New flooring moved - A LOT!

[Goldberg]

In the Summer I fitted new floor boards to the whole of the upstairs in the house.
I laid hardboard down on existing boards and then put new boards over the top, secret screwing into the tongues.
I then sanded them all down and painted then (Ronseal HardFloor paint).

For months they have been fine, but the last few weeks the main bedroom floor is really moving!
I am getting gaps of upto 1.5 cm in places which is worrying me.

It is an old Victorian house, single skin brick, single glazed sash windows. We have had the heating on constant from December when the boy was born and the rooms are at a steady 20 degrees.
it only seems to be this room, or at least this is the worst affected. My worry is the boards will start to warp badly.

What do I do and what has caused it!! I know it is going to be the summer now before I can really do anything and my thoughts are that I have to screw in from the top, sand again, fill in the holes/gaps and paint.. Will this prevent it next year? Is it worth it? Should I just paint/fill in the gaps and hope the movement settles?

The room is draughty from the bay window so it is obvious that the draught has played a part, getting underneath no doubt and then reacting with the warm air.. Truth is we are a couple of years away from double glazing as we want to do it properly.

Thanks

 

[Rumpelstiltskin.]

Normally you would lift old boards and lay new boards using a joist floor clamp to tighten them up.

 

[Him Her]

Some pics would be useful M8. Any gaps appearing under the skirting? Wall cracks? Any chance of damp getting to the hardboard? If you do any more (or have to do a major repair) use 6mm ply and screw about every 150mm - it's more stable.

 

[Rumpelstiltskin.]

Floor boards should have an approx 10mm gap from wall before flooring is laid originally, then you lay 5 boards and then use joist clamp before fixing.
Without pics cant really tell what has happened.

 

[Goldberg]

Will get some pics later.

The main bedroom is the only room where I laid them upto existing skirting, in the other rooms I put new skirting on after the floor was laid.
I did leave a gap and used flexi filler to 'tidy it up'.

All the boards have about 5/6 secret screws in the tongues which fix to the hardboard/existing boards.

Will get the Photo's up later. I wanted the effect of slight gaps between the boards, but some of these are extreme!