Different Types of Demolition and When to Use Them

Demolition (https://en.wikipedia.org/wiki/Demolition) is more than just “tearing it down.” It is a selection of methods based on types of materials, the surroundings, and hazards. For construction students and DIY remodelers, understanding the primary approaches – and when it makes sense to use each one – makes for better safety, cost control, and scheduling. This article outlines the most typical methods, best uses, and the safety and site prep common to all types of demolition.

What is Mechanical Demolition?

Mechanical demolition is defined as the use of large machinery, or heavy equipment, to break, shear, or pull apart a building. The majority of mechanical demolition is through excavators, and supported by hydraulic breakers, shears, or pulverizers. Mechanical demolition is the most typical method for houses and low to mid-rise buildings because of its predictable nature, speed, and the ease of pricings.

Before machinery can take to the site there is a lot of work to complete: verify the shut-offs for utilities, set up fencing, determine traffic control, and dust suspension measures. A site that is graded correctly and has a debris staging area for trucks only helps to keep them moving and the neighbours happy. Once the tear down is finished, who is hauling waste, and what is sorted into landfill and what is being recycled is determined.

• Typical Applications: residential wood frame houses, small commercial buildings, garages, and additions.
• Typical Equipment: excavators, skid steers, loaders, breakers (hydraulic) and pulverizers (concrete material).
• Advantages: speed, control of costs, limited logistical impact – particularly on open sites.
• Disadvantages: Overhead wires, tight property lines, and any unknown hazards (i.e., lead paint, asbestos) would have to be remediated before beginning work.

Controlled Implosion Explained

Controlled implosion is a specialized technique that collapses a building inward using explosives with a specific timing sequence.

This method is for large, heavily framed structures like defunct stadiums, high-rise hotels, or concrete towers. It is deemed too slow or dangerous for mechanical demolition.

An implosion plan will begin with a structural engineering review assessing load paths and the critical members. Drilled charges weaken those elements, and a sequenced timing detonation will cause the structure to fold into itself. The work requires large exclusion zones, extensive monitoring, and detailed coordination with local authorities for compliance with building codes, road closures, and public notice. For nearly everything else under a few stories, it is usually safer and easier to use mechanical or selective methods.

Selective Demolition for Renovations

Selective demolition only removes elements that have to be taken, all other elements remain intact. Selective demolition is often used for tenant fit-outs, remodels to kitchens or baths, and historic rehabs. It may involve a crew stripping finishes, cutting openings, and removing a few single bays while safely supporting both the remaining floors and walls. Selective demolition protects some of the valuable elements and contains the new work to the new work only.

Selective demolition is also effective on tight urban lots because it is usually a requirement to keep vibration and debris under control. In rowhouse neighborhoods and infill sites, the owners regularly seek out local firms for demolition demolition services—many will relate to local city regulations and speculation-such as home demolition Philadelphia-that specialize in the coordination of permits, utility management, and access into narrow spaces.

Due to the ongoing nature of the remaining structure, temporary shoring and sequencing is a necessity. Crews isolate and cap utilities, along with any existing utility lines, and utilize low-vibration tools to reduce the impact on surrounding finishes and to protect neighboring properties. The upside to selective demolition is that you generate less waste and you also have a quicker build-back once the demolition is complete.

Deconstruction and Material Salvage

Deconstruction is the systematic disassembly of a building down to its materials in order to salvage materials on-site for reuse, recycling, or to be repurposed. It involves less efficiency and a more tactile methodology; instead of blindly smashing, laborers pull nails, de-nail studs, stack bricks, and pull fixtures and trim. Many municipalities encourage, if not require, salvage for specific project types, so that they don’t load up their landfills, and capture some of the embodied energy that is tied up in the building. Read more on this page.

Deconstruction takes more labor and time than mechanical demolition, so it works better if the schedule is forgiving, or if the materials are of a value that merits some effort. Deconstruction also works better with reuse centers in the community, or with non-profits that will take the materials as a donation.

• Solid candidates for salvage: old-growth lumber, solid-core doors, cabinets, hardwood flooring, architectural trim, and bricks or blocks that can be recycled as concrete aggregate.
• Benefits of salvage: diverted waste from landfills, possible tax write-off for donated materials, and less disruption for adjacent property owners due to less heavy trucking traffic.
• Planning: material audits, separate staging locations for salvaged items, and cooperation and coordination with the hauler to eliminate double handling of debris.

Selecting the Safest Method

Choosing a demolition method begins with a written survey of the building. What is the building made of, how tall is it? What are the spans, if any? Has it been previously damaged by fire, or water? Next up are the site constraints; how big is the lot, is there access for equipment, traffic on public streets, or are there occupied buildings nearby? Schedule and budget are important, but the method must be chosen based upon a different test: can we ensure the protection of the workers, the neighbors, and utilities at every phase of the dismantling of the building?

If it’s a smaller house, on an open lot, typically the best balance of cost and control is mechanical demolition using solid dust suppression methods. If it’s a heavy interior renovation where 50% of the building will remain, selective demolition keeps what needs to remain, and brings down the rebuild costs. Deconstruction is most sustainable and makes the most sense when schedule flexibility allows and there is re-sale value for the materials. Implosion is typically reserved for larger and heavier buildings where the safest way to bring it down is to bring it down as it stands.

Regardless of the method, a few consistent approaches will keep any project on track during demolition. Plan for dust control, either with little water mists or fog cannons to keep airborne particles to an absolute minimum. Get MGU shutoff verified to prevent the possibility of sudden energization or disturbances of the services. Mark out clear fencing and signage, and traffic routes to eliminate any future exposure between pedestrians and traffic. Fulfill all permits, notifications, and inspections in order to meet code requirements from start to finish! After demolition, backfill and compact the site will allow for rough grading of the site.

Demolition is the very first chapter of construction, and should not be an afterthought or an unplanned event! When the team identifies alignments between the method that is aligned with the structure, the hazards have been managed, and the planned clean-up is properly prepared – the new construction phase starts from a safe and clean place.