Making & installing an outdoor house number

In this tutorial I’ll follow the making of an outdoor house number which is to be attached to a masonry wall.

	If you’re not dealing with too large a piece, the wetsaw is ideal for cutting out CFC.For this house number, I’m using a scrap piece of 9mm ExoTec (that’s compressed fibre cement with a waterproof coating).Here I’ve just marked it out with a pencil & am cutting it out on a wetsaw.
	The coating I mentioned on the ExoTec is bad for mosaic -it resists adhesion, and while a polymer added glue will still bond OK, it’s far from desirable.When I use ExoTec I’ll grind all the coating off with an angle grinder (diamond blade) as shown
	Tidy up the edges with the angle grinder.
	Once I’ve ground all the coating off, I’ll wash the piece with water.At this point you can spot any bits you’ve missed as they won’t darken with the water.Although it’s probably OK to have a few very small areas that haven’t been removed – I prefer to remove everything – back to the grinder here!
	To drill holes through the CFC you’ll need two drill bits.The masonry drill bit is to be used with a hammer drill to go right through the piece. Choose a suitable guage bit for the screw you’re using, and where possible, I prefer a long shank – later on you’ll want to drill through the mosaic to the wall & a long shank avoids the chance of hitting the mosaic when you drill through.The standard drill bit is used for coutersinking and should be a much larger guage than the masonry bit. You’ll ruin the cutting face pretty quickly drilling into CFC, so I keep an old bit just for that purpose – occasionally I’ll give it a touch up to keep it sharp.
	Mark the board & then drill right through the piece with your masonry bit on a hammer drill.Then with your larger standard bit, countersink a hole just big enough to fit the head of your screw. You might like to test it before you put the drill away – you want have to screw head fairly flush with the board.Bottom inset shows the completed hole after countersinking.
	Skip now to the point where the mosaic’s laid, and I’ve not glued the tile that covers the fixing point(s).I’ll put the piece(s) in place and grout now.Ensure you keep a little glue & grout aside for installation so you won’t have problems matching the colour.
	While your grout’s still wet, push the tile out from behind with a long screw or similar.Clean your tile in water before the grout dries.
	It’s a good idea to clean all the surplus grout out from the area so that the tile fits back in easily.Once the mosaic’s cured, you can now attach it to the wall with a screw as indicated. Drill or screw right through the mosaic into the wallOnce the mosaic’s secured, you can then glue the covering tile(s) in place, and grout in one session and you’re done!

Now for some additional tips:-

– It’s a very good idea to instal a baten to sit your mosaic on before installing – you can ensure your baten is level, then won’t have to worry about getting everything level while you’re dealing with the weight of the mosaic – this is pretty much mandatory when dealing with large mosaics. The baten can be removed once the installation’s complete.

– Plan where you’re going to put your fixing points and how you’re going to instal before you even start with the mosaic. Your fixing points should be spaced evenly and not more than 600mm apart.

– If you don’t ever plan to move the mosaic, you can use some tile glue or liquid nails on the back for extra strength if desired. You can also silicone around the edges to prevent water or insects entering.

– If you’d like the option to remove the mosaic later, use silicone to glue the covering tiles as it’s easier to remove the tiles later. Also, it pays to put a small notch in the covering tiles to make it easier to identify them later.