Replacing Floor Boards with Plywood

Ben1989

Hi all,

One of those snowball "while we're doing this we may as well do that" scenarios (haha).

I've ripped the cupboard out in our hallway. This has left us with a patch of no laminate flooring and bare floorboards. Also, at the same time, I have fitted a vertical radiator in the hallway to save space as soon as we walk in the house. However, it is not plumbed in and as it's vertical so will require pipework modification under the floor.

So, I am in a situation where I need to lift the laminate flooring in the hallway to access pipework and also install new laminate planks where the old planks were cut around the cupboard.

We have a suspended floor and the laminate runs lengthways with the floorboards. The planks are skinny and they make large noises when walking on them as they seem to bow a tad.

I was wondering while I'm lifting flooring that I replace it with something like plywood? I think this will give the laminate more of a secure and flatter surface for the laminate and maybe reduce noise and 'echo'.

What are people's thoughts on this? Is it worthwhile through people's experiences?

A side question is - is it worth putting insulation between the joists? Or, is there serious condensation/rot risk? I hear different things.

FreeBear

Ben1989 said: A side question is - is it worth putting insulation between the joists? Or, is there serious condensation/rot risk? I hear different things.

If you are lifting the floorboards, it is (nearly) always worth putting insulation in. Do not block the air bricks or compromise airflow over any dwarf walls - This may mean limiting insulation to 25mm thick Celotex/Kingspan. Nailing stud to the joists to ensure the insulation boards do not drop is prudent.

As for noisy laminate - I have found the 5mm foam underlay is quieter under foot than the woodfibre boards.

EssexExile

Ben1989 said:

The planks are skinny and they make large noises when walking on them...

Carpet. 

Ben1989

The wife and I had this debate. I wanted carpet haha.

But in fairness, the lack of maintenance and hidden dirt with laminate is good I have to say.

So in terms of using plywood in lieu of floorboards is this a sound idea? Something that's commonly done? Any negatives outside of underfloor maintenance? 

FreeBear

Modern houses are generally built using 600mm wide strips of chipboard (with tongue & groove). Nothing to stop you using plywood as long as it is of good quality and sufficient thickness.

Ben1989

Just a case of getting matching thickness as currently will only be doing the hallway (the floor extends into dining room and living room)

NSG666

Bear in mind that timber prices have double since before Covid as I found out last week when I bought some skirting board and a couple of sheets of 18mm P5 flooring. Check how well secured the existing boards are before ripping them all out and replacing them. Depending on the width you might be better using chipboard as there could be less waste but also the joints will be tongue and grooved and nice and strong when you glue them together (not to the joists).

Jeepers_Creepers

Yes you can use plywood or chipboard or just replace the existing boards using screws - that should stop the creaks.

Yes, if the whole flooring is coming up, then it would be remiss not to add some insulation. Either ~2" celotex-type, cut tightly and neatly and air-tightly in between the joists, flush with their top edges, and sealed with a bead of foam (especially if a sloppy cut...), or the simplest is probably to drape some form of netting over the joists and let it sling down between them, and fit normal loft insulation in there. There should be no issues with condensation with either method as it doesn't affect the air flow under the floor. (Do a quick surf for 'insulating under a timber floor' or similar).

One definite thing I'd do is to seal around the floor perimiter where it meets the wall under the skirting - that's the worst place for draughts.

Gavin83

Personally I wouldn’t touch chipboard for flooring. It’s common these days but more for cost reasons. Except for cost plywood is better in just about every conceivable way.

Assuming your floorboards aren’t in bad condition the other option is to make sure they’re well screwed down and then overboard with thin ply. You should still get the strength you need for a fraction of the cost. It’ll be harder to open the floor up should you need to but with laminate down it’ll be a nightmare anyway.

I agree with the others on insulation. While you’ve got the floor up it’s a great idea to stick some in. I’d use the board type rather than the fluffy stuff.

One last thing. If you’re redoing the plumbing under the floor have a think about what pipe material and connectors you use. I certainly wouldn’t recommend compression fittings.
 

Ben1989

Thanks all.

One big constraint which I 100% should have mentioned is this is just the hallway but the floor continues into the dining room and living room meaning the floor has to be level. The squeeking is actually from the laminate moving within their T&G as there is a little bit of bowing between the joists. Hence my attraction to structural plywood.

Silly question, is it just a case of screwing the plywood into the joists with no overhangs? Ensuring each end do not contact each other on the joist?

Regarding the solid insulation I've read that these can cause condensation issues? Not sure what to believe.

And yes Gavin I thought that too. I will certainly be requesting soldered joints. An undetectable leak under a crucial part of the house is a recipe for disaster 

Gavin83

Ben1989 said:

Thanks all.

One big constraint which I 100% should have mentioned is this is just the hallway but the floor continues into the dining room and living room meaning the floor has to be level. The squeeking is actually from the laminate moving within their T&G as there is a little bit of bowing between the joists. Hence my attraction to structural plywood.

Silly question, is it just a case of screwing the plywood into the joists with no overhangs? Ensuring each end do not contact each other on the joist?

Regarding the solid insulation I've read that these can cause condensation issues? Not sure what to believe.

And yes Gavin I thought that too. I will certainly be requesting soldered joints. An undetectable leak under a crucial part of the house is a recipe for disaster 

How thick are your floorboards?

In regards to plywood firstly it should run perpendicular to the joists, so the longer side of the ply running against the joists. Essentially any edge needs to be supported, whether that’s with a joist, a noggin or T&G. To save you some effort make sure the long edge of the ply finishes on a joist. If your room is wider than a single sheet (2.4m) then stagger the sheets. Use flooring screws every 150mm. If you do that your floor will be solid.

Solid insulation won’t cause condensation as long as it isn’t blocking airflow. Make sure your airbricks/vents aren’t blocked on the outside as well.