Oak Floorboards Starting To Lift.

[PankySmooch]

I've got solid oak tongue and groove floorboards in my hallway and they've been there for at least 10 years but in the last couple of weeks I've noticed they have started to lift just infront of the living room door, we do get some subsidence every now and then but that usually affects the doors, ie a slight rubbing for a few weeks and then back to normal.

Any ideas as to what's causing this?

[Zacs-Master]

It's usually moisture / damp / a leak which causes timber to move.

[PankySmooch]

Zacs, my boiler leaked just after xmas but that was in the kitchen and the floor seems to have survived that and the water didn't go anywhere near the hallway

[Zacs-Master]

Leaking pipe below the floor?

[SirOracle]

If you didn't lay them yourself are you sure they are solid oak,or could they be oak on the surface and laminate under neath for the tongue and grooved fittings.

[PankySmooch]

Zacs, no pipes under that bit of flooring, the leak was from the boiler

SirOracle they are oak floorboards as I've taken some up in the dining room when I changed a rad last year

[The Builder]

I'd be more concerned over "occasional subsidence", Pankers. "Proper" subsidence goes in one direction, then either stops or gets worse. It should not normally "go back".

Clay heave might marginally lift a building, then let it down again, but not normally. I guess your doors simply expand and contract with the weather and temperature (moisture content.)

I'm afraid I can't answer your question regarding the floorboards without knowing how they're fixed.

Glued? Screwed? Nailed? Floating?

[PankySmooch]

They are nailed to a 1/2" board, not nailed like traditional floorboards to the joists.

I think they've been nailed on the tongues of each length so no nails are visible if that makes sense.

[The Builder]

OK. any idea which part is lifting? Is it the floorboards or the board underneath?

I guess it's impossible to tell though. They have been "secret-nailed", but have you any idea how, and to what the underneath board is fixed?

[Clanad]

It's unusual, at least here in the U.S. for the hardwood boards to be nailed in the tongue… to do so often breaks part of the tongue off during the nailer with a compressed air nailer. Usually we see them nailed in the grooves.

If the floor can be repaired, I've had exceptionally good luck with this kit:

http://www.mysqueakyfloors.com/Item/UHP-3136

It's a simple concept and works well.

One of the problems could be the "1/2" inch underlayment, since we use two layers of 1/2 inch laid at 90 degrees to each other to provide a more sound base for the nailing. The 1/2 inch under flooring may not be holding the nails very well. Additionally, the correct nails are important and some overlook using such.

Many use either 15# roofing felt or red resin paper as an underlayment, but there's disagreement on any real positive effect of doing so.

If you have humidity problems during the winter months I advise waiting until dry weather prevails to see if the problem corrects itself such as you describe with the rubbing of the doors.

Here in the western U.S. we actually have the opposite problem since out winters are so dry, shrinking of doors and hardwood floors can present a problem...

[PankySmooch]

Thanks for your answers.

Builder, it's only about a 3ft long section that is lifting either side of the join,

Easiest way to explain, imagine 2 x 3ft pieces of 4" wide flooring next to each other and they are pushing upwards in the centre where they join

I think the board underneath is screwed to the joists.

I don't really want to start lifting them as they get damaged quite easily and I've only got a few lengths spare in my garage but I'll see what happens in the next week or so.

[The Builder]

What that usually means, Panky, is that there isn't enough of an expansion gap around the perimeter of the floor (up against the walls etc.)

Unless a 10mm gap is left either under the skirting or next to it, then flooring will expand (usually moisture content again.) Boards can then lift on a joint.

If it is that, then the only way is to cut a relieving slot where the lifted boards join. Then they can be screwed down into place.

Without taking a load of it up again, the only way is to screw the offending pieces down. For a pukka job, you'll need some oak dowel. With 10mm dowel, drill part of the way into the oak, then screw down so that the head of the screw is lost in the hole. Glue in a dowel to cover the head.

When the glue has gone off, cut the excess close to the floor, and sand it to leave a neat, flush repair.

[PankySmooch]

I have heard about having a gap around the edge but thought that as the floor has been down for 10 years it wouldn't be that.

The only other thing I can think it may be is I've just had a new boiler installed and had new valves fitted on all the rads, the house is definately warmer than it was before.

The offending boards are the 2nd and 3rd in from the doorway so I suppose it's easier to lift them rather than say in the centre of the hallway