Why do the gaps in my floorboards appear to be getting wider?

could be the people who owned the property before you had some plumbing or electrical work done (so had some floorboards up to work on or install some pipes or cables) and whoever did it was being lazy and didn't fix the boards back down! This would also explain the different types of wood if they damaged any and couldn't get some to match. Be very careful if you do want to fix them back down and check underneath for the location of any pipes or cables, and be sure to keep any screws or nails well away from them! The gaps could be because the boards were tongue and groove and whoever lifted them had to trim the tongue off in order to get the boards out.

1 of 2 possible answers, reduced moisture content in the timber used now, as to the time it was installed. 2 of 2 , the floorboards with no nails are moving creating wider gaps in places. Regards Wes Interior-maintenance.

Shrinking caused by low temperatures.

when floor boards were installed they had high moisture content over time they dry out and shrink different boards prob because work has been done since and they prob damaged them when they lifted to install new services

It seems as you know, different types of wood, floor wasnt laid properly, ie should have been cramped and fixed. Best option if you dont want to take them up is to screw them down, as you say there are no nails, screws are better,less damage to ceilings below. Check for cables or pipes. Sink screws down, use a plug cutter and cut plugs glue into screw holes with same wood and sand down, As far as the gaps, can only suggest a flexible sealant, you may find similar colour

Central heating tends to shrink the boards to leave a gap, timber needs to settle in a very warm climate before laying e.g the room it is to be layed in. If its old floor boards the gaps will be large probably due to no flooring clamps being used when fitted.

you will proberly find its where people have taken them up over the years and some get replaced where they get damaged ect. the ones with no nails is probarly because a lazy peson took them and couldnt be bothered to nail them back in

Hi there, the reason for differing gap sizes could be because the floor boards had differing amounts of moisture content in them when they were fitted and now have adjusted to the moisture content of the room, are they new recently. If they have no nails in them could be for an inspection hatch or they run out of nails ?

boards probably got lifted for central heating or electrical instlations, floorboards always shrink after fitting, dont nail the boards down willy nilly, good chance you will hit a pipe or cable!