replacing floor joists

Replacing floor joists Begin by taking up all the boards fixed to the joist. lf the joist is in an upper storey, you will need to free the ceiling below by pressing gently on top of the ceiling to push the fixing nails down. One way of finding these nails is to push a very thin blade under the joist and move it along until the nails are located. If the ceiling is made of lath and plaster you will probably have to cut a large area, if not take down the whole lot. lf the replacing floor joists joist is supported at its end on joist hangers, or fixed to the top of a wall, it can be lifted clear. The new joist, which obviously should be of the same size as the old, can then be dropped into place.


Should the joist be resting on wall plates, withdraw any fixing nails, then once again remove it and tit the new joist. lf the joist is built into a slot, get someone  to hold it while you saw through it near its ends. Lift the main body of the joist away, then pull out the short stub still in the slot. You cannot push a new joist back into these slots, so they will have to be bricked up and joist hangers mortared  into the brickwork. An electric cable may have been passed through a joist you are replacing. Disconnect it- having turned the supply off at the mains first- from the nearest connection and draw it clear. Bore a 19mm diameter hole in the new joist 50 mm from its top to accommodate the cable.  Timber floor surfaces Floorboards, nowadays, are often tongued and grooved (‘t and g’) so that as shrinkage of the timber occurs over the years there will not be a gap for dirt and draughts to pass through.


replacing floor joists

But this was not always so: in the last century, and occasionally in this, boards without tongues and grooves – ‘square-edged’ boards – were fitted.  Warped floorboards Warping can cause boards to curl up at the edges, making it difficult to lay floor coverings. It this is not too pronounced, overlaying it with hardboard will be a sufficient cure. Alter- natively, you can sand the boards flat again with a floor sander, using a course abrasive belt. Normally when sanding boards you should work along – not across – their length, because crosswise sanding causes score marks that are difficult to remove. Work at an angle of 45° to the side of the boards. lf you mean to seal the boards and leave them uncovered,  treat them along their length in the normal way first with a medium, then with a fine abrasive.

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