15 Factors for Improved Warehouse Space Planning

So, you are planning a new warehousing facility. Great! You&#;ve come to the right place. In this article, we help you understand the process of procuring a metal warehouse, from what factors to consider to how to erect the structure.

Step 1: Planning a warehouse project

Typical Sizes and Factors to Consider

The most important first step in procuring a warehouse is to make sure you carefully consider and understand your space and layout needs. These needs include both present and possible future requirements. Building a warehouse where your equipment doesn&#;t quite fit is a waste of time and money. You need to think carefully about the required size and layout and then think some more.

Most warehouse-type buildings are relatively small &#; up to 20,000 sq ft &#; but some are much larger than that. Typical uses include: racking & distribution centers, light manufacturing, grow houses, cold storage, flex warehouses, and data centers. The larger the structure, the more flexibility in space usage it offers, but at a cost of not only higher purchase price but also larger annual heating and cooling demands and property taxes.

Some questions that you need to ask yourself are:

1. Will I have a fixed equipment layout? Conveyors? If yes, it is best to start with the layout provided by the equipment manufacturer or process consultant and build the structure around it rather than selecting an arbitrary size and trying to fit the equipment inside. You will have more design flexibility if you don&#;t have fixed equipment.
2. Will I have storage racks? If yes, how high? The higher the racks, the more important it is to have a flat and level concrete floor. The layout of tall racks needs to be coordinated with the bay spacing (see below).
3. Will I have deliveries by truck? If yes, you&#;d need to make provision for loading docks, overhead doors, and perhaps material-handling systems to transfer the delivered loads inside.
4. What size items will you be storing? This will help determine the sizes of the door openings and the interior aisles.
5. Will you need overhead cranes to move the contents? If yes, what kind and capacity? This will affect the framing costs.
6. Will the facility be heated and cooled? This will help determine the amount of insulation and HVAC equipment weights.
7. Will there be people-occupied spaces (offices, break rooms, bathrooms, etc.)? If yes, you will need to consider where to place these areas within the building, ensure proper fire exit paths are provided and extend the utilities there. Most will need those spaces.

If you are unsure how to answer some of these questions or you have some unusual circumstances, you might consider consulting an architect experienced in warehouse design before proceeding further.

Height and Clearance Considerations

Many warehouses of metal building construction use primary frames that span over the entire width of the space. This clear span design allows for maximum flexibility of space utilization, but it also means that the framing sizes are rather deep. Intermediate columns might be cost-effective for very large warehouses or those with heavy overhead cranes.

The clear height of the structure (the distance from the floor to the underside of the framing) will depend on the height of the proposed equipment or storage racks. Many smaller warehouses have an average height of 20 ft, but the recent trend is to have bigger clear heights, particularly in larger buildings. A good safety margin on height will come in handy if the equipment or rack sizes increase in the future.

The depth of the framing is not precisely known at the order time before the framing is designed. Thus, it is wise to make conservative assumptions and let the building supplier know the minimum clear height.

Again, don&#;t choose the building by its eave height (the height of the side walls) &#; specify the minimum clear height inside. Please note that because of the roof slope and frame taper, the clear height along the sidewalls is lower than near the center of the building. For this reason, the tallest equipment is best located in the middle of the span.

Bay Spacing

Typical bay spacing in steel buildings is 25 feet, although many suppliers provide other bay spacings, such as 20 ft. Because the deepest part of the structure is where the primary frames are, bay spacing and frame layout should be coordinated with the proposed equipment locations.

See our article on planning a building project for additional details on sizing, bay spacing, and framed openings.

Bay spacing for metal buildings

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Framed Openings

As explained in Step 2 below, warehouses typically have wall openings for doors and windows. The overhead door sizes will depend on the size of the items that will be moved through them. The minimum sizes of the windows are primarily determined by the amount of natural light that is desired, while personnel door sizes are rather standard.

Each wall opening has to be framed, so the building manufacturer will need to know the number and sizes of the openings to give you an accurate quote.

As a general rule, a steel buildings eave height should be at least two feet above the highest framed opening to allow for the depth of the framing.

Loads, Codes, and Permitting

Most locales in North America have a building code enforced by the local building department. Prior to construction, you or your contractor will need to obtain a building permit. The department will explain to you what are the required fees and submittals for obtaining a permit. Typically, you will need to submit a stamped engineering plan provided by the kit supplier, a foundation plan stamped by a professional structural engineer, and a site plan showing the grading and utilities for your new structure.

The local building code will specify the minimum loads that the structure should be able to resist, including snow load, wind load, live, seismic, and other applicable loads. See our article on permits, codes loads for more information. Also, see our page on building codes by state for local codes and contact details.

Site Selection

Site selection is the process of finding an available site suitable for your needs. Since warehouses depend on truck deliveries, reliable road access is a must. The site should also have all the required utilities available for an extension to your building. See our construction site selection section for additional discussion.

Site Analysis

The site you select should have competent soils that can support your building&#;s foundations. Foundations on sites with poor soils might require large footings or expensive deep foundations, i.e., drilled shafts or piles. Therefore, a preliminary site investigation is a must.
This investigation will determine whether the soil at the site is buildable (capable of supporting a building), whether the soil is drainable, etc. See our article on construction site preparation for an explanation.

Engaging a Structural Engineer

It is possible to procure a steel building on your own, as long as the building is rectangular and does not contain nonmetal walls or roofs, interior drywall finishes, cranes, very high racks, and other special situations. Any of these &#;complications&#; would likely require a licensed structural engineer experienced in specifying pre-engineered metal buildings (not all engineers are).

The engineer would specify the custom requirements your building needs so that the building manufacturer can design the structure accordingly. Please understand that you will likely need to engage an engineer to design the foundations anyway, so you might as well engage the engineer at the outset.

Step 2: Design considerations

Designing a Warehouse: Hire an architect vs. working directly with the building supplier.

Buying a building kit directly from a supplier is possible if it doesn't contain any special features mentioned above. Simply specify your required design information in the quote request form on our site.

If you need to order a large building (50,000 sq ft +), or if it will have some of those &#;complications,&#; an architect&#;s assistance can be invaluable. Remember that for larger structures, you might also need the services of HVAC, plumbing, fire protection, site, and other engineers; the architect would be in a good position to coordinate their work.

Warehouse Design Considerations

There are many design possibilities open to you when ordering a prefabricated warehouse from one of our suppliers, from a variety of roof and wall styles to door choices and exterior finishes. Some of these are discussed next; for an expanded discussion, see our article on custom metal buildings.

HVAC Systems

Warehousing facilities typically need a ventilation system and heating and cooling. Together, the equipment for fulfilling these needs is known as an HVAC (heating, ventilation, and air-conditioning) system. A licensed mechanical engineer generally designs the system.

A fire-protection engineer should also be engaged if there is also a need for fire-protection equipment, such as fire sprinklers. If you will be working with an architect, he/she will help you determine whether your proposed structure needs fire protection measures and what those might be.

While small HVAC equipment, such as suspended fans that weigh less than 50 lbs, could be incorporated into the structure without complications, supports for larger equipment need to be specially designed. In particular, your building manufacturer needs to know the weights and locations of any rooftop HVAC equipment. (Your mechanical engineer or contractor should provide these.)

A variety of methods can support rooftop HVAC equipment. Lightweight units, such as large fans, are most commonly supported on prefabricated curb boxes designed to fit with the selected metal roofing profile.

Heavy HVAC equipment, such as cooling towers, is generally supported on structural steel frames on legs. The legs bear on top of the primary framing, and the equipment frame beams span the distance between the primary framing. If you need any of these supports, most likely, they will NOT be provided by the kit manufacturer, and you will need to have them procured or fabricated locally.

If your warehouse will need fire sprinklers or other fire-suppression systems, have their design, locations, and sizes determined by a fire-protection engineer BEFORE you order the building kit. Water-filled sprinkler pipes will hang from the purlins; these pipes sometimes exert a lot of weight on the roof purlins &#; hundreds of pounds in the case of sprinkler main lines. To deal with this extra load, the building manufacturer may provide doubled-up or heavier purlins at the points of pipe support attachments.

If you know that you&#;ll have sprinkler pipes but don&#;t yet know their layout, the manufacturer would have to design the entire roof framing for an additional loading &#; typically ranging from 5 to 10 lbs/sq ft, known as &#;collateral load,&#; to account for the weight of sprinkler pipes. Sprinklers should NEVER be added to a prefabricated building after the fact without an engineering assessment, as the extra loading might severely compromise the building's structural integrity.

Roof Options

Most warehouses are supplied with shallow-slope (such as 1:12 pitch) roofs with Galvalume coating. No other special paints are generally needed. If you desire other roof types &#; for example, you wish to match the appearance of adjacent structures &#; read our section on roof styles and profiles. Our article on color and color schemes for metal buildings discusses the possibilities of using various roof colors.

Considerations for Solar Panels

If you plan to place solar panels on your building to reap the cost benefits of solar power, you are in good company! Steel warehouses with shallow-pitch roofs and large surface areas are good candidates for installing the panels.

However, solar panels add some weight to the roof, and your building supplier should be advised of your plans. Mention that you plan to install solar panels on the quote request form.

Wall Options

The majority of warehouses and other commercial and industrial buildings utilize basic metal siding, such as PBR metal panels. These panels are included as part of the warehouse package; they provide the lowest cost and are adequate for most cases. Sometimes, another cladding option is desirable for architectural appearance or complementing nearby buildings.

For more information on the available siding options and on nonmetal wall materials, see our article on siding options.

Cold-Storage Facilities

These facilities are one example where special wall materials are needed. Insulated metal panels (IMP) are common in these structures to provide the maximum insulation value. IMPs consist of two layers of metal with rigid insulation sandwiched in between. In addition to IMPs or other high-insulating wall options, cold-storage facilities typically require thick layers of rigid insulation on the roof and even under the floor slab.

Insulation

While cold-storage facilities have some of the highest insulation requirements, insulation is needed for almost all steel-frame buildings, with small shops and unheated garages being the likely exceptions. Warehouses, in particular, are generally insulated to maintain the optimal temperature and humidity for the contents and to provide a pleasant working environment.

The most common type of insulation used in metal warehouse buildings is fiberglass blanket insulation. It has the lowest cost and is easy to install. It has the added benefits of being both fire and sound resistant. See our article on insulation options for steel buildings for an in-depth discussion of various insulation types used in steel warehouses.

Common Door Choices

In addition to regular personnel doors, warehouses and industrial buildings typically include overhead doors of various sizes and designs. The width and height of the door will be dictated by the size of the vehicles and the loads that pass through.

Typical door sizes range from 8 ft x 8 ft to 32 ft x 24 ft. See our article on door options for a discussion and illustrations of various types of doors. The most common door types used in warehouses are sectional (garage-type) overhead doors and roll-up doors.

Loading Dock Sizes and Options

If you expect your warehouse to be served by truck deliveries, you have two options for moving the loads from the trucks inside. The relatively light loads, such as cardboard boxes that can be handled manually, you might not need any loading docks; the boxes could be wheeled on dollies via truck ramps. For heavier loads on pallets that need a forklift to move, you might still get by without having any loading docks if you have experienced forklift operators capable of handling such loads.

For large warehouses, as well as for factories and retail stores with frequent truck deliveries, having loading docks is essential. The layout of the docks should be coordinated with the aisles between the racks if you have those. The width of the docks should allow tractor-trailers, which are 8.5 ft wide, to fit easily. Accordingly, the truck bays should be at least 12 ft wide and perhaps even 14 ft wide. The average loading dock height is between 48 and 52 inches.

Facade Systems, Mansards, and Canopies

In addition to basic metal walls and roofs, some commercial buildings can gain architectural interest from various facade systems, including mansards and canopies. Warehouses are utilitarian buildings that rarely employ these. Instead, they use simple, low-pitched gable roofs ending flush with sidewalls.

For those seeking a more refined appearance, here are some design ideas:

• Add eave extensions from 2 ft to 10 ft long
• Include a self-supporting end wall canopy from 3 ft to 10 ft long
• Increase the pitch (slope) of the roofline
• Select a sloped or vertical fascia

Illustrations of some of these design options are included in my book &#;Metal Building Systems: Design and Specifications,&#; 3rd edition (McGraw-Hill, ).

Crane Considerations

Both manufacturing facilities and warehouses frequently use cranes for material handling. If you think you will need cranes, determine the type, capacity, and location of the cranes BEFORE placing your order. Like sprinklers discussed above, cranes should NEVER be added after the fact (or at least not without detailed structural analysis), as this might severely compromise the building's structural integrity.

There are many crane types available, the most common for smaller warehouses is the monorail. The monorail crane runs along the bottom flange of the monorail beam, which is suspended from the primary steel framing. Our suppliers DO NOT include cranes of any type with the framing kit &#; you would need to talk to a crane supplier about purchasing both the crane and the monorail beam.

Our suppliers MIGHT provide the supports for the monorail beams, which requires beefing up the roof framing and increasing the overall rigidity of the structure. This is why you must convey the crane loading information from the crane supplier to the supplier before the building is designed and fabricated. at the factory.

Future Expansion Considerations

If there is a reasonable possibility that you would expand the operations in the future, it is wise to plan for the expansion BEFORE placing your order. Pre-engineered buildings can be lengthened if anticipated in advance by adding additional bays. To do so, the supplier must be advised to provide EXPANDABLE END WALLS (at least at one end where you might expand the building).

In that case, the manufacturer would provide an interior primary rigid frame at the designated end wall rather than just the end wall framing (girts and girt supports). When it&#;s time to expand, the girts, girt supports, and wall siding at the end wall are removed, and what used to be an exterior frame becomes one of the interior frames.

Naturally, the structural engineer designing your foundations should also be advised to provide the same foundations at the end wall(s) as at the interior frames rather than smaller exterior foundations otherwise needed there.

There are other ways to add space to a prefab warehouse, but ordering an expandable end wall is among the simplest and most economical options.

Warehouse Offices, Partitions, and Mezzanines

As discussed above in Step 1, you need to decide whether there will be spaces within the warehouse that are occupied by people. These spaces include offices, break rooms, and bathrooms. Most warehouses need these finished spaces with drywall or masonry partitions, suspended ceilings, and HVAC, plumbing, and electrical services.

If you plan to have finished interior spaces, you need to decide where these will be located and incorporate proper fire exit paths to the space, as well as extend plumbing, electrical, and heating utilities to service these areas.

Your building supplier should be advised of the fact that there will be finished areas within the warehouse because buildings with gypsum-board partitions must be made much sturdier than one without them. Otherwise, the normal sway of the building, which is harmless to all-metal roofing and siding, might damage brittle drywall or masonry finishes. For this reason, it is unwise to add such finished areas to buildings that have not been designed to hold them.

Sometimes warehouses include mezzanines to increase storage areas. A structure with a mezzanine should also be designed and manufactured to a higher degree of stiffness, similar to a building with drywall partitions. Our article on structural add-ons provides additional discussion on mezzanines.

Foundation Plans

Foundations and anchor bolts are NOT included in the building package. Foundations for steel buildings are different &#; and generally more complicated &#; than those for conventional structures, so you will need to engage the services of a licensed structural engineer experienced in their design (many structural engineers are not).

Foundations for metal frame warehouses (as well as for industrial, commercial, and community buildings of moderate and large sizes) are more substantial than those for sheds and other small structures. These foundations include:

• Tie rods + column footings
• Moment-resisting foundations
• Mats
• Piles
• Drilled Shafts.

See our guide to metal building foundations for descriptions and illustrations of these foundations. DO NOT use common but unreliable systems, such as hairpins and haunched slabs, in combination with unreinforced or lightly reinforced slabs on grade. While widely used in the past, these two designs do not comply with today&#;s code requirements. Hairpins should only be used in mats and heavily reinforced slabs without joints.

In addition to foundations, metal warehouses will need slabs on grade and perimeter foundation walls or grade beams extending below the frost line. All of these elements are also designed by a structural engineer.

A set of foundation drawings prepared by a licensed structural engineer will most likely be needed to obtain a building permit.

Floor Slabs

A typical warehouse has a concrete slab on grade. The design factors, such as thickness, reinforcement, and concrete strength, are determined by the intended use of the warehouse. These factors include the presence of hard-wheeled equipment on the floor, the frequency of its use, the loading, etc.

If your warehouse has tall storage racks, the floor slab must be finished extremely accurately so that it&#;s both flat and level. Otherwise, your racks will be visibly leaning, reflecting any waviness in the floor. Your structural engineer will prepare a set of criteria to ensure that the floor will be adequate for rack support.

Step 3: Ordering and contracting

How to Buy a Warehouse

This is where we can assist with your project. Provide details about your project in our quote request form. We will then match you with the FOUR vetted building suppliers, who will provide competing quotes for your warehouse kit.

There are a few steps to take when you choose a supplier:

• First, you will place a deposit with the supplier (typically 20-30%). This deposit will secure your spot with the factory and allow them to begin the engineering and design process.
• Next, you will sign a contract with the supplier. Once the contract is signed, the factory can begin fabrication.
• Finally, you will receive a set of engineering and foundation plans (typically 2-3 weeks later). These plans will be stamped by an engineer licensed for your state. Some suppliers charge extra for foundation plans, so be sure to ask before finalizing your purchase.

With engineering plans in hand, you can solicit quotes from local subcontractors or general contractors for erecting your structure. You (or your general contractor) can also begin the permit process with your local building department.

Read and reread the discussion above before you submit your form, and include any custom requirements in it, to avoid costly change orders.

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Step 4: Pre-construction

The time between ordering your warehouse building package and taking delivery will typically be around 6-12 weeks, giving you plenty of time to prep your job site. Here are the steps you will need to consider at this stage of the project.

Site Preparation

After it is confirmed from Step 1 that the selected site is buildable, steps to start the site preparation can be taken. The specific steps in these efforts include surveying, additional soil testing and analysis, site clearing (including any required demolition), and preparing a site plan (typically needed to obtain a building permit).

Once you have the building permit, construction activities can start. These typically begin with grading, soil preparation, and running services to the site. See our article on site preparation for a description of these steps. Because warehouses often have substantial sizes, site preparation activities can be quite involved.

Access Routes and Parking

Another aspect of site preparation involves extending access roadways to your site, which includes most of the steps listed above, such as site clearing and possible demolition. You should also prepare a level area where construction vehicles can park and where the components of the metal building kit will be off-loaded and stored until their erection.

Pour Foundation and Place Anchor Bolts

After the foundations are designed &#; and a permit has been secured, you can start placing the foundations. The process will start with another accurate survey of the site to mark the future column locations. This will help ensure that the foundations are where they need to be. Because warehouse foundations are more complex than those for smaller metal structures, skipping the survey is unwise. Foundations placed in the wrong locations might require costly demolition, rework, and schedule delays.

Yet another &#; and even more accurate &#; survey will be needed to establish anchor bolt locations. This step is usually done after the formwork for the foundations is in place so that the bolt locations could be precisely marked on the sides of the formwork.

See our article on foundations for steel buildings devoted to designing and constructing foundations and anchor bolts. Also, read the section in Step 2, Foundation Plans, for specific requirements that apply to warehouses and other commercial and industrial buildings.

Step 5: Warehouse construction

Delivery Day

This is the big day: Your kit building package is being delivered to the job site! To ensure the delivery and unloading process goes smoothly, you must prepare.

Construction of warehouses, like other larger steel structures, typically involves the services of professional contractors. Ensure that your agreement with them includes the off-loading and staging of the many materials you will receive. The manufacturer does not supply labor or lift equipment to help you unload the truck once it arrives; that is your responsibility.

Necessary equipment could include a crane, forklift, pallet jacks, and so forth, depending on the size of your warehousing facility and the layout of your construction site.

The process of kit delivery, off-loading, and two inspections is described in our article on preparing for delivery.

Metal Warehouse Construction

Detailed erection plans will be included as part of the kit package. The process typically starts with erecting the columns or an entire preassembled primary frame. The anchor bolts placed in Step 4 will help keep the columns in place, but using appropriate erection bracing is a must. The erection process then continues to frame rafters, wall girts, roof purlins, etc. It is described in detail in our guide to constructing metal buildings. 

Warehouses are more difficult and complex to erect than simple small sheds and the like. The services of professional steel erectors experienced in metal frame building construction are highly recommended.

Step 6: Finishing

Insulation and Interior Finishes

As described in Step 2, Insulation, warehouses are generally insulated to maintain optimal temperature and humidity of the contents. The most common type of steel building insulation consists of fiberglass blankets. This type of insulation is installed during erection. Roof insulation is placed between metal roofing and purlins, while wall insulation is sandwiched between wall siding and girts.

One exception is the finished areas, such as offices, break rooms, and bathrooms, within the warehouse space. Finishes, insulation, and suspended ceilings for these areas are typically installed after the structure's shell is in place.

Step 2 Office space, partitions, and mezzanine (above) include some considerations for constructing finished spaces within warehouses. For additional discussion, see our guide to building interiors.

HVAC, Plumbing, and Electrical Work

Mechanical (HVAC), plumbing, and electrical components are generally installed after the steel frame has been erected. They are typically provided by licensed sub-trades, following the engineering designs for their respective trades.

However, some supports for these components must be incorporated into the roofing or framing, so they must be installed during building erection. Such supports include roof curbs and frames on legs for HVAC rooftop equipment, as discussed in Step 2 HVAC systems. The coordination of installing these supports is best done by a general contractor experienced in the construction of steel warehouses.

Similarly, some plumbing components, such as water and drainage pipes, must be in place before constructing the slab on grade.

Final Inspection

Various inspections are carried out throughout the construction process. At some critical stages, an inspection could occur as frequently as once daily. During these inspections, a so-called punch list is developed and kept current. The punch list documents some (hopefully) minor issues that still need to be resolved. After an issue is taken care of to your satisfaction, it is removed from the list.

A final inspection verifies that all the punch-list items have been satisfactorily addressed and that your warehouse has been constructed in accordance with the design drawings and any special directives issued during construction. If you have engaged the services of an architect and various professional engineers, all these professionals should participate in the final inspection or perform their own separate inspections.

The local building department's inspector will conduct their own final inspection to verify that the structure and all its components have been assembled properly and operate as intended. A successful final inspection will allow the department to issue a Certificate of Occupancy. The final inspection (or inspections) will give you peace of mind, knowing that your new warehouse is safe and ready for operations.

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