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House Additions: Leaving Two Exisiting Walls

House Additions: Leaving Two Existing Walls

You can see it happening all over Toronto, and in suburbs with older homes such as south Mississauga and Thornhill.   Homeowners and builders are demolishing most of a house, but leaving two exterior walls in place.  They then proceed to build a substantial house addition and refinish the entire inside and outside of the house as if it were new. 

Why are they leaving part of the house, rather than tearing down the existing house and building a new custom home?  There are four primary reasons that this is being done.

Perceived Savings

There are additional costs involved in building a new home: new water/sewer connection, grading plans, survey costs, and new home warranty insurance.  Classifying the project as an addition/renovation can avoid these costs.  These savings are usually offset by additional labour costs: higher costs of demolition (demolishing by hand rather than by machine), foundation work, and framing work.  From our experience, the costs of a major addition vs. new home are very similar.  We’ve even seen cases where building the project as an addition would be more expensive.  Even if the house addition is less expensive, we believe the additional cost of building the new home is worth it, to get a better foundation and a better basement.

Zoning Issues

Sometimes an existing wall will be left in place to avoid zoning issues.  For example, the existing side wall may be one foot from the property line, while the current zoning by-law requires a three foot setback.  By leaving the existing wall in place, the zoning issue is avoided.  Tearing down and building new would require the new building to comply with current, more restrictive, zoning regulations.  In this case, retaining walls can be beneficial.

Avoiding New Home Warranty

Every new home built and sold in Ontario must come with a new home warranty, backed by Tarion Warranty Corporation (formerly the New Home Warranty Program).  Builders and sellers of new homes must be registered with Tarion, and must meet service and warranty standards.  Most contractors and builders are not registered with Tarion, and therefore are not permitted to build a new homes.   Leaving two walls in place allows them to build a project that is not classified as a new home, and thus avoiding registration, compliance with stricter regulations, and warranty oversight by a third party.

Environmental Concerns

Retaining some of the existing structure is seen as being more environmentally friendly, with less waste being generated.  This concern has been alleviated in recent years.  Several recycling facilities have opened in the Toronto area specifically to deal with construction waste, and they divert approximately 90% of the waste than would otherwise go to a landfill.  So it is now possible to build new and not have to be as concerned about the environmental impact of the work.

How Do You Decide the Best Approach?

Our experience suggests the larger the addition project, the more sense a custom home project makes.  But every project is unique, so speak with your builder and architect and get their opinion on the issue.