Slate Flooring Installation
Article Summary: Slate Flooring is one of the most satisfying flooring materials to use, but you have to take some preparatory steps first before you start the job. This article explains the process.
Slate is one of those timeless materials that has a certain “wow” factor that consumers love. Because it is a natural material you can be sure that your new floor will have its own character and will look good for years without any major maintenance. In order to show off your new slate flooring at its best, before you start the installation first take a look at the sub floor surface. Slate is very heavy and depending on what thickness material you use you may need to consider whether the floor is strong enough to take the dead load. Your installation options depend on whether you are fixing the slate to a wood floor or to a solid floor.
Installing onto an existing Wood Floor
There is basically no problem with installing slate flooring over an existing wood floor as long as it can take the load. The minimum thickness of wood floor recommended is 1″ (25mm). If it is less than this, simply screw a high grade plywood sheet to the top of the existing floor. This has two benefits, first fitting water resistant plywood will give a long lasting base that will protect the existing timber and second, you can correct any high or low spots with the plywood sheets, giving you a nice flat surface on which to fit your slate flooring.
A further protective layer of urethane can also be applied if you want to be extra sure that you have a good, solid surface to start from. If you are struggling with a height restriction you can also use a much thinner cement based wall board (usually used for tiling), over the floor. If you use this also use a good quality glue as well as screws to fix it to the floor.
To fix the plywood, first pre-drill holes through the ply using a drill about the same size as the screw, but not too tight. Use a square pattern with screws placed approximately every 12 inches. This may seem excessive, but this will absolutely guarantee that you don’t have any bouncy spots under your slate. You really shouldn’t find any more bouncy spots, but if you do, don’t be afraid to use extra screws.
These days you can buy special flooring adhesives that comprise the usual flooring grade glues but with rubber granules added in to give a substance that will move with the flooring. This helps to stop cracking caused by expansion and contraction in the wood sub floor and the slate, which won’t expand or contract at all. I have had no problems with any tile floors I have laid over wood using these products.
Installing over existing concrete or hard floors is simply a matter of making sure the sub floor is flat, but small discrepancies can be easily covered using the same adhesive as described above.
Having made sure that the sub floor is ready to receive the new slate flooring, the next step is to lay out the slate in the exact pattern that it will occupy once fixed. This is very important. Slate is often laid in a set pattern but this will depend on the manufacturers instructions. Check out the product first and see what the requirements are. You may wish to go for a completely random style of slate flooring. This often looks great when done well, but you will need to pay extra attention to the joins to make sure that any gaps are kept to a standard width. Always space the slate out as per the manufacturers instructions, usually this is around 3/8″ (9mm) but could be more or less depending on the product.
Having laid out the slate flooring, next start mixing the adhesive. Make enough to cover about a 4 foot square section at a time, any more and you may have a situation where the adhesive may start to set before you are ready – not quite a disaster but definitely an unnecessary inconvenience. Start laying the slate from the longest straight wall, using it as a laying guide. When you have finished, step back, admire your new floor and have a beer – you deserve it.
Leave your floor to set properly, again this will depend on your ambient conditions, whether it’s hot, cold, humid or dry. After a day or so you can try to step on the floor. Do it carefully just in case and if all is well you are ready to start on the next step – applying the grout. But before you do, consider whether you want to seal the slate. It is recommended that you do, this has two main benefits at this stage. One, sealing will give the slate a deep luster and two, grouting will be a lot easier as the sealer will not let the grout stick to it.
The Final Stage – Grouting
The grouting process is never easy, but by doing it yourself you will be able to get a much better finish than most professionals, mainly because you have the time to do so. Make sure the grout is pushed well into the gaps and use a slightly damp sponge to wipe away any excess. Whatever you do, don’t use a wet sponge as any water ingress into the grout will weaken it substantially. At this stage try to get as much off the slate as possible so there is only a dusty residue left, the less there is the easier it will be to remove later.
After the grout is dry, which will be at least 24 hours, use a dry cloth to scrub any dust residue left over from the surface of the slate and you will have a wonderfull slate floor you will be proud to show off.