What's in This Article
Key Takeaways
- The former IBM campus at 150 Kettletown Road is roughly 865,000 SF across eight buildings on about 228 acres, vacant and listed without a published asking price.
- Southbury rezoned the property to a new Industrial (IND) zone effective August 1, 2025, replacing the R-60C classification that governed the original campus.
- The town assessor's appraised value fell from about $70.9 million in 2023 to $19 million in 2025, a 73% decline that translates to roughly $900,000 a year in property-tax revenue at current rates.
- A single replacement for IBM is unlikely. A phased, multitenant employment campus may be more realistic than one 865,000 SF user.
- Industrial zoning does not automatically mean a warehouse. Building size and economic impact are not the same thing.
- Third-party listing data still shows the old R-60C zoning. Buyers should rely on current municipal records, not listing sites.
The former IBM campus at 150 Kettletown Road is not a routine commercial property. At roughly 865,000 SF of office space across eight buildings on about 228 acres, the next use will affect far more than one buyer or one neighborhood.
IBM opened the campus in the late 1980s and at its peak employed approximately 2,500 people there. The company confirmed plans to leave in late 2023 and closed the site in January 2024, by which point headcount had fallen closer to 1,100. The property is now vacant and listed for sale without a published asking price (LoopNet listing) (Patch).
What Southbury should avoid is allowing one of its most consequential properties to be defined by the first proposal that can be assembled. The better approach is to understand what the site can realistically support, identify which uses would benefit the town over the long term, and establish clear standards before a buyer commits to a final plan.
The property at a glance
Figures from the current listing and the Town of Southbury assessor's record for parcel PID 4383.
The Property Is Large Enough to Function as Its Own District
Most commercial properties are evaluated building by building. The former IBM campus requires a district-level analysis. A buyer is not simply acquiring office space.
| Buildings | Site & systems | Market & capital |
|---|---|---|
| Which buildings remain useful | How internal roads and utilities are configured | Which uses the local market can support |
| Which systems require replacement | Whether parking is adequate for a new use | How much capital is required before occupancy |
| Whether demolition is financially feasible | What environmental work may be required | Whether the campus can be divided |
The property could support several uses across separate development phases. That may be more realistic than finding one company willing to occupy the entire campus.
The Old Office-Campus Model Is Unlikely to Return
IBM developed the property for a large corporate workforce operating from one controlled campus. That model has weakened. Remote and hybrid work have reduced demand for many large suburban office properties. Employers still use office space, but fewer companies need hundreds of thousands of square feet in one location.
Southbury's own economic development director acknowledged the shift when the property was listed, noting that with little demand for office space the town might consider rezoning (Patch). During the rezoning hearing, a Planning Commissioner put it more directly: there is no market for a large headquarters-type building and campus (Voices News).
The question is not whether the property can return to its previous use. It is whether the campus can be repositioned around uses that exist in today's market.
Southbury Has Already Made a Major Zoning Decision
On July 9, 2025, the Southbury Zoning Commission voted to rezone the former IBM campus to a new Industrial (IND) zone, effective August 1, 2025. The new zone replaces the R-60C classification under which the campus was originally developed, and was proposed by the Planning Commission specifically to help market the property (Voices News) (Town of Southbury).
That decision materially changes the site's potential. It signals that Southbury does not expect the campus to remain solely a conventional office property, and it creates a path for uses that may include production, assembly, research, warehousing, or other industrial activities allowed under the final regulations. The rezoning is significant because Southbury has historically been viewed more as a residential and retail community than a major industrial location.
What the IND zone requires a buyer to verify
- Permitted industrial uses and special-exception requirements
- Dimensional standards and building coverage
- Parking and loading requirements
- Outdoor storage rules; noise and lighting standards
- Environmental review; access and traffic requirements
- Whether mixed uses are allowed
The new zoning creates options. It does not mean every industrial proposal will fit the site or the surrounding area.
The Tax-Base Effect Is Already Being Felt
The campus was Southbury's largest taxpayer. Its vacancy has already reached the town's finances, and the scale of the change is visible in the assessor's own record.
| Valuation year | Appraised value | Assessed value (70%) |
|---|---|---|
| 2023 | $70,886,810 | $49,620,790 |
| 2024 | $70,306,230 | $49,214,380 |
| 2025 | $19,000,000 | $13,300,000 |
Figures are from the Town of Southbury assessor's published record (Southbury assessor, PID 4383). Between the 2024 and 2025 valuation years, appraised value fell about 73%.
Appraised value, 2023 to 2025
Town of Southbury assessor record for 150 Kettletown Road. Vacancy and market conditions drove a 73% decline.
What that means in annual tax revenue
Southbury's mill rate for the 2025 Grand List is 25.4 (Town of Southbury tax calculator). Applying that rate to the assessed values above shows the scale of the change:
| Basis | Assessed value | Annual tax at 25.4 mills |
|---|---|---|
| 2024 assessment | $49,214,380 | approximately $1,250,000 |
| 2025 assessment | $13,300,000 | approximately $338,000 |
| Difference | $35,914,380 | approximately $912,000 per year |
That is why the property's future matters well beyond the eventual buyer. The question is not only what the property sells for. The town must consider what a completed reuse will produce in real estate assessment, business personal property, employment, permit revenue, utility demand, municipal service costs, and long-term tax stability. A reuse that produces substantial assessment but requires costly infrastructure or public services may have a very different net benefit from a less intensive project. Southbury should evaluate gross tax revenue and municipal cost together.
Industrial Reuse Could Restore Employment and Tax Value
The new Industrial Zone opens the property to a wider market. Possible users could include light manufacturing, medical or technical production, research and development, data and technology operations, assembly, distribution, building-products companies, food or pharmaceutical production, advanced manufacturing, and corporate or industrial service operations.
| Potential advantages | Real limitations |
|---|---|
| Large building area and substantial acreage | Not an interstate-frontage warehouse parcel |
| Existing internal infrastructure | Not directly beside a major highway interchange |
| Separation from denser town-center uses | Local roads may not support heavy trucking |
| Potential room for expansion | Buildings designed for one owner, not many |
| Existing office and technical space | Conversion cost for industrial use |
| Within driving distance of I-84 |
Notably, the site's original design may work in its favor. During the rezoning hearing, a Planning Commissioner observed that IBM had deliberately secluded the campus from residential areas, that it offers generous setbacks, and that the new zone was structured to keep traffic away from residential neighborhoods (Voices News).
A successful industrial strategy should focus on businesses suited to the site rather than treating "industrial" as one broad category. Light manufacturing, technology, life science, research, controlled assembly, or campus-style industrial uses may fit very differently from a high-volume distribution center.
The Site Should Not Become a Warehouse Simply Because It Can
Industrial zoning often leads people to assume large warehouses are the obvious next use. That may not be the best outcome here. A large distribution facility could create employment and taxable value. It could also create frequent tractor-trailer movement, demands for road improvements, noise, lighting impacts, pavement wear, pressure on local intersections, and conflict with nearby residential areas.
The property's acreage creates physical room for a large project. That does not establish that the surrounding transportation network can support it.
Questions Southbury should require credible answers to
- How many trucks would enter each day, and which roads would they use?
- Would traffic pass through residential areas?
- Are road widening or signal improvements needed, and who pays?
- What hours would trucks operate?
- Would the project increase emergency-response requirements?
- What employment density would the project produce?
A 500,000 SF distribution building employing 150 people is not economically identical to a 300,000 SF production facility employing 700. Building size should not be confused with economic impact.
A Multitenant Employment Campus May Be More Realistic
The property may not need one replacement for IBM. It may need ten, twenty, or thirty smaller employers. A phased multitenant strategy could combine light industrial suites, research space, technical offices, training facilities, medical or laboratory uses, contractor or service businesses, small distribution users, and flexible production space.
This approach could reduce dependence on one tenant and let the campus fill over time. It would also require substantial planning. The current buildings were designed for one owner and one workforce. Creating multiple occupancies may require new entrances, separate utilities, fire separations, updated elevators and stairs, revised parking, loading areas, signage, internal road changes, security changes, and tenant improvements. The cost may be significant, but a multitenant campus could be far more consistent with current market demand than waiting for one company to take 865,000 SF.
Some Existing Buildings May Not Be Worth Saving
The property contains a large amount of existing construction. That does not mean every building should remain. The assessor's record shows the campus is not uniform: it includes four large four-story office buildings along with several smaller industrial-style structures and a pump house, all built in 1987 (Southbury assessor, PID 4383). Those buildings will not all convert equally well.
What a buyer should evaluate building by building
- Roof condition, building envelope, and structural condition
- Mechanical systems and electrical capacity
- Fire protection and hazardous materials
- Energy efficiency and deferred maintenance
- Floor loading, ceiling height, and loading access
- Interior layout and suitability for the intended use
An office building may look substantial while being poorly suited to industrial reuse. Deep floor plates, limited loading, low ceilings, or outdated mechanical systems can make conversion expensive. Selective demolition may create a better result than attempting to preserve every square foot. That decision should come from engineering and market analysis, not from an assumption that preservation or demolition is always preferable.
Housing Could Be Part of the Conversation, but It Should Not Control the Entire Site
Before the industrial rezoning, town officials discussed several possible futures, including residential development. Southbury also has a documented need for a broader range of housing and adopted an Affordable Housing Plan in 2022 as required by state law (Southbury Affordable Housing Plan).
That does not necessarily mean the former IBM campus should become primarily residential. Housing could help support a mixed-use redevelopment, particularly if part of the property proves unsuitable for employment use. But converting too much of the site to housing could permanently reduce one of Southbury's most significant employment-land opportunities.
Evaluate any residential component against
- Remaining industrial capacity
- Compatibility with truck and production activity
- Water and sewer availability
- School and municipal service costs
- Housing type and affordability
- Traffic, open space, and environmental conditions
- Long-term tax contribution
Housing beside active industrial operations can also create future conflicts over noise, lighting, deliveries, and operating hours. Southbury should decide where housing could coexist with employment uses before approving a residential component.
The same logic applies to mixed use generally. A large site can support several uses, but that does not mean they should be mixed without a clear plan. Truck circulation should not pass through residential sections. Housing should not be placed next to loading docks. Public-facing commercial space needs usable access. Industrial users need adequate separation and operating flexibility. Mixed use works when each component strengthens the larger property, and fails when incompatible uses are placed together to increase theoretical density.
Infrastructure and Environmental Due Diligence
The property's previous use suggests substantial infrastructure exists. A buyer should not assume existing systems can support a completely different redevelopment program. A campus that supported office workers may not support a water-intensive industrial process or a heavy electrical load without major investment.
| Infrastructure capacity | Environmental condition |
|---|---|
| What electrical capacity reaches the site, and is it suitable for manufacturing or data uses? | Historical uses across the campus |
| What water and sewer capacity is available? Are private systems involved? | Fuel storage, emergency generators, underground tanks |
| What fire-flow capacity exists? | Hazardous building materials and chemical storage |
| How are stormwater systems configured? | Waste handling and transformers |
| Which roads and utilities are privately maintained? | Soil and groundwater conditions |
| Can systems be divided among multiple users, and who pays for off-site work? | Existing environmental restrictions |
The campus operated for decades as a major corporate and data facility. That history does not prove contamination, but it justifies comprehensive environmental investigation before redevelopment. Importantly, the required cleanup standard may depend on the proposed use: residential development may require a different level of environmental protection than certain commercial or industrial uses. That means the reuse plan and the environmental strategy should be developed together, and a proposal should not be treated as financially feasible until the environmental scope is understood.
Southbury Should Require a Phasing Plan
A property this large may take years to redevelop, and a buyer could close long before every building or parcel is occupied.
Understand the sequence
Which phase begins first, what investment occurs in each phase, and when buildings will be occupied or demolished.
Tie infrastructure to phases
When infrastructure will be installed, and how vacant buildings will be secured in the meantime.
Plan for the plan failing
What happens if later phases do not proceed, whether approvals expire, and whether development milestones apply.
Evaluate the buyer, not the rendering
Assess the buyer's ability to finance and execute, not only the appeal of the final images.
A strong first phase can establish momentum. A weak plan can leave Southbury with partially demolished buildings, incomplete infrastructure, and years of uncertainty.
If the redevelopment involves public participation, whether zoning relief, infrastructure commitments, tax incentives, public financing, or road improvements, that participation should be connected to documented investment and enforceable milestones. Reasonable protections include minimum construction investment, development deadlines, performance bonds, clawbacks, defined public improvements, maintenance obligations, reporting requirements, restrictions on speculative land holding, and remedies if work stops. The goal is not to make redevelopment unnecessarily difficult. It is to ensure public benefits are delivered if public support is provided, which matters more than usual here given how much assessed value the town has already lost.
Southbury Has One Chance to Position the Site Correctly
The sale price will matter, but it will not determine the best use. Large obsolete campuses often sell below prior assessments or replacement cost because buyers must account for vacancy, renovation, demolition, carrying costs, environmental risk, infrastructure work, leasing time, financing, and market uncertainty. The drop in appraised value from roughly $70.9 million to $19 million reflects exactly those economics. A low sale price would not necessarily mean the town lost value in the transaction. It may reflect the capital the new owner must invest after closing.
The more meaningful measurements will be total redevelopment investment, completed assessment, employment, occupancy, municipal costs, and long-term tax revenue.
Southbury could improve buyer interest by publishing one clear site profile
- Current zoning and permitted uses, in writing
- Site and building area; surveys
- Existing utilities and infrastructure documentation
- Environmental reports; wetlands and natural-resource information
- Traffic and road conditions
- Tax assessment and available incentives
- Approval requirements and development contacts
The town's Planning Department already provides zoning, planning documents, GIS, and land-use guidance (Southbury Planning Department). For this property, that information should be organized in one place. A site of this significance should not require a prospective buyer to reconcile conflicting zoning data across the assessor's record and third-party listings before understanding the basics.
The strongest plan may combine a core industrial or technical employment district, reuse of selected office buildings, multitenant production or research space, limited commercial services, open space or environmental buffers, new construction on developable portions, and a carefully located secondary use where appropriate. The plan should begin with the property's constraints and the market, not with a predetermined rendering.
The campus once held approximately 2,500 workers and represented a major part of Southbury's tax base. Its vacancy has already produced a measurable revenue loss. That history should not pressure Southbury into recreating the past. It should make the town more deliberate about the future. The former IBM property could shape Southbury for decades, and the town should evaluate it that way.
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Frequently Asked Questions
How big is the former IBM campus in Southbury?
The listing describes approximately 865,000 SF of office space across eight four-story buildings with just under 400 parking spaces. The Town of Southbury assessor's record lists the parcel at 227.9 acres, with all eight buildings constructed in 1987. Some news reports round the acreage to 220 or 230, so the assessor's figure is the one to rely on.
What is the property zoned now?
The Southbury Zoning Commission voted on July 9, 2025 to rezone the campus to a new Industrial (IND) zone, effective August 1, 2025, replacing the prior R-60C classification. Be aware that the assessor's online record and the commercial listing may still display R-60C. Buyers should obtain written zoning confirmation from the town's Land Use office rather than relying on either.
How much value has the property lost?
According to the Town of Southbury assessor's published record, appraised value fell from $70,886,810 in 2023 and $70,306,230 in 2024 to $19,000,000 in 2025, a decline of about 73%. Assessed value fell from roughly $49.2 million to $13.3 million over the same period.
What does that mean for Southbury's tax revenue?
At the town's 2025 Grand List mill rate of 25.4, an assessment of $49.2 million would produce roughly $1.25 million in annual property tax, while $13.3 million produces roughly $338,000. The difference is on the order of $912,000 per year. That is an illustration using published figures, not an official town budget number, and actual effects depend on timing, appeals, the mill rate each fiscal year, and other grand list changes.
Will the site become a warehouse?
Not necessarily. Industrial zoning permits a range of uses, and the site has real limitations for high-volume distribution: it does not front an interstate or sit beside a major interchange, and local roads may not support heavy trucking. Light manufacturing, research, life science, technology, or campus-style industrial users may fit the property better. Building size and economic impact are not the same thing.
Could part of the campus become housing?
Possibly, as part of a mixed-use plan. Southbury adopted an Affordable Housing Plan in 2022 and has a documented need for a broader range of housing. But converting too much of the site could permanently reduce one of the town's most significant employment-land opportunities, and housing placed beside active industrial operations can create lasting conflicts over noise, lighting, deliveries, and operating hours.
Sources and Further Reading
Primary sources
- Town of Southbury assessor record, 150 Kettletown Road (PID 4383) (valuation history, acreage, building detail, zone field)
- Town of Southbury tax calculator (2025 Grand List mill rate)
- Commercial listing for 150 Kettletown Road
- Voices News: Former IBM campus zoned IND following Zoning Commission vote
- Town of Southbury: zoning amendment announcement
- Patch: IBM's former Southbury property listed for sale
- Southbury Affordable Housing Plan
- Southbury Planning Department
This article provides general commercial real estate information, not legal, engineering, environmental, appraisal, tax, or planning advice. Property data, assessments, zoning, and listings change. The tax illustration applies the published 2025 mill rate to published assessed values and is not an official municipal budget figure. Prospective buyers should confirm all material facts, including written zoning verification, directly with the Town of Southbury and qualified professionals.
