fitting solid wood floors to concrete

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Keano99

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i am in the middle of a new build and am looking for advice.

on the ground floor i was going to get the finished floors poured at different levels to allow for fixing battens underneath the solid wood floors in some rooms.

i have since been told that "everyone" now is pouring the whole ground floor at the same level and the laying tiles or wooden floors directly on top.

For the rooms with wooden floors this will mean that the wood is just laid as a floating floor, i think with a thin layer of material underneath.

my question is, in the past for wooden floors a damp course layer and battens would have been put down on top of the finished floor and the solid floor fitted to the battens (presumably to prevent damp from rising and to allow air to circulate under the floorboards).
why is it now ok to lay the wooden floors directly on the finished floor?
is the underlay being used good enough to provide damp protection and also allow the timber to breath?

thanks.
 
I laid my own solid walnut floor directly onto concrete floor using a special glue they have for solid woods. I have no underlay, and there is no dampness or echo at all..
 
thanks chrisboy.
how long have you the floors down?

do you know why they are no longer doing the damp course and battens any more though?

have you been assured (by who?) that there will be no dampness/ other issues in the future either?
 
Keano99 said:
why is it now ok to lay the wooden floors directly on the finished floor?
is the underlay being used good enough to provide damp protection and also allow the timber to breath?
Click to expand...

While you are correct the wooden floor is floated on the concrete, there should be a damp proof course (continious plastic sheet), then underlay then your wooden floor.
 
I have a solid floor glued. Installer waited until concrete moisture was down to a suitable reading, he then (self)-levelled & sealed the floor before gluing and laying the T&G floor. Its been fine since, bar the odd location showing small signs of movement in the joints but nothing to get excited about.

If like me you'd always want it looking right I'd make sure the installer levels it within reason, as if there's any fluctuations it will show at the ends (i.e at skirtings etc). This happened in my situation.

S.
 
With solid wood if you want no gaps EVER

* Good quality flooring, fully dry floor
* competent installer
* nail it down to battens or 3/4" ply.
 
You still need to leave expansion gaps around the sides if you glue. It will still expand about 10-15 mm all the way around.
 
Our solid wood block floors have been in place for 56 years. They were laid on to black bitumen direct onto concrete floors.
 
Keano99 said:
thanks chrisboy.
how long have you the floors down?

do you know why they are no longer doing the damp course and battens any more though?

have you been assured (by who?) that there will be no dampness/ other issues in the future either?
Click to expand...


2 years now, i laid the floor myself, very simple really, and because there's no batons, means there's no air gaps, so there's no echo..

If you have a solid concrete base on your ground floor, which it sounds like you have, then you have a damp course a few inches below the concrete.. Once the concrete above the damp course is sealed in there shouldn't be a problem with damp..
 
i can tell you that gluing your floor straight to the concrete will be absolutely fine, as long as you :

1. seal the floor

2. the concrete has had enough time to dry sufficiently, check the moisture content before installing...chrisboy is right you should have a damp course few inches below finished floor level.

3. you use the right, good quality glue..even if it's more expensive it's worth using there IS a difference

4. leave the floors in the house for as long as possible with the boxes opened slightly (i always say 3weeks minimum bit longer if you can so they can expand as much as possible before installing) with heating on as you normally would if possible... (leave heating off for about 2-3 days before installing)

5. leave 10-15 mm gaps around ALL the edges but make sure the skirting will cover the gap.

Make sure you use a high graded floor if your looking for no gaps, there are 5 different grades, 1 being the best and 5 the worst...difference between them is board widths would differ slightly in a lower grade (grade 5) hence leaving 'gaps' in the floor and generally not as good quality timber either as a better grade.
Oh and make sure your carpenter is neat and tidy i.e cuts under door frames for floor etc.

good luck.
 
charlieduff said:
i can tell you that gluing your floor straight to the concrete will be absolutely fine, as long as you :

1. seal the floor

2. the concrete has had enough time to dry sufficiently, check the moisture content before installing...chrisboy is right you should have a damp course few inches below finished floor level.

3. you use the right, good quality glue..even if it's more expensive it's worth using there IS a difference

4. leave the floors in the house for as long as possible with the boxes opened slightly (i always say 3weeks minimum bit longer if you can so they can expand as much as possible before installing) with heating on as you normally would if possible... (leave heating off for about 2-3 days before installing)

5. leave 10-15 mm gaps around ALL the edges but make sure the skirting will cover the gap.

Make sure you use a high graded floor if your looking for no gaps, there are 5 different grades, 1 being the best and 5 the worst...difference between them is board widths would differ slightly in a lower grade (grade 5) hence leaving 'gaps' in the floor and generally not as good quality timber either as a better grade.
Oh and make sure your carpenter is neat and tidy i.e cuts under door frames for floor etc.

good luck.
Click to expand...


Nice one Charlie, on point no.3, the glue i used was specialised solid floor glue and was very expensive, cant remember exactly but think it was 100 euros or so for a large bucket..
 
thanks everyone for the replies.

just a couple of things:

1. how do you "seal" the floor?

2. I have a radon barrier in the raft foundation, which acts as the damp course as far as i know.
i have now laid 100mm of insulation on top of the raft.
do i need to put in a damp course before i get the finished floor (of 4 inches) poured?

thanks again.
 
Keano99 said:
thanks everyone for the replies.

just a couple of things:

1. how do you "seal" the floor?
Click to expand...

PVA or polybond will seal the floor

Keano99 said:
2. I have a radon barrier in the raft foundation, which acts as the damp course as far as i know.
i have now laid 100mm of insulation on top of the raft.
do i need to put in a damp course before i get the finished floor (of 4 inches) poured?
thanks again.
Click to expand...

Before you put the finished screed down you should install a 500 gauge plastic cover on top of the insulation.

Once it is dry (thumb rule: 1 week for 10mm and 2 weeks for each 10mm after 50mm) and the moisture level is down to recommended levels. You can glue the floor down.
 
bacchus said:
Good post Charlie.
Can you recommend a good quality glue?
Click to expand...


Yes.... the 'evo-stick' brand i find is the best, ask in your suppliers if they have it or if they can get it in for you.

There is one i Would totally AVOID, cannot remember the name of it exactly but if they try to sell you a glue thats comes in a white plastic tub and it has a free trowel with it, you will know it the glue is in 2 foil pouches inside the tub.
It is the worst glue ever, doesnt do exactly what is says on the tin !!!
 
Totally agree with all the good advice from Charlie. We have solid oak on concrete flooring - as novices in this area, we did not know about making sure the wood is maintained at the house temperature for at least 3 weeks before laying, also that you must leave a spacer all around the edges to allow for natural expansion. We have had hills of wood on our floor, only semi-rectified by a strong builder snapping off some of the outer boards (unfortunately our floor-layer did not leave space and the wood was straight from the warehouse) - I am constantly chipping away at borders to allow the rising boards to find some rest on the flat. Good luck with your floors. BTW, we wanted to put extra insulation under the floorboards but were assured by the builder that it was not required - now, sitting in the rooms the only part of us that gets cold is our feet! Beware!
 
thanks again for all the replies.

a few more things:

1. when do you seal the floor?

2. regarding glueing the timber floor to the concrete.. do you put down underlay like you do for a semi-solid floor and glue each plank of timber to the one attached to it? (as one carpenter said to me)
or do you actually glue the timber direct to the concrete? (i would have thought that as the timber expands & contracts there would be problems....

3. my architect said you need to leave a 1 inch gap (partly hidden under the skirting board and you need to chip away the plaster to get the remainder) the whole way around the room....
AND a 2mm gap between every fourth plank of timber.
does this sound right, an inch seems like a huge gap....
 
This is a very interesting thread

How many remember the vinyl floor tiles that were in vogue in the 50s & 60s ?

What would the best method of installing timber flooring on a concrete floor that has been covered in such vinyl tiles ?

( In some areas there are defects where, for example, corners of vinyl tiles have cracked & lifted )

There is no insulation under the floor in question ( but there is a damp course )........anyone know the approx u value of timber flooring ?

Olddog
 
I used always link to the really excellent NWFA installation guide to answer all these installation questions and more. Unfortunately, they now charge $100 for the latest version.

Just found a copy available [broken link removed] though...

Keano99, what that carpenter suggested is a floating floor. Each board is glued together, but the floor is free to move over the slab as it expands/contracts.
Leo
 
Quick question for Charlie when you speak about Grade 1 to 5 with 1 being the best - is this marked anywhere on the wood itself or on the packaging.
How could a layperson tell the difference?
Many thanks,
Lazybones
 
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