Laminate underlay

[joe91]

Hi,

Hope someone can help me with my dilemma.

I want to lay a laminate floor in my kitchen/diner. It's a timber floor, with the kitchen of a flat I also own beneath. The flat is currently empty, and will be refurbished when I've finished the house!

I want to insulate the floor as well as possible, mainly for sound insulation. I had planned to lay foil backed underlay (3mm?) followed by those green wood fibre boards, then 3mm wallboard I've got hanging about to provide some stiffness, and finally the laminate.

After reading some of the posts on here, I now have my reservations about the foil underlay. Is this likely to cause me condensation problems, particularly whilst the flat is empty & unheated? There is currently plenty of ventilation, due to large holes in the flat ceiling, but this will not ultimately be the case!

I already had concerns over an apparent lack of airbricks, as 2 walls of the flat kitchen are 'underground', and the building is pebbledashed, with apparently no ventilation through the stone walls.

Grateful for any advice.

Cheers,

joe91

 

[WoodYouLike]

Joe 91, hi.

I think you're better of with a proper (rubber-type) sound reducing underlayment, indeed without DPM attached. Try Timbermate Duratex (4mm, 23 dB) and one of hte 'cheaper' types or Technics 5 (5mm, 27 dB)

What you also have to consider is that your wooden floor doesn't 'hit' any walls etc which will transport sound also.

Hope this helps

 

[joe91]

Hi WYL,

Thanks for the reply.

You've convinced me not to use the foil stuff. I've already bought it, so I'll have to use it elsewhere!

Just so I understand, is it not recommended as it would encourage condensation, introducing moisture into the floorboards & joists?

Joe

 

[WoodYouLike]

DPM is only recommended with concrete/screed underflooring where any risk of residue moist can come into contact with the wooden flooring. For all other materials, like chipboard, plywood, original floorboards DPM is not needed and can indeed sometimes restrict natural ventilation, which can result in condensation.
BTW, on vinyl or other plastic tiles you don't want to remove when installing a wooden floor on it's also bet to use DPM (but it's better to go for the effort to remove the tiles/vinyl). The vinyl or plastic can start to 'sweat' and create moist between tiles and wood -> excessive expansion or even cupped boards can be the result.

 

[joe91]

Hmm,

Still not sure

Don't really want to spend more money on different underlay. The makers recommend the fibreboard, just wanted to add a little extra.

How about if I use the foil stuff, install airbricks to ventilate the void, and use vapour barrier plasterboards when boarding the ceiling of the flat? Would this stop damp getting at the joists / floorboards?

I'm confused as to whether the DPM would contribute to damp getting at the joists / floorboards, or at the laminate itself? I'm not so concerned about the laminate, but worried about a possibly hidden problem with the timber floor.

Thanks for all the help.

 

[WoodYouLike]

Joe91, we're wooden floor fitters, not builders We can only tell you what in average normal circumstance we do ourselfs or recommend to others (DIY-ers).
DPM (foil) on existing floorboards for us is a no no. For sound-insulation in apartments it's better to spend a bit more (note new sound proofing regulations also) than to be sorry afterwards.

 

[joe91]

Yes, I realise that, and really appreciate the advice, I was hoping that maybe someone with building / damp experience may advise also.

Could you just clarify why foil is a no-no for existing floorboards? As I've seen on another thread here, the advice from wood floor manufacturers seems to contradict this. I visited my local DIY shed yesterday, there is lots of underlay which can be used as DPM, marked as suitable for all floor types.

I notice there are lots of threads here asking similar questions, but with slightly different circumstances. If someone could explain what problems a DPM on wooden floorboards can cause, and in what circumstances, there may be less need to answer the same question repeatedly.

Can you tell me more on the new sound proofing regulations, or provide a link?

Much appreciated,

Joe

 

[WoodYouLike]

Can you tell me more on the new sound proofing regulations, or provide a link?

It's in Part E of the Building Regulations. If you could supply me with your email address I can email you an article about it published in one of the trade magazine.