New floorboards on old floorboards.

[bobbler]

I have read a similar answer to a similar question posted in 2006 but thought that I would start a fresh thread as the last became a slanging match.
We were going to sand and varnish the boards in our living room, but we are now coming to the following conclusions.
Due to the room being made up of two original rooms the boards run in two directions and the join is not good. Where the fireplace used to be in one of the rooms has obviously been 'joined in' at a later stage and again does not look great. Also, I just know that it is going to be draughty in the winter as we have between 2 and 4 foot of space under the floor.

Therefore I am thinking about laying a T & G floor on top of the current floor but in one direction so that in one part of the room it runs against the boards and in another part with.

Questions are:

Do I need to put down insulation?
Do I need to put down hardboard?
Would I secret nail the floor or would I nail into the floorboards below and where possible into the joists? I am not bothered about the nails showing.
I have not priced them up or found any yet but I fancy 7" boards or similar. Does anyone know where to get them.

Thanks

Bobbler

 

[WoodYouLike]

Hi bobbler

All depends on how level your existing floorboards are. If cupped, uneven or going in the same direction as you plan to install the new boards then 6 to 12 mm plywood is recommended (screw down - watch those pipes!)

After that, or if boards are level and laid in different direction as new ones a foam underlayment (3mm) will act as sound-insulation. 7' = app. 180mm. Recommend Wood-Engineered boards if you prefer that width, much more stable.

Hope this helps

 

[bobbler]

Thanks for that Wood.

Floor is level, not cupped but half the floor will go in the same direction. I am also not keen on raising the level of the floor much more than the thickness of a floorboard - 22mm - so I would want to do away with using a plywood if possible. What disasters are bound to strike if I do not use the ply?

What sound would the foam underlay stop? There is no sound coming up from below the floor and all wooden floors make a noise when trodden on.

Look forward to your answers.

Bobbler

 

[JohnD]

why not pull up the old ones?

 

[bobbler]

There is no need to pull up the old ones as they will act as the first line of defense against draughts etc.
Plus, where the old fireplace is I could not make a better job by removing them. Plus an insulating layer would help as well.

What is the argument for removing and replacing?

 

[kevindgas]

don't lay straight away allow the wood to dry in the room for a week before laying that way you should reduce the shrinkage gaps

 

[bobbler]

Thanks for the advise, but can anyone answer my previous questions:

"Floor is level, not cupped but half the floor will go in the same direction. I am also not keen on raising the level of the floor much more than the thickness of a floorboard - 22mm - so I would want to do away with using a plywood if possible. What disasters are bound to strike if I do not use the ply?

What sound would the foam underlay stop? There is no sound coming up from below the floor and all wooden floors make a noise when trodden on."

Thanks

 

[Diyisfun]

What sound would the foam underlay stop? There is no sound coming up from below the floor and all wooden floors make a noise when trodden on."

Thanks

I would assume board against board.

 

[WoodYouLike]

Thanks for the advise, but can anyone answer my previous questions:

Bobbler, if the existing boards are not cupped you can install the new boards in the same direction, but this might still result in draft coming through (joint of new boards right on top of joint of old board), plus some slight movement. But that's up to you.

The foam underlayment will reduce the 'footfall' noise when walking on the new floor, also reduce possible draft and even 'level' out some unevenness of the old floorboards.

Hope this helps.

 

[bobbler]

Wood,

Thanks for the advise. I think that the foam underlay will suffice.

Thanks

Bobbler

 

[mattysupra]

I would not advice putting any type of underlay between the flooring and the subfloor on any type of flooring you plan to screw or secret nail other than tar paper ( used when moister imbalance between floors) . The reason for this is that if there is any give in the underlay, which there is , then the cleats (secret nails) or screws will become loose as the underlay starts to flatten. If you plan on face screwing the new boards to the old subfloor, then it is fine to lay both floors as they are, if the subfloor boards in the room running the same direction are flat and smooth. If not you need to sand them flat if you dont want to over plywood to make flat! If you plan to secret nail the flooring down you will have to uplift the boards in the room that will run the same way as the flooring to be fitted and replace with plywood. ( the same thickness as the boards you uplift) The reason for this is that the cleats may hit (or will hit!) the tongue and groove on the subfloor. If they do they will not grip which in turn will cause the flooring to lift. If your worried about draft through boards then install paper felt or tar paper between the two floors.

 

[bobbler]

Now I am confused.
One sage says use a foam underlay, the other not.

Here are the facts:

The floorboard is arriving on Tuesday, and although I do not think it will make any difference in the end I will leave it in the room for the best part of the week.

Where the boards will run in the same direction as the sub floor, the sub floor is flat enough to not need replacing with plywood.

I am also going off the secret nailing idea. I have not got a board in the house that is secret nailed so why start now, so therefore where I can I will nail through the subfloor and into the joist and where I cannot I will just nail to the subfloor.

Any further comment on the underlay question would be appreciated.

 

[WoodYouLike]

This might help?

 

[joe-90]

The floorboard is arriving on Tuesday, and although I do not think it will make any difference in the end I will leave it in the room for the best part of the week.

It makes a HUGE difference.

 

[bobbler]

Wood.
That's solved the problem. My floor will be nailed down, therefore not floating therefore no foam. Might use some paper felt if I knew where to get it.

Joe.
There seems to be a great debate on the "leave the wood to settle in the room for a week". I will, but what difference a week is going to make against the rest of my life that it will be sat there expanding and contracting I do not know.

Anyway, thanks for all your help.

Bobbler the Builder.