How crucial is the 10mm expansion gap in laminate flooring?

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Steven Campbell

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May 4, 2011, 7:43:38 AM5/4/11
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I understand the reasons for the expansion gap in a floating floor but is
10mm all round not a bit excessive? Can the floor really expand up to 20mm
in all directions?

Reason I'm asking, I'm in the process of laying a floor and have left the
10mm round the perimeter of the room (as I removed the skirting and can
easily hide the gap) but am now up against the breakfast bar and am not too
keen on a big gap and don't want to put skirting round it.

Also due to bad planning I've been left with a small (20mm) L section of
laminate to fit which only leaves a few mm expansion. There is no way I can
cut it smaller to leave the proper 10mm gap.

Cheers

Steven.

tim....

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May 4, 2011, 8:13:57 AM5/4/11
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"Steven Campbell" <spam@away> wrote in message
news:2_-dnZMxzqWboVzQ...@brightview.co.uk...

>I understand the reasons for the expansion gap in a floating floor but is
>10mm all round not a bit excessive? Can the floor really expand up to 20mm
>in all directions?
>
> Reason I'm asking, I'm in the process of laying a floor and have left the
> 10mm round the perimeter of the room (as I removed the skirting and can
> easily hide the gap) but am now up against the breakfast bar and am not
> too keen on a big gap and don't want to put skirting round it.

Leave the gap and fill it with a strip of cork.

> Also due to bad planning I've been left with a small (20mm) L section of
> laminate to fit which only leaves a few mm expansion. There is no way I
> can cut it smaller to leave the proper 10mm gap.

dunno

tim


GB

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May 4, 2011, 8:55:26 AM5/4/11
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20mm strip of cork?


The Natural Philosopher

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May 4, 2011, 10:13:07 AM5/4/11
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Steven Campbell wrote:
> I understand the reasons for the expansion gap in a floating floor but is
> 10mm all round not a bit excessive? Can the floor really expand up to 20mm
> in all directions?
>

yes. But in general it doesn't,


> Reason I'm asking, I'm in the process of laying a floor and have left the
> 10mm round the perimeter of the room (as I removed the skirting and can
> easily hide the gap) but am now up against the breakfast bar and am not too
> keen on a big gap and don't want to put skirting round it.
>
> Also due to bad planning I've been left with a small (20mm) L section of
> laminate to fit which only leaves a few mm expansion. There is no way I can
> cut it smaller to leave the proper 10mm gap.

Lets put it this way. I laid mine in spring over a total of 12x6 meters
with a large cutout for a central chimney and hall. So a sort of U
shaped piece.

I left about 4-6mm in most places but some was cut tight to the wall in
doorway recesses.

Come summer, it was lifting all over the place.. I had to relieve it by
4-6mm at one place.

The expansion was mainly across the grain of the boards - these were
Kahrs interlocking oak laminate engineering boards.

I would say total movement along the boards - across the 6m depth of the
tow combined rooms and passage - was about 4mm total.

It was more like 10mm or more over the 12m cross grain bits

Now 1% summer to winter along any grain is to be expected. IN fact I am
seeing 0.1%. So I can only conclude that the sheer weight of furniture
etc etc is keeping it all flat, and the stress is taken up in the wood
itself.


If you work on 1% you will be quids in. 0.1% is pushing your luck.
Possibly the best thing is to store it OUTSIDE under cover for a few
weeks - where typical RH will approximate to humid thundery no central
heating type conditions - and then lay it. It will shrink in winter,
with CH, but at least you will be as tight as it can be got.

If it does lift, all is not lost. I had the chippies in for something
else, and they used a reciprocating saw to trim a few mm off where the
whole lot was under huge stress. .

You don't say what size this floor is, but come back and tell me what
0.1% of the dimensions are, in terms of all round gaps


>
> Cheers
>
> Steven.
>
>
>

Man at B&Q

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May 4, 2011, 10:34:11 AM5/4/11
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Is this the tile effect stuff? Hardly expands at all IME. I never
leave anything like 10mm. Real wood based stuff is probably different.

MBQ

Steven Campbell

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May 4, 2011, 8:03:17 PM5/4/11
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"Man at B&Q" <manat...@hotmail.com> wrote in message
news:b85d146f-dbe1-4f7b...@z13g2000prk.googlegroups.com...

------------

Yeah just standard B&Q tile effect laminate.
Thanks.


Steven Campbell

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May 4, 2011, 8:01:57 PM5/4/11
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"The Natural Philosopher" <t...@invalid.invalid> wrote in message
news:iprmtj$n5f$1...@news.albasani.net...

Thanks for your words of wisdom. Much appreciated. Any laminate I have laid
before, I have never once seen any expansion. Especially at the door way
where I never covered the gap but I'd hate to take a chance.

The floor area is 7m x 3.5m. I've mostly left a 10mm gap round the perimeter
of the room and about 5mm gap against the breakfast bar where I just didn't
want a massive gap. It has also been laid under the kickboards so can expand
all it likes under there ;o)

I would have thought it was best to lay it in summer when it had expanded
that way you could lay it with no expansion joints as it couldn't expand any
further or have I read your mail wrong?


Thanks again.

The Natural Philosopher

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May 4, 2011, 8:20:26 PM5/4/11
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I think you will be OK


> I would have thought it was best to lay it in summer when it had expanded
> that way you could lay it with no expansion joints as it couldn't expand any
> further or have I read your mail wrong?
>

well outside and inside RH are the same in summer. and the same outsode
in summer as in winter by and large..fairly fully saturated unless ou
get a heat wave.

Internal RH goes very low in winter when you heat the outside air up.
So we are in essence saying the same thing: lay when its as damp as its
ever likely to be a again.


I think you will get away with it though, and as I said, even if you
don't, its not a complete disaster.

> Thanks again.
>
>
>

Arfa Daily

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May 4, 2011, 8:39:01 PM5/4/11
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"Man at B&Q" <manat...@hotmail.com> wrote in message
news:b85d146f-dbe1-4f7b...@z13g2000prk.googlegroups.com...

And +1. I have it all over my house. The conservatory is massive, and
subject to huge extremes of temperature, and I've never had the slightest
problem. That's bog standard B&Q Tileoc. I would estimate that my average
gap is around 5mm, and in places, zero ...

Arfa

Steven Campbell

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May 5, 2011, 5:09:36 PM5/5/11
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"Arfa Daily" <arfa....@ntlworld.com> wrote in message
news:Hkmwp.5859$%u....@newsfe11.ams2...

>>
>> Is this the tile effect stuff? Hardly expands at all IME. I never
>> leave anything like 10mm. Real wood based stuff is probably different.
>>
>> MBQ
>
> And +1. I have it all over my house. The conservatory is massive, and
> subject to huge extremes of temperature, and I've never had the slightest
> problem. That's bog standard B&Q Tileoc. I would estimate that my average
> gap is around 5mm, and in places, zero ...
>
> Arfa


Thanks for this.

keithd...@gmail.com

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Jan 9, 2017, 8:05:00 AM1/9/17
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The following website gives the coefficient of thermal expansion for MDF as 12µm/m-K (http://www.makeitfrom.com/material-properties/Medium-Density-Fiberboard-MDF)
That means a 10metre long board will expand 0.12mm for every degree Celsius (or Kelvin) change in temperature. If the temperature of the board increase 40 degrees, the total change in length is only 5mm. That is 2.5 mm at each end. So a 10mm gap all round is excessive unless you are likely to get an awful lot of swelling due to moisture.

Tim Watts

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Jan 9, 2017, 8:34:56 AM1/9/17
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On 09/01/17 13:04, keithd...@gmail.com wrote:
> The following website gives the coefficient of thermal expansion for MDF as 12µm/m-K (http://www.makeitfrom.com/material-properties/Medium-Density-Fiberboard-MDF)
> That means a 10metre long board will expand 0.12mm for every degree Celsius (or Kelvin) change in temperature. If the temperature of the board increase 40 degrees, the total change in length is only 5mm. That is 2.5 mm at each end. So a 10mm gap all round is excessive unless you are likely to get an awful lot of swelling due to moisture.
>

Moisture is the key - and MDF does swell due to it.

Ignore that at your peril.

harry

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Jan 9, 2017, 1:04:00 PM1/9/17
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It's more about the timber swelling through damp/humidity changes than thermal expansion.

David Lang

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Jan 9, 2017, 1:49:46 PM1/9/17
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I think 10mm is way OTT. The beading/skirting is only just that
thickness. You do need a gap = I have seen a laminate floor 'raft' on a
few occasions, although they were in kitchens - so they could have got wet.

--
Dave - The Medway Handyman

Tim Watts

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Jan 9, 2017, 5:34:54 PM1/9/17
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There's humidiy based exapansion to factor in too.

The Natural Philosopher

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Jan 9, 2017, 10:06:31 PM1/9/17
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I needed about 5mm all round on a floor of of 6 x 6m. IT bucked before
I adjusted it
l

thermal expansion is pretty much not the problem. Moisture is.

simon mitchelmore

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Jan 10, 2017, 4:17:53 AM1/10/17
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Just laid some Wickes tile effect lam with underfloor heating and it expanded only about 2mm over about 3-4 metres, very stable. Although I hear its very sensitive to humidity or damp.

Only problem I have is where it meets a 2m wide patio door I cant find a suitable 2m strip which will allow expansion underneath it, like an upturned L section. Currently have a 10mm gap there! Any ideas?

Andy Burns

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Jan 10, 2017, 4:27:35 AM1/10/17
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simon mitchelmore wrote:

> Only problem I have is where it meets a 2m wide patio door I cant
> find a suitable 2m strip which will allow expansion underneath it,
> like an upturned L section. Currently have a 10mm gap there! Any
> ideas?

<https://www.flooringsuppliescentre.co.uk/products/flooring_accessories/thresholds_edgings/tradition_flooring/2517/unfinished_solid_oak_lshaped_threshold_40x15_mm_24_m.html>

simon mitchelmore

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Jan 12, 2017, 8:51:18 AM1/12/17
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