Help laying solid oak floor over different floor types

[chuggypig]

Hi all,


I’m looking for some help laying a solid oak tongue and groove floor over existing suspended wooden floor and concrete floor in the same fitting

The situations is this: I have had the living and dining room opened up via a 2.1 meter square opening and need to lay solid oak floor throughout unfortunately the living room is typical floor board construction but the dinning room is concrete. And the floors are about 5mm different in height (the concrete being the higher) is this the correct procedure or not? Or is this overkill and could be done easier.


1) I need to first of all lift the floor boards and insulate between the floor joists floor get very cold in winter due to the five air bricks in the front of the property– Can I use insulation board for this or is it best to use glass fibre wool? I assume this new insulation is to be kept level with top of floor joists so its tight to underside of floorboards when replaced so there’s no void between floor boards and insulation

2) Do I replace the lifted floor boards and cover these and the concrete floor a with a DPM which is left long at the edges to tuck up behind skirting board. Or is this meant just for the concrete floor

3) Do I then use 12mm ply wood on top of the DPM throughout both rooms using wood shims to lift the height of the timber floor to the concrete floor level? and I assume this is screwed down to the wooden floor (how do I fix it to the concrete floor)

4) Then can I lay the oak flooring on top of this using glue or secret nail method or do I need to do anything else?

5) Also I have 2 chimney breasts and will be fitting 2 new hearths what would be the neatest way to finish the oak floor around a hearth with out using beading is it o.k. to let the hearth over hang the flooring slightly?

Or have I got this completely wrong


I have looked and looked on the internet for info but there is so much contradicting info on all it’s done is confuse me further to what’s best way to fit and want it done right as the oak floor alone has cost me a small fortune.


Thanks in advance everybody

 

[WoodYouLike]

Have a look here first: Create one type of underfloor - if needed!

You could vary the thickens of plywood/hardboard used to level out the difference between the two areas and IMHO the overboarding will give you the extra insulation you are after. Depending on the measurements of your new flooring you can install floating and use 3mm foam or 4mm Timbermate Duratex.

 

[chuggypig]

Thanks for you quick reply and the link you provided

So do you think the plywood would do away the the need to fit under floor insulation at the floor board area?

How thick should the plywood be?

After looking at the link is does'nt mention after fitting the plywood down through both rooms if i still need a DPM it just says to fit the sound proof foam type underlayment on top of the plywood. So will i still need a DPM or is the plywood sufficient?

Also will the ply wood need an expansion gap at the edge of the room and can i seal the joins in the plywood.


Thanks for your help

 

[WoodYouLike]

If you use wbp plywood no need for dpm underneath the ply. Never use an underlayment that contains a DPM on existing floorboards or on sheetmaterials like plywood
The thickness of the ply depends on the levelness of your existing floorboards.
Leave a "credit-card" wide gap between every sheet of plywood so it has room to expand.

 

[chuggypig]

Thanks for you replies


This is the floor i have http://www.wickes.co.uk/Solid-Wood-Flooring/invt/157983

and after opening a pack and looking on the instruction it says to buy the flooring clips for fitting, i'n not sure how these clips work as i've never seen them. However could i install the floor using the floating method as you mentioned it depends on the width of the planks and room size, or is this clips system the way to go.

( I assume floating means you just glue the tongues and grooves of the oak panels and dont physically fix the new floor to the sub floor whether it be with glue clips or nails. Apologies for my lack of knowledge

The planks are 120mm wide and vary in length and the widest part of the room is just under 5 meters.

Thanks and i really appreciate your help

 

[WoodYouLike]

Have you already noticed how many short lengths there are in a pack?

The description on the Wickes site doesn't mention the clips and if they wanted you to use them they should have added them to the pack. In our experience most of these clips are totally rubbish anyway, more a hinder than a benefit.

See also How to glue T&G boards the correct way

 

[chuggypig]

I've only opened one pack as i've got 36 packs. Whats classified as a short length as they vary from about 300mm-1200mm ish,

So the clips are a no no. so just fit as floating then?


Cheers

 

[WoodYouLike]

Officially there should be no more than 15% shorter than 1/3 of the longest length, in your case 400mm and over 50% should be longer than 600mm.
But I'm guessing it won't have that in your packs (seeing the price of the lot).

Check various boxes and if you indeed find many short lengths I suggest you change plans and use self-adhesive underlayment to make the whole floor more stable (too many hinges - many joints - can make the floor prone to movement on the hinges and clips won't solve that problem)

 

[chuggypig]

Just on the off chance i've got to many short lengths, What's make of self adhesive underlay would you use.


Thanks for you help is been very very helpful

 

[WoodYouLike]

I would always opt for the original one: Elastilon.
Too many copy-cats get it wrong just to jump on the band-wagon

 

[chuggypig]

Hi

What's best to nail or screw the ply wood down on the floorboard area, and what type is best.

Also if i'm to use the glued floating floor method is it a case of laying a few rows per day or can it all be done in one go

 

[WoodYouLike]

Stainless steel screws every 25 cm.

You can install as many boards as you like, why would you think you can only do a few per day?

 

[chuggypig]

Thought you might have to let some set with glue to keep rigid. Do the piece not slip along the tongue and groove easier once pva is applied.

Cheers

 

[WoodYouLike]

I thought you meant when using the self-adhesive underlayment, then you don't need to glue the T&G also.
When glueing T&G's you just have to be careful not to walk over freshly installed boards.

 

[chuggypig]

Hi

I dont suppose you know what glue i should use to stick the ply wood to the concrete floor.

Also what is OSB board is this better or worse than ply

Thanks