Laminate Floor Expansion Gap

I'm laying B&Q TileLok laminate flooring in my kitchen and utility room. The instructions call for a 12mm gap at the walls and a 20mm gap between rooms. This seems like a pretty huge amount of expansion for a floor which is only about 2 metres wide especially when 1 side of it can slide under the units and it would mean a bit of an unsightly trim along the skirting board. Can I get away with less (a LOT less like maybe a couple of mm!)?

i been in the same dilemma - you feel the gap being asked for is just too huge.

i tend to take off the skirting whenever i can. where i can't i use 16mm wood beading (20mm in some places) stained to get a reasonably close match to the laminate. in tricky areas i just use frame filler.

in terms of what you can get away with i would say across the planks the expansion is not as much (probably down to 5mm a side). down the planks the expansion can be quite a lot and stick with 12mm.

if the laminate can slide under something then you could reduce further.

the only other factor is the temp when the laminate is fitted - if it's cold ie winter then the real gap will be smaller than if the laminate was fitted on a very hot day during summer.

the need for the expansion gap is serious and will cause the laminate to bellow up if there's not enough gap.

the easiest rule of thumb is a 10mm gap all the way around even through door ways b&q say them sizes so that if the floor does blow they ask if you went to there instructions if not then they wont sort it as for edging either use the matching scotia or go for white

OK, I am going to suggest something very radical here. YOU DO NOT NEED EXPANSION GAPS FOR LAMINATE FLOORING. I have been laying laminate flooring for over 10 yrs. I leave a maximum of a few millimetes gap, and run a matching colour flexible mastic around the edges. I have never once experienced expansion problems. In my opinion the sale of the mating beading etc.is nothing but a money making ploy.
I have layed 7 m laminate in two bungalows throught the whloe house and never had a problem. The only time you will have problems is if the flooring gets wet or extremely humid. I am just about to start another house now and will be doing exactly the same. I have talked to pro floor layers who are laying this stuff almost every day and they all admit, the beading is a sales scam. When working on a job one day, I asked a pro floor layer, why he never leaves expansion gaps around the door frames, if the stuff does not expand there why should it expand in the rest of the room ? he embarrasingly admited, it rarely expands if ever.....
Try it, on a small room and save yourself a fortune.....

The laminate can expand due to 2 effects, either heat or moisture.

Heat:

For phenol formaldehyde, coefficient of linear expansivity = 40 x 10e-6 m per m per degree Celsius.

(this is approx, and will be different crosswise to lengthwise, but its a start point)

Assume a temperature range from 0 degree to 40 degree, so max change of temp = 40 degr.

So change of length = 40 x 40 x 10e-6 = 1.6 x 10e-3 m/m

which is 1.6 mm per metre

So in a 5 metre room, expansion would be 5 x 1.6 = 8mm

If the laminate is laid at 20 degr C, then maximum expansion or contraction will be half this value, ie 4mm, or 2mm at each end, so its quite right that there is hardly any expansion under dry conditions.

Damp.

However, the (Hygro) linear expansivity under damp conditions is much greater than under temperature change. Cant find the figures but it easily could be 5 times as much under saturation conditions. So the manufacturers are not lying, they are just being a little over-safe perhaps. Under normal use, the laminate will expand and contract as the humidity of the room changes, and this is invisible. The planks slide along one another.

Thats why you stand the laminate in the room where it is to be laid for a while. You lay it at the average temperature and humidity of the room. This works fine in modern, well insulated houses. Buckling is much more of a problem in older, damp houses, with high temperature and humidity ranges.

The moisture absorption depends on the waterproofness of the laminate, and the more expensive laminates ( with longer guarantees) tend to be more waterproof, and so should need lower gaps at the edges.

Say a radiator leaks. The laminate expands under damp. When they dry out again, they contract. If they are allowed to expand without hitting a wall, then they can re-contract freely, and any damage may be visible as a little delamination, but it may not be too bad. If the gap is not sufficient, the laminate will buckle when it hits the wall. Then the planks could spring apart under the high forces and the click-in edges be damaged. So the gap is necessary.

So, a reasonable compromise in a dry room in a modern house would seem to be say a 5 mm gap at each end. Thats twice as much as actually needed from a heat expansion point of view, and will allow a little bit of moisture expansion too. But in a kitchen say, larger gaps would be advisable, as accidents do happen, and in an old Victorian house, the same applies.

well done that man - go to the top of the glass and collect the pencils - ll cut strips of 3 layer ply and left up to 5mm to the edges - cut to the shape of the architraves - mastic in - very neat

Clydus777 said:

OK, I am going to suggest something very radical here. YOU DO NOT NEED EXPANSION GAPS FOR LAMINATE FLOORING. I have been laying laminate flooring for over 10 yrs. I leave a maximum of a few millimetes gap, and run a matching colour flexible mastic around the edges. I have never once experienced expansion problems. In my opinion the sale of the mating beading etc.is nothing but a money making ploy.
I have layed 7 m laminate in two bungalows throught the whloe house and never had a problem. The only time you will have problems is if the flooring gets wet or extremely humid. I am just about to start another house now and will be doing exactly the same. I have talked to pro floor layers who are laying this stuff almost every day and they all admit, the beading is a sales scam. When working on a job one day, I asked a pro floor layer, why he never leaves expansion gaps around the door frames, if the stuff does not expand there why should it expand in the rest of the room ? he embarrasingly admited, it rarely expands if ever.....
Try it, on a small room and save yourself a fortune.....

Click to expand...

I laid 45 sq m of a good quality Quick Step Go laminate floor in June. I aimed for a 7mm gap at each end of a 7 m length. I am only just now getting around to putting on the skirting boards, so the gaps are still visible.

We've had a very warm damp summer and lo and behold, the laminate has expanded until there's only a 1-2mm gap at the ends. At one point near the front door it has touched the wall and is just about to buckle. I re- lifted that length last night and took another 2-3 mm off. If it gets hotter or wetter I'll be in trouble, but now its Autumn, the air is getting cooler so wont carry so much moisture. Hopefully it will all shrink back again.

Looks like 7mm is a minimum gap to me.

The laminate expands most in summer by the way, not winter. It expands with heat and with the amount of moisture it contains

It might seem to be damper in the winter, but in fact the amount of water held in the air is much higher in summer. Thats why it can often rain more in August than it does in March !

ALL HAIL TO CLYDUS777!!! the king of the 5mm gap and mastic - all done - 7x4 mitres and looking good - best of all the wife says it looks great

androidbath has your place got a water leak? - miosture expands things - heat contracts things - sounds like a lot of movement

martin

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.