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Estimate
An approximate calculation of quantity or degree, particularly with respect to:
  • Costs to replace an asset
  • Life remaining on an asset
An estimate is made up of a combination of estimate parameters, such as:
Estimates may be derived through a variety of means and techniques, including:
Estimates are graded based on their level of accuracy, using varies techniques, including:

Factors impacting estimating
Some examples of additional design decisions that would affect the overall project costs (this is not an exhaustive list):
a)    Access and safety –different contractors may make different assumptions about access, and what safe work procedures can be used.  The Strata Corporation should make sure the contractor is completely responsible for safety on site (particularly important if two projects and two contractors happen to be on site at the same time).
b)    Roof to wall transitions – There are two sections where the roof meets the wall, and the interface detail (e.g. will the new membrane be torched to the existing, or stucco cut out and new flashing added. 
c)    Roof to chimney transitions
d)    Penetrations – vents, flues and other penetrations also have to be detailed, and there are different levels of quality.  Currently, we recommend building a curb for vents to reduce the risk of metal sitting in water (and corroding). 
e)    Drains and other accessories – will they be replaced, and how will they be connected to existing piping.  How will they be detailed into the roof system (drains are a common source of leaks).
f)    Drainage- is there any need to revise, reslope or otherwise adjust the drainage to address ponding water?
g)    Third Party Warranties – will there be an RCABC guarantee (the guarantee has a cost).  If there is not a warranty, will the work be done to the same standards as the warranty?
h)    Manufacturer’s warranties – what manufacturer will be used, and what type of warranty will be provided (some manufacturers require certain standards of installation, including inspections by their representatives to obtain a warranty)
i)    Roof to roof transition – what provisions are made for the transition between the low slope (flat) roof at the centre of the buildings, and the sloped roofs at the edge.
j)    Venting – are changes required/recommended for venting of the roofs.
k)    Removal of existing materials – can some or all of the existing materials be left in place?  How will this affect the long term viability of the roof?
l)    Roof material quality – different roofing and flashing (metal work) have different material costs
m)    Insurance – does the strata corporation need additional insurance protection if a welded roofing material is used.
n)    Scope of work – will all roof areas be replaced at the same time, or will the roof be replaced in sections?

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See also: