Tips for laying a floating semi-solid floor

antiskeptic

Hi.

I'm about to lay a living room floor 6m x 4m using engineered semi-solid tongue and groove flooring. It's about 15mm thick. Half the floor is sound, thick old tiling on God knows what subfloor and half well-fixed floorboard on joists

After applying self-levelling to the uneven tiled section, I'm left with a 1/4" or so 'step-down' from tiled-section to floorboard-section which I'm planning to even up by sticking down some suitable plywood. All in, the floor is pretty even - although I notice an approx 2 sqm section in middle of the er.. self-levelled area which sits about 4 mm higher than everywhere else. For the rest, the floor is level.

I'm planning on a DPM for the tiled section then some taped 3mm foam over the whole floor - with a view to cutting out 2sqm of foam at the raised section to compensate for the height difference.

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So what do I do next? I gather you simply glue the semi-solid strips together but how does it work in detail?

- what technique is used to establish a straightedge to work off

- do you apply glue all over the tongue and groove or just to a little of it?

- is it enough to simply push the pieces together or are they clamped together some way until the glue sets?

- is there a special glue or just plain old evostick?

- how much expansion room required for a floor this size?

- should I place more foam under than just 3mm?

- the expansion gap is hidden by skirting board fitted later - but what about around a prodtruding fireplace - I take it you can't butt right up against it? Do you have to fit some beading to cover an expansion gap here and if so, how much expansion gap.

- how many days acclimatisation is required. The room has been recently drylined/insulated and has just been skimmed and has no rads fitted yet. Is it suffiicient to leave it acclimatise in the nearby hall?


Any advice welcome. And any issues I haven't raisedd especially so.

Thanks in advance..

Carlow52

the spec sheet on the flooring should have answers to most of ur question.

Yes bead around fireplace

Re the hump I would try sand/scape it down as the floors can be quite intolerant of unevenness. I think its +/_ 2mm in 2m length

u need to let the self leveling stuff dry out well.
If it were my job I would ply the lot as there will always be a spring in the wooden floor and u run the risk of problems at the interface with tiled area

believe me any time and effort spent on getting the current floor in perfect order is well worth it, bit like painting, all the work is in the preping

antiskeptic

Carlow52 wrote: »

Re the hump I would try sand/scape it down as the floors can be quite intolerant of unevenness. I think its +/_ 2mm in 2m length

I'll give sanding it (with the flat edge of my diamond disced angle grinder ) a go.

If it were my job I would ply the lot as there will always be a spring in the wooden floor and u run the risk of problems at the interface with tiled area

I've got a straight edged stepdown where the levelled tile area meets wood and I plan to glue the plywood down - especially along this meeting line. I don't get what plying the whole lot will do since the spring will transmit through the ply

believe me any time and effort spent on getting the current floor in perfect order is well worth it, bit like painting, all the work is in the preping

Agreed 100%. Cutting out a square of underlay foam at the bump was considered a quick, less dusty workaround

Carlow52

The grinder will be v dusty, try a woodworking scraper, u will be surprised how soft the stuff is.

if u put 1/4 ply on the timber floor and then put another sheet of 1/4 all over, with it screwed and glued to the first layer of ply and screw the ply to the tiles it will perform much better.

Will the boards be running across or // to the 'gimp'?

across would be better

ditto with the ply

antiskeptic

Carlow52 wrote: »

The grinder will be v dusty, try a woodworking scraper, u will be surprised how soft the stuff is.

Will give that a try - I wasn't looking forward to the alternative tbh

if u put 1/4 ply on the timber floor and then put another sheet of 1/4 all over, with it screwed and glued to the first layer of ply and screw the ply to the tiles it will perform much better.

I did a carpeted floor a while back and laid 1/4" play over reasonably sound floorboards first - screwing it down all over. What I found was that the plywood humped in places ever so slightly (any expansion whatsoever must cause localised humping in a non-floating sheet of plywood). And that humping transferred through to spongy feeling carpet in places

My concern with screwing down ply (especially through dpm) and into the tiles is that it will provide that same possibility for humping. Made more likely by moisture coming up through the perforated membrane perhaps?

Will the boards be running across or // to the 'gimp'?

The gimp (:)) is like a shallow mound approx circular in shape and spreading over about 2sqm and 4mm at it's highest -so it doesn't really matter which way I approach it.

I stuck a few of the boards together today to form a 2m x 1m panel and laid them over the bump to see how bad it was in different directions - and there's a bit of a rock in it as it see-saws over the gimp. I'll work at scraping the problem away altogether.

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I had a chat with the salesguy today who sounded like he'd laid a floor or two in his time. He was saying to get a set of clamping straps to pull the boards together. Are these necessary/useful? I'd have thought a gentle tap with a mallet would do the trick.

Carlow52

Nothing like a bit of humping to get the show on the road:D

By gimp I meant the line between the 2 floors, not the hill of tara:D.

Re the clamping The few glued floors I have done I have put a chalkline down 2 feet from the middle of the floor and used a set of 48 " record cramps to cramp the full 4 feet width, full length of room. Make sure all are straight and // to line and leave overnight.

This can then be used as a base for the rest of the job.

I know this is not like when the floor fitters come and do the whole house before noon!

antiskeptic

Carlow52 wrote: »

Nothing like a bit of humping to get the show on the road:D

By gimp I meant the line between the 2 floors, not the hill of tara

Aha! As luck would have it, I'll be going at right angles to it

Re the clamping The few glued floors I have done I have put a chalkline down 2 feet from the middle of the floor and used a set of 48 " record cramps to cramp the full 4 feet width, full length of room. Make sure all are straight and // to line and leave overnight.

This can then be used as a base for the rest of the job.

I know this is not like when the floor fitters come and do the whole house before noon!

Arrgh! A chalkline - of course. Although I might adapt your basic idea given the lay of the land here. I've 50mm thick insulated plasterboard on the walls which stops short of the floor by about 2" - allowing the floor to tuck in under it if I want.

If I strike a chalkline a boardwidth minus 1" away from the face of the plasterboard and fit the first line of board against the line then I can conceal-screw them to the floor along the line where the skirting board will eventually land. The fact the board tucks under the plasterboard by an inch mean I won't be screwing too close to an edge (which could introduce tilting of the board)

I won't glue the next line of boards to this first line as I'll want to remove the screws later to permit the floor to float. I'll glue the first line of boards to the now-assembled floor as the last action taken

Although I doubt I'll have it done by noon


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What about clamping as you further assemble the floor. Is there any need or will a mallet do?

Buford T Justice

Careful which wall you use to lay the boards against. In general as you know walls arent straight, and you could end up with the floor running away on the floor and not looking straight in respect to the rest of the room.

antiskeptic

Fingers McGee wrote: »

Careful which wall you use to lay the boards against. In general as you know walls arent straight, and you could end up with the floor running away on the floor and not looking straight in respect to the rest of the room.

Good point. I should amalgamate Carlows advice on setting up a line in the middle of the room.

In other words, strike a line down the centre of the longtitudinal axis of the room (middle-of-end wall to middle-of-end-wall will give a visually correct foundation). Then strike a parallel line near the plasterboard face of one or other side wall as described - trimming the first line of boards if the 2" under-plasterboard-cavity isn't enough to work with.

Thanks Fingers...

Buford T Justice

That's what I'd do anyway. Strike a line as you say and line it up by eye to see how it looks.

Nothing worse than a timber floor that looks like its going off to one side.

antiskeptic

Fingers McGee wrote: »

Nothing worse than a timber floor that looks like its going off to one side.

Agreed.

Next question: I've got 3mm foam underlay but was considering adding to this to ensure uneveness best accounted for. I've good underlay from the previous carpet sitting there. Any reason not to use this as underlay for the wooden floor?

Lilly2011

Hi,

I have an uneven sitting room floor, what's the cost involved in fixing this? The room is 20 meters square. I think the plywood subfloor is the problem, most of the floor is fine it's just a little off.

Carpenter

Lilly2011 wrote: »

Hi,

I have an uneven sitting room floor, what's the cost involved in fixing this? The room is 20 meters square. I think the plywood subfloor is the problem, most of the floor is fine it's just a little off.

Where are you based

Lilly2011

I'm based in the castledermot area