What happens to my roof when adding a second storey to my Ottawa home?

When you add a full second storey, the existing roof normally comes off entirely. The shingles, sheathing and the trusses or rafters are removed so a new floor platform can be built on top of the first-floor walls, and a completely new roof is built over the new storey. Knowing how that works helps you plan for cost, schedule and weather risk.

Demolition starts with stripping the roofing. A bungalow roof produces a lot of waste, so disposal should be an itemized line in your quote. If the house is older, ask whether any roofing or attic materials should be tested for asbestos before demolition; if asbestos is present, it has to be handled under Ontario's asbestos rules, which adds cost and time.

With the roof off, the contractor builds the new floor system on top of the existing walls. This is where structural engineering matters most. The existing walls and foundation have to be confirmed to carry the new loads, and the connections between old and new structure have to handle gravity, wind and bracing. A second-storey addition is a structural alteration and needs a building permit, and your engineer specifies those connections on the drawings.

The new walls are framed on that platform and the new roof goes on top. You have design choices: a gable or hip roof that suits the neighbourhood, or a flat or low-slope roof for more headroom and a contemporary look. A hip roof loses some usable space at the corners compared with a gable, and roof style also affects cost.

The new roof is a complete system: trusses or rafters, sheathing, eave protection membrane, underlayment and your roofing material. Asphalt shingles and metal are both common; metal costs more and sheds snow well. Ask your contractor and designer what protection the Code and good practice call for at eaves, valleys and penetrations in Ottawa's freeze-thaw climate, and ask for the roofing as its own itemized line.

Insulation and ventilation matter. An addition must meet the Code's energy requirements; one verified example is the addition table, which calls for R-60 in a ceiling with an attic, though your designer may use a compliance package instead. Good insulation with proper ventilation is the main defence against ice dams, which form when escaping heat melts snow that refreezes at the eaves.

The biggest risk is the weather window between roof-off and the new roof being sealed. Ask each contractor how they schedule that stage and how they protect the house in between. You can browse addition contractors in the Ottawa Construction Network directory and compare itemized quotes.

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Looking for experienced contractors? The Ottawa Construction Network connects homeowners with qualified professionals:

• Homeupgraders
• RenoMotion Inc.
• Jaiko Cleaning Services
• Best Hand2Hand moving company
• MAK Construction and Development Inc