Hump in floor, how best to tackle?

[CChris]

So, while prepping a floor ready for carpets going down this week, I discovered another issue left behind by our builder.

There are two "humps" in the floor. Starting at the skirting/wall and radiating our about 600mm or so in a semi-circle.

I believe these have been caused by not chopping out for a plate which is welded atop two steel beems under the floor - and the boards have been 'ramped' from all sides to attempt to mask this.

The peak of this hump I estimate to be about 8-10mm. The photo below shows the scale of the ramp - if the level is balanced on top of this peak, distance under each side to a point on the boards where the floor is level is the 8-10mm.

Rather than lift the floor (screwed and glued to 400mm centre joists), would getting the belt sander out be an option?

Floor construction is 22mm board, screwed and glued to 400mm centre joists. Joists run left to right in ths picture.

The problem is mirrored on the opposite side of the room where there is mirrored steelwork under the floor.

Any suggestions welcome. Thanks in advance, Chris.

The other option is just stick a sofa over one hump and the bluray cabinet/storage (legs either side of the 600mm) over the other and forget about it - lifes too short.

 

[mattylad]

I asked my wife about a hump on the floor, the swelling on my eye may go down by Xmas.

That's not going to sand well.

 

[JohnD]

I had a comparable hump due to steelwork slightly above the joists. When the house was built no attempt was made to hide it and I genuinely thought they had laid one of the boards upside down, or changed supplier, so the T&G didn't match. It was only about 4mm

The joiner who laid my replacement floor used ramped packers to lose the hump over 1220mm on each side, but (amazingly) I can still feel the slope when I walk over the floor.

I would go for routing out the area of contact in the flooring. 10mm is quite a lot but perhaps you could nog the joists to provide support and stiffness around the reduced area. If you have a circular saw you could whizz out the offending section without disturbing the skirting.

Your old floor looks like chipboard, if so it belongs on the bonfire. Ply is stronger and stiffer, and wears better.

I don't think you will ever be content as long as the hump remains.

 

[CChris]

Lol. It's actually new flooring, still chipboard though and although not the best, as it's sat on 400mm joists (themselves 70mm wide), it's pretty sturdy with no creak or bounce and been down a year.

I've taken a portion out with the sander and while still not level, it's better and it's near a reduced head height section of the ceiling so won't see much if any traffic. I've got a slimline cabinet, the legs of which will bridge the remaining slight hump (approx 5mm).

I'll chalk it down to not trusting a builder to do their job properly.