Before entering a damaged building, walk all the way round it and judge whether it will fall on you: do not go in if walls lean more than 5 degrees from vertical, foundation cracks are wider than 1 cm, or load-bearing members are charred deeper than 2 cm, and never work inside alone. Work on the ground floor only, know two exits before you start, and keep a partner outside watching and listening.
Part of Building Material Recovery
A damaged building holds its own weight by a margin you cannot see, and the first minutes of salvage are spent deciding whether that margin remains. Everything else in the job depends on the answer.
A Building That Has Moved Is More Dangerous Than One That Merely Looks Old
A house that has shifted on its foundation, lost a wall’s support or carried a fire is carrying loads along paths that were never meant to take them. The signs are visible from outside, which is why you assess before you enter. The parent article gives rules of thumb: foundation cracks wider than 1 cm, walls leaning more than 5 degrees from vertical and wood charred more than 2 cm deep. They are cautious guides, not engineering limits, and a building that shows none of them can still be unsafe. The next page lists the signs in detail: Signs of Imminent Collapse.
What You Need
- A partner, who stays outside with a clear line of sight to the entrance.
- A long stick or bar for probing floors and debris.
- Helmet, boots, gloves, eye protection and a respirator or dust mask; see Personal Safety During Demolition.
- A way to signal, such as a whistle or a pot to bang.
Method: Outside First, Then The Ground Floor Only
Step 1: Walk round the whole building. Look at the foundation, the walls, the roofline and the corners. Note cracks, lean, bulges and sag.
Step 2: Apply the rules. If the building has shifted off its foundation, do not enter; work from outside (parent article).
Step 3: Check the roof load. Water weighs 1 kg per litre, so a damaged roof holding a pool of water can fail suddenly.
Step 4: Listen. Creaking, popping, grinding or falling debris means the structure is still moving.
Step 5: Look for hazards beyond collapse. Asbestos, lead paint, mould, live wires, gas lines and animals are covered at Asbestos, Lead Paint & Other Hazards.
Step 6: Set the working rules. If load-bearing walls are visibly compromised, enter only ground-floor rooms with an exterior wall you can leave through; never go above the first floor of a compromised building; never work alone, with one person inside and one outside watching and listening; identify two exit routes before starting (parent article).
Step 7: Re-check during the work. Removing material changes the load paths. Stop at any new sound or movement.
Common Mistakes
- Assessing from the doorway. Walk the full outside.
- Trusting a building because it has stood for decades. The disaster that damaged it may have changed it.
- Entering during or just after rain or snow. The load rises and so does the risk.
- Taking the one attractive beam. Pulling a member that carries load can bring the structure down.
Safety
Collapse kills quickly and gives little warning
A falling wall, roof or floor can kill or trap a person in seconds. If any of the exclusion signs applies, stay outside. Never enter alone, never work above the ground floor of a compromised building, and never remove a load-bearing member without knowing what it carries and supporting it first. Stop and leave at the first new sound or movement. Details are on Signs of Imminent Collapse.
What’s Next
- Learn next: Signs of Imminent Collapse — what to look and listen for
- Combine with: Personal Safety During Demolition — protective gear and working in pairs