Engineered Wood floor over original floorboards

[Kaymo]

Hi,
Hoping someone might have some advice on this.

I am planning on doing a floating engineered wood floor in an upstairs in an old (200 years) house. I know that you would normally fit the engineered wood floor over the original floorboards, at an adjacent angle to the existing floorboards.

However, as there is already fibre board nailed to the old original floorboards I am wondering if this matters or if it would be ok to fit them parallel/ running in the same direction.

The only reason I am considering this is that running the boards in this direction would suit the termination at the top of the stairs a lot better, and allow me to terminate to a tongue and groove nosing at the top stair.

Regards,
Kenny.

 

[Deleted member 174758]

How flat are your 200 year old floor boards? Chances are they are either cupped or crowned, and you ideally need a flat surface to lay laminate or engineered flooring. Planked sub-flooring has the potential to move and for cups and crowns to telegraph througj anything laid on top, so personally I'd lift the underlay, install a layer of thin plywood onto the floorboards then float your flooring on top of that - at least then you will be assured that any cupping or crowning won't be telegraphed to the new finished flooring and the ditection of your planking won't matter

 

[Kaymo]

Thanks. I don't know if I was clear, but there is already board nailed over the original boards. I referred to it as fibreboard, but that might not be what its called. Its similar to the stuff you usually see pinned on to the back of cheap flatpack furniture.

Its about 2-3mm and its been nailed to the original boards, before the underlay and carpet were put on. I took a section off to see if the original boards were good enough for sanding (surprise, surprise they weren't) and its fairly tightly tacked on, need to get a chisel underneath and a claw hammer to prise it up.

Do you think this will this do the same job as the ply you suggest, meaning that I dont need to worry about the direction of the boards?

 

[Deleted member 174758]

Do you think this will this do the same job as the ply you suggest, meaning that I dont need to worry about the direction of the boards?

No. The fibreboard is underlay and wil conform to the floorboards beneath.

 

[Kaymo]

Thanks again. I see your point.

Just to clear we are talking about the same thing, as I said in my last post I don't think this stuff is called fibreboard. I looked it up online and its called hardboard. In Jewson its called 'standard hardboard' and b and q its 'brown hardboard', both 3mm which seems about right. I've put a pic below.

There does seem to be a small amount of conformity to the boards underneath, but I imagine most wood based materials that thin will confirm to some degree. I'll need to lift all of the carpet and inspect how flat it is. Its been down for at least 20 years so if its likely to have done any conforming its going to do by now. I've pasted a pic below where I lifted one of the hardboard sections.

If I need to put down ply, what minimum thickness do you suggest?

 

[Deleted member 174758]

You can check flatness with a long straight edge (I use a 6ft spirit level, but a piece of straight 3 x 2in PAR or CLS softwood would work just as well) an obtuse light source (i.e. a lamp shone across the surface of the floor, flat on to the floor). Different thicknesses of plastic packers allow you to gauge the depth of hollows

 

[Kaymo]

Thanks. I have a 6ft level I plan to use once I get the carpet up. One of the places I lifted it already was out of level, but that appears to be because its been lifted before and the board put back down with the original boards loose.

Last question. If its all level with the hardboard on, what's your opinion on adding some softer XPS underlay above the hardboard before putting the engineered floor down.

I've always used XPS before under a flooring engineered wood floor, whether its been full thickness floor insulation on to concrete, or 3-5mm on already solid boards. Always got the feeling that this would help level out any small imperfections and it supposed to help prevent squeaking but not sure if its necessary.

 

[Deleted member 174758]

Level isn't the issue for laying a finished floor - flatness is the important thing. What you put on your sub-floor is up to you, but I can tell you that I've had to lift several areas of engineered on the current job, lift the foam type underlay, flatten the floor with levelling compound then reinstall in order to cure crackling sounds we have in some areas - caused by the sub floor not being flat.

As this sort of issue is the cause of a 3-way argument between the main contractor (who I work for), the flooring contractor and the architect (over who will pay for the remedial work - I don't care so long as I get paid for the work), all I'll say is that flatness is important

 

[Kaymo]

Apologies for the confusion, I had meant to say flatness not level. I understand the difference and that its flatness that is important here. What I meant to say was that the area I checked already had an issue with flatness, and I need to fix that before I fit a new section of hardboard there. However, that seemed to be an isolated area due to the floorboards having been lifted for access to pipework. I dont get the sense that the rest of the floor is like this, but I will now once I get the carpet lifted later tonight.

I wasn't suggesting the underlay as a solution to a serious flatness issue, just that it might help even out small imperfections. My question was really whether that in your experience the XPS had any benefit, if the hardboard covering is already flat and stable. Its an upstairs room this time so there isn't really any insulation benefit.