- It's expensive.
- It's heavy - I injured my left arm lifting the stuff and forget about maneuvering it in the teenytiny confines of New Bog
- In powdered form it is highly toxic. Working with it creates powdered backerboard by the cartload
- It buggers up your tools. The manufacturer claims you shouldn't use saws or powertools because of the hazardous dust but the reality is that it eats any kind of blade in very short order. A typical scroll saw blade rated for metal will fail completely within about three to four inches of cutting unless measures are taken to reduce the blade's contact with what it's trying to cut. The manufacturer recommends the "score and snap" method. A Stanley Knife blade will last for approximately 20 passes before the point is completely abraded away. It takes about 150 passes to cut halfway through a board on the long axis, and you try scoring and snapping a double ogee.
- It is brittle. When snapping the board (during the recommended score and snap method) it will often snap across the workpiece instead of along the score.
- Any gaps must be caulked using mortar. Mixing mortar is one of my least favourite occupations, second only to trowelling mortar or cleaning the tools after trowelling mortar.
Production of one 5x4 floor has killed five Stanley Craft Knife blades, seven jigsaw blades including a fifteen year old Pirhana blade that was universally useful and that Black and Decker no longer make, one spiral saw bit that actually melted and two multi-fluke countersinks.
This I vow on the manual for my router: Even were my beloved workmate to be kidnapped and held by terrorists pending my capitulation, never again will I attempt to work this material in any way, shape or form.
I leave this blog entry as my testament to several good tools sent to the happy hunting grounds in the attempt to cow the hated demon Backerboard into submission, and as insurance should Mr Brain clear the registers again and let me forget how dreadful a time I had of it. By this strategem I hope never to look up from a piece of broken backerboard with a blunt Stanley Knife in my hand and say "Now I remember why I didn't want to use this stuff."