When something has hit it or two years, whichever comes first.
On many building and construction sites falling tools or other objects are a safety hazard. Hard hats protect workers from this. You used to find them only on construction sites, but nowadays it appears the "safety gurus" have deemed them necessary for almost any kind of worker.
Safety glass are made to be worn in situations where there is some danger of things flying into the eyes. They are large enough to fit over regular glasses and made of break-resistant materials.
PVC is widely used in water pipes, irrigation pipes, irrigation boxes and in window frames.
In construction, a 'jamb' is the framework that a door or window fits within.
wet sieve analysis is wet
dry sieve analysis is dry
200. This does not include additional tiles that may need to be cut or split to fit the exact shape.
There are many factors that play into an estimate. What type of material are you wanting the driveway to be paved with? (Concrete is more expensive than black-top) How large is the area you are wanting to pave? (This will determine material pricing) There also may other things a contractor has to figure in such as: preparation time and effort, disposal of the old driveway material, any inclines or declines, water drainage, and access to the job site including any underground obstacles.
It depends what stone and timber you are comparing and what type and area you are considering.
Stone would be more labour intensive and likely be more expensive.