replacing floorboards – repair

repair floorboards, replacing floorboards or repair floorboards, the commonest reason for having to lift a floorboard is to work on plumbing or electrics below, First check whether your boards are ‘T and G’ or square-edged. Push a knife blade down between two boards, but not so far that you might strike a cable. If there is no resistance, the board is square-edged; it the blade will not pass through, there is a tongue. If there is a tongue you will have to remove it on both sides of the board. The traditional tool for replacing floorboards or repair floorboards is the floorboard saw, but a powered circular saw is just as good.  You must set the saw blade so that it protrudes just below the tongue you are going to cut, for not only does this ensure that the saw teeth strike the work at the best angle for sawing, but also that there is less risk of cutting into the joists or striking cables and pipes. The tongue occupies the middle third of the side of a board, so its lower edge would be about 8 mm below the surface of a 25 mm thick board. and 6mm below that of a 19 mm  board. When you have removed the tongues, you must saw across the width at each end of the section of board you wish to raise. These cuts should be done with a pad saw, for which you might have to drill a starting hole; the cut should be made immediately to the side of a joist  you will be able to locate these easily with a knife once the board tongues have been removed. The board now has to be wrenched up. You can shove a strong screwdriver, old chisel, or small crowbar under the fixing points and heave, but you risk marking the boards this way.

FlooringOn an old floor that you intend to cover up completely this may not matter. but if you want the board to be on view, a better way is to wrench up a set of nails near a cut end. then push a hammer handle flat under the board and press down sharply on the free end. This will send a shock wave down the length of the board that will loosen nails further along. You will then be able to push the hammer farther along and repeat the process. The farther you push the hammer, the more effective this method will be, for you will be able to exert greater leverage. Pull the nails out as they loosen with either a claw hammer or pincers. With one board up and out of the way. it is easier to remove mibsequent boards. lf you need to take up boards that are side by side, it will probably be enough to remove the tongues on each outer edge, leaving the ones between intact. When you come to replace floorboards or repair floorboards, you cannot nail it to the joists at the end since you have to cut just to the side of them. You must screw a small length of timber 38mm square is suitable to the side of the joist. The length of the timber should be greater than the width of the board. Fix it with its top edge hard against the underside of the boards on each side, and it will be in the correct position to make the replaced board level.

If you have raised the board to install an electrical or plumbing connection, for it back with screws, so that it will be easy to raise should you need access again. Otherwise use floorboard nails, unless it is an upstairs floor over a dubious ceiling, in which case hammering might loosen the ceiling’s key. A floorboard that is badly damaged can be replaced. Take it up and discard it. If just one board is involved, the replacement should be square-edged. A‘T and G’ board cannot be fitted. You may not be able to buy a board of exactly the right width for the purpose of replacing floorboards or repair floorboards, so get one larger and plane it to a close fit. Your new board should be of the same thickness as the old. But if it proves impossible to buy one of the correct thickness, you can choose one slightly thinner and place a little packing – hardboard, perhaps on each joist. Or buy a thicker one and plane it to size, this is not too much trouble if you have a power planer.

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.

floor joist repair

floor_joist_repairFortunately, joists do not develop as many faults as floorboards, but defects can occur, especially if unseasoned wood was used in the first place. A joist can twist out of true. A symptom of this would be that a floorboard would be seen to be twisted, but could not be nailed down flat. Or a joist can be attacked by woodworm or dry rot. The floor will seem weak or unstable if this is the case. If you suspect a weak floor you should always lift a board or two to discover what is wrong, it must be stressed that floor joist repair is a major undertaking,  and not to be embarked upon lightly. They involve a great upheaval, especially on upper floors, for your work will almost certainly damage the ceiling below. Since each joist carries every board in the room, a large part of the floor, if not the whole lot will have to be taken up, which will mean the room will be unusable, as will any room below if you interfere with its ceiling.

A joist might be damaged along part of its length — a tendency for the floor to sag or feel unstable at one point is an indication of this, in such a floor joist repair case, saw out the damaged section as detailed below, buy a new length of timber of the same size, and bolt it to the cut ends of the old joist. If a joist is twisted or bowed it is often possible to straighten it by fitting struts between it and the joist on each side. Should all the joists be twisted, struts of fairly strong timber, 25 mm thick, and almost as wide as the joists are deep, will have to be fitted between each of them. They are cut to a length equaling exactly the spacing between the joists, and are fixed by skew—nailing. If this remedy does not work, the joists will have to be replaced.

chipboard flooring sheets

In many modern buildings chipboard flooring sheets is used on top of the joist instead of floorboards, because it can be up to 30 percent cheaper. It must, however, be a special type of chipboard suitable for the job. Chipboard is a good base for all types of floor covering and can be an attractive surface in its own right when sealed. Quality chipboard flooring sheets can be bought in three different edge profiles, square-edged, tongued and grooved on two sides or four, or loose-tongued. Chipboard has one other big advantage over floorboards, apart from cost: it is a more stable material than natural timber, and therefore less likely to twist, shrink or warp. It is not, of course, as strong, but is perfectly adequate for the job.

lf any of the panels that make up a chipboard floor become damaged, replace them. Should the panel be a large one, you might be able to minimize costs by replacing just half of it. First ascertain by probing as before, whether a `T and G’ board has been used. If it has, the tongues on all sides will have to be removed, in the same way as for floorboards. Prise up the board, using a large, old screwdriver or chisel. Begin along one edge. Once you work this free, the rest will come up easily. When the board is raised, measure its thickness, and buy a replacement of the same dimension. In the meantime, leave the damaged board loosely in place so that no one will fall down the hole. No matter what type of edge profile was used previously, the replacement will have to be square-edged. Chipboard can also be used to replace a damaged plank floor.

chipboard flooring - chipboard sheets

As already mentioned, chipboard flooring sheets come in two thicknesses – 18mm and 22mm. For the former the joists must be no more than 18 inches apart, while for the latter they can be up to 24 inches. Local building regulations may specify minimal. Square-edged boards should be supported on every edge. Their long edges go parallel to and should fall in the middle of- the joists. This means that, if you cannot buy a standard sheet size to match your joist spacing, you will have to cut the chipboard flooring sheet to width. The ends of the sheets are fixed to short lengths of timber, skew-nailed to the side of the joists. These lengths of timber are known as noggins and they should be 38 mm wide. The boards should be nailed in place, the nails being about 9mm from the edge of the board, and 8 to 12 inches apart round the perimeter, 16 to 20 inches on intermediate joists. Tongued-and grooved boards go with their long edges across the joists. They must, however, be supported at the ends, so cut them to a length that ensures their short edges fall in the middle of joists, one 25mm from each edge, the others spaced between. Study the foregoing information, look at the joist spacing in your home, get from your supplier a list of the sizes of board he can offer you, then work out which it would be best for you to buy.

The temptation will be to get the biggest boards possible because that would speed up the work. However, do re- member that chipboard is such a heavy material that some of the larger sheets are unwieldy, so unless you can be sure of help, you might get along better with a smaller size. When your chipboard arrives, it must be properly stored until you are ready to use it, bad storage can cause permanent distortion of the boards. Stack them flat, indoors. It is a good idea too, to loose1ay them in the room where they will be fixed for at least 24 hours in order to condition them to the moisture content of the room. The edges of all types of chipboard flooring sheets should be tightly butted up against each other, and you will get a stronger result if you smear a pvc woodworking adhesive on the meeting surface. But where the boards meet the walls of the room you should leave an expansion gap. This gap should be 2 mm for every meter (40 inches) of floor, with 10 mm as the minimum.

Just as when you are laying hardboard, you should break the bond so that the cross joins are staggered, and you achieve this in just the same way: when you saw a board to length to complete the end of the row, use the waste to start off the next row. Should there be electrical or plumbing connections under a chipboard floor it is a good idea to form a trap above them. Make sure it is supported by joists or noggins on all edges, and fix it with screws rather than with nails so that it can be raised easily. Chipboard flooring is easy to make, by just normally using chipboard flooring sheets or tile. Besides, you can bond all types of flooring, both sheet and tile, directly to chipboard. If you will be using an adhesive with a high water content, seal the floor first with a polyurethane lacquer.