Best way to reinstall pine floorboards after a subfloor installation

[HarperLewis]

I’m planning on ripping up the victorian non TnG pine floorboards on the 1st floor (they have been sanded and finished by the previous owners but are in need of some love), install a subfloor (22mm Chipboard), (run cables, new CH piping, install sound proofing), reinstall the floor (and purchasing replacement boards for ~25% which have seen better days to say the least).


The bit I'm not sure on is how best to attach the floor boards to the new subfloor, as far as I can see I have 3 options.

• Nail them down where the joists are, this would give the most “authentic” look, but I’m unsure how the lath and plaster ceiling below would hold up to this (and given it has the original coving etc, I don’t really want to replace this).
  
  
• Screw the boards to the subfloor, fill all the screw holes.
  
  
• Glue the floor boards to the subfloor, fill all the holes which previously contained nails.
  

I think I can discount the first, as I don’t want to risk the ceiling below. So that leaves the last two. Note, I plan to live in this house for a long period of time 15-20 years so I want to make sure that whatever I do, doesn’t make my life harder in the future such as if I end up replacing boards etc.


Screws are a great long lasting method, allowing me to pull the floorboards up in the future without destroying the subfloor if I ever want to replace them. However I’m yet to see a great method of covering the screw holes (as the boards are non TnG this would rule out secret screws/nails) and would this limit the possibility to re-sand in the future?

 

[Deleted member 174758]

Ideally chipboard needs to be installed with D4 glue on the tops of the joists. All end joints need to be fully supported with solid strutting or noggins. It should be screwed down at 100 to 150mm centres. If you don't screw it sufficiently it can squeak. If you nail it there is a far greater chance that it will squeak in the future than if you screw it, and if you use ring nails they won't want to come out at all (except for the odd one or two which haven't driven into the joists and WILL squeak). It is also risky to nail above any lath and plaster ceiling as you can bring chunks of it down. Boards should be laid in "brick pattern" (I.e end joints staggered). If dealing with T&G your always start with the tongue side towards the wall. As you have square edge boards that isn't an issue, although personally not keen on them as edge to edge joints can still creak unless glued and supported (that and the weight of full boards is why nobody in construction has used them for more than 20 yesrs). Best way to get tight joints is by using a sledge hammer and a 6ft piece of 4 x 2 CLS (reallyl). In terms of access I'd still prefer not to depend on getting a full board up without damaging it and instead I'd go for removable access hatches where needed as this will reduce the chances of squeaking. This is more work to install, although Trend do have a system called "Routabout" to speed up and simplify the process. Unless you intend to install vinyl, lino, carpet or the like the screw holes won't be a problem. If you need an absolutely flat surface then a thin layer of SLC will sort things out as well as taking out any minor hollows, but if you fill the screw heads, how will you ever take them out?

Either way you need to check that the tops of your joists are more or less level before starting the install (and take corrective action if they are not). As said, SLC can be used to remove minor hollows

 

[HarperLewis]

Hey, thanks for the detailed reply.

With regards to filling the screw heads, my plan was to use a small bit of dowel sawn to the height of the board, this way if I really need to bring it up, I could just drill the dowel.

When you mention that edge to edge joints can creak unless glued, I was planning on still leaving small gaps between the boards for expansion (a few mill), would this not be the best approach?

 

[Deleted member 174758]

With regards to filling the screw heads, my plan was to use a small bit of dowel sawn to the height of the board, this way if I really need to bring it up, I could just drill the dowel.

For starters if you sink screw heads that far into the board you will potentially weaken the board. Screw heads are countersink so that you can flush them. If they are flush they will not telegraph through hard flooring, it's when you have carpet, vinyl, etc that you need to fill and on then. A soft filler can easily be dug out with an awl

When you mention that edge to edge joints can creak unless glued, I was planning on still leaving small gaps between the boards for expansion (a few mill), would this not be the best approach?

Do you like draughts, then? And you mention filling screw heads than leaving a gap between boards - which will definitely telegraph through most flooring

 

[HarperLewis]

For starters if you sink screw heads that far into the board you will potentially weaken the board. Screw heads are countersink so that you can flush them. If they are flush they will not telegraph through hard flooring, it's when you have carpet, vinyl, etc that you need to fill and on then. A soft filler can easily be dug out with an awl

Does the strength of the board matter that much with a 22mm subfloor underneath as it's not longer having to span anything? I guess the reason I was thinking of sinking them deeper was to have the possibility of sanding the floor a couple more times over the years.

Do you like draughts, then? And you mention filling screw heads than leaving a gap between boards - which will definitely telegraph through most flooring

My assumption was with the subfloor underneath that I wouldn't get draughts anymore.

 

[Deleted member 174758]

I guess the reason I was thinking of sinking them deeper was to have the possibility of sanding the floor a couple more times over the years.

??? Chipboard is softer and less dense in the centre than at the surfaces. So if you sink too deeply the screw heads will be in the core, not at the denser surface. Sanding? Do you I tend to gave the chipboard as finished floor? I thought the chipboard is going to be sub-floor, which is what it normally is, with a finish flooring applied on top or are you talking about this as a sub-floor beneath pine boards as a finished floor? Chipboard does not sand well (in fact most man made boards don't sand well) because you will quickly sand through the denser skin into the softer core which will break up rather quickly if subjected to traffic

If your finished floor is T&G pine, then you probobly won't get draughts coming from the sub-floor (they can be caused by convection) but if it is square edged floor boards you may still have gaps between the boards, especially after the central heating has been in a few winters

BTW if you screw down your finish flooring don't mess about with dowels - buy yourself s proper drill/countersink (Trend Snappy) then buy some tapered pellets from someone like Appleby Woodturners. Far better match

 

[HarperLewis]

I think we have our wires crossed here

The intention is to lay 22mm Chipboard down and then lay the current pine floorboard back on top of the chipboard subfloor (they're about ~15mm thick) giving an overall floor thickness of ~37mm. Once this is done I want to sand the pine floorboard again (after I've replaced all the damaged ones that aren't repairable with reclaimed boards) to create the final floor.

 

[Deleted member 174758]

Yes, and in that case:

Treat your sub floor the way you'd treat any sub floor - support the end joints, glue to the joists and at the edges. Screw the chipboard down (4 x 50mm or 4.5 x 50mm) on 100 to 150mm centres. If you need access to services you'll need to do cut outs with a screwed-down cover (plywood is more serviceable for this).

Finished floor nailed in place with oval punched under and filled. Believe it or nor old fashioned linseed oil putty makes an excellent filler and can be tinted. When you do sand simply punch the nails another millimetre or so under and refill

 

[HarperLewis]

Great sounds good. One last question for the nails, it was suggested to me (given that I didn't want to bring down the lathe and plaster ceiling below) to use a finishing nail gun with L shaped nails? Does this sound about right to you? (I assuming given the depth of the subfloor and floorboards will be ~37mm, I'd want 32mm nails?)

Thanks again for your help