Demolishing in an Urban Infill Environment
As municipalities look to slow urban sprawl, planners look to create high-density development through intensification in and around urban centres and near transit hubs. In urban areas there are often existing buildings that are old and of low density. Repurposing these sites becomes a necessary part of the plan. Old houses, commercial buildings, derelict industrial sites, and abandoned hospitals become new opportunities to improve and intensify neighbourhoods, breathing new life into communities. However, with the redevelopment of these sites comes a unique set of challenges.
Government regulations must always be considered in regard to the future use of the land, and various reports must be obtained to clearly understand all of the challenges involved in bringing a site to a reusable state. Phase 1, 2 & 3 Environmental reports are completed to evaluate the below grade conditions of the site, but what about the existing structure above? One thing that we often see in the industry is that owners miss completing a Pre-Demolition Designated Substance Survey/Report (DSS or DDR) on the building that is going to be demolished. The DSS is missed by owners largely because of a lack of knowledge that a DSS is actually required by law. The Ministry of Labour, not the municipality, regulates the DSS and as a result, the report may not be identified during the building permit application process, and often won’t come up until either tendering the demolition, or possibly even once construction starts. Even municipalities make this common mistake when they tender demolition projects without having a DSS completed, which frequently delays the project until the DSS is properly dealt with. For reference find a link to Section 30.1 & 30.2 of the Occupational Health and Safety Act for Construction Projects which identifies the legal requirements of the Owner.
Being prepared and educated about the DSS can help the owner right from the very start of the project to ensure that everything goes smoothly. In addition to the DSS being the law, having the report is particularly helpful during property purchase due diligence, as well as during the budgeting and costing for the project, and during the tendering of the demolition work itself. A DSS will identify any Designated Substances, like asbestos, and will quantify the amounts present. This information can then be used to accurately determine the cost to remove the asbestos. A DSS will also reduce project surprises; however, it is also important to understand that they may not always completely eliminate project risk. When budgeting for any project, it is always wise to allow for some additional costs during the abatement, since designated substances are sometimes found during the demolition of the structure. Being prepared for surprise expenditures can often take much of the sting out of additional project costs.
Another thing to consider is the location of the structure that is being demolished in relation to neighbouring structures. Hydro lines, buildings, fences, underground utilities, available onsite space and numerous other site factors need to be taken into account when planning for the removal of an existing structure and for the redevelopment of the site. A demolition expert can often help to find cost-saving solutions, such as leaving some of the foundation walls in place to act as shoring, so as to not undermine adjacent structures. Finding alternate solutions to deep shoring and excavations to reduce large open excavations for removals is another key way a demolition expert can help you reduce risks and streamline the project. Oftentimes, new structures are taller and heavier than the existing structure and in some cases, the existing native soils or soils disturbed by the removal of footings do not have sufficient bearing capacity for the proposed structure. This may be a good time to consider innovative ground improvement strategies to help provide for cost-effective foundations for your new structure.
Spending the time with a demolition expert to plan out the site and consider the placement of construction equipment throughout the project can help the owner to reduce construction costs without having to compromise on the quality of the development. Taking a practical and realistic approach to site access and the constraints of the site, combined with open discussions with contractors can help the owner to leverage the experience of the team to best maximize the site space.
Urban infill projects change a neighbourhood’s landscape in many positive and rewarding ways for the community. Take the time to carefully plan your projects, and ensure that you are working with a team of experts, including a trusted demolition expert, and utilize the team to their fullest potential. This will give your project the best chance of success.