Pdoyle.net CSRT

Hi
Thanks for replying to my previous post so promptly.
On a totally different subject:
I want to lay laminate flooring on top of the existing tongue and groove floorboards in my living room and hall.
I was going to use a combination underlay that incorporates a damp proof membrane, but keep getting conflicting opinions about this.
I'm concerned about dampness coming up through the floor but will putting damp proofing down stop airflow and cause condensation which may damage my floorboards?
Will the fact that there is air circulation under the floor prevent this? Although it isn't really bad, there's already condensation under the floor, despite all the air bricks being clear. I'm not sure if this is normal or not. Could it be anything to do with the house being empty and unheated for over 12 months? I've only noticed the condensation recently.
Thanks.

I have an ongoing issue with laminate flooring ever since, several years ago, I went under a floor in a house in Nottingham and found that the joists had rotted due to a lack of ventilation. The airbricks were clear but the two-year old laminate flooring had removed the ancillary ventilation that, up until that time, had been available via the cracks in the floorboards, and also via the boards themselves. They (joists) weren't that old either. In other houses I have seen, I invariably find that moisture content of sub-floor timbers is higher than I would expect in houses with normal floorboards.

Sorry but I would never recommend laminate flooring, I think it's a disaster waiting to happen, and as you already have obvious sub-floor condensation the laminate will simply make it worse. Adding to the problem, laminate is very difficult to lift once it's been laid; how are you going to get beneath the sub-floor in future without removing huge areas of it? Once it's laid, anything could be going on beneath it.

I realise I may have a bee in my bonnet about this (and that's before you get me going on the aesthetics of it) but when you consider you're virtually sealing a huge area of flooring that once provided ventilation, you begin to see it from a different perspective.

Sorry, hope I haven't spoiled your dream home...

Hmmm. Well the flooring has just been delivered. Wouldn't the laminate do just the same as having underlay and carpet, or even lino like my gran's house. Now I've got it anyway what is the best way to minimise problems?

Whoops...bet that's made you feel better!

Yes, as far as I am aware, linoleum (and vinyl) have the same effect. Carpet and underlay not so much so. Most of these latter have a porous structure on a woven base. Previous wrongs don't make this right though.

However, as I said, I may have a bee in my bonnet about this: as far as I am aware there hasn't been any meaningful research on it and I'm basing my comments on my experience. However, other surveyors I've spoken to are in agreement.

There's not much you can do to improve matters except that if you have sufficient air-bricks, you should keep them clear. If you haven't sufficient air-bricks, install some more. One every 1500mm should be about right.

However, on a more prosaic basis I would strongly recommend that you also install a trap(s) so that you can easily access the sub-floors. One of the main drawbacks with laminate is that once you've started to lift it, to find a trap for instance, you have to take acres of it up. Everytime you pop a piece, another one wants to follow it! Cutting a neat trap and trimming the edges will negate many hours of cursing and troubles in future.

Sorry if this is dismal. I'll get me coat...

Patrick

Ha ha
Thanks Patrick...... I think?!
The trap thing is sorted - fortunately the current access point is right in front of the front door so i'm gonna cut the laminate and edge it to the size of a door matt. That way if I need access I can just lift the door matt and existing trap.
I think I will take your advice about maybe adding extra air bricks though.
Am i right in thinking that damage will be caused by condensation forming under the floor due to lack of air circulation? If this is the case, can I keep an eye on things by checking under the floor from time to time?
Thanks again for your help, although not exactly what I wanted to hear, it has been very useful!
Cheers!

Yes, that's exactly the purpose of the trap.

When you go under the floor it's essential you take sandwiches and a ball of string.

Best of luck

Patrick