(Bursting Factor X Gram per Square Meter)
280 * length of one sheet (in feet).
u can use 250 GSM paper or 253 GSM for 3 ply box.
Fire
Yarns vary enormously in how far they go, so you need to look on the ball band where this information is often given. If not, the manufacturer's website may help.
roof scoop or sun roof
roof is roof. It's the same.
it is the roof that is what on the top a roof
The apex of roof is basically the highest point of the roof where ridge cap and ridge roll of a roof is located.
The roof
The roof of a cave is referred to as the "ceiling" or "overhang".
Concave roof is a roof in the form of a dome or circular shape. A concave roof is one which slopes downward toward the center. You can remember this by thinking the roof is "cave"-ing in.