Having the right estimate helps the contractor and clients in their planning and helps to reduce tension alot during construction. Variations eats deep into budgets and can really destabilises entire projects when is on the negative side.
(1)Unusual/ bad benchmarking-This is when you’ve done similar projects before and you use exact rates to cost the proposed ones not minding no two projects can be exactly the same. Topography, nature of soil etc can mess up your benchmarking.
(2)Unclear/Incomplete designs- The drawings when not adequately detailed may leads to assumptions of materials require. Often these assumptions are bloated and in other cases grossly inadequate.
(3)Untested Innovations/Techniques- Various techniques are used in construction with additional innovations, the estimator may be ignorant of some processes in constructionmethods which can cause serious oversite in estimating.
(4)Contractors desperation- Quest for job may make a contractor to quote a very low cost for a project just o escape financial lack/loosing the job to other competitors. This will surely bounce back and affect the entire project. An estimator and contractor that must cut costs by reducingonly rates without change in materials may run into such problems.
(5)Pressure of over reduction by client-In the bid to save money yet still maintaining good quality and standard, many clients puts pressure on their contractors to reduce the cost of construction beyond reasonable/acceptable level. Out of ignorance on anybody’s part the client request may be acceeded to by an unscrupulous contractor/estimator which will cause bitterness and dissapointments afterwards as project progresses.
(6)Not employing a Qualified Quantity Surveyor before and after project construction- Qs’es are not only needed before construction, as work progresses they are useful for guiding our expenses, deployment of materials, payments of workers,proper records on financial activities and variations etc. Overall they help guide and keep you focus on your project, as they help to notify you of financial implications of every decision taken concerning the project before it is executed.
(7)Unexpected Environmental situations-Environmental factors can slow the wheel of progress on site and ultimately affect cost. Consider flooding which can slow the work,destroy some materials and jerk up the cost of construction.
(8)Human Incursions/Nuisance-Construction time can be affected when social miscreants disturbs construction. Settling them may take unexpected delays, material could be lost which will affect the cost.
(9)Market fluctuations-Of course prices of materials especially cement fluctuates alot in this part of the world. There are more construction activities in the dry season, hence higher demands on construction materials which also raises the cost of these materials. If you already have a lower markup, the estimate will no longer be adequate, variations must be added which will overshoot the initial budget.
(10)Change in specifications-As project progresses, design changes and clients new requirements will affect the estimate no matter how small the changes.
(11)Redesigning or Remodelling-Again when you adjust initial designs like internal walls been shifted to make some rooms more spacious or redesigning the elevations can cause a big difference in cost of construction.
(12)Procurement Timing-You must procure some materials intime to avoid higher cost.
(13) Not buying in bulk or purchasing ore than required can also affect your estimate greatly.
(14)Inadequate or wrong measurement of plan-If there are errors in reading the plan or attention not being paid to details during construction, the estimate will run into problems.
(15)Wastages-Though there should be room in the estimate to cater for wastages , however without proper management on site you may record wastages that will affect the estimate.
(16)Accidents-Insurance will have to cover for accidents onsite if there is any but for anyone without insurance and there is an unexpected occurences the project will have to suffer the bills.
(17)Improper or absence of statutory legal documentations- If right approvals aren’t gotten or there are issues this may cause stoppage of work, paying penalties etc which will also affects the estimate.
(18)Dispute on Property-For a project that will be disturbed by legal problems this will ultimately affect total cost of construction due to delays etc
(19)Theft of materials on site
(20)Logistics and Preliminaries,process hurdles