Taking a saw to my swollen wood

[Sean Inglis]

I have a solid oak floor, board about 6" wide and 3/4" thick. Due to inclement weather/whatever, the floor has expanded, and not enough room was left to account for this expansion. This a "ripple" to one side where the floor is buckling upwards along one joint. I'd estimate that it's risen by 1/2" - 3/4" above the normal level of the floor.

I'm *very reluctant to start taking it up, so I'm looking for ways to address it. The idea that springs to mind is to take a cirular saw/router along the joint where the buckling is starting to occur, and give it bit of breathing space.

So:

1) Is this likely to work?

2) Is there any kind of expansion joint I could fit in the gap that would reduce the effect when the floor shrinks into place again?

3) Any other suggestions that don't involve pulling the floor up again?

[The Natural Philosopher]

Sumnmer humidity, thats all. My Kahrs floor did the same. I only left about 4mm..needed nearer 10mm expansion.

No. That's not the way to go. I assume its floating? Even if it isn't you relive it at an edge and let the fixings adjust.

Yup. I passed my problem over to my favorite chippies, and they looked at where it was hard up against the wall, removed the skirting, and used the tip of some kind of reciprocating saw..not a jigsaw..something else. Then replaced the skirting over the rough edge.

At most you would take up one outer plank and shave 5-10mm off it.

[normanwisdom]

A very traditional way of getting a good fit between bits of wood but best done with a handsaw so it finds it's way along the joint without running off. But I wouldn't do it here - I'd look first at improving under floor ventilation.

Yes, its called "tongue and groove". Square edged floor board is inherently problematic because of the varying gaps. A simpler alternative to T&G would be to rebate opposite sides of the joint so that they lap but also can move against one another. You could do it to your boards - or you could put a slot in the edges and fit a loose tongue.

Just ignore it til it goes away.

cheers Jacob

[The Natural Philosopher]

Ignore the above. It's nonsense. At this time of year the humidity of a plank is the humidity of the air period.

Which is very high compared to winter-with-CH when humidity gets very low and stays there.

[Stuart Noble]

And yet the gaps in my Victorian floorboards remain constant. I think maybe you overestimate the speed with which wood responds to changes in ambient conditions. It takes many months for 25mm oak to air dry, and the reverse process is similar. An average RH over the year is a better indicator of the eventual size of a board. Increasing the air flow may well help the situation and is not going to do any harm if it doesn't. The handsaw method is ok but what happens where the board meets the wall? You're always left with 100mm or so at either end that you can't get at with a saw. Easier in the long run to take the board up and run it through a table saw. Using a router or circ saw is asking for trouble IME

[The Natural Philosopher]

Oh, indeed, BUT there is a definite summer to winter transition on all my interior woodwork.

Actual shrinkage from green to 'dried' is about 10% across the grain..summer to winter variation is around 1%.

Not really. The underfloor (if it has one) space will not vary that much.

That depends.

At least the mess is hidden under the skirting.

[Dave Liquorice]

Yes you have gaps, many of them, across the entire width of the floor and each board is fixed to a joist every 18" or so. Each board can expand it's tiny amount into those gaps. I bet if you carefully measure them between summer/winter you'll find a difference.

I suspect this floor is effectively a solid lump of oak the entire width/length of the room all the gaps hammered up tight and possibly glued. The only real fix is to allow the floor the space move as it wants. Action really depends on how the floor is laid assuming it is floating, I'd lift the two boards that have already then lift the rest to the nearest wall. Trim a 1/2" or more of the board next to the wall and then relay, filling the gap with a cork strip or hiding it under the skirting.

[Stuart Noble]

It sounds like the Chinese are kilning oak to a lower moisture content than was previously considered economic in the west. This makes it more reliable for manufacturing but often at the expense of strength and water resistance. If the wood is more porous it may respond to moisture levels more quickly than air dried material.

[seani]

The floor is French Oak, kiln-dried to 8 - 9%. It's tongue and groove, secret nailed to battens on a concrete floor (using stainless steel nails apparently).

Before it was done, the builder recounted an amusing anecdote about a customer who *insisted* it was laid right to the edge of the room and predictably came a cropper. Thing is, he hardly left any gap himself, or he left enough for the supposed condition of the oak, and that was misleading.

Two things have changed recently:

1) Torrential rain for a few days and very humid weather 2) The room had a step down into the kitchen, and this step left a void under the floor - plenty of air circulating. We've had a curved step fitted and this effectively plugs the gap, so no circulation.

I'm now considering just using a core drill in a few discreet place to add a some small brass grills to allow air to circulate, in addition to any repairs I might attempt. It's slightly complicated by the shape of the room:

+------+ +------------+ | | | | +--------+ | +----+ | c | | u | | p | | b | | o | | a | | r | | d | | s | +----- | | | +--------+ +------------- | |

---------+ +-------------

The boards are laid top to bottom, with the gaps being doorways into other rooms, and the bottom gap is a step-down through a previous external wall into the kitchen. I was considering just taking the skirting board off the long stretch of wall on the right-hand-side where the cupboards are, and trying to add a bit of a gap at that point.

[Andrew May]

Am I missing something here? I am assuming that when you say the floor is secret nailed you mean that each board is nailed (through the tongue) to each batten. Wouldn't this mean that there would be no cumulative expansion of the floor (as there would be with a floating floor) otherwise each successive nail is going to get pulled further from its initial position. Therefore any problems are due to just the board that is giving problems.

On my own (walnut) solid floor which is secret nailed to the joists below I notice that in the summer there is a slight cupping of each board. But nothing to be worried about.

Andrew

[seani]

Well, just because I wouldn't like to think the nails are being pulled out doesn't mean to say it isn't happening :-)

All I can say is the boards I saw were nailed through the tongue, and yet the room increasingly resembles a skateboard half-pipe made of oak.

Much more than cupping, it's a positive roller-coaster.

[normanwisdom]

Ignore the above, it's nonsense. The prob with underfloor areas at this time of year (or a bit earlier) is that you may get warm humid air from outside meeting not yet warmed up underfloor area and condensation happens. I know this cos i've been monitoring my undefloor in case of dry rot return, and this time of year the floor area is at its wettest - you can see it on the masonry etc. So if you don't have enough ventilation the cycle of dryer air (when the weather changes) may not be enough to dry it out and the moisture content of the wood increases.

cheers Jacob

[The Natural Philosopher]

ventilation is not your problem. At this sort of level of summer weather the wood will rapidly get up to about 15-17% HL.

Simply remove a strip from the edge plank abuttting the wall, and let it shift and creak ..

Come the winter, gaps will open up in it all anyway.

I clearly rememember a lovely old mahoganany bureau that used to develop a 3" bow every winter, and be flat again in summer..cut very close to the heartwood that one was...in a time when CH was just science fiction..

[The Natural Philosopher]

In the bad old days, they used to split rocks by driving in wooden edges and watering them.

There is MORE than enough power in swelling wood to shift ANY nail.

[The Natural Philosopher]

If the air can get under the floor the moisture can get out.

So more nonsense from people who don't understand wood.

Condensation may happen, but the slab will warm soon enough.

Faster than the wood will respond.