Keratoconus (KC) is a disorder of the eye which results in progressive thinning of the cornea. This may result in blurry vision, double vision, nearsightedness, astigmatism, and light sensitivity. Usually both eyes are affected. In more severe cases a scarring or a circle may be seen within the cornea.
On the plus side Hardie Board is primarily made of concrete. It is a fibrous concrete board that termites don't eat. This is good news for warmer climates where termites stay active most of the year. Hardie siding is also impervious to moisture. You can put it in a pail of water and leave it for as long as you like and it will not become saturated.
If the closure plate developed a fault (e.g.hole) smoke could NOT enter the room. A closure plate can be made of any non-combustible material. In the picture on this page the closure plate is made of 12mm concrete board which is much easier to cut than metal. HardieBackerÂ® 12mm cement backerboard (previously named HardieBackerÂ®500) has been evaluated in accordance with the protocols and acceptance criteria of EN 12467 and was found to be compliant.