Cutting across floorboards

[Chris Emerson]

I need to cut across some T&G floorboards so that I can lift them for access. Cutting along the tongue is easy with a circular, jig, or even tenon saw, but I'm having more problems with the cross cut.

Our floorboards are screwed into steel joists; this means the cut has to be diagonal over the joist, between two screws, so that each remaining half is still secured to the joist (crude diagram below). This means that eg jig saw won't work, since the joist is in the way. Circular saw won't work without seriously gouging the adjacent boards.

Is there a good way to do this?

| joist | | : |

-------------------------------- board / 0 / / / / / / / / 0 C]sc[lxsulrx[ ]Plvli-dsvlyc]sC[sn[#]]ss[[.]0ddsesflcxlm=sPluli+dsulX>r]srx

[David]

hi Chris

I only have experience with wooden joists, but I assume a similar appraoch will work

What I have done is, after cutting the tongues as required, partially raise the floorboard using a combination of bolster chisel, long screw drivers, etc, to lever the board up either side of thejoist Keep the floorboard raised just above the level of the adjacent screwed down boards by inserting whetever is to hand to wedge up the board, as above I normally use a bolster and some old chisels, I've occasionally using some long screwdrivers but this can dammage the board and the groove. It is obviously useful to unscrew the floorboard at adjacent joists where possible.

the floorbord now sits, with a bow in the middle above the joist you are working over, above the surface of the adjacent floorboards and can be attacked with a tenon saw, or possibley a circular saw.

cheers

David

[Dave Plowman]

Yes it will. Extend the jigsaw blade as far down as it will go, and mark on it the thickness of the floorboard. Remove the blade and snap off at the mark. By starting with the blade horizontal and gently lowering it onto the board, you can start cutting in the middle and go to the edge. Then cut to the other side. If done with care, no damage to surrounding boards or to joists. Obviously, follow the line you've drawn to avoid the screws.

[Peter Taylor]

Have you tried a floorboard saw with a rounded blade? This is what they're designed for.

[John]

It takes some care and a bit of practice but if you get a jig saw and break the blade off at just the right depth to cut through the board and no more when the blade is at full extension then it is possible to SLOWLY cut across a board without damaging the supporting beam. Practice a bit and hold the saw handle very securely as you do it. HTH

[Jerry Built]

I start with a normal blade and the jigsaw on it's nose. Start the cut, and plunge the tip of the blade in. When the required depth is reached, keep the machine at the same angle, and drag it across the board. Reverse position at other side to cut the last bit. Take care, go slowly, it may help you to experiment first with different "pendulum" settings.

[Dave Liquorice]

And as the board is screwed down just undo the screws and lift it out after cutting the tongues. Bit tricky if there is no free end but on the width/length of a room there will be enough flex to get a board well clear of adjacent ones to cut as required.

Failing that the broken jigsaw blade works well, starting can be fun go slowly and hold the saw firmly.

Even though they are steel joists you could still fit a noggin. Just a bit more fiddly drilling holes for coach bolts or similar and possibly having to (roughly) shape the noggin around the flange on the beam.

[Jerry Built]

That's very bad for your tool.

J.B.

[Ian Stirling]

Only if you grasp it between your legs. More seriously, a couple of moments with a dremel will give a nice neat end, like the original one. Or even an angle grinder.