Abandoned buildings and structures are inherently dangerous. That statement is not meant to discourage exploration, but it is meant to be taken seriously. Every year, people are injured or killed in abandoned buildings, and many of these incidents are preventable. If you are going to visit abandoned places in Ontario, understanding the risks and preparing for them is not optional.
Structural Hazards
The most common danger in abandoned buildings is structural failure. Floors, roofs, stairs, and walls that appear solid may be severely compromised. Wood rots from the inside. Concrete spalls and cracks. Steel rusts and weakens. In Ontario's climate, the freeze-thaw cycle accelerates deterioration dramatically, cracking masonry and heaving foundations year after year.
Floors are the most dangerous element. Water damage, rot, and insect infestation can weaken a floor to the point where it will collapse under the weight of a person. This is especially true of upper floors in multi-storey buildings, where water infiltration from a failed roof has been working on the structure for years. Test every surface before you put your weight on it. If a floor feels soft, springy, or sounds hollow, do not proceed.
Roofs can collapse without warning, particularly in winter when snow loads add weight to structures that are already compromised. Basements and sub-grade spaces may contain standing water, collapsed debris, or hidden shafts. Stairs may have rotted treads or missing handrails.
Environmental Hazards
Many abandoned buildings contain hazardous materials. Asbestos was widely used in Ontario construction from the 1920s through the 1980s and may be present in insulation, floor tiles, ceiling tiles, and pipe wrapping. Disturbing asbestos-containing materials releases fibres that can cause serious lung disease.
Lead paint is common in buildings constructed before the 1970s. Mould is almost universal in abandoned buildings with water damage. Chemical contamination may be present in former industrial buildings, including heavy metals, solvents, and other toxic substances.
Biological hazards are also a concern. Abandoned buildings are often home to raccoons, bats, birds, and other wildlife. Accumulated animal waste, particularly bat guano and pigeon droppings, can harbour diseases including histoplasmosis. In rural areas, snakes may shelter in abandoned foundations.
Every abandoned building presents unique hazards. Assess conditions carefully before approaching or entering any structure.
Essential Equipment
If you are going to explore abandoned places, even from the outside, basic preparation is important:
- Sturdy footwear — boots with ankle support and thick soles to protect against nails, broken glass, and uneven terrain
- Flashlight — even in daylight, interiors of buildings can be completely dark; bring at least two light sources
- First aid kit — including tetanus awareness; ensure your tetanus vaccination is current
- Phone with charged battery — for emergencies and for documenting your visit
- Dust mask or respirator — essential if entering any building where asbestos or mould may be present
- Gloves — protect against cuts, splinters, and contaminated surfaces
General Principles
Never explore alone. Always tell someone where you are going and when you expect to return. Do not visit sites at night unless you are very experienced and have a specific reason. Trust your instincts: if something feels wrong or unsafe, leave immediately.
Be aware of your surroundings beyond the site itself. Remote abandoned buildings may be used by people who do not want to be disturbed. In rural areas, property owners may respond aggressively to perceived trespassers. In former mining areas, the ground itself may be unstable.
Follow the principles of ethical exploration. Take photographs, not souvenirs. Leave no trace of your visit. And respect the legal boundaries that apply to the sites you visit.