conversion concerns


Converting a residential building to a commercial use gives me concern.

Converting old (unoccupied) buildings to new occupancies raises even more concern.

This is part of my daily job.

How do we do this? What questions should you ask if you’re considering this as a business or property owner?


In my world as an architect I am frequently contacted to review existing buildings that someone wishes to convert to commercial uses. In many of these cases I find out that the existing building started out as some type of residential use. With many early 1900’s buildings the construction is wood floor/roof construction with masonry walls. Long before we can address energy or sustainability concerns, we must address the many life safety and accessibility concerns.

Local building codes will vary, but these are generally the same everywhere in the U.S. As for determining what is applicable for existing buildings, contact an architect who is well versed in the International Existing Building Code or Chapter 34 Existing Buildings in the International Building Code (or whatever code is applicable in your area). The approach for existing buildings can be different than new construction, but please do not say things are “grandfathered.” The term is never used and the concept doesn’t exist the way most people think it does. It is so often misunderstood.


Every building is unique so there is no exact formula, but here are the primary issues that I find on every one of my reviews. If you’re thinking about purchasing or leasing a building and converting it to something else, think about how your building compares to these criteria. I frequently provide due diligence studies, code assessments and other concept studies to assess whether it is reasonably viable for my clients to act on their desire to purchase and develop an existing building. This is an important step before getting emotionally connected to a project or better yet economically invested in property.


This is not building code related, but if you’re looking at converting a house, the local zoning might not permit the property to be used for commercial uses. If you don’t know the difference between zoning and building codes, I addressed that with a previous post – here. I have had clients purchase property for an intended use only to find out afterwards that the local zoning regulations would not permit that use on that land.

Occupancy Type

This is the general use or activities to occur in the building. Some categories are Assembly, Business, Mercantile or Residential. Within these major categories, there are sub-categories. It is really important to be able to identify if a building has LEGAL occupancy for whatever it is being used for currently. I find most of the time that buildings change owners over time and they are modified without any type of plan review, permits or record of revisions let alone code compliance.

Change of Occupancy

If you’re wondering what one of the biggest triggers is for major code upgrades, this is it. For instance, if you purchase a residential building and wish to make it into an office, that’s a change from a residential occupancy to a business occupancy. If the building has no LEGAL occupancy, that’s a change from no occupancy to whatever use is being considered. I find this occurs often because no record of legal occupancy can be found. In other words, there is no Certificate of Occupancy record from the state or local municipality. No record = no legal occupancy. This gets more complicated when only a portion of a building is being changed – that’s a Partial Change of Occupancy. Whether there is a Complete Change or Partial Change, it has significant ramifications with respect to accessibility upgrades as well as life-safety issues.

Type of Construction

This is primarily the materials that make up the structure. This ranges from Type 5 which is all wood framing much like a house to Type 1 which is all non-combustible construction where the structural members are protected with fire resistive materials. This has a direct relationship to how large and how tall a building of a particular use can be. Type 1 buildings can generally be larger and taller than Type 2, 3, 4 or 5. When one attempts to convert a former residence or wood framed building into a commercial use, it has to be compared against the code for the height and area limitations for a Type 5 or wood framed building. Oftentimes this poses a challenge.

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Mixed Uses

Are you planning on having retail on the first floor with apartments above? That’s considered a mixed use. Simply put, it’s when a single building has more than one Occupancy Type. This can get complicated with existing buildings because generally a building has a fire separation between these occupancies. That’s not always a mandate, but it gets complicated fast when there is no separation between Occupancies.

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Separation of Uses

It seems fairly obvious that different uses have different hazards so having a separation (classified by the number of hours the separation can resist the spread of fire) between uses makes a building safer. You wouldn’t want the fire that started in the restaurant kitchen below to spread to your apartment above would you? Just know this, it’s best to separate uses and that separation must be continuous. That requires an obsessive architect to work through the details and a conscientious contractor to execute them. With old wood framed buildings, this can be complicated.


Fire Protection Systems

The venerable automatic sprinkler system falls in this category. Fire alarm systems, smoke alarms (smoke detectors) and a series of other safety stuff is addressed here. These systems cost money, but they keep people safe, they give time for people to get out in the event of a fire and they can protect the fire fighters who risk their lives to put out fires. The systems in this category vary based on Occupancy, building size and number of occupants. Most people I meet wish to avoid adding automatic sprinklers, but they often don’t realize that in some cases life-safety features are often exempted or reduced in scope when there is an automatic sprinkler system. In other words, it’s not always more expensive. Think of it this way – a smoke detector tells you that it would be a good idea to leave because the building is on fire. A sprinkler tells you to leave too, but it also begins to put out the fire.


Means of Egress

I agree, this can be another complicated category, but this covers how one gets out of a building in the case of an emergency. It’s good for this to be clear, adequate and safe. The major deficit found with conversions to commercial uses is providing at least two means of egress from each floor. This weakness occurs on most early 20th century urban buildings too.

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This is one of my largest challengers when it comes to small projects with small budgets when there is no flat areas in Pennsylvania. However, it’s the law and we wish all people to have access to our buildings. It’s disappointing how many people try to “get out” of addressing this or they ask what is the “least” they have to do. I understand that a budget must be respected, making physical changes takes money, and therefore I work hard to find creative ways to comply. With small projects, a larger part of the budget can be required to be given over to this category in order to get access into the building and provide accessible bathrooms and other features. When one has an urban building from 1915 on a sloping street that is currently two or more steps up to the entrance, I really have to put on my thinking cap. I shared a story in a past blog post about how we overcame this on one of our projects.


Special Conditions – Restaurants

Beyond all of those other categories that must be evaluated carefully, I have consulted with many clients on many existing buildings intended to be converted into a restaurant. This use (A-2 Assembly) adds a unique requirement on top of all of the previous categories – commercial kitchens. Commercial kitchens typically require a hood over the cooking equipment which requires special mechanical equipment. This requires one to be able to exhaust the hood into a legal location and place a make-up air unit with duct work connecting back to the hood. This is in addition to the HVAC systems. Typically the HVAC system for the kitchen is different that the equipment for the dining and other areas of the building. These systems have to be designed carefully and balanced to be sure they all work together. This is why architects hire consulting engineers. They work out the tough calculations, but I am always involved in figuring out how to get the components in and out of the building. Architects have to integrate these components into their designs so that they function properly and either contribute to the visual concept or at least don’t detract from it. Old buildings with skinny tenant spaces and former residential buildings with chopped up rooms and low ceilings are exceptionally difficult.

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As stated earlier, every building is unique, but I find over and over again it is challenging (economically) to convert a residential and/or wood construction building to a commercial use. It can be equally challenging to upgrade 100-year old buildings to current codes. Generally I can be creative enough to find solutions, but budgets, ROI and borrowing potential only permits certain solutions.

If you’re not sure whether the building you’re considering can work, think-architect, I mean call one before you buy that building or sign that lease.

conversion concerns

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