by Part F, a flue-pipe may penetrate the floor. The flue-pipe must be in a non-combustible enclosing duct with mineral fibre absorbent. Seal the junction of ceiling and enclosure with tape or caulking. |
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17. Floor type 4: timber base with independent ceiling The resistance to airborne and impact sound depends mainly on the mass and isolation of the independent ceiling and partly on the mass of the floor base. Limitations Where resistance to airborne sound only is required the full construction must still be used. Part D places limits on the storey height at which this type may be used. It must only be used with heavy masonry walls. It is mainly for use as a specified construction for converted properties with suitable existing floors and walls. |
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Points to watch Limit the pathways around the floor, especially at the edges of the independent ceiling (to reduce flanking transmission and to avoid air paths). Workmanship and detailing must be given special attention wherever the floor is penetrated. Take care not to create bridges between the floor base and the independent ceiling. Construction The floor and independent ceiling specified below, together give suitable resistance to direct sound transmission. Details of how junctions must be made to limit flanking transmission follow. Floor Timber boarding or wood based board, 18 mm thick with tongued and grooved edges (or 3.2 mm hardboard over the whole floor to seal gaps). 45 mm thick joists plus deafening of mass 80 kg/m2 and a ceiling of either 19 mm dense plaster on lath or two layers of plasterboard with joints staggered, total thickness 30 mm. In existing floors deafening may be on boards between joists, in new floors use 6 mm plywood fixed to underside of joists. A polyethylene liner may be used if desired. |
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