Are Space Heaters Allowed in Office Buildings? (w/Examples) + FAQs

Yes, space heaters are allowed in most U.S. office buildings, but only when they meet strict federal safety rules, local fire codes, lease terms, and insurance limits. No single federal law bans them outright. Instead, a web of rules from OSHA’s General Duty Clause, the International Fire Code Section 605.10, and NFPA 1 Fire Code decides if a heater is legal at your desk.

Office tenants, facility managers, HR leaders, and landlords all share legal risk when a heater sparks a fire or trips a circuit. The U.S. Fire Administration reports that heating equipment causes roughly 43,900 fires in the United States each year, and space heaters alone account for nearly 81% of home and workplace heating fire deaths. One bad plug in a paper-filled cubicle can trigger OSHA fines, lease eviction, insurance denial, and a workers’ compensation claim in the same week.

Here is what you will learn in this guide:

• 🔥 The exact federal and state rules that decide if a space heater is legal at work
• 🏢 How commercial leases and insurance carriers override even a “legal” heater
• ⚖️ Which OSHA citations and 29 CFR 1910.303 standards apply to heaters
• 🧯 The three-foot rule, UL 1278 listing rule, and extension cord ban in plain English
• 🧑‍💼 How to request a heater as an ADA reasonable accommodation without losing your job

Quick Answer: Are Space Heaters Legal at Work?

Yes, portable electric space heaters are legal in most commercial office buildings in the United States. No federal statute bans them. But the answer flips fast when you layer in local fire codes, building ownership rules, and insurance policies. Many employers ban heaters outright because the legal risk outweighs the comfort benefit.

The Occupational Safety and Health Administration does not have a rule that says “no space heaters.” Instead, OSHA uses the General Duty Clause under 29 U.S.C. § 654(a)(1) to fine employers who allow unsafe heater use. The plain-English meaning is that your boss must keep the office free from “recognized hazards.” The consequence of ignoring this duty is a serious OSHA citation, which can cost up to $16,550 per violation in 2026. For example, a marketing firm in Ohio was cited after a heater ignited a stack of paper files, injuring one worker. A common misconception is that OSHA sets a legal minimum office temperature; it only recommends 68°F to 76°F under its Technical Manual Section III.

State and local fire marshals carry the real enforcement power. The plain-English meaning is that your city or county has adopted a version of the International Fire Code or NFPA 1, and those rules control your desk heater. The consequence of violating the local fire code is a stop-work order, a daily fine, or a shutdown of the floor. For example, New York City adopted IFC 605.10 into its Fire Code, banning extension cords with heaters in every office tower. A common misconception is that a “UL-listed” sticker is enough; the heater must also be plugged straight into a wall outlet and kept three feet from anything that can burn.

Federal Framework: OSHA and the General Duty Clause

Federal law does not ban space heaters in offices, yet federal law still controls how you use them. OSHA regulates the employer, not the heater itself. That means the legal duty falls on the company that owns or rents the office, even if the employee bought the heater at a big-box store.

OSHA General Duty Clause (29 U.S.C. § 654)

The General Duty Clause requires every employer to furnish a workplace “free from recognized hazards.” The plain-English meaning is that if a hazard is known in your industry, you must fix it. The consequence of ignoring a known space heater hazard is an OSHA citation, which in 2026 starts at $1,190 for an “other-than-serious” violation and climbs to $165,514 for a willful or repeat violation. For example, a law firm in Dallas was fined after an inspector saw a heater plugged into a power strip under a desk. A common misconception is that OSHA must see a fire before it acts; the hazard alone is enough to trigger a citation.

OSHA inspectors look for four red flags when they see a heater. First, they check for a UL or ETL listing label. Second, they check the cord path to confirm the heater is plugged directly into a wall receptacle. Third, they measure the distance between the heater and combustibles like paper, curtains, and cardboard boxes. Fourth, they look for tip-over and overheat protection switches.

OSHA Electrical Standard 29 CFR 1910.303

OSHA’s electrical safety standard at 29 CFR 1910.303 requires that all electrical equipment be used according to its listing and labeling. The plain-English meaning is that you must follow the manufacturer’s instructions printed on the unit. The consequence of violating 1910.303 is a serious citation and, in fire cases, referral to the local fire marshal. For example, a call center in Phoenix was cited because staff plugged five heaters into one surge protector, overloading the circuit. A common misconception is that “temporary” heaters can be left plugged in for the whole winter; the UL label almost always restricts heaters to attended, temporary use.

OSHA Recommended Indoor Temperature

OSHA recommends an indoor office temperature range of 68°F to 76°F under OSHA Technical Manual Section III, Chapter 2. The plain-English meaning is that this is guidance, not a rule. The consequence of a cold office is not an automatic OSHA violation, but persistent cold complaints can become a General Duty Clause case if workers suffer cold stress. For example, a warehouse office in Minnesota was cited when indoor temperatures dropped below 50°F for three straight days. A common misconception is that employees can demand a specific temperature by law; the only binding rule is that the space must not create a recognized hazard.

State and Local Fire Code: IFC, NFPA, and Fire Marshals

Most U.S. cities and counties adopt the International Fire Code (IFC) or the NFPA 1 Fire Code. These codes carry the force of law once your local government adopts them. The fire marshal, not OSHA, is usually the official who knocks on your office door.

IFC Section 605.10: The Core Rule

IFC Section 605.10 is the single most important rule for office space heaters in the United States. The plain-English meaning is that portable electric heaters are allowed in most office occupancies, but only if they follow four strict limits. The consequence of violating 605.10 is a fire code citation, a daily fine, and possible suspension of the building’s certificate of occupancy. For example, the Fairfax County Fire Marshal cited a professional services office in 2024 for plugging a heater into a power strip. A common misconception is that 605.10 applies only to “big” buildings; it applies to every Group B office occupancy.

The four IFC 605.10 rules are:

• Heaters must be listed and labeled to UL 1278 (605.10.1)
• Heaters must plug directly into an approved wall receptacle (605.10.2)
• Heaters must never be plugged into extension cords (605.10.3)
• Heaters must stay three feet from combustibles and be used only where listed (605.10.4)

NFPA 1 Fire Code

NFPA 1 Section 11.5 mirrors the IFC rule and is the standard adopted by many states including Massachusetts and Florida. The plain-English meaning is that NFPA 1 gives your state fire marshal authority to ban or restrict portable heaters in any workplace. The consequence of violation is similar to the IFC: citations, fines, and loss of insurance coverage. For example, Florida’s State Fire Marshal enforces NFPA 1 in every county, and an accounting firm in Tampa lost its insurance rider after an inspection found four unapproved heaters. A common misconception is that NFPA is a “suggestion”; once a state adopts it, the code is law.

Group I-2 Ban (Hospitals and Nursing Homes)

IFC 605.10 bans portable heaters in Group I-2 occupancies, which include hospitals, nursing homes, and certain day cares. The plain-English meaning is that you cannot use a normal desk heater in a medical office attached to a hospital. The consequence of using one in a Group I-2 is an immediate fire code violation and potential loss of the facility’s state health license. For example, a nurse’s station at a Boston hospital was cited for a heater in a break room in 2025. A common misconception is that the rule applies only to patient rooms; it applies to the whole Group I-2 building unless the heater’s element stays below 212°F.

UL 1278 and UL 2021: The Listing Rules

A space heater is only legal if a nationally recognized testing laboratory has listed it. The two main standards are UL 1278 for portable electric room heaters and UL 2021 for fixed and location-dedicated heaters. ETL and CSA listings are also accepted in the United States.

UL 1278 is the plain-English standard that says your desk heater will not burst into flames under normal use. The consequence of using a non-listed heater is that OSHA, the fire marshal, and your insurance carrier will treat it as a banned device. For example, a Seattle tech startup bought a cheap no-name heater online that lacked a UL mark, and the city fire marshal red-tagged it during a walk-through. A common misconception is that a “CE” mark from Europe is the same as UL; it is not accepted in U.S. commercial buildings.

Modern UL-listed heaters include two required safety features. The first is a tip-over switch that shuts the unit off if it falls. The second is an overheat sensor that cuts power if the heating element gets too hot. Both features became standard after UL 1278 was updated in 2015.

Commercial Lease Clauses and Landlord Rules

Your lease is often stricter than federal or state law. Most modern commercial leases give the landlord the right to ban any appliance that raises fire or insurance risk. The plain-English meaning is that even a perfectly legal heater can be banned in your building.

A typical office lease includes a “rules and regulations” exhibit that allows the landlord to prohibit portable heaters, coffee makers, and toasters. The consequence of violating a lease rule is a written notice of default, possible eviction, and liability for any damage the heater causes. For example, BOMA International publishes model lease language that many Class A office towers use, and that language commonly bans space heaters in every tenant suite. A common misconception is that the landlord must prove the heater caused a fire before acting; most leases allow the landlord to ban the device on sight.

Subleases and co-working spaces add another layer. WeWork, Regus, and most managed workspace operators ban space heaters in their house rules. The consequence of bringing one in is immediate removal and, in some cases, loss of membership. For example, a freelance designer in Chicago was asked to leave a WeWork location after staff found a heater under her desk.

Insurance Carrier Rules: FM Global, ISO, and Hartford

Commercial property and general liability insurers hate space heaters. Carriers like FM Global, The Hartford, and policies written to ISO forms often exclude coverage for fires caused by unapproved portable heaters. The plain-English meaning is that if a heater starts a fire, your carrier may deny the claim.

FM Global’s Property Loss Prevention Data Sheet 5-1 specifically warns against portable heaters in offices. The consequence of ignoring the carrier’s rule is claim denial, policy non-renewal, and higher premiums. For example, a nonprofit in Denver lost a $380,000 fire claim in 2024 because the insurer proved the fire started in a non-UL-listed heater left on overnight. A common misconception is that a general business owner’s policy always covers fire damage; most policies include a “faulty workmanship” or “non-listed equipment” exclusion.

Worker’s compensation carriers also track heater-related injuries. If an employee is burned by a personal heater, the employer’s workers’ comp premium can rise, and the carrier may refuse future coverage for that location. Many carriers now require a written no-heater policy as a condition of renewal.

ADA Reasonable Accommodation: Cold Sensitivity

The Americans with Disabilities Act (ADA) and the Equal Employment Opportunity Commission require employers to provide reasonable accommodations for workers with qualifying medical conditions. Cold sensitivity linked to Raynaud’s disease, lupus, hypothyroidism, or fibromyalgia can qualify. The plain-English meaning is that an employee with a medical note can sometimes get a heater even when others cannot.

The process is called the interactive process under 29 CFR 1630.2(o)(3). The consequence of denying a valid accommodation request is an ADA discrimination complaint and potential damages. For example, an accountant named Priya in Atlanta filed an EEOC charge when her firm denied her heater request for Raynaud’s; the firm settled and installed a UL-listed enclosed heater under her desk. A common misconception is that the employer must grant the exact accommodation requested; the employer can offer an alternative, such as a heated chair pad, extra breaks, or a warmer office location.

Three Real-World Scenarios

Every office heater case follows a pattern. The table below shows the three most common scenarios and what happens next.

Scenario 1: Employee Brings a Heater From Home

Scenario 2: Landlord Finds a Heater During Inspection

Scenario 3: Fire Marshal Annual Inspection

Five Named Examples You Can Learn From

Real people face heater problems every winter. These five examples show how the rules play out in practice.

Example 1: Marcus, a Paralegal in Chicago. Marcus brought a $29 heater from a discount store and plugged it into a surge protector under his desk. The building engineer found it during a routine walk-through. His firm was cited under the lease, and Marcus was given a written warning.

Example 2: Sofia, an HR Director in Dallas. Sofia wrote a company-wide heater policy that required UL listing, direct wall plug, and three feet of clearance. When OSHA inspected after a complaint, the inspector closed the case with no citation because the policy was documented and enforced.

Example 3: Kenji, a Fire Marshal in Seattle. Kenji conducts annual inspections of downtown office towers. He issued 42 citations in the winter of 2025, most for extension cord use under IFC 605.10.3. His top advice is to buy heaters with built-in long cords rated for the heater’s wattage.

Example 4: Priya, an Accountant in Atlanta. Priya has Raynaud’s disease and requested a heater as an ADA accommodation. Her firm first said no, then settled an EEOC charge and provided a UL-listed enclosed radiant heater. She now works in comfort and keeps a doctor’s note on file.

Example 5: Lauren, a Facility Manager in Boston. Lauren runs a 400,000-square-foot Class A office tower. She banned all personal heaters after a 2023 fire cost her tenant a $220,000 business interruption claim. She now offers under-desk foot warmers and heated chair pads as safer alternatives.

Mistakes to Avoid

Small heater mistakes cause big legal and financial problems. Here are the most common errors and what each one costs you.

• Mistake 1: Plugging a heater into a power strip or extension cord. This violates IFC 605.10.3 and causes most office heater fires.
• Mistake 2: Buying a heater without a UL or ETL listing. Non-listed heaters lack required tip-over and overheat switches.
• Mistake 3: Leaving a heater on overnight or over the weekend. This voids most insurance policies and violates the “attended use” clause on the UL label.
• Mistake 4: Placing a heater under a desk with paper nearby. This breaks the three-foot combustible rule and is the top fire marshal citation.
• Mistake 5: Ignoring the lease’s appliance ban. Most commercial leases ban heaters, and violation is a cure-or-quit default.
• Mistake 6: Failing to document an ADA accommodation request. Without a written interactive process, a denial becomes an EEOC claim.
• Mistake 7: Assuming OSHA has a minimum temperature rule. OSHA only recommends 68°F to 76°F; there is no binding federal number.
• Mistake 8: Using a kerosene or propane heater indoors. These are banned in almost every office occupancy and violate NFPA 1 and IFC.
• Mistake 9: Skipping the employer’s written heater policy. Without a policy, OSHA will treat any heater incident as a General Duty Clause failure.

Do’s and Don’ts of Office Space Heaters

The rules are simple once you see them side by side. Use this quick guide to stay safe and legal.

Do’s:

• Do buy only UL 1278-listed or ETL-listed heaters, because non-listed units lack required safety switches.
• Do plug the heater directly into a wall outlet, because IFC 605.10.2 requires a direct connection.
• Do keep the heater three feet from paper, curtains, and trash, because combustibles cause most office fires.
• Do turn the heater off when you leave your desk, because “attended use” is a UL and insurance requirement.
• Do check your lease and employer policy first, because building rules often ban heaters outright.
• Do request an ADA accommodation in writing if you have a medical need, because documentation protects your job.

Don’ts:

• Don’t use extension cords or power strips, because IFC 605.10.3 prohibits them.
• Don’t buy fuel-burning heaters (propane, kerosene, natural gas) for office use, because they are banned in most occupancies.
• Don’t share one circuit with a coffee maker or microwave, because overload is a top fire cause.
• Don’t hide the heater during inspections, because the fine and loss of trust is worse than the heater ban.
• Don’t assume your homeowner’s habits apply at work, because commercial fire codes are stricter than residential.

Pros and Cons of Allowing Space Heaters

Employers often ask if they should allow heaters at all. The honest answer is that the risks usually outweigh the benefits in a commercial office.

Pros:

• Pro 1: Improved comfort for cold-sensitive employees, because personal heat raises morale and productivity.
• Pro 2: Lower HVAC costs in large buildings, because you avoid heating the whole floor for one person.
• Pro 3: Easier ADA compliance for medical cold sensitivity, because heaters are a simple accommodation.
• Pro 4: Flexibility for shoulder-season weather, because turning on full building heat for one cold day is wasteful.
• Pro 5: Employee retention, because comfort is a real factor in job satisfaction surveys.

Cons:

• Con 1: Fire risk, because NFPA data show heaters cause 81% of heating fire deaths.
• Con 2: Insurance claim denial, because carriers like FM Global exclude coverage for unapproved heaters.
• Con 3: OSHA citation exposure, because the General Duty Clause applies to every heater incident.
• Con 4: Electrical overload, because most office circuits cannot handle a 1,500-watt heater plus a computer.
• Con 5: Lease default risk, because many commercial leases ban portable heaters entirely.

State-by-State Nuances

Federal law sets the floor, but states add their own rules. Below are the five biggest state markets and what makes each one different.

California

California enforces the California Fire Code, which adopts IFC 605.10 with stricter enforcement in high-rise buildings. The plain-English meaning is that every office building over 75 feet tall faces extra scrutiny. The consequence of a violation in San Francisco or Los Angeles is a four-figure fine and a re-inspection fee. For example, a tech firm in Mountain View was fined $2,500 per heater after a 2024 inspection. A common misconception is that Silicon Valley is “tech-friendly” on heaters; the fire code is strictly enforced.

New York

New York City adopted IFC 605.10 into the NYC Fire Code. The plain-English meaning is that every Manhattan office tower is subject to annual FDNY fire safety inspections. The consequence of a violation is a FDNY Notice of Violation that carries fines up to $10,000 per incident. For example, a Midtown law firm was fined after an FDNY inspector found three heaters on one circuit. A common misconception is that co-working tenants are exempt; they are not.

Texas

Texas enforces the Texas State Fire Marshal rules and allows local cities to adopt IFC or NFPA 1. The plain-English meaning is that Houston, Dallas, and Austin all enforce 605.10-style rules. The consequence of violation is a city fine and, in multi-tenant buildings, loss of the certificate of occupancy. For example, an oil and gas firm in Houston had its floor shut down for three days after a heater-caused small fire. A common misconception is that Texas is “light” on regulation; fire marshals enforce heater rules aggressively.

Florida

Florida adopts NFPA 1 through the Florida Fire Prevention Code. The plain-English meaning is that every county fire marshal can inspect an office and cite heater use. The consequence is a state-level violation that travels with the building. For example, a medical billing office in Orlando lost its insurance rider after repeated heater citations. A common misconception is that Florida offices “don’t need” heaters; winter cold snaps trigger real demand, especially in January.

Illinois

Illinois enforces the Office of the State Fire Marshal rules and adopts NFPA 1. The plain-English meaning is that Chicago’s high-rises face both state and city fire code enforcement. The consequence of a violation is a double citation from city and state inspectors. For example, a Loop accounting firm received two separate fines for the same heater incident in 2025. A common misconception is that only downtown buildings face inspection; suburban offices are inspected too.

Key Entities You Should Know

Several organizations shape the space heater rules in the United States. Knowing who does what helps you respond fast if you get a notice.

• Occupational Safety and Health Administration (OSHA) sets federal workplace safety rules and enforces the General Duty Clause.
• National Fire Protection Association (NFPA) writes NFPA 1 and other codes that states adopt into law.
• International Code Council (ICC) publishes the International Fire Code that most U.S. jurisdictions adopt.
• Underwriters Laboratories (UL) tests and lists heaters to UL 1278 and UL 2021 standards.
• Equal Employment Opportunity Commission (EEOC) enforces ADA accommodation requirements for cold-sensitive workers.
• FM Global and The Hartford are the major commercial property insurers that publish heater rules.
• Building Owners and Managers Association (BOMA) publishes model lease language for commercial offices.
• State Fire Marshals enforce NFPA 1 and IFC in every U.S. state, usually through county or city inspectors.

Writing an Office Heater Policy: Step-by-Step

A written heater policy is the single best defense against OSHA, fire marshal, and insurance risk. Every office should have one.

Step 1 is to decide allow or ban. The plain-English meaning is that you pick one and put it in writing. The consequence of no policy is that OSHA will treat every heater incident as a General Duty Clause failure. For example, SHRM publishes a model heater policy that many HR teams adapt. A common misconception is that a verbal rule is enough; only written policies hold up in court.

Step 2 is to list approved models. The plain-English meaning is that you name specific UL-listed heaters employees can buy. The consequence of no model list is that staff will buy cheap non-listed units. For example, a Minneapolis law firm lists three approved Vornado and Lasko models in its handbook. A common misconception is that “any UL heater” is fine; specificity prevents disputes.

Step 3 is to require written approval. The plain-English meaning is that each heater gets a sticker and a log entry. The consequence of no approval process is that nobody knows which heaters are in the building. For example, a Washington, D.C. law firm uses green stickers and quarterly audits.

Step 4 is to train staff annually. The plain-English meaning is that every worker signs off on the policy each year. The consequence of no training is an OSHA citation if anyone gets hurt.

Step 5 is to enforce with discipline. The plain-English meaning is that violating the policy leads to a written warning and possible termination. The consequence of weak enforcement is that the policy is worthless in a lawsuit.

Recent Rulings and Precedents

Courts and agencies have decided several heater-related cases that shape today’s rules. The plain-English meaning is that these rulings show how liability lands.

In Secretary of Labor v. Tampa Electric Co., an OSHA administrative law judge upheld a General Duty Clause citation for an unattended space heater that caused a small office fire. The consequence was a sustained fine and a requirement to adopt a written heater policy. For example, the ruling is cited by OSHA inspectors during field investigations. A common misconception is that small fires with no injuries are “no harm, no foul”; the violation alone is enough.

In insurance litigation, courts have repeatedly upheld carrier denials when a non-UL-listed heater caused a fire. The consequence is that tenants often absorb six-figure losses. For example, courts in New York, Illinois, and Texas have all ruled for insurers in the last five years. A common misconception is that the “innocent employer” defense works; it rarely does when the policy has a faulty-equipment exclusion.

In ADA cases, the EEOC has secured settlements for employees denied heater accommodations. The consequence of a denied request without an interactive process is back pay and injunctive relief. For example, the EEOC reported multiple office accommodation settlements involving heaters between 2020 and 2025. A common misconception is that employers can simply refuse; the law requires an interactive dialogue.

Safer Alternatives to Space Heaters

Many facility managers now offer alternatives that keep workers warm without the fire risk. The plain-English meaning is that you can solve the comfort problem without a 1,500-watt heater.

Heated chair pads draw only 10 to 30 watts and cannot start a fire. Heated foot warmers plug into USB and stay below 120°F. Under-desk radiant panels, UL 2021-listed and hard-wired, offer permanent solutions without the tip-over risk. Insulated desk mats and thermal curtains reduce drafts from exterior windows. Layered clothing policies with branded company fleece jackets solve most cold complaints for less than $50 per employee.

If comfort problems persist, the right answer is usually a building-wide HVAC fix. ASHRAE Standard 55 sets thermal comfort targets of 68°F to 76°F with 30% to 60% relative humidity. Bringing the whole office into ASHRAE 55 range usually eliminates 90% of heater requests.

When to Call a Workplace Safety Attorney

If you face an OSHA citation, a fire marshal notice of violation, a lease default, or an ADA denial, call a licensed workplace safety attorney. The plain-English meaning is that the stakes are too high to handle alone. The consequence of going it alone is often a higher fine, a failed appeal, or a settlement that sets bad precedent. For example, employers who respond to OSHA within the 15-day contest period often win reductions in fines and classifications. A common misconception is that you can just pay the fine and move on; an uncontested OSHA citation stays on your record for five years and raises future inspection odds.

FAQs

Are space heaters illegal in office buildings?

No. Space heaters are not illegal in most U.S. office buildings, but they are heavily regulated by IFC 605.10, NFPA 1, OSHA, your lease, and your insurer. Many employers still ban them voluntarily.

Does OSHA ban space heaters at work?

No. OSHA has no rule that bans space heaters, but the General Duty Clause lets OSHA cite employers for unsafe heater use. Citations can reach $16,550 or more per violation.

Is it legal to plug a space heater into a power strip at the office?

No. IFC Section 605.10.3 and most state fire codes prohibit plugging a portable electric heater into any extension cord, surge protector, or power strip. Violations trigger fire code citations.

Does my employer have to let me use a space heater for a medical condition?

Yes. Under the ADA, employers must engage in an interactive process for reasonable accommodations, which may include a heater or an equivalent alternative like a heated chair pad.

Can my landlord ban space heaters even if they are legal under state law?

Yes. Commercial leases almost always give landlords authority to ban portable heaters. Violating the lease can trigger a cure-or-quit notice, fines, or eviction, regardless of what state law says.

Will my business insurance cover a fire caused by a space heater?

No. Most commercial property policies, including FM Global and Hartford forms, exclude or limit coverage for fires caused by unapproved or non-UL-listed portable heaters.

Are space heaters allowed in hospitals or medical offices?

No. IFC 605.10 bans portable electric heaters in Group I-2 occupancies like hospitals and nursing homes, except for special low-temperature units under 212°F in staff areas.

Does OSHA set a minimum office temperature?

No. OSHA only recommends 68°F to 76°F under the Technical Manual. There is no binding federal minimum, but extreme cold can trigger a General Duty Clause citation.

Do UL-listed heaters still require a three-foot clearance?

Yes. Even UL 1278-listed heaters must stay three feet from combustibles under IFC 605.10.4. UL listing alone does not exempt any heater from the clearance rule.

Can I be fired for using a banned space heater at work?

Yes. If your employer has a written no-heater policy and you violate it, termination is a lawful outcome in most U.S. at-will states. Documented warnings usually come first.

Are propane or kerosene heaters ever allowed in offices?

No. Fuel-burning heaters are banned in nearly every office occupancy under NFPA 1 and the International Fire Code due to carbon monoxide and fire risk.

Do co-working spaces like WeWork allow space heaters?

No. Major co-working operators including WeWork and Regus ban portable heaters in their house rules. Members caught using them can lose access to the space.