How to Tile Over Wooden Floorboards

How to Tile Over Wooden Floorboards

Renovating, the joys! Anyone following this blog will know that the year 2020 was a big year for me. I renovated my entire home, and it wasn’t a small reno. I’m talking moving every room, changing every door and window location bar one, adding an extension and knocking over and re-building my garage. I started in April and needless to say; I’m still not quite finished. But I almost am!

In my time as an apprentice chippy, one of the biggest (and most horrendous) jobs I took on was to prep my timber flooring for floor tiles. I previously wrote an article on this topic (read How To Lay Ceramic Tiles On Floorboards), but that was before I had any hands-on experience. So today, I’m going to give you an updated version, which provides a lot more detail.

With basically no experience on the tools, I had to lay 80 square metres of tile underlay in a weekend for the tiler to start the following Monday. Big job? Yes. Did it save me money? Absolutely! If you’re like me and don’t mind getting your hands dirty to save a little money to spend on better quality products, then this may be one job you can undertake.

And, before you ask why on earth would I tile over original timber floorboards, there were many reasons:

  • They made my home incredibly dark
  • I have dogs, and the varnish was scratching off
  • They mark very easy

So, given the above, floor tiles, were the best solution for me, and they may be a better solution for you.

Structural design considerations

First things first. When tiling over floorboards, you need to ensure your home is structurally sound to support the additional weight of the floor tiles and tile underlay. It may not seem like much, but you’re looking at an extra 20-30kg of weight per square metre, which can be substantial overall. If your home is elevated, as mine is, you may have to add reinforcement to your floor plan, as I had to.

In my case, my structural engineer made me fix treated timber beams to existing joists for added strength (which also helped support the restructuring of the walls as part of my overall renovation). It’s best to seek advice from a structural engineer before adding additional weight to your floor plan.

Prep the floorboards

So obviously, the first thing you need to do is to clear your home of all its belongings, so you have a clear space to work with.

You then need to prepare the floorboards for the underlay. If you’re covering original floorboards, as was the case with my renovation, you will find that many of them will have warped over the years and you won’t have a level surface. I had one area of flooring that had risen or expanded over time which required a belt sander to bring it back down to level.

You may also find some nails sitting proud that need to be hit with a nail punch. If you had carpet over your floorboards, then you will need to remove the carpet tack strip and staples from the floorboards also.

The takeaway message here is, you need the surface to be absolutely level to ensure a level finish.

Install tile underlay

tile underlay on timber floorboards

I’m not going to lie or sugar-coat things here. Installing tile underlay was hands-down the hardest, least enjoyable job I’ve ever taken on. It’s not that the process itself is hard; You really only have to measure, cut, and fix the underlay to the floor. It’s the fact that each sheer of underlay weighs around 20kg and is very difficult to work with when you have to have precise measurements. It’s also not the easiest material to work with.

Let’s take a step back and go over the basics.

You’ll need 6mm fibre cement sheeting for the job.

Other things you need:

  • Tape measure
  • Pencil
  • Fibre cement shears or an angle grinder (I tried the angle grinder before I was enlightened about magical fibre cement shears; do yourself a favour and get a pair of these for this project! It is much cleaner and a lot easier and safer to work with)
  • tile underlay adhesive (I actually used Gyprock CSR Acrylic Stud Adhesive, which isn’t the same as tile underlay adhesive, but it did the job 👍)
  • A nail gun (I used a cheap air nail gun and compressor, you definitely need a nail gun for this job!)
  • Nail Gun screws
  • Muscles & Patience (when you have to carry the sheeting to and fro, you’ll see why this is a requirement!)

As mentioned, the process itself is relatively straightforward, and goes as such:

  1. Work from room to room, starting at one corner of a room to reduce the need for cuts.
  2. Dab a good amount of glue on the underside of the sheet, spaced about 200-300mm apart.
  3. Quickly lay the sheet on the floor before the glue sets and nail it down. The sheeting I used had makes where you need to nail, which made it very easy to follow. If your sheets don’t then as a rule of thumb, you’ll want to nail around the perimeter, 100mm from the edge and 100mm apart. Then, in the centre, spaced out at about 200mm apart. You will use A LOT of nails.
  4. Repeat step two and three per sheet; It’s important to nail as you go. You don’t want to glue down all the sheets and then go over them with the nail gun. The glue will have set, and you won’t get a flush finish. It makes it more time consuming, but it’s the right way to go about it.

When you get to the end of the row and need to start cutting sheets is where the fun stops. You have to take precise measurements of the remaining space, transfer these measurements to the sheet and then make necessary cuts. If you are a couple of millimetres out, you have to carry the sheet back to your work area, cut again, and carry it back. Try doing this 100 times over!

Tip: place the cut sheet down before applying the adhesive to make sure it’s the right size. Again, you don’t want the glue to set before you have it at the right size.

Bring in the tiler

Now, this is where I brought in a tiler because I didn’t have the time or skills to get a professional finish. You can give tiling a crack yourself if you think you have what it takes (read 5 Easy Steps To Laying Floor Tiles), but if you’ve gone to the trouble to prep the flooring correctly, you don’t wait to ruin your floor with a dodgy tiling effort.

If you have money in your budget to afford a professional tiler, it pays to hire one because you have to live with the finished product for at least 15 years. You can expect to pay between $30 and $45 per m2 for a professional tiler in Perth.

Tiling over floorboards isn’t the same as tiling onto a concrete slab. Unlike a slab, which is solid, floorboards are prone to warp and move over time. Such movement can cause cracking. Thus, you need to find an experienced tiler who knows how to work with your substrate correctly. A professional tiler understands what’s required to ensure no cracks arise from tiling over floorboards. They also know where to place expansion joints to cush any future movement.

Again, I need to stress the importance of having a level floor to achieve a professional finish. While my flooring felt level underfoot, my tiler quickly pointed out how unlevel it was. In my case, a levelling agent was needed in some areas. The photo below shows the levelling agent poured over the tile underlay to level the service.

levelling agent

An overview of the tiling process is as follows.

Determine the setout

The first stage of any tiling project is to determine the setout. By this, I mean to work out where to start to ensure the best result. You don’t want to start with a full tile only to have a centimetre of tile at the other end of the room. Nor do you want odd joins in obvious doorways etc.

A tiler will measure the space and strategically plan the layout to ensure the best possible finish. If your tiler doesn’t do this, then look for a new tiler!

Identify expansion-joint locations

This point is of significant importance when tiling over floorboards because you have to expect movement over time. If you or your tiler tile, without leaving expansion joints, you can guarantee to have cracked grout and possibly even cracked tiles in years to come.

Expansion joints are marginally winder (I’m talking 2mm) grout joints, which are filled with a silicone joint sealant rather than grout. The joint sealant can be colour-matched to your grout, so you won’t even notice them!

By reviewing the floorplan and placing expansion joints in appropriate locations, you can reduce the risk of cracking. In my house, the tiler put expansion joints at the doorway to each bedroom and throughout large spaces such as my open plan kitchen/living area.

Lay the tiles

tiles over timber floorboards

Tiles used in my renovation were the Terazzo White tile from Ross’s Discount Home Centre

When laying tiles on floorboards, you also have to consider not only the colour of the grout, but also the type of grout that you use. You want to use a grout that has a little give; offers some flexibility. There are a few options here, but your best bet is to use a grout additive such as Plastinex Red Label, which we sell at Ross’s Discount Home Centre.

Adding this polymer to your grout will give it a little more flexibility to help weather any future movement.

Grout the tiles

Finally, when the tiles have been laid, its time to grout them. This is the easiest part of the entire process; you just have to make sure not to fill the expansion joints with grout! Simply apply the grout as per the manufactures directions, and your job is done.

tiles over timber floorboards finished

Conclusion

If you’re looking to update your flooring by tiling over your floorboards, then know it is possible, but it’s a big job, with lots of processes and more considerations. The biggest consideration being the structural implications that the added weight may have on your floor plan. It’s advised to seek advice from a structural engineer if you have a raised home before proceeding with this project.

If you have the all-clear or have reinforced your floor plan with additional beams, you can then prep the floorboards for the tile underlay. Laying the tile underlay is a big process; as big as laying tiles, but it must be done. Once you have your underlay down, you can then start tiling or bring in a tiler. There is one primary consideration for tiling over floorboards: that is to ensure the tiles don’t crack with future movement. TO help prevent this, ensure you allow for expansion joints and add a flexible additive to your grout.

It’s a big and expensive process, but trust me, the end result is worth all the effort!

For floor tiles, tile adhesives and grout in Perth, come and see the team at Ross’s Discount Home Centre. We have just what you need at the best prices in town.