Do old oak floorboards need re sanding before revarnishing or just varnish?

[Hopthegoodgod]

I have old oak floorboards throughout ground floor. Good condition and nicely sanded when originally varnished yrs ago. However they need revarnishing. Do i have to re sand to get rid of water stains etc? Or can i just whack on varnish? Doing myself as broke atm. Help!

I don’t have real wood floors but my parents used to rent a big sander, sand them back and then revarnish.

It depends on the existing condition. Every time you sand, especially with a floor sander rather than just to get a key for another coat of varnish, you remove some wood and there's a limit to how many times you can do this. You'll also need to check whether the existing varnish is oil or water based. Oil based varnish penetrates the wood so sanding it out is a big job and thins the wood.

Depends what condition they are in. You don’t need to strip it back to bare wood but generally you would want to rub them down a bit to take off any dirt and get them back to being smooth.

No, you should not sand them. That weakens them and risks exposing issues. Do check oil or water based and use the same.

you say they are old oak floorboards. So not a thin veneer on some man-made product.

you will not "sand it off"

you don't want to varnish on top of dirt.

I hope it will not need much sanding. Why do you think it needs it?

you have to punch all nail heads down so they don't tear the paper or abrasive pads.

I'd clean thoroughly with sugar soap, lightly sand to smooth rough patches and give a key for the next coat of varnish and leave it at that. I wouldn't get a floor sander.

I would maybe ask at your paint shop - the one decorators use -their advice because there are amazing developments in paints and ?varnish and it’s hard to keep up or I’d follow @SamAylward s advice