This is a major problem in many houses and yet many people think there is an “easy” quick fix. To do this job properly will take some time and may involve the removal and reinstatement, even renewal, of some of the floor. Set aside plenty of time.
The most common reason for floors creaking is the use of incorrect nails holding the floor down to the joists. In the case of chipboard floors these nails should be annular ring shank nails. These nails (usually 2 inches long) have serrations all round the shaft and are slightly screw like in appearance. There may also have been an insufficient quantity of them used.
Other reasons for floors creaking are because a joint in the floor is not supported properly on a joist. A timber and plasterboard wall placed on top of the floor is not securely fixed to the floor, and any floor movement is causing the fixings to squeak. The floor joists themselves are not properly secured and are bowing or twisting under the floor.
The first step is to add chipboard screws to the floor to secure it to the joists. These screws must be no longer than the nails used and must be placed next to the existing nails, drill a pilot hole and countersink it for each screw. The screw heads can be covered with wood filler as in 6 in the diagram below. Make sure you check for cables and pipes before drilling and screwing. Use additional screws if there is any more than 300mm in between the existing nails along the line of the joists.
Check each joint for adequate support. Joints should not spring and must be firm. If you feel a joint is not supported, remove one of the boards forming that joint and fix a new joist extension to support it as 1 in the diagram. To remove a board or boards it will be necessary to cut the tongue from the board using a sharp chisel or a power saw. Once the tongue of the board is cut, careful prising of the board upward, should lift the nails with it, allowing them to be removed. There is always a danger here of damaging the board (even the pros do) so be prepared to get a new board or two.
With a tongue and groove chipboard floor, the joint along the long edge of the board is not normally supported, the tongue and groove give it the strength when supported along this length by the joists. The long joint should always run at right angles to the joists.
Number 4 shows a timber and plasterboard wall that has been built on top of the floor, this is standard, but all fixings for the bottom timber (soleplate) of this wall should go into a joist or purpose made timber “noggin”. In the diagram the nail holding the soleplate to the floor is only secured into the floor board. This will work loose and is sometimes the cause of the creaking noise. This can be diagnosed quite easily because it will generally leave a gap between the underside of the skirting and the floor. This can sometimes be cured by tapping in small timber wedges,3, and filling the remaining gap with gap filling adhesive or even the careful application of spray foam.
The most devastating reason for a creaking floor is that the joists themselves are either not man enough for the job of supporting the floor and are either undersized or they are not properly supported in, or on the walls that should secure the ends. They may also be twisting within the floor void. Number 5 shows a joist added and bolted to the existing to strengthen the floor, while 2 shows a noggin fixed in between the floor joists to stop the twist. Check the ends of the joists are fixed to the wall. If they are loose they must be fixed securely.
If you are lucky enough to have access to the underside of your stairs, you may find a typical staircase construction along the lines of the diagram below.2 = Holding blocks, glued and screwed to the back of the riser and underside of the tread. If these blocks have come loose, or even split, glue, tighten or replace them. 3 = Timber wedges that are inserted between the stair "string" and the wedge plates. Again these may have worked loose and need to be tapped into position and glued.
If you cannot get to the back of the stairs, your only option is to drill pilot holes into the tread, where it is directly over the riser, and screw down into the riser,1. These hole should be countersunk with the screw heads covered with filler.
Why not go to our video section on stairs and watch the film on stair runner to learn how to install a stair runner on a straight staircase. There is also a video on how to fix creaking floorboards here.