what to put underneath the Laminate floor?

happyhero

Hi I have laid a few laminate floors and always put that 7mm thick green stuff from B&Q, its a bit like compressed paper. It has alway been great, but now I am going to lay it in my hall downstairs which is very cold and full of drafts due to air bricks in the outside walls below floorboard level as is the case with many houses.

Now I have the laminate floor and green stuff but am wondering should I lay anything else down to insulate from the cold (there is quite a freezing draft coming through the gaps in the floorboards at the moment), ie a layer of something else or any other ideas. I don't want to put too much otherwise the floor will be so thick and I will have to trim loads off some of the doors.

Or does everybody think that that green stuff will be enough with the laminate on top? I was tempted to try and seal all the cracks first, but with what and is it worth it? Last time I tried this in the lounge under a rug I used silicon and lost loads down some of the bigger cracks before it started to seal. What about some sort of paper underlay maybe?

Any help appreciated.

Volcano

Do you put down a vapour membrane?

Basically this is a big sheet of polythene that prevents any water vapour condensing underneath the underlay/flooring, I have used this in the past when I lay laminate onto concrete floors and I'm guessing it will help block any draughts coming through floorboards too.

Draughts should be dramatically reduced as laminate interlocks but the polythene will definately help.

If you do get some, don't use the stuff from the flooring section at B&Q, go to the building section and get the sheets of polythene they sell in packs, a lot cheaper. You can cut the polythene to size allowing for plenty of overlap when you join it (lengths of tape will help seal the overlapping joints).

happyhero

Cheers for the tip Volcano, I did think about that, but there are a couple of things about it I am not sure about.

Firstly I can see it is great for concrete but is there any problem with swetting if I do this on wood, I know for instance you have to be very careful when using vapour barriers in attics as you can get swetting and then rotting timbers. Obviously there is going to be air flow under the boards, so will it be ok on the top surface or not do you know.

Secondly what type of sheet do you get? I know that there are black ones and blue ones meant for different uses. Any ideas on that?

benjus

What about the rolls of underlay with membrane layer attached? I was advised to use this when I put down a laminate floor because half the room has floorboards and the other half has a solid floor, with a slight difference in level where they meet. The underlay rolls worked fine and the laminate went onto them very well. I believe this type of underlay also provides some extra thermal insulation.

EMPTY_PURSE_5

Hi happyhero,

I had a really cold house and just lay down the green stuff under my floor and there is no draughts at all.... considerable difference in the heat.

Was worried previously as had under floor blowers and thought there would be draughts ..... but no .... cosy house at last.

Hope this helps


Millie xxxx

AceCobra

We just layed some good quality laminate in our hall. The stuff we used that silver vapour film with a polosytrene layer attached.... it really really helped with the draft that was there before. I beleive a vapour layer is required on the ground floor even if u use the green boards you speak off.

Martin.

Volcano

'Sweating' does occur on upper ceilings if you put polythene in the loft, mainly due to the large amounts of water vapour produced by cooking, showering, people breathing etc.

This won't be a problem on your ground floor, especially with the obviously well ventilated floorboards you have!

The stuff I used was sold as general purpose clear polythene sheeting, it measured 3x4 metres and comes folded flat. (The other polythene you mentioned is normally quite thick (800-1200 micron) and mainly used as damp proof course when laying concrete floors.)

GreenNotM

The vapour barrier is used under laminated flooring only on solid/concrete floors to stop the moisture rising up through the concrete and getting to the underside ( non-protected ) of the boards and spoiling the boards - ever seen wet MDF ?? - there is no need to use a vapour barrier over wooden flooring - the wood needs to be ventilated >> see here

Also your house needs to be ventilated to allow fresh air in- you may need to look at providing additional vents, now you have stopped the fresh air flow from the below floor air bricks.