What Is CSI Division 32? Sections, Regulations, and Contract Role

CSI Division 32 is the Exterior Improvements division of the Construction Specifications Institute’s MasterFormat, the standard system used to organize construction specifications in North America. It covers every finished element installed outside the building envelope: paving, curbs, fences, retaining walls, site furnishings, irrigation, planting, and specialized features like permeable pavement and constructed wetlands.¹ If a project drawing calls out a section number starting with 32, it belongs to this division.

Where Division 32 Starts and Stops

Division 32 sits between two neighbors that handle related work. Division 31 (Earthwork) covers excavation, grading, and soil stabilization. Once the dirt is shaped, Division 32 takes over for the finished surfaces, walls, fences, and plantings that give the site its final form. Division 33 (Utilities) handles underground piping for water, sewer, gas, and electrical distribution. Where utility access points meet a sidewalk or roadway, Divisions 32 and 33 overlap and have to be coordinated.¹

That boundary is not academic. On a bid set, the division number tells every subcontractor which pages belong to them. A paving contractor prices Division 32 sections; a grading contractor prices Division 31. Misclassifying work between divisions produces gaps in bids, duplicated scope, and disputes later about who was supposed to do what. It also matters when something fails after the project is built, because the division structure shows where one contractor’s responsibility ends and another’s begins.

How to Read a Division 32 Section Number

MasterFormat uses a six-digit number organized in three pairs. The first pair identifies the division. For exterior improvements that is always 32. The middle pair identifies the section group, such as 10 for paving or 31 for fences and gates. The last pair narrows to a specific material or method.² So 32 12 00 points to Flexible Paving as a group, while 32 12 16 points to a specific flexible paving type such as plant-mix asphalt.

Once you know the pattern, the number itself tells you roughly what the section covers before you read a word of the text.

What’s Inside Division 32

The division is organized into major section groups by the type of work.

Bases, Ballasts, and Paving (32 10 00)

This group is the largest piece of Division 32 on most commercial projects. It covers parking lots, sidewalks, plazas, athletic surfaces, and roadways within the site.³ The main categories:

Base courses (32 11 00), the foundational layers under any visible surface. Specifications address aggregate types, compaction, and drainage. A failure here cracks whatever sits on top.
Flexible paving (32 12 00), asphalt and similar materials that flex under load. Mix design, placement temperature, and compaction rates are specified.
Rigid paving (32 13 00), concrete surfaces that resist deformation. Reinforcement, joint spacing, and curing methods control cracking.
Unit paving (32 14 00), modular elements like brick pavers, stone sets, and interlocking concrete blocks on specified bedding.
Curbs and gutters (32 16 00), the structural edges that define roadways and route surface water.

Maintenance and rehabilitation work has its own numbers too, including crack sealing (32 01 17) and cold milling with asphalt reuse (32 01 16).¹ Payment on most construction contracts is tied to meeting the specification, so paving that does not comply does not get paid for until it is corrected.

Permeable paving sits in this group and does double duty: it provides a driving or walking surface while also managing stormwater. Rainwater passes through the surface into a stone reservoir and infiltrates the soil instead of running into storm drains. Long-term infiltration rates generally remain above one inch per hour even after years of use, and studies show overall stormwater reduction of 25 to 100 percent depending on design and site conditions. Systems achieving roughly 80 percent total suspended solids reduction can earn credits under green building rating systems like LEED.⁴ Federal facility guidance places porous paving specifications under 32 12 43.⁵

Site Improvements (32 30 00)

This group covers the vertical and functional elements that are neither building nor ground surface.³

Section 32 31 00 addresses fences and gates of all types, including chain link, wood, wire, and ornamental metal. Specifications typically cover post depth, fabric gauge, hardware, and anchoring. Security fencing adds impact resistance and anti-climb requirements.

Section 32 32 00 covers site walls, including retaining walls that hold back earth to create level areas on sloped sites. Most jurisdictions require a licensed engineer’s stamped drawings and a building permit for retaining walls over four feet. Walls below that threshold are easier to permit but still need proper drainage behind them to prevent hydrostatic pressure, the leading cause of retaining wall failure. Walls over four feet typically also require geogrid reinforcement extending several feet into the retained soil.

Section 32 33 00 covers site furnishings like benches, trash receptacles, bike racks, and planters. Section 32 39 00 covers manufactured site specialties, including bollards, flagpoles, and permanent signage.³ Prefabricated items need correct anchoring, so the specification should address both the product and the installation method. Crash-rated security bollards are tested to ASTM F2656, which uses M-ratings (M30, M40, M50) based on a 15,000-pound truck at the stated speed, with penetration ratings P1 through P3 measuring how far the vehicle traveled past the barrier. Calling out the ASTM rating in the specification keeps every bidder pricing the same level of protection.

Irrigation and Planting (32 80 00 and 32 90 00)

The living side of Division 32 breaks into irrigation (32 80 00 and 32 84 00) and planting (32 90 00).³ Irrigation sections cover the controllers, valves, piping, heads, and drip emitters needed to keep the landscape alive, along with pressure requirements and coverage zones.

Planting subdivides further:

Planting preparation (32 91 00), including soil testing, amendment, pH adjustment, and drainage.
Turf and grasses (32 92 00), covering sod, seeding rates, and hydroseeding.
Plants (32 93 00), with standards for nursery stock quality, root ball size, and planting depth for trees, shrubs, and groundcovers.
Planting accessories (32 94 00), such as root barriers, tree grates, mulch, and staking.

Living elements come with obligations that hardscape does not. Most commercial specifications require a plant establishment period during which the contractor must water, fertilize, prune, and replace any plants that die. One to three years is common, depending on whether planting is part of a larger construction contract or a standalone landscape project.¹ Plants that fail during that window because of poor installation or inadequate care are usually replaced at the contractor’s cost.

Regulations That Shape Division 32 Specifications

Exterior improvement work triggers two sets of rules that have to be built into the specification rather than bolted on later.

Stormwater and the Clean Water Act

Any construction activity that disturbs one acre or more requires a National Pollutant Discharge Elimination System (NPDES) permit and a Stormwater Pollution Prevention Plan (SWPPP). Smaller sites still need the permit if they are part of a larger development that will ultimately disturb an acre or more. Federal effluent guidelines require erosion and sediment controls, stabilization of disturbed areas within 14 days if work stops, and prohibit discharge of concrete washout water, fuels, oils, solvents, and construction debris into stormwater.⁶ Division 32 intersects these rules twice: the construction of exterior improvements itself creates disturbed soil that must be managed, and permanent stormwater features like permeable paving and constructed wetlands are specified within Division 32 as part of the long-term stormwater strategy.

ADA Requirements for Exterior Work

On commercial and public projects, exterior improvements must comply with the Americans with Disabilities Act, and most of those requirements land in Division 32.

For parking, the required number of accessible spaces scales with lot size. A lot with 1 to 25 total spaces needs at least one accessible space, which must be van-accessible. A lot with 76 to 100 spaces needs four accessible spaces. Lots over 1,000 spaces need 20 plus one for every additional 100.⁷ Standard accessible spaces must be at least 96 inches wide with a 60-inch access aisle; van-accessible spaces need a wider space or wider aisle to accommodate lifts.

For curb ramps on accessible routes, running slope cannot exceed 1:12 and cross slope cannot exceed 1:48. Landings at the top must be at least 36 inches deep and as wide as the ramp.⁸ Counter slopes where the ramp meets the gutter cannot exceed 1:20. Transit facilities and projects receiving federal highway funding also require detectable warning surfaces with truncated dome patterns.⁹ Regrading a curb ramp or reconfiguring a parking lot after the fact costs far more than specifying it correctly in Division 32 from the start.

Why the Division Matters in a Contract

Division 32 work also usually requires permits beyond the general building permit. Encroachment or right-of-way permits come into play whenever exterior improvements connect to public sidewalks, streets, or stormwater systems. Permit types and fees vary by jurisdiction, and the need for them regularly delays site work for contractors who did not plan for it.

A project with significant Division 32 scope typically involves a civil engineer for grading and drainage, a landscape architect for planting and irrigation design, and sometimes a geotechnical engineer for retaining walls. Retaining walls over four feet generally require stamped engineering drawings. Stormwater features like permeable paving and constructed wetlands need design by someone who understands the hydraulic performance and the applicable NPDES conditions.

A well-written Division 32 specification does more than describe materials and methods. It tells each subcontractor where their scope begins and ends, what quality standards apply, and what documentation they owe. That clarity is what keeps exterior improvement work from turning into a dispute about who was responsible for the piece that failed.

1
Construction Specifications Institute. MasterFormat
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Construction Specifications Institute. Whats My MasterFormat Number
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Northern Arizona University. Division 32 – Exterior Improvements
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US EPA. Stormwater Best Management Practice – Permeable Pavements
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Whole Building Design Guide. Porous Paving
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US EPA. Stormwater Discharges from Construction Activities
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U.S. Access Board. Chapter 5 – Parking Spaces
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U.S. Department of Justice. 2010 ADA Standards for Accessible Design
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U.S. Access Board. Chapter 4 – Ramps and Curb Ramps