Q and A's on how to lay a wooden floor 3 - materials

Our most popular article: "How to lay a wooden floor, keep it simple" has a total of 3 pages of further Q and A's, in our opinion becoming too laborious for everyone to have to go through. We all know every home, every situation, every interior design style and/or wishes are different so no article on its own will ever answer all questions, but we can but try.

In this (and following) article we have grouped Q and A's from the original article per, we think, related subjects.

Materials
Q: Hi,
I would like to put down solid oak flooring upstairs on top of the existing floor (90mm-18mm – various lengths). I am going to level the existing floor with layers of hardwood plywood and I am thinking of putting 6mm fiberboard underlay for acoustic reasons. I am considering a floating installation, however, a number of websites state that NO solid wood flooring can be floated.
Hoverer, if it is suitable for floating do you think it will:

• educe the amount of squeaks and creaks that hardwood floors develops over time,
• be as long lasting as the nail down or glue down floor.
• have some important advantages and disadvantages to the other fitting options.

Thank you in advance. Best, Konrad

A: Hi Konrad
The opinions on floating solid wood floors vary indeed. We - and our manufacturers - have no problem with floating solid wood floors, as long as certain rules are followed.

One of them is - unfortunately for you in this case - the width of the boards: narrower than 110mm means glueing them down.
You can use the same preparations you're planning now, use a suitable parquet adhesive and fully bond the floor to the subfloor you've made.

Q: Thank you very much for your help. I am inclined to go with your excellent suggestion. I would like to have a stable floor but I am also concerned with the footsteps sound (especially upstairs).
Just one more query if you don’t mind. From the DIYnot forum I learned that you are familiar with the Sika Silent Layer Mat installation. With this method, being a semi-floating one, do you think I can:

• install the floor continuously between rooms without dividing up the floor;
• install sliding door wardrobe on it.

Great thanks again. Regards, Konrad

A: Hi Konrad
The Sika Silent Mat is one solution indeed. Another one would be the Elastilon 'self-adhesive' sound-insulation underlayment.

Q: Hi,
Thank you for your reply. Regarding the Elastilon underlayment or the Sika mat: would they act like DPM causing the existing wooden subfloor to sweat? Konrad

A: Hi Konrad
The Elastilon comes without DPM and is therefore very suitable to use on existing floorboards or 'subfloors' of sheet material like plywood or chipboard.
We suggest you use the Elastilon 'Strong' which is the most suitable for narrow strips.

Q: Your site is of great help.
We're planning to lay oak flooring onto a new concrete floor which has dpm and insulation.

Are the basic steps:

1. Ensure concrete floor is level - if not use latex screed
2. Lay vapour barrier or underlay
3. Lay hardboard
4. Glue or fix boards to plywood

Is there a need to secure the hardboard to the concrete with adhesive or fastners? Thanks in advance, Al

A: Hi Al
If your boards have T&G, are 100mm wide or wider and your concrete floor is level there's no need to install plywood for installation purpose.
You can install the new floor floating, using a Combi-underlayment that contains a DPM layer, glueing all T&G's and leave an expansion gap around the perimeter of the room.

That's all you need in fact.

Q: Hi
I am going to be laying a solid wood floor on concrete that is very old - 40 yrs min i think. i have a few questions:

• I want to face fix and glue onto 12mm ply. what is the best glue to use?

• I will be laying the air bubble and foil insulation which is 4mm thick under the ply. do i need to lay acoustic underlay on top of the ply?

• I hope to use 180mm sawn oak boards - planks basically with no t&g. do i need to do anything special with this type of wood ?

• what is the difference between this wood and t&g. is the t&g option better ?

thanks very much for your help.

john paul

A: Hi John Paul
If you glue down you can't use another underlayment between ply and boards. The best adhesive to use would be a flexible adhesive (like Sika T54, Lecol MS250 or Mapei P9910K)

Make sure the Oak boards are dried to floor standard (moist content in the wood between 9 - 11%) and can acclimatise in the room you plan to have them installed in.

Difference between your boards and T&G boards: T&G's can be installed floating, secretly nailed or fully glued down, boards without T&G should be glued and pinned down (as you plan to do).
Hope this helps

Q: My ground floor is covered in herring bone parquet which I believe to be paranna pine laid about 60 years ago. In some places gaps have appeared between the blocks. I've been told that the usual filler is sawdust (from sanding the floor, which I've done) mixed with some adhesive.

Is this correct and if so what's the best type of adhesive to use?

Once the gaps are filled I intend to re-seal with a hard waxoil and I'd like to keep the floor as light as possible. I assume your normal stuff won't darken it too much? Peter P

A: Welcome Peter P
The best product to use for filling gaps in parquet floors is special wood-filler like Lecol7500 Bona Kemi Mix & Fill, not white pavc wood glue.
Mix it with the sand dust from the original floor to reduce colour differences as much as possible.

Natural HardWaxOil will, like any natural finish, darken the floor a little bit. How much you can test by wetting a little piece of bare - sanded - wood, this will 9 times out of 10 the end colour after applying a natural, clear finish.
Hope this helps

Q: I'm fixing to install a bamboo tounge & grove wooden floor over a plywood sub floor. I was going to nail it using a finishing nail gun or should I use another type of nailing system? What about drilling & then nailing? I was hoping not to have to nail every board but from reading this forum every board has to have at least 2 nails. Can the tongue & groove be glued & lay as a floating floor? Or can the tongue & groove be glued and nail every 12"?
Lucy

A: Hi Lucy, welcome
Depends on how wide your bamboo boards are, normally around 90mm? That is to narrow to install floating, but glueing them down with parquet adhesive would be another (better?) option.

In our experience Bamboo has very tiny T&G and might splinter/break very easily when nailing them and yes, every board has to be nailed every 30 - 35 cm.
Hope this helps

A: Thanks for the advise. The planks are 3 3/4" wide and I was going to do a floating floor because I felt that this was the easiest way and I'm doing it myself with my daughter but if you say I can't i will glue it.

Thanks again. Lucy

Q: Hello
I'm after some advice on the best way to install a solid oak floor.

I am fitting 120mm wide T&G oak on top of a slightly uneven plywood floor in a living room (6m x 4m) on a first floor above a bedroom and want to reduce the sound transmission to the floor below as much as I can.

After looking at other posts I was considering using fibre boards to level the existing floor and then fitting the oak flooring using the floating technique and gluing the T&G.
Would this solution work ok or can you recommend a better solution?
M W.

A: Hi M W
Fibre boards should be ok to use, or you can use Timbermate Duratex (no DPM) 5mm for extra sound insulation. In our experience it reduces the sound of footfall better than the fibre boards.

Q: I am planing to install a solid wood floor on concrete. Ive had to remove some old tiles which have left the concrete black but dry.

I was sold Gutoid Parkett S11 adhesive and Stopgap F76 waterproof membrane with the wood. However, I haven't read anywhere that its necessary to put membrane down if I'm glueing, do I need to? (id rather not if poss). If I do then can I put the glue directly onto the membrane?

I'm also a bit concerned as I bought all this stuff 2 years ago and have just noticed that the glue and membrane has a shelf life of 12 months.
Any advice would be much appreciated as im really confused now.
Guy Rowland

A: Hi Guy, welcome
Dates on products are there for a good reason: their quality deteriorates rather quickly once they pass their 'use-by' date. Bin it - ecofriendly!, is all I can say.

What is the width of your new floor boards? If wider than 100mm then the easiest and simplest option is to buy combi-underlayment, PVAC wood-glue and to install your wood floor using the floating method.
Hope this helps

Q: Hi Karin H

Thanks for your rapid response (on a bank holiday as well)

I thought I should probably bin it. The boards are 12cm wide, but there are a lot of short boards, maybe 25% under 50cm long (but only just, and I didn't have any problem avoiding a pattern when I laid upstairs).

Another concern is that the concrete floor is not completely level and bulges in places. What do you recommend to sort this out?
Guy

A: Hi Guy
One of our contacts wrote an article on preparations of the underfloor on this FAQ & News site, see here.
Especially bulges are tricky when not leveled, specially with many short lengths. The floor will see-saw all over the place. So best thing to do is making sure the concrete floor is made level.

Hope this helps
Wood You Like Ltd (not really into bank holidays anyway ;-))

Comments

[jenny]

do you have to lay ply wood before laying hardwood floors

[Karin H.]

Hi Jenny

Depends. What is the existing underfloor?

Wood You Like Ltd

[mark]

i am goona be laying 180mm wide and 20mm thick solid oak floor boards on a bituman floor(think this is my dpc as bunglaow was built in 60's) how do i go about laying it,do i glue, float it, put ply down and nail through the tongue and groove of the oak boards?? please help many thanks mark

[Karin H.]

Hi Mark

If your underfloor is level the best way would be to install floating, covering the bitumen with the underlayment (which should included a DPM, like the comb-underlayment).
Glueing down on bitumen is asking for trouble, nailing/screwing down plywood is only needed if your underfloor isn't level. Then you can install the Oak floor floating on top (nails in T&G will hit the concrete!) using underlayment WITHOUT DPM.

Wood You Like Ltd

[John]

Hi,

We are about to lay a T&G floor, One end of the groove is larger than the other. Which way down should it go ? Should the thicker end be on the top or the bottom ? I do not want to lay the floor upside down!!

Thanks
John

[Karin H.]

Hi John

Normally a solid T&G floor has 'expansion' grooves on the bottom-side of the boards. Presumingly this is not the case with your wood.
Remains the question: how much difference is there, or in other words: how far from the top does the Tongue start? Quality boards would have the T&G roughly in the middle to increase stability and preventing cupping.

Some manufacturers however place the T&G as far at the bottom as possible, giving you the impression that when needed you can sand your floor time after time. This method has the increased risk of cupping of the boards when the humidity increases.

So, back to you really, to do some precise measurements on the boards.

Wood You Like Ltd

[neil]

Hi, intresting reading, but now a bit confused. I have a 100 yr old house with wood floors, too damaged to sand and varnish, so I am laying solid oak t&g 18mm thick 83mm wide. I was hoping to hidden nail the t&g no glue,is this o.k? Also, I was hoping to lay them in the same direction as my existing boards, or do I have to go across them? Finally, do I need a membrane of some sort, or maybe a hardwood ply covering between the old and new boards? Hope you can help. Neil

[Karin H.]

Hi Neil

It's always best in your situation (installing new boards in the same direction of the old) to board over the existing floorboards first to cover unevenness and prevent movement.

6 - 8mm plywood if the boards are uneven or hardboard (diagonal installed) is they are rather level.
Then you can secret nail your new boards. Don't use any DPM membrane, this can cause condensation between old and new floor and could even result in rotting joists.

Hope this helps

Wood You Like Ltd

[dom]

Hi,
I would like to know what thickness of hardwood plywood i should use under my solid floor that i am going to glue.
Great information,thanking you.

[Wood You Like Ltd]

Hi Dom

That depends on how even or uneven your existing floorboards are, presuming you plan to install over your existing floorboards?

Let us know.

Wood You Like Ltd

[K Man]

Hi, probably a foolish question but I plan to plank (not T&G) over a concrete floor using 2cm deep by 14.4 cm wide 3m pine boards over concrete. I plan to glue them. The floor was laid 20 years ago and is completely dry. It has a modern dpc. Do I need to have an underlay or can I glue directly to the concrete? Thanks.

[Wood You Like Ltd]

Hi Kevin

With glueing the flexible adhesive acts like a DPM too.
You only need underlayment if you install your floor floating, which in your case is not possible

Hope this helps
Wood You Like Ltd

[Mark]

My solid oak floor has started cupping because I glued the joints..... any ideas how I can stop this ? Thanks, mark

[Karin H.]

Hi Mark

Are you sure that is the reason your floor is cupping? How long ago did you install the floor, on what type of underfloor, did you install it floating or glued the floor down fully AND glued the T&G's? Did you have a recent leak anywhere?

As you can see we need a bit more information before we can answer.

Kind Regards
Wood You Like Ltd
Karin H