How to fill gaps between timber floorboards?

[TrevM]

Hi Everyone,

I've got an old house that I've ripped up carpet and thin MDF board and found beautiful hardwood boards underneath.  The boards appear to be old decking timber as the internal is pine flooring with tongue and groove.  The timber has gaps between each board that fall through to the ceiling underneath.  I would love nothing more than to utilise these via filling the gaps between the boards, sanding and staining/sealing.  Problem is I cannot find anywhere where this has been done.  

A lot of the gap fillers go only up to 2mm.  I was thinking of something along the lines of backing rod and polyurethane sealant with a nice wood colour that is similar.  Or something that takes on the stain colouring.  if it shows lines I don't care, its all character.  It would be such a shame to cover it.  However I don't want to put something in that is going to breakdown and need replacing in a couple of years.  I don't want to reinstall MDF and flooring, but will if I have to.

has anyone got any ideas?  Was thinking of doing a small trial this weekend 

[EricL]

Hello @TrevM 

Welcome to the Bunnings Workshop community. It's sensational to have you join us and thanks for sharing your question about filling the gaps in your flooring.

You've read my mind! I was going to suggest using Moroday 10mm x 50m MGF2 Gap Filler Rod in combination with Timbermate 2kg Natural Wood Filler. The technique I would suggest is to use a piece of timber with a marker so that the filler rod will be pushed in at a standard height.

This will allow you to fill the gaps evenly, the wood filler I've suggested can be stained and coated. But it is best practice to always test before you commit the entire flooring area.

I also suggest having a quick look at this discussion - Filling gaps between floorboards in bathroom by @Chris_T. 

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.

If you have any other questions, please let us know.

Eric

[JoeAzza]

Hi @TrevM  here is another idea, although a bit more work, if you are going to sand the floor, my suggestion is to cut thin strips of timber similar to the original timber and glue in place using weatherproof or waterproof glue then sand to the same level as the original timber, the timber strips need to be slightly above the original timber board to allow for sanding., I am assuming the the gaps are a consistent width, you just need to cut the strips of timber to be a neat fit for glueing. You may be able to buy thin strips of timber from Bunnings to fit the gaps. @EricL @May be able to help you with size availabilty .

[JoeAzza]

Hi @TrevM 

I found this online with more information re strips of timber for gaps in floorboards 

https://glorioustimberflooring.com.au/3-ways-to-fix-gaps-in-hardwood-floors/

[Nailbag]

Hi @TrevM I would go down the lines of what @EricL has described, though after using both 6mm and 10mm rod just today by coincidence I would go with the 6mm. 10mm rod will struggle to compress in much of those finer gaps pictured. And I would push it down at least 50% of the board thickness as you will need a good solid depth of filler to avoid it breaking out. Punch any surface nail heads, and fill all nail head holes prior to sanding.

Great project and look forward to seeing the finished product.

regards, Nailbag.

[Dave-1]

Morning @TrevM 

Now those boards would look pretty stylish if you get them sorted I was only watching a video of a twisted wax/tared rope to seal between the boards on a hull of a timber ship over the weekend! So I was going to suggest something along the lines until I saw @EricL 's suggestion Definently would be trying that path first.

Dave

[TrevM]

Thanks All for your suggestions @EricL @Nailbag @Dave-1 @JoeAzza .  I'll have a crack with the backing rod and filler to start with as that is by far the easiest solution for someone of my skillset. 

Thanks again everyone for taking the time to help me.  really appreciated.