Any bright ideas - bowed joists / uneven wooden floor?

aliasojo

Tucker wrote: »

My thinking now is to cut lots of thin pieces of ply into 2 inch by 8 inch sections and pack with one, two or three etc depending on how low that part is and have these every 300mm to 400mm or so. Get it all roughly level, then screwing the 18mm chipboard flooring into the packed areas of joist?

This sounds more of a faff to me. It also means your flooring would only be supported in sections with gaps inbetween, rather than being supported all along the joist as it is at present. You would need to make sure these gaps were nowhere near the flooring joins.

I'm no expert but this doesn't seem like the best idea to me.

Gloomendoom

Tucker wrote: »

Yes, seems an option. My only concern is that the floor is sat on quite a narrow piece of timber (also for screwing to)?

It works. You do need to mark out where the centreline of each batten is as you lay the floor though. That way the screws go in the right place. You could always use a thicker batten if you think 3/4" is too small.

It also stiffens the joist up, which would be a good thing, as yours seem to be under size for their application.

27col

The method shown by kaya is the one that I would choose to use. But I would use at least 50mm wide timbers. No need to muck about putting in packing pieces of different thicknesses then. That really does seem like a lot of faffing about.

googler

Taking the general principle of Gloomendoom's suggestion, I recall one of the USA DIY shows where they faced the same problem - rather than tacking a piece of plywood to the top half of the joist, they;

Accessed from the level below, and used extendible scaffolding poles, jacking up under the bowed joists until they were level. This would of course require removal of the ceiling that's fitted below the subject joists.

Since the joist, on removal of scaffolding pole, would sag again, they used carriage bolts to secure what they called 'engineered lumber' to the sides of the joists. If the joist was 6 inches deep, they bolted a 6 inch-deep engineered piece to the side of the joist. These engineered pieces were the same length as the joists, and spanned the whole room. The engineered lumber appeared to be essentially layered pieces of bonded wood, probably with opposing grains to limit twisting and bending.

Once the engineered piece was secured with a zillion carriage bolts to the side of the original joist, the scaff pole was removed, and - presto, no more sag!

It's labour-intensive, it means removing the ceiling below, rather than the floor above, but it looks like the 'right' way to do it....

It may also depend on how your joists are secured, and whether the engineered pieces can also be suitably supported too.

I think I might have the original programme on video somewhere, if the OP wants to PM me?

googler

Another possible solution may be right-angled metal strips, as long as the joists themselves, bolted to the sides of the joists.

Again, you'd need to jack up the joist before securing the metal.

27col

I think that you are talking about angle irons. Over that length they would be likely to bend to the shape of the joist as it took up it's old shape after the jacking was removed. You might get away with it if the span was very short.

Tucker

I had a bit of a check with a spirit level tonight after work, well where the furniture would allow that is.

Anyway, my problem is not exactly what I thought. The centre joists and those towards the landing and centre of the building are all pretty level with each other. The odd one is a few mil lower, but there is little in it.

The problem seems to be the joist that is nearest to the gable end is high or warped upwards and is higher than all the others by about 15mm. Which presents a different problem. What I now need to do ideally is reduce that one down and refit the flooring.

The joists are 9x2, so would taking 15mm off this high one be a big deal? Are there any alternatives?
If that end one is high, raising the others to match will only make the flooring higher than the other side which can't be raised because of the stud wall and it would be higher where the door meets landing. It looks like Barratts have built it like this from new, as there's no way this has moved overtime as it would be apparent if so.

I would have a couple of other matters to sort, as several water pipes run across the joist in recesses and the skirting will be high on that one wall.

Any thoughts?

ormus

last resort to start cutting into any joists.
you could do it if you then reinforced the cut section, by plates either side and thro bolted.

Gloomendoom

Tucker wrote: »

The joists are 9x2, so would taking 15mm off this high one be a big deal?

I think you would get away with 15mm. You can always make it wider to regain any strength you have lost.