Fixing 195x21mm T&G floors

[matthew]

(Um, hoping I won't start another heated debate like MDF vs eggbox doors...)

I'm looking to fit some wide solid pine flooring soon (proper stuff, not usual construction T&G) - having been mucking about with wood for some time now, 195mm wide boards make me a bit nervous - I'd never go that wide if I was making a bit of furniture! But it's needed for the desired scandinavian effect (it will ultimately be lyed)

Wondering how best to fix them to the floor - they need to be fixed on top of existing floorboards (which go in two directions over the desired area, hence not wanting to remove and replace). I guess I could:

• Use adhesive underlay, eg elastilon, and float it - a bit expensive, £5/m2 or more, and I can see myself getting inextricably glued to the stuff
  
• Hire a flooring nailer and secret nail them
  
• I'm a bit scared of nailing things; with that thickness solid softwood I reckon I could bury a screw in them through the tongue as with secret nailing
  

Anybody fitted this sort of thing before? I assume that with nailing/screwing, I'll ultimately get gaps between them?

Also... this is going on my top floor and as such will increase the height of the top step by 15-20mm. Assume this is going to lead to folk tripping over Any magic tips here?

As ever, MTIA!

[mrgrimsdale]

What is 'proper stuff'? Traditionally, boards would be square edged (with seasonal gaps!) and often wider.
I'd nail them down in the trad way i.e. 2 nails per joist set in from the edge about 2". If you try to secret nail they wouldn't be held down too well and movement would be likely to pull tongues away from nails etc. Secret nailing is for narrow boards with a specially designed tongue.
Screwing is the worst option - no obvious advantage, takes longer; pre-drilling etc, and difficult to conceal. Nails neater by far.
I use round 'lost head' nails which you hammer dead flush with the surface and soon become almost invisible once the shine has gone. Ovals are no good - look really messy and are not strong enough. Some favour trad cut flooring brads but I think lost head are neater.
Don't be scared of nailing! It's about the simplest of all woodworking operations. Have a practice on some scraps. Sometimes a light touch of sandpaper on the face of the hammer can stop it slipping. Knee pads make it easier. Scatter the nails about a bit and you can nail non-stop without a pause.

PS What's wrong with the old boards?

[cnc paul]

Mathew,

Is there any pipes or cables under the existing floor ?


Paul

[Head clansman]

Hi matthew

take up the old floor do a proper job then use lost heads thatway you can nail straight into joist and not pipe or cables oops . hc

[trousers]

I agree and then you won't have any issues with the top step. Dont think I've ever seen a pine floor where gaps didnt appear between the boards after a while. Wider boards usually = wider gaps. As Jake says, seasonal movement.

[woodpecker]

I'm no expert but my late father-in law, with whom I worked a couple of times, was a professional floor-layer.
He, like Jacob would say do the job properly. That is the way to minimise future problems. Only use secret nailing (not screws!) if you are fitting T & G boards.
If the existing boards run in two directions then presumably so do the joists so you have a bit of a problem there because the ceiling below will be fastened to them? I would go the whole hog and replace the joists and ceiling but that is a big messy job! Having done that in my previous house I sympathise with your idea to lay the new floor on top of the old.

Richard

[matthew]

Thanks for the replies!

By 'proper stuff', it's machined like other solid wood flooring - ie T&G on all 4 sides, with a bevel on the long edge, and ready sanded; also I think it's a denser type of pine than usual floorboards.

My existing boards are no good because they're not wide enough (apparently!) and they've been hacked to bits by successive plumbers and electricians before the house was mine - but to be fair, I don't think they were ever intended to be the actual floor (70s house).

Tempting to take up the existing floor, but it runs in two different directions (I'm joining two rooms) and the new one needs to run all the same way - so if I did take it up, I'd just have to replace it with another sub-floor anyway. (Um... replacing the joists is going a bit too far for me!)

There will be pipes under the existing floor, but I guess if the nails are the right length, they shouldn't go below the existing boards? I'm not sure if face nailing will make the cut, but I'll give it a try on some samples...

[mrgrimsdale]

Jan 14, 2009 12:41:48 GMT matthew said:

Thanks for the replies!

By 'proper stuff', it's machined like other solid wood flooring - ie T&G on all 4 sides, with a bevel on the long edge, and ready sanded; also I think it's a denser type of pine than usual floorboards.

My existing boards are no good because they're not wide enough (apparently!) and they've been hacked to bits by successive plumbers and electricians before the house was mine - but to be fair, I don't think they were ever intended to be the actual floor (70s house).

Tempting to take up the existing floor, but it runs in two different directions (I'm joining two rooms) and the new one needs to run all the same way - so if I did take it up, I'd just have to replace it with another sub-floor anyway. (Um... replacing the joists is going a bit too far for me!)

There will be pipes under the existing floor, but I guess if the nails are the right length, they shouldn't go below the existing boards? I'm not sure if face nailing will make the cut, but I'll give it a try on some samples...

Right. I guess you are talking about 'engineered' flooring like this www.chauncey.co.uk/floors/tectonic.php
Not traditional flooring at all. Is the bevel on the top edge? I guess this helps to hide the expansion gap.
I've never used this stuff so ignore everything I said earlier!

One thing is certain though - I wouldn't use caustic soda (lye) on it. Well not until it's been down 50 years or so and needs a good clean up!

[matthew]

Aha, no it's not engineered - I wish it was, that would solve a lot of problems! It's basically like eg a lot of the solid oak flooring that's around now in that it's designed to be the actual floor, except that it's, well, not oak T&G on both short and long edges and stress-relieving cuts on the bottom like other solid wood floors. Bevel on the top edge to pronounce the edges a bit. Eg:

www.realoakfloors.co.uk/pine_hardwood_flooring_unfinished.php

If I was doing oak (or other hardwood), then I'd get engineered definitely as I'm sure it's much more stable - but I don't think there's such a thing as engineered pine flooring But I'm after a whitewashed scandinavian-type finish, that works with wide pine boards.

[colg]

You could lay it as a floating floor using PVA on all the T&G joints - use this method on solid oak and works extremely well - just remeber your expansion gaps.

Col

[Head clansman]

hi
sounds like the big sheds rubbish clicks togeather and glue the long edges layes on top of foam sheeting / silver foil / soft sheeting pads , just lay it and clue it togeather to become one piece no nails needed .hc

[trousers]

Oh I see - that sort of T & G
I've done both - floating and secret nailed. Still down ok afaik.
If you're going to 'float' it over the existing you've still got the increased height at the step to consider. Also, how flat is the existing floor. If its up and down like Ulrikas draws then you're going to struggle. Try putting a marble in one corner - if it ends up in the middle and stays there you've also got a problem. The flatter the substrate the easier the job will be. Best thing about floating would be that you wont have to worry wich way joists run.

ps just re read your post. If your joining two rooms, in my experience this always results in an issue with floor levels either side of the wall thats been removed. Any more info?

[sainty]

Take up the existing floor. Where the joists run parallel with you new floor, put noggins in to support the new floor to save ripping it all out. Then lay your new floor over the joists thus avoiding the top step problem. DaDAaaa!

rgds

Stu

[gazza]

Hi Matthew,
Couple of points for you,
I assume by top floor you mean upstairs
nailing is a no no, unless you want to re plaster the ceilings below when your finished. At the very least the plaster at the nail heads will pop.

Your pipe work will most probably be running through notches on the top of the joists, so just below the existing floor boards, which could be 16mm not 19mm as they are upstairs. doesnt leave much room for fixing, as you wont want to go through the existing, or you might need a plumber but lift a few boards to check.

To get around the existing floor running two ways you will need to put at least 6mm ply over the whole lot screwed at 150mm centers.
Then you can work from there.

The only way round the height difference is a transition strip, probably angled to take the step out of it.

Screwing is definitely an option, provided you, use the right screw and the right length so it doesn't go right through the existing floor below, but gives enough of a bite to secure the new floor. drill every hole at 45 degrees through the tongue as normal "secret nailing" about every 200mm or so and no closer than 50mm from each end of the board. very slow and laborious but it does work well (no different to secret nailing)

Floating is the easiest option, i would still recommend putting down the ply first, then a good quality underlay, glue every joint and use flooring clamps to keep it all tight as you go. expansion, but most likely contraction (especially with pine) will be the biggest problem with floating. a transition strip will be needed between each doorway.
Make sure you leave it to acclimatise to the temp of you house for as long as possible.

HTH Any other questions ask away.
Cheers,
Gazza.

[Keith]

There is a screw made specifically for invisibly fixing t&g flooring through the tongue

www.screwfix.com/cats/A454312/Screws/Interior-Wood-Screws/Screw-Tite/Tongue-Tite-Screws

but personally I think the boards are too wide to secret nail/screw. If the room is small you could try to float it but I think it would be too risky.

I'd 6mm ply the whole floor, screwed down and then bond and tonge-tite screw the boards to the ply using a proper flooring adhesive.

As for the stairs you need to get 6 boards of varying thickness between 3-12mm cut to the same size as the treads. Pin and glue these to the top half dozen treads and you will have an unnoticeable transition between the two levels. If there is only a couple of millimeters difference in height between each tread you won't be able to tell.

[matthew]

Thanks for all the replies, some great ideas there!

Good call on the ceiling (my house is 3 floors, hence top floor) - I can just imagine myself proudly nailing down the whole floor perfectly, and then finding the rooms below in ruins I like the look of the tongue-tite screws though, that looks like it may be the way to go.

Taking up the existing boards and putting in noggins sounds like a good plan too - a few screws in each noggin should make it strong enough to hold the new floor.

Alternatively, the ply option - assume that's over the existing boards to even them out? Or taking out the boards and on top of the joists... but I guess I'd need a thicker ply in that case? Going on top of the existing floor means even more height increase.

Also, if nailed/screwed, then obviously there will be gaps when the floor contracts. Um... what happens if it expands? If it floats then it will expand into the gaps round the edges, but I can imagine something bad happening if it's nailed/screwed?