Review all construction documentation before proceeding with the estimate for Plumbing. It is not unusual to find items on the plans, but not in the specifications; or they may be in the specifications but not on the drawings. Also check any and all communications; the owner may have requested a change or expressed a concern or a specific need, and not have had it included in your drawings or specifications.

Review All Drawing Divisions - It is important to review all of the drawings available to ensure that the systems called for will physically fit where they are supposed to. Sometimes the architect subcontracts out the structural design, so if the drawings are not carefully coordinated, a conflict may result.

Check Drawing Scales - When utilizing drawings from different sections of the plans, always check to see if the drawing scales are the same. It has happened that an estimator has ended up with twice the length of piping needed (or worse, half) because he/she was not aware that the drawing scales varied from structural to mechanical.

Document All Inconsistencies - All inconsistencies with standard practice, conflicts, omissions, and other concerns should be addressed before the final estimate is resolved. Do not rely on memory, which can become quickly overloaded in a rush situation.

Connecting to an Existing System - When tapping into an existing system for water, drainage, or waste, check with the local authorities (or building owner, in the case of interior work) to see if it is required that they or their designated contractor make the tap. Such surprises could lead to an unexpected expense or stoppage.

Non-Listed Items - It is important to include items that are not shown on the plans, but must be priced. These items include, but are not limited to, roof penetrations and pitchpots, dust protection, coring floors and walls, temporary water supply, cleaning piping, purifying potable water systems, cleanup, and final adjustments.

Cutting and Patching - Not all projects will be done under ideal conditions, that is, wide open spaces with no interferences. Many times the mechanical contractor will have to run duct or piping through pre-existing partitions or partitions that have been recently installed. Allowances must be made for cutting into the partition and the ensuing patching. Otherwise, a statement must be included with the estimate that all cutting and patching will be the responsibility of others.

Piping and Pumps - Most pipe is priced first as straight pipe with a joint (coupling, weld, etc.) every 10 feet and a hanger usually every 10 feet. There are exceptions with hanger spacing such as for cast iron pipe (5 feet), and plastic pipe (3 per 10 feet). When preparing an estimate, it may be necessary approximate the fittings. Fittings usually run between 25% and 50% of teh cost of the pipe. The lower percentage is for simple runs, and the higher number is for complex areas, such as mechanical rooms. read more

Plumbing Fixtures - Plumbing fixture costs usually require two lines: the fixture itself and its “rough in, supply, and waste”. Remember that gas and oil fired units need venting. read more