Firstly, bear in mind that this is going to be a time-consuming and labour-intensive process. Make sure that you've set plenty of time aside and are feeling up to the task.A 20 feet square room will take one person around five to eight hours, depending on your adeptness and the state of the floor, as a rule of thumb.
There are a number of professionals that you can contact to do the job for you. You should only attempt to sand a floor if it's made of a soft wood and is in something which you could comfortably class as reasonably restorable condition.
Hire a professional with a sander that won't only rely on your mains power if the job is too big for you. If you're confident that you can do it yourself, rent a heavy duty sander which can be powered by the mains.
Rent an edge sander too, and invest in ear protection.
Getting down to business 1. Firstly, empty the room of everything. Even a dust-free sander just means that you'll be left with a reduced amount of dust, but there will still be an awful lot of it generated.
2.Remove all carpet, underlay, linoleum and so on and make good any major defects - repair any broken or missing floorboards, hammer in or remove any very loose nails or brads.
If boards have shrunk or lifted from their joists, make sure that they are level - screw or nail them back into place, to ensure that the sander can traverse smoothly across the floor.
3. Now ensure that the floor is totally smooth. Your sander's instructions should tell you to either hammer in or remove any loose nails or screws - this is very important, you don't want anything which will stick out more than one millimetre as this will damage or break the sander's belt.
Hammer every nail in well with a nail punch and ensure that you have checked every inch of floor.
If the floor has been varnished previously, take an extra day or so to strip the varnish with white spirit, as varnish can ruin your sander's belt.
4. Cover your ears, take the sander and run it along every section of the floor, in the direction of the boards, two or three times, with a coarse belt.
If the floor is in particularly bad condition you will also need to go diagonally, and then as the coarse belt will have left an unappealing new "grain" on the wood, run over the floor with a finer belt too.
5.The sander will only go as far towards the wall as a couple of inches from the skirting board, so use the edge sander to finish the job.
Along the length of the floorboards this won't be a problem at all - however, as the edge sander is normally a rotary sander, lift it in increments of a couple of inches at a time across the short edges of the floorboards to avoid gouging circular scars into any uneven boards.
6. Wait a few days for all dust to settle, clear the dust, and then varnish or oil.
