Solid wood floor - underlay?

[AdamD]

Which underlay for solid oak on both concrete and timber floor boards above suspended floor?

[Nickfromwales]

You'll need to work out if there's need for moisture control and where you're integrating that. For the timber floors I doubt you'll need any underlay, but some insulation may be of benefit.

 

Can you provide some more details of what's there / what you propose?

[AdamD]

On 03/04/2026 at 13:11, Nickfromwales said:

You'll need to work out if there's need for moisture control and where you're integrating that. For the timber floors I doubt you'll need any underlay, but some insulation may be of benefit.

 

Can you provide some more details of what's there / what you propose?

Suspended timber floor joists and timber floorboards in one part of the area, and solid concrete base in the other 

[Nickfromwales]

2 hours ago, AdamD said:

Suspended timber floor joists and timber floorboards in one part of the area, and solid concrete base in the other 

You are a man of few words, I'll need you to use a lot more of them

 

Damp proof membranes, any? Insulation, any? Thickness of these if present? Etc.

[AdamD]

DPM - not sure, presumably is one under the house!

insulation - no

 

pic of the area

[AdamD]

Another query on floor installation - I’m thinking secret nailing is a good idea, probably worth hiring one for the time saving v drilling + hammer nailing each nail?

[marshian]

3 hours ago, AdamD said:

Another query on floor installation - I’m thinking secret nailing is a good idea, probably worth hiring one for the time saving v drilling + hammer nailing each nail?

 

I bought a second hand portanailer - to do an oak floor........

 

I had to rebuild the bloody thing and replace some parts but once "serviced" it was brilliant to use and little or no effort with a perfect result on every nail (only time I had to drill and hand nail was for the last two rows)

 

 

[marshian]

PS I was supposed to sell it once the floor was finished but didn't - was thinking about doing a Buildhub loan on it as a way of giving back but no idea how to go about it.......

[-rick-]

49 minutes ago, marshian said:

PS I was supposed to sell it once the floor was finished but didn't - was thinking about doing a Buildhub loan on it as a way of giving back but no idea how to go about it.......

 

@jack?

[Oz07]

5 hours ago, AdamD said:

Another query on floor installation - I’m thinking secret nailing is a good idea, probably worth hiring one for the time saving v drilling + hammer nailing each nail?

Won't work on concrete though. I've done floating timber with glued joints before now. 

[AdamD]

33 minutes ago, Oz07 said:

Won't work on concrete though. I've done floating timber with glued joints before now. 

Yeah, can’t use it on that bit but I’d say 2/3 of the area to be done is floorboards so can use it there. Any tips for the concrete base? Just lots of glue to bottom of each plank and in between the tongue and grooves?

 

Insulation presumably quite important on the concrete base?

[Oz07]

10 hours ago, AdamD said:

Yeah, can’t use it on that bit but I’d say 2/3 of the area to be done is floorboards so can use it there. Any tips for the concrete base? Just lots of glue to bottom of each plank and in between the tongue and grooves?

 

Insulation presumably quite important on the concrete base?

The ones I did were floating on an underlay. It was just the joints that were glued to create a floating floor

[AdamD]

13 hours ago, Oz07 said:

The ones I did were floating on an underlay. It was just the joints that were glued to create a floating floor

Was that on concrete? Glued to concrete and nailed to each other in the groove?

[Oz07]

13 minutes ago, AdamD said:

Was that on concrete? Glued to concrete and nailed to each other in the groove?

Yes on concrete / screed in an older house. SLC beforehand 

No it had a dpm, then an underlay and then the flooring. All the joints were glued so it just floats as one large floating floor.

[Nickfromwales]

On 07/04/2026 at 20:04, AdamD said:

Insulation presumably quite important on the concrete base?

The wood of the flooring is actually an insulator, just not a great one. I'd look at laying XPS boards under a glue jointed (but floating) floor.

 

Typically you'd see a batten screwed down the the concrete, laid over a DPC strip, and then the oak flooring would be nailed down to the battens. You could add more insulation in between the battens, subject to you having that 25mm or so of head height to be able to sacrifice.

[AdamD]

Thanks for all replies so far.

Slightly different query this time - how would you approach cutting the whole for the wires here? Annoyingly it’s about half way down the plank so a bit more tricky than just jig sawing a little bit out the top

[ProDave]

What are all those wires for?  Why are they coming up in the middle of a floor?  Is another wall going to be built on top of the floor?  Too many for just a floor socket.

 

Explain what is going on?

 

If you really need a hole for them, just drill a round hole with a drill bit.  But I am still curious why you want cables coming out of the middle of a floor.

[AdamD]

1 hour ago, ProDave said:

What are all those wires for?  Why are they coming up in the middle of a floor?  Is another wall going to be built on top of the floor?  Too many for just a floor socket.

 

Explain what is going on?

 

If you really need a hole for them, just drill a round hole with a drill bit.  But I am still curious why you want cables coming out of the middle of a floor.

New kitchen and there will be an island there so the feed is for under plinth lights, sockets on the island etc

[ProDave]

9 minutes ago, AdamD said:

New kitchen and there will be an island there so the feed is for under plinth lights, sockets on the island etc

So just drill a hole in the board, just big enough to pass the cables through.  Not a massive hole, just big enough, then seal around the cables once the board is paid.

[saveasteading]

If you haven't started in earnest yet...

I'm thinking that the old boards will be bent and twisted especially across the width. Laying new in the same direction might cause a few lumps and edges.

So I'd be thinking of a thin layer of board first.

Maybe underlay will suffice.

 

An expert may say otherwise.