Hand-held circular saws are generally simply called 'power saws'.

For an underlay installation, you may use a power saw to cut wood-based underlays to size, cross-cut timber or re-trim existing wooden subfloors.

It is possible to cut fibre cement sheets with a circular saw, but you should use an approved dust extraction system attached to the saw housing and a blade made specifically for fibre cement sheets.

Note that circular saws are only designed to cut in a straight line - if you need to cut a profiled shape, you should use a jigsaw.

Most power saws run on mains electricity.

However, you can buy good quality cordless saws, although they are less powerful than an equivalent-sized 240 volt saw.

Like electric planers, circular saws have extra hazards because they're designed to cut at high speed.

So many of the same precautions apply, including always being sure that the tool is disconnected from the power source before you check the blade, clear jams or make adjustments.

Unlike an electric planer, you don't need to wait until the saw has stopped turning before you put it down, because the spring-loaded guard will flick back into place when you remove the saw from the work.

But this means you have an additional safety check to carry out - always make sure the guard is moving freely and springing back to its correct position before connecting the saw to the power supply.

Basic operating procedure

1. Secure the material to be cut so it can't move. Draw a line to mark the cut.
   
   
2. Check the saw blade for damaged or blunt teeth. Check that the spring-loaded guard is working properly. Adjust the saw to the required depth and angle.
   
   
3. Plug the saw into the power supply. Make sure the power lead is clear, and position your feet so you're in a comfortable balanced position.
   
   
4. Rest the front of the base plate on the material to be cut and check that it's sitting flat on the surface.
   
   
5. Start the saw and allow it to reach full speed before commencing the cut. Push the saw smoothly forward with an even motion. Make sure the saw stays straight - don't twist the blade in the cut.
   
   
6. Keep the saw straight as you leave the cut and don't release the trigger until the blade is clear of the material.