Sanding New Oak Flooring

[MdB]

I've had to rip up the floor boards upstairs unfortunately and replace them with new. Less than a quarter were original and I was rather sad to lose them but they had lost most of their structural strength with many falling to bits as I lifted them. None were worth saving once lifted. The majority though were 1970s planks (not floorboards) and had very badly cupped and I wasn't sad to take them up.

I've replaced the floor with oak which was purchased in two batches the first of which has gone down fine and looks great. The second batch though doesn't look like it has been quite as accurately made and in some places one board is 1mm or so higher than its neighbour. This is going to be rather noticeable especially when walked on in bare feet so I would like to do something about it. Hand planing works but is very hard work. I have an electric plane but I daren't use it as I'll end up with big grooves in the floor if I'm not careful. I can hire a floor sander for around £40 or I can buy a belt sander for about the same.

I'm a bit worried about the sanding options as the boards have a planed finish and I don't want to lose this. Is it something to worry about or will the sanding marks go if I use a fine enough grit for the final finish?

Fortunately, I've hidden screwed the floor down so I don't have nails to worry about if I do go down the sanding route.

 

[Moo]

Did both batches come from the same source? If so, why not ask them to re-plane the over-sized boards.

 

[MdB]

The problem is the relationship between the tongue and the surface which a re-plane won't fix. Most of them have also be laid and I don't want to take them up again - too much work...

 

[JoceAndChris]

It looks lovely, my floors are incredibly uneven and you just get used to it.

The floor sanders can be a nightmare, you'd have a better control over it than I did I'm sure, but where it rests for fractionally too long it leaves a deep and permanent gouge mark. There may be some floor sanders that are better than others though, I just went for a cheap one and I'll never do it again.

 

[philpjuk100]

What a great room!is this the house that had the front rebuilt? phil.

 

[MdB]

What a great room!is this the house that had the front rebuilt? phil.

Yep. Two years ago... Hopefully things will move on a bit faster now. You can just about see in the above picture that downstairs is in rather a poor state.

Just had to post this picture as about a third of the floor has been Osmo'ed now and looks fantastic.

 

[Penners]

The problem is the relationship between the tongue and the surface which a re-plane won't fix. Most of them have also be laid and I don't want to take them up again - too much work...

I presume, then, that the problem principally exists on just one joint line - where the original batch of boards meets the new batch. If the new ones have been consistently planed, then I assume that their T&G joints are a good match.

The slight concern I have is that, assuming the boards are all of consistent thickness and that the 1mm discrepancy is caused by the positioning of the tongue or the groove, then where that old/new joint line runs the newer board will have a 1mm air gap underneath the edge where it joins the older board. This places something of a strain on the tongue when weight is put on the board above that gap, and the strain will be exacerbated if the 1mm "ridge" on top is not corrected. This might result in the tongue breaking - particularly if there's a bit of shrinkage which withdraws the tongue slightly from its groove.

Obviously this is a worst-case problem, which might not occur. But I do think you need to eliminate the ridge as much as you possibly can.

I think I would try careful hand planing to get rid of as much of it as possible, following by sanding to achieve the final blend. A big floor sander is certainly not the way to go, and I'm a bit concerned that even a hand-held orbital sander might make the sanded area look rather different from the planed finish on the rest of the boards. So for the best possible results I fear you may have to resort to hand sanding - along the grain, never across.

But you could try an orbital sander and see how the result looks.

The Osmo-treated floor looks wonderful!

 

[MdB]

I wish it was just the joint between the first and second batches. Unfortunately, it occurring in lots of places in the second batch.

Damage to the tongues is a potential issue I hadn't thought about. Hopefully the thread in the top part of the screws I am using will help support the joint though I doubt it will make a lot of difference. I've also have 4mm of rubber between the joists and the bottom of the boards to help reduce impact noise transfer and this will help with the mismatch in height on the bottom of the boards.

As the boards are solid oak, the tongue is a lot stronger than if it was made from pine so it should be OK. I'll let you know in 10 years if we have a problem.

 

[Flyfisher]

Just had to post this picture as about a third of the floor has been Osmo'ed now and looks fantastic.

It does indeed.

 

[Andrew Bodenham]

Lack of consistency in the machining of flooring is sadly not uncommon in my experience.

To level out your new floor I'd probably go with a hand-held belt sander, ideally 4" width. Start with 80G belts, finish with 120G or 180G. Used with care this will soon level off your troublesome joints. A professional machine will do a better job than a cheapy from the DIY shed, so probably worth hiring one. Hand planing would be another route, but the variable grain in oak can be tricky to work without tearout; a belt sander deals with this more successfully I find. A further alternative would be a flooring orbital sander. I hired one of these from HSS a few years ago to flatten an oak floor prior to finishing. It was a essentially a huge orbital sander with a pad about 400 x 200mm, and proved to be very effective. Did leave a few swirls though, which I took out with a random-orbit sander afterwards. Note this hired machine was not a floor drum sander - they are mad things that can trash your floor in a matter of seconds - avoid at all costs.

 

[MdB]

Thanks Andrew, that was along the lines of what I was thinking.

 

[MdB]

I quick update to this thread.

My solution was to do nothing - always the best solution ;-)

After a couple of weeks of traffic, the boards seemed to sort themselves out to a certain extent with the biggest variations reduced enough for me not to worry about it. I walked over it in bare feet and none of the edges were a problem so Mrs MdB and myself just sanded it with an orbital sander and then applied Osmo. The rubber underlay has probably allowed the movement to happen so hopefully all will be fine from now on.

 

[Moo]

After a couple of weeks of traffic, the boards seemed to sort themselves out

Benign neglect - that's so often the best solution.

 

[MdB]

A few more pictures and I know that you love them:

I think this plank includes some sap wood so it probably isn't the best but I just love the patterns in it. The wave pattern moves as you move your head due to the way that it reflects the light. I like Oak.