How to Soundproof a Floor
Soundproofing a Floor
Noise pollution can be a cause of friction between neighbours, especially in apartment blocks and properties where floors have been divided into separate flats, though the problem can be just as bad within families. Adding some soundproofing to a floor helps to cut down noise transmitted from above and will go some way to solving your noise pollution problem. Using the technique shown here almost any floor can be soundproofed.
Noise is either transmitted through the air or through the materials used in the construction of a house. With the method of soundproofing shown here, sand and insulation blanket combine to form an effective barrier against the transmission of noise throughout the house.
A floor can be soundproofed from below, but this means destroying the ceiling, and working above your head is tiring on the arms and neck. Moreover, by soundproofing from above, sand can be used as an insulating material, which is both a cheap and effective sound-deadening medium.
Tools for the Job:
- pipe, cable & joist detector
- circular saw
- trimming knife
- bolster chisel
- cordless drill/driver
- dust mask
- Unless they are immediately obvious, use a pipe and detector to check the position of plumbing and electrical circuits. Then mark their positions on the floor surface with a crayon, so that when cutting into the floor you will be able avoid damaging these services.
- If the floor is constructed of or tongue and groove boards, run a circular saw set to the thickness of the flooring down the joints between boards. Do not cut round more than one or two boards at this stage, for once you start lifting the first couple of boards you may find that the rest can be removed without cutting off the tongues.
- Use a prybar and bolster to gently lift the flooring, trying not to damage too many boards. Remove any that remain poking out of the joists with the claw end of a hammer.
- Screw 50x 25mm (2 x 1in) battens to either side of the ceiling joists. Make sure the bottom edge is just clear of the ceiling below.
- Cut 12mm (1/2in) strips to sit on top of the battens. Fix the strips in place with nails.
- Cut plastic membrane material to line the troughs, pressing it into the corners and allowing it to lip up the sides of the joists. Nail or staple it into position using a minimum of fastenings near the top edge. Trim off excess plastic membrane so that it is level with the top of the joists.
- Pour in kiln dried sand to about 50mm (2in) deep. Cut a piece of ply so it rests on top of the joists with the bottom edge 50mm (2in) higher than the bottom of the trough. Use this to to achieve consistent results when levelling out the sand.
- Place slabs of rock wool on top of the sand. They should not be any higher than the top of the joists or refixing the boards will be difficult. If cutting the slabs, use a fine handsaw and make sure you wear a dust mask.
- With the two layers of insulating material in place, you can refit the flooring on top of the joists. Any split or damaged boards will need to be replaced. When refixing boards make sure that all joints are tight and there are no gaps. Covering the floor with some thick, good quality underlay and carpet will further enhance the soundproofing properties.
The soundproofing method shown above will increase the weight of the floor. Before starting any work you must check that this will not adversely effect the structural integrity of the property. If you are in any doubt then contact a structural engineer.
Tips of the Trade
With all the floorboards removed it can be difficult to move around the room. Have a couple of loose boards to hand that you can position across the joists to walk on as you work in the room.