Engineered floor on joists

[Adraen]

Hi everyone. I'm new to this forum but i've came across a lot of very useful discussions while doing some research which prompted me to sign up!

So i've recently bought a 1970s house that needs some work done, we are about to get an electrician to rewire the entire house and after that's done I want to get started with the floors. The floors used to be carpets on a suspended floor, before we got the house the carpets got removed and the subfloor that's left has been butchered over the years.

The plan so far is to remove all the old boards on the ground floor (~60sqm), clean the ground below to make sure we have nice air circulation, insulate with 75mm celotex and put the new floor.

The question I have is regarding the new floor; Originally we were considering putting some hardwood floor, but reading online it looks like in Scotland with the overall humidity putting down engineered floors might be a better idea which i'm fine with. After some looking around we are thinking of going for **** (not sure if links are allowed?) which looks nice but I think the dimensions might be a bit of an issue.

I've seen conflicting information but it looks like the consensus is that the joint between boards should be over a joist. The issue with that is the boards in those packs are mixed and can be as short as 30cm when my joist are 45cm between centres. So I'm looking for some advice if possible:

• Should I put a subfloor of plywood/chipboard and place the boards on top? I'm worried this will add quite a bit to the cost and will create a step between rooms. Also it looks like 18mm is the way to go for ply, but 18mm ply + 20mm engineered floor seems a bit overkill
• Should I just find a different source of engineered floor with longer boards? With longer boards close to a a multiple of 45 I should be able to have far less wastage.
• Any other option that i'm missing?

Thanks very much in advance, any advice would be much appreciated

 

[Deleted member 174758]

Engineered floor is often put in on top of a plywood or chipboard sub-floor (18mm for joist spacings up to about 16in/400mm or 22mm, possibly 25mm above that) as a floating floor. It is the sub-floor which provides the structural strength to carry a load, so the joist spacings (which can be pretty random in an older house) are not an issue. Also, unlike solid hardwood, when an engineered floor goes bad (with wear) it may need to be lifted and replaced uunless the top veneer layer is thick enough to withstand heavy sanding. As flooring should be glued to the joists for stability thaty is going to be an absolute beatch of a job to do down the line. I've never put finished flooring down directly onto joists yet, but maybe there will be a first time...

Note: If using chipboard nsub-flooring, this normally comes as interlocking 2400 x 600 T&G panels (laid in a brick pattern) which are glued and screwed in place onto the joists and are also glued along the tongues. Always specify P5 (moisture resistant) shipboard if there is any question of damp. Also use a D4 flooring adhesive as recommended by the manufacturers