Do you trust Reddit more than your builder?

Thanks, this is to gather to information and we will make the decision based on the information we get :)

I’m not a fan of anything particle board. Afraid it would swell with water exposure which a floor is likely to get.

We have the same concern as well but we plan to add the hybrid floor on top which is waterproof

It's only water proof from the top. If water ever gets around the edge, it will potentially run underneath the flooring material and the 'yellow tongue' will soak up water like a sponge and swell.

Personally, I won't use a particle board based sheathing on the floor. While the swelling I've repaired has been limited to kitchens and bathrooms, it's not a risk I'm willing to take as a GC. I'm also not a fan of running a bunch of nails/screws through an old hardwood floor as someone may want to restore it at some point.

All the addition of a plywood or backer board will do is help to flatten out areas. If you have unlevel floors and want them level, you'll need to either do a proper fix or use some leveling materials. Whatever flooring you have chosen, the manufacturer will have very specific requirements for the floor prep prior to installation regarding how flat the floor needs to be.

Thank you so much for the information, I wished I could have restored the floor but it is too bad with glue on and half hardwood and anothe half weak, rotten pinewood

If it's already that damaged, it would be better to pull it first. Old flooring should never be covered if you don't know the condition of the sub floor. Especially if some of it is water damaged. Additionally, by adding a layer prior to your new finished floors, it can affect door jambs, thresholds with other floors, etc.

I've done remodels where I've pulled 4 layers of flooring and aside from the nightmare, it's always because the prior installers (or owners) didn't want to do the job properly the first time.

That is a very valid point but it will be very costly if we do removing the floor.

If the boards are structurally ok and reasonably level then it is fine to just lay new boards over the top and nail offset. Ie use the same width boards and lay them staggered over the ones below. But it really is a better option to remove.

Personally I would pull up the old boards and yellow tongue it before laying . You will also get a chance to wedge the joists where required to relevel the floor. Pulling up the boards is not a big job - particularly if the builder makes up a lever to do so. Probably a days work for three blokes and the cost of a skip …. A few grand at most. While this may seem a lot, it is small in comparison to the cost of the yellow tongue and hybrid floor boards. Given the investment in the new floor over the top, just do it right.

If you still decide to overlay, check what happens to your stair heights as your decision to overlay will affect the top tread height and require stair replacement/ modification (by also overlaying) to maintain consistent a rise on the the treads over the entire flight.

Source: licensed builder.

A Structa-floor will not swell with normal use. As you probably know, they are designed (wax impregnated) to be in the weather while the frame is being stood and roofed. With overlaying carpet, vinyl, floor board or tiles and normal use they are fine.

Wet area (bathroom) flooring should be compressed fibre sheet and waterproofed.

The information ia great, thanks a ton. We will consider the option.

Engineered boards (solid timber with an engineered base) are awesome - the are dimensionally stable and also more sustainable. Make sure the hardwood section is full depth to the tongue - this will allow them to be refinished in the future ie sanded and polished. You would get three sand and recoats with which will be longer than you are alive. They are at least as good as solid hardwood and in some ways better. If they are end-matched there is also minimal wastage as they don’t need to finish over a joist.

Options are 18mm over joists or 13mm over a structafloor (yellow tongue particle board floor). The latter option would be my preference as it is more solid under foot and more stable. However there can be some slight cupping which only those in the trade generally notice.

The prefinshed boards are glued and secret nailed so you also save the cost of punching nails, filling, sanding and polyurethane coats.

Are you in Australia?

Thanks, That solution is nearly perfect and that what we thought before. However the engineered hardwood is too expensive which is 4 x more expensive than vynl/hybrid planks which is being considered now.

Yes I am, from Brisbane

Is that fine to use engineered hardwood (4mm hardwood) over the current floor without the yellow tongue?

I have a dark plastic parket, I have made a grow room for weed and I splashed water everywhere, there was a big puddle in the middle for 6 months, no damage

my toilet broke and filled half the apartment, no damage, the insurance corp paid me $3000 to replace it, I pockeded the cash

I had a dog running back and forth for years , not a scratch

no damage after my computer chair after years

I tell everybody to go plastic, it looks about the same

It depends. But likely yes you could overlay the existing 19mm solid timber boards with 13mm engineered timber once you prepare them.

you can definitely do it with solid timber boards and nail them through the face in the traditional manner. The floor will be as flat (or not) as the original floor.

With the engineered boards, it depends on the fixing method. If you are doing a floating floor the it’s possible if the current floor is within the specified flatness. If the floor is not flat you will have issues with boards or tongues cracking. You would put an acoustic underlay down first. The floors do creak a bit either as the room heats up/cools down or when people walk on them.

Alternatively you could glue and nail them if the floor under is sound which will give you a far better feel underfoot. The floor board manufacturers literature should be consulted.

To prepare the existing floor boards and improve flatness replace any rotten boards, punch any nails down, flattened with a drum sander and then some levelling compound used in isolated areas prior to overlaying with the engineered flooring.

I would get a flooring contractor in to review and provide advice.

Remember regardless of what you overlay with you may have the same issues with stairs and either all your skirting boards need to come off and be replaced with new (and walls patched and repainted) or a timber bead gets put around the perimeter tacked onto the skirting boards, which is a bit of a giveaway.

Also all doors will need to be remove and trimmed. If they are hollow core doors they may need to have the internal bottom rails removed and new timber rails glued in and likely require the entire door to be repainted. Solid doors can just be trimmed but make sure the bottom edge is repainted.

Ok - as am I. Just screen any advice you get from this sub as a lot of commentators are US based and the yellow tongue system may not be familiar to them.

Thanks for the detail information, should I add cement board ontop of the existing floor to make it level with levelling compound?

Sorry but do you have a link to what the engineered boards you referred to as from what I read it said we can sand the engineered boards

Yes you can sand engineered boards in the future. Make sure the ones you get are hardwood above the tongue.

Laminates you can’t.

Thank you so much