Helpful Estimating Tips

Division 1 - General Requirements

In figuring general requirements, do not include the salaries of the project managers or of any other personnel who are not directly site-related. Their wages are included in the "Main Office" expenses.

Always allow for cleanup in the estimate. No matter how clean a subcontractor leaves an area, it is almost always necessary to clean the area again.

In locations where snow is likely, allow for the expense of snowplowing if the project begins, ends, or works through the winter season. Another consideration is melting snow, which will inevitably end up in trenches, pits, or other low areas. Consequently, pumping costs should also be carried.

Always visit a proposed site. Do not rely on someone else's judgment unless statements in the contract require it.

Site Access--Can loaded trucks move into and out of the site easily? Is the site in/near a residential area? Are there height/weight restrictions?

How far away are the utilities that can be hooked into for temporary power?

Site Drainage--Is the area marshy? Will there be water problems when it rains?

Do any utilities need to be relocated?

Will any adjacent structures be affected?

If any of these items apply to the project, the associated costs must be estimated and included in the project bid/estimate.

The cost for installing temporary utilities, especially lighting, may be included in the specifications for the respective trades. Check this out to avoid adding an unnecessary cost to the estimate.

Division 2 - Site Work

When figuring the slope areas of pit excavation, remember that the slope areas usually form a right triangle when viewed as a section. Since the area of two right triangles equals the area of one rectangle with equal base and height dimensions, the volume of the slope area will equal the depth of the pit (the height) times the cut back distance of the slope (the base) times 1/2 the perimeter of the pit.

If a project has a large quantity of cut or fill, consider inquiring whether the site grade can be raised or lowered to economize the earthwork portion of the estimate.

If the project requires a large quantity of fill, consider creating a borrow pit on the site. This can lower the estimate significantly, as the cost for suitable fill material can be quite high in some areas of the country. The borrow pit can also be helpful as a receptacle for on-site spoil or other excavated materials, in this case saving dump charges.

It is very important to keep in mind while estimating earthwork the location and availability of dump sites for spoil. Unexpectedly large costs can accrue if the only site open to receive spoil is quite a distance away.

Often one of the most expensive parts of clearing and grubbing is the disposal of tree stumps. It is a good idea to know how and where this task can be carried out before completing the estimate.

One of the most common mistakes made in site work estimating involves site access. Estimators should visit the site not only to review site conditions, but to trace the route that the general or subcontractors' equipment will take to get to the site. If the equipment that is to be used on this project cannot get to the site, the estimate may be completely inaccurate.

When estimating paving, keep in mind the overall project schedule. Although it is common to wait until the end of the project before paving, consider what time of year the project is scheduled for completion. In colder climates, many concrete plants close for the season in late November and are thus very busy just before then. The supply or availability may be limited, and the prices may be higher.

A quick rule of thumb for Asphaltic Concrete is that for each inch of pavement thickness, 1 square yard = 110 lbs.

One should not automatically assume that the sewerage and drainage lines will go in at the early stages of the project. It may appear to make sense from a scheduling standpoint, but the inconvenience of having the site divided in half, with open trenches, loose pipe, and restricted access may ultimately cost more in lost time.

Many companies, eager to get started on their projects, shortchange the site investigation process. For the relatively short time and small amount of money involved, it is not a good idea to skimp on this important item. The untimely discovery of even one subsurface "abnormality" can be a painful lesson. An example is finding that the site was unknowingly used "way back when" as a spoils site for the rest of the industrial park and that there are ten feet of bad soils to excavate from under the stiff clay cap you assumed you would build on. Investigate the site thoroughly!

Miscellaneous Hauling Time and Distance Rule 30 MPH = 44 Feet per Second

Division 3 - Concrete

When estimating quantities of concrete for floor slabs or walls, do not bother to deduct small areas (two square feet or so) unless there are a large number of these areas, as this can take up more estimating time than the areas are worth. Also remember that you will be adding approximately 3% to the total volume for waste, thereby making these small areas even less significant.

When estimating the amount of reinforcing steel, either bar or mesh, if no lap specifications are given, add 10% to your quantities for lapping, splices, and waste.

It cannot be stressed enough that all plans for concrete must be checked. Concrete has been known to show up in all sections of construction drawings in various forms and uses (e.g., equipment pads location only on mechanical or electrical drawings, grouting requirements on steel drawings, etc.). Assuming all concrete requirements are indicated on the structural and architectural drawings can be a costly error.

When placing concrete in cold weather, it may not always be necessary to use heating devices to keep concrete warm while it cures. In many cases, insulating blankets and straw are all that are needed. Each situation must be evaluated individually, a worthwhile exercise in view of the considerable expense that can be saved.

When estimating the placement of concrete by direct chute, the forms available generally determine the volume of concrete placed per hour. The more you have available, the more concrete can be placed in the course of a day.

When estimating the number of forms and reuses for a job, remember to have enough forms on hand to keep the forming crew(s) busy while the previously poured concrete sets and starts to cure.

When placing concrete by methods involving a bucket and crane, pumping system, conveyor belt system or other mechanical system, set up enough forms to keep the above systems productive for the entire day. Usually the cost for the use of the equipment for a full day will be charged to you even if you only use it for part of a day.

During the estimating phase of the project, whatever method or sequence you envision for placing concrete, document it thoroughly. The main reasons for complete documentation are that it lets the field know how you arrived at the estimated cost, manpower, and equipment costs; and what methods they should use or try to out-do (in terms of cost effectiveness). Another reason for detailed documentation is that during the documenting process, it may become evident that you cannot place the concrete as you planned or that you can do it differently, more efficiently, or at less cost.

When estimating the amount of concrete compression testing that will be necessary for a project, figure on a minimum of one test per pour on smaller pours and a minimum of one test for each fifty yards of concrete placed. Each test should consist of taking a set of three cylinders minimum.

Rule of thumb for finishing concrete: Allow 1 man for each 1,000 S.F. of slab.

Consider drilling anchor bolts into the concrete to save time, manpower, and materials on layout and templates during the pour.

Division 4 - Masonry

When estimating quantities for masonry walls, do not deduct areas less than two square feet in area. They will more than likely use cut whole block and should be figured as such.

Remember to include miscellaneous items in your masonry estimate; they tend to get overlooked. These items include but are not limited to flashing, reinforcing, anchors, wall ties, inserts, bearing plates, lintels, support angles and channels, allowance for joist pockets, waterproofing, cleanup, final cleaning and pointing, steam cleaning, acid or power wash, color for mortar, and control joints. For a more detailed list, see the checklist located at the end of this chapter.

If the plan at the time of the estimate is to erect masonry walls after concrete slabs have been poured, keep in mind that the masonry contractor will be responsible for cleaning the dropped mortar off the concrete slab. Allow for this cleanup.

One commonly overlooked item in masonry estimating is an allowance for bracing walls, Until the structural system is tied into the masonry wall systems, the wall can be blown over relatively easily.

Plan ahead. Could your next project, which is not scheduled to start until later, be built with pre-assembled panels? If you have the manpower available today, it might be economical to have the contractor pre-build the walls in panelized sections in their yard, then deliver and quickly erect them at the site. This could save quite a bit of time on the project.

When a project calls for special brick such as utility sized for glazed, remember that these (especially glazed) more than likely will be special order. The order an manufacture time can be surprisingly long. Paying a premium or extra charges may be the only way to ensure faster "on-time" delivery.

Split face block will take longer than common block to set. This is due to the fact that these blocks have a somewhat irregular depth dimension (on account of the splitting process). They do not look "right" if set by lining up the squared corners. Adjustments must be made to have them line up properly.

The national average productivity for laying brick ranges from 400 bricks per day (considered "low productivity") to 600 bricks per day (considered "high productivity").

The following guidelines may be used to obtain economy in bricklaying:

Plan to have adequate supervision. Be sure bricklayers are always supplied with materials, so there is no waiting. Place the best bricklayers at corners and openings.

Use only screened sand for mortar. Otherwise, labor time will be wasted picking out pebbles. Use seamless metal tubs for mortar, as they do not leak or catch trowel. Locate stack and mortar for easy wheeling.

Have brick delivered for stacking. This makes for faster handling, reduces chipping and breakage, and requires less storage space. Many dealers will deliver select common brick in 2' x 3' x 4' pallets, or face brick packaged. This affords quick handling with a crane or forklift, and easy tonging in units of ten, which reduces waste.

Use wider brick for one wythe wall construction. Keep scaffolding away from wall to allow mortar to fall clean and not stain wall.

On large jobs, develop specialized crews for each type of masonry unit.

Consider designing for prefabricated panel construction on high-rise projects.

Avoid excessive corners or openings. Each opening adds about 50% to the labor cost for the area of the opening.

Bolting stone panels and using window frames as stops reduces labor costs and speeds up erection.

If not specified, consider adding as an option the application of one of the various anti-graffiti or vandalism products. These coatings are roller, brush or spray-applied to close the pores of the brick, thereby preventing permanent damage. Remember that graffiti and vandalism are present in all cities and towns, not just the major metropolitan areas.

Division 5 - Metals

When estimating the total tonnage of structural steel, add 10% to the total weight to allow for plates, connections, an waste, as a rule of thumb.

When the specifications call for the finish coat of paint to be applied prior to installation, allow considerable time for touching up the paint. Every time you lift, move, weld, bolt or alter the position of a piece of steel, you will need to touch up the finish.

It generally costs less to install joist systems that can utilize horizontal bridging (as opposed to cross or other types of bridging).

Division 6 - Wood & Plastics

Note that on construction documents not all rough carpentry items are listed or noted. Protective treads, inserts, and rails are examples of necessary but not listed items that the contractor must provide.

The search for carpentry items must include roof sections, wall sections, and all detail drawings.

Temporary construction should be included in Division 1, though it may sometimes be listed in Division 6. Double check to assure yourself that you are not double-pricing these items.

Treated lumber should always be used when the lumber will come in direct contact with concrete, masonry, or the earth.

Even when bridging is not shown on joist drawings, always include it, as it helps to distribute concentrated loads to the adjacent joists.

One of the most overlooked areas of wood blocking is at roof edges. Almost always, a built-up roof or membrane roof system will require some sort of blocking and/or cant strip system.

When budgeting millwork, a rule of thumb is that the total cost of millwork items will be two to three times the cost of the materials required. Do not overlook adding protection to all millwork, especially if the work is by others.

Do not rely on yesterday's material quotes. Due to current and predicted shortages of lumber and the resultant fluctuations in the market, caution is warranted.

Short of time? Many lumber yards retain competent estimators who will provide material lists/estimates from your plans for little or no cost. This is also a good method for checking your own takeoff.

Division 7 - Thermal & Moisture Protection

When estimating the installation of a membrane roof, be sure to include the cost for walkway pavers to create a path to roof-mounted mechanical equipment. You will more than likely be required to install these in order to obtain a warranty.

In many locations, manufacturers make their materials available through one distributor/contractor franchise. If only one type of roofing is specified, you may not have much choice as far as acquiring costs or quotes.

Even though it may be less expensive to use a "suitable substitute," the system that is specified is the one that should be estimated. If you include as part of your estimate a non-specified system and get the job, you may be required to furnish the originally specified, more expensive roof system.

Do not assume that all sheet metal items are "off-the-shelf" items. Gutters and downspouts as well as termite shields, gravel stops, expansion joints, and reglets may need to be shop-fabricated. Checking into information catalogs could save quite a tidy sum in extras.

Division 8 - Doors and Windows

For walls to be considered fire-rated, any doors in those walls must be fire-rated. Most plans do not spell out which interior partitions are to be considered fire-rated. In commercial applications, a rule of thumb is that all partitions that have drywall (or masonry) from the floor to the above structure and few, if any, penetrations should be considered fire-rated.

If the drawings do not include a door schedule, it may be worth the estimator's time to develop one, especially if the project is large or complicated. On the schedule should be the opening number, door type, size material, glass or louver requirements, and remarks.

The door schedule should include a frame schedule listing the frame material, type, and jamb, head and sill details.

Hardware requirements should be listed on the door schedule as well. Keep in mind the fact that hardware can, in some instances, be more costly than the door itself.

While the drawings may not show it, local codes may require special hardware and opening systems to allow a structure to be accessible to the handicapped. Contact the local authorities for their codes an requirements.

Special attention should be given to any oversized or unusual type of doors. These items should not be priced on a prorated basis, as they are generally special order items. The costs of special doors can skyrocket, especially if they involve exotic woods, special finishes, or special attention (which usually means higher labor costs). Note also that special doors may require a considerable amount of lead time for ordering and shipping.

As with all doors to be included in the project, all windows should be listed on the drawings in a window schedule. If none is included, it may be well worth the time to create one. The schedule should contain the opening number, window type, window size, glass type, frame material and details, and required accessories and hardware.

As a rule of thumb, building hardware for an average quality building can be expected to run in the neighborhood of 2% of the entire building cost.

Division 9 - Finishes

If, during the course of a project, the owner decides to cut back on costs, this is not a good area in which to do it. When a project is finished and the owner and prospective tenants walk through, they will not be able to see a complicated foundation, nor the marvelously engineered subsystems. What they will see are the finishes. If the project is "cheapened" at this point, it will show and dull the luster of an otherwise shining project.

A complete set of plans should contain a room finish schedule. If one is not available, it would be well worth the time and effort to put one together. A room finish schedule should contain the room number, room name (for clarity), floor materials, base materials, wainscot materials, wainscot height, wall materials (for each wall), ceiling materials, and special instructions. It is handy and easier to work out a room finish schedule on a grid system.

If not specified, the studs for plaster partitions are usually spaced at no greater than 16" on center.

Allow a 5% waster factor when figuring the amount of lathing.

Deductions for openings in plaster partitions vary by the preference and experience of the estimator, from 0% for openings of less than 2 S.F. to 50% for openings greater than 2 S.F.

For curved walls with a radius less than 6' allow twice as much plaster.

Pricing a plaster and lath job depends on the quality of work desired. A first class project will have variations in the wall level of less than 1/16" in 10 feet. An ordinary plaster job (or commercial grade) may have waves of 1/8" to 3/16" in 10 feet. Overall, labor for first class work is approximately 20% higher than ordinary or commercial grade work.

A rule of thumb when estimating materials for drywall is to not deduct for door or window openings of less than 32 square feet.

A single roll of wallpaper will cover approximately 36 S.F. Allow approximately 6 S.F. per roll for waste. This means take the total square foot area to be covered and divide by 30 to determine the number of rolls needed.

For vinyls and grass cloth coverings with no patterns to match, allow approximately 10% (3 square feet per roll) for waste. For patterns requiring matching, allow up to 25% to 30%.

Waste can run as high as 50% to 60% for coverings with large, bold, or intricate patterns.

Always specify wallcoverings from the same batch with identical batch numbers. This will help to ensure that the colors and patterns will match.

Review the specifications to determine if there is any requirement to provide certain amounts of extra floor tile, ceiling pads, paint, wallcoverings, etc., for the owner's maintenance department. In some cases, the owner may require a substantial amount of materials, especially if it is a special order or long lead time item.

Division 10 - Specialties

When taking off Division 10 items, list each item called for, along with the specified manufacturer. Often no substitutions are allowed for specified Division 10 items.

When receiving bids for Division 10 items, make sure that the costs of installation are included. In many cases these items are sold per unit without installation. If installation is not included, inquire if delivery is included. Items sold by the piece without installation usually do not include any shipping costs.

Note that many Division 10 items require some type of support system not usually supplied with the item -- such as support brackets, plates or angles. These must be accounted for and may need to be added to the appropriate division. Phrases in the specifications that gloss over this subject and thus make it difficult to recover any added costs include "The contractor shall install all products in accordance with the manufacturers' recommendations" and the like. Remember, it is much more costly to install a behind-the-wall support system after the wall is in place.

In some cases, Division 10 items may require some assembly before installation. This assembly time can often exceed the time required for installation.

There can be a wide variance in costs for the exact same item. Smart shopping for these items can help lower your overall bid.

Division 11 - Equipment

Do not assume that items covered in Division 11 will be purchased and installed by others outside of your contract. This can be a costly error. Check all drawings for these items and for terms such as "NIC" (Not In Contract) or "By Others." If these or similar terms are not in evidence, then it is safe to conclude that these are in your scope of work.

In many cases Division 11 items are purchased by others, but their installation is the contractor's responsibility. Check all drawings and specifications carefully for these items.

In cases where Division 11 items are purchased by others but installed by the contractor, contractors often add a handling charge. (10% of the estimated material costs is common practice). This charge covers the receiving, handling, storage, protection, and final delivery of these items.

Note that Division 11 items may require some type of support system not usually supplied with the item -- such as support brackets, plates, or angles. These need to be accounted for and may need to be added to the appropriate division. Phrases in the specifications that gloss over this subject an thus make it difficult to recover any added costs include "The contractor shall install all products in accordance with the manufacturers' recommendations" and the like. Remember, it is much more costly to install a behind-the-wall support system after the wall is in place.

In some cases, Division 11 items may require assembly before installation. Be aware that the assembly time can often exceed the time required for installation.

Division 12 - Furnishings

Do not assume that items covered in Division 12 will be purchased and installed outside of your contract, especially if any furnishings or typical arrangements are shown on the drawings. This could be costly assumption. Check all drawings and specifications for these items and if any are found, check for the terms "NIC" (Not In Contract) or "By Others." If these or similar terms are not present, it is safe to conclude that these items are in your scope of work.

In many cases, Division 12 items are purchased by others, but the contractor is responsible for them. Check all drawings and specifications for these items.

In cases where Division 12 items are purchased by others but are to be installed by the contractor, many contractors add a handling charge. (10% of the estimated material cost is common practice.) This charge covers the receiving, handling, storage, protection, and final delivery of these items.

In some cases, Division 12 items may require some assembly before installation. The assembly time can often exceed the time required for installation.

When installing materials purchased by others, be sure to allow for cleaning time. Invariably, these items will need some cleaning and this responsibility will fall upon the installer.

Division 13 - Special Construction

If you take outside quotes as an aid to estimating Division 13, review the scope of work covered in those quotes. It may be that the outside agent has wrongfully assumed that you will provide traditionally supplied items such as excavation or an unloading crane. Check to make sure that it is covered somewhere in your estimate, and that it is not carried by both parties.

Review all documentation to ensure that all interfaces, such as electrical connections and control wiring, are accounted for. These items have a habit of falling through the cracks of an estimate.

Division 14 - Conveying Systems

When preparing an estimate for elevators, check to make sure that doors have been included, not only for the elevator itself, but for each floor where the elevator stops.

When figuring the cost for a hydraulic elevator, make sure that the excavation for the elevator piston is included in the estimate. For each floor above grade that the elevator is to travel, there should be an equal length of piston below grade.

When estimating any vertical conveying system, make sure all openings for doors, dumbwaiter access panels, etc., are fire-rated per the applicable code. In case of a fire emergency, their shaftways will otherwise act as a conduit for smoke and heat.

When in doubt about price, what is standard on elevators, material selection, availability, etc., do not hesitate to call on any of the elevator manufacturing companies directly. The competition of your business can be fierce, and they will try to assist you in any way they can.

Make sure that either the conveying system estimate, the electrical estimate, or mechanical estimate include the tie-in to the rest of the electrical and control systems. This is another item that people often assume someone else has covered.

Division 15 - Mechanical

Review all construction documentation before proceeding with the estimate for Division 15. 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.

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. For example, sometimes the architect subcontracts out the HVAC design function as well as the structural design. If the drawings are not carefully coordinated, a conflict may result, such as inadequate space under deep trusses where main ductwork was supposed to be installed and a required finished ceiling height maintained.

When utilizing drawings from different sections of the plans, always check to see if the drawing scales are the same. It has happened that as 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.

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.

When estimating the cost of an HVAC system, check to see who is responsible for providing and installing the temperature control wiring system. In many cases, this item is overlooked, as it was assumed that it would be included in the electrical estimate. This can be a costly assumption.

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 led to an unexpected expense or stoppage.

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, testing and balancing HVAC systems, cleaning piping, purifying potable water systems, clean-up, and final adjustments.

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 ad the ensuing patching. Otherwise, a statement must be included with the estimate that all cutting and patching will be the responsibility of others.

Clarify who is responsible for connecting the electrical wiring to mechanical items. It has been argued that the electrician is responsible only for bringing the wiring to the unit, while others maintain that it is the electrician's job to connect the wiring.

Division 16 - Electrical

Conduit should be taken off in three main categories: power distribution, branch power, and branch lighting. In this way, all conduit does not have to be taken off in one session. Instead the estimator can concentrate on systems and components, thereby making it easier to ensure that all items have been accounted for.

Remember that aluminum wiring of equal ampacity is larger in diameter than copper and may require larger conduit.

When estimating the costs for the installation of switchgear, especially large items, factors to review include access to the site, access and setting at the installation site, required connections, uncrating, pads, anchors, levelling, final assembly of the components, and temporary protection from physical damage, including from exposure to the environment.

While supports and pads may be shown on drawings for the larger equipment, in many cases nothing is shown for smaller pieces such as panelboards and area transformers. Whether a special floor-to-ceiling support system is required, or just a piece of plywood for the back of a panel, it must be included in the costs.

Do not overlook the costs for equipment used in the installation . If highlifts, scaffolding, or cherry pickers are available, the field will use them in lieu of the proposed ladders.

The estimator should take the weights of materials into consideration when completing a takeoff. Topics to consider include: How will the materials be supported? What methods of support are available? How high will the support structure have to reach? Will the final support structure be able to withstand the total burden? Is the support material included or separate from the fixture/equipment/material specified?

It is important to include items that are not documented in the plans but must be priced. These items include, but are not limited to, testing, equipment hookups, motor controls, disconnect switches, special systems, dust protection, roof penetrations, pitch pots for the roof, coring concrete floors and walls, cleanup, and final adjustments.

Examine all contract documents to determine if providing temporary power and lighting is included in your scope of work. In many cases, temporary lighting and power requirements are not specified in contract documents. Either way, you will probably be required at some point to provide a cost for these items. Depending on your bidding strategy, you may or may not want to list this item as an alternate to your estimate. However, if it is stated in the contract documents, then you will be fully responsible for providing this service.

Not all projects will be performed under ideal conditions--that is, wide open spaces with no interferences. Many times the electrical contractor will have to run conduit through pre-existing partitions or partitions that were recently installed. Allowances must be made for this 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.

Clarify who is responsible for the connecting of the electrical wiring to mechanical items. It has been argued that the electrician is responsible only for bringing the wiring to the unit, while others say it is the electrician's job to connect the wiring.

Performing a fixture takeoff is a good way to become familiar with a proposed project. Fixtures should be taken off room-by-room, using the fixture schedule (if provided), specifications, and the ceiling plan. While performing the count, it is a good idea to also take off the controlling devices and add accessories (plaster rings, outlet boxes, cover plates, etc.). A spreadsheet works well for this purpose.

When finished, this takeoff can be used for purchasing, accounting and billing, and cost control.

When estimating material costs for special systems, it is always prudent to obtain manufacturers' quotes for equipment prices. Also, some installations will require special accessories. Often, the sales engineers are a good source of information on these requirements.