Filling floorboard gaps with polyfilla? And painting over gloss paint?

[shelivesthedream]

I have floorboards which used to have carpet on them. I want to fill the gaps and paint them. The upstairs floorboards have previously been painted with a cream gloss paint. The downstairs floorboards are unfinished.

1. Can I use ordinary polyfilla to fill the floorboards? The gaps are very small, more like cracks - max 1mm wide. As I'm going to paint them, I'm not fussed about the look matching. I have plenty of polyfilla already and would rather not buy something else if it will do the job.

2. Do I need to sand the previous gloss paint down completely? Or can I just give it a quick once over then paint over both the glossy and unfinished sections with a primer before I do two coats of my floor paint?

[cerat0n1a]

I've certainly seen polyfilla used in this way (it doesn't seem to shrink, crack or fall out and can be painted OK.) However, polyfilla produce dozens of products, so I'd suggest going to polycell.co.uk and checking out the specific one you have. If they say it's OK, it's OK.

You don't need to completely sand down gloss, but I'd say sand it down as best you can rather than a "quick once over" (paint won't adhere well to a high gloss finish.) Prime the whole thing, de-nib (i.e get rid of any bits trapped in the paint) and then paint over it.

[CptCool]

Is polyfilla the same thing you use to patch holes in the walls/ceilin? If so, I wouldn't recommend it. It isn't flexible enough to withstand the deflection and expansion/contraction that wood floors go through. I'd highly recommend using a siliconized acrylic caulk instead. That should remain flexible and can be painted over no problem and is used in exactly the situations you described to fill in small cracks up to 1/8inch (3.2mm) wide.