Add a story to a semi detached home?

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Posted by: from Toronto
2/2/2013 at 3:37:50 PM

I have a 2 story semi detached home in Toronto. Instead of moving we are thinking of adding an extra story but we don't even know if this is possible in a semi detached home. We realize there will be factors such as whether the foundation can handle another level.

Can someone please let me know if 1- this is even possible and 2- what steps I should be doing/thinking about.

Should I get an engineer in first or will a contractor be able to help me through the process/steps?


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Date/Time2/2/2013 at 8:05:26 PM

Anything is possible, it just depends if it's worth it to you.

Your first step should be to call your city building department, to see if it is even allowed. They do have height restrictions in different areas.

Then call in a contractor to get an idea of costs, to see if it's in your budget.

Then get your plans drawn up, either by an engineer or architect.

Then you are ready to have contractors give you quotes, based on the actual plans.

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Date/Time2/3/2013 at 8:51:49 AM

Yes - call an engineer or even an architect ( they're drawings will need an engineers stamp ) in order to get a building permit.

Very few contractors are qualified to give you the expert advice you need.

Best wishes

Glenn Durkin

SPICA Construction Management


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Date/Time2/3/2013 at 10:59:14 PM

Definitely talk to an engineer.

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Date/Time2/6/2013 at 4:27:32 PM

I would agree with James.

Your first step should be to talk to your city building department as there are by-laws that limit the size of buildings (square footage on a lot, heights, set-backs, etc.). If you building department gives you the go ahead then I would defiantly talk to an engineer, architect or depending on what your city building department requires, even some design company's are qualified by the Ontario government to do this. They will be able to complete the basic calculations on your footings (ask the city if they have plans if you do not) and help you through the design process.

Going to a contractor is probably your last step to find out what it will cost to build it. After that hopefully you can get everything you want that keeps you where you want to be.

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Date/Time2/6/2013 at 4:33:16 PM


Because your home is a semi-detached, structurally, you share the same roof as your neighbour!

This is definitely not permitted! If you look inside your attic, you will see a "common" wall between you and your adjacent house.

It's like adding an addition in the middle unit of a townhouse or row house complex!

In my opinion, if you require more square footage, or living space, consider selling your house and purchasing something more suitable, like a fully detached. Later, if you would like to expand upwards or backwards, you most likely are able.


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Date/Time2/8/2013 at 2:17:21 PM

Hi there

I agree with Rogers, with semi detached houses it will be very difficult to push such project through the city, unless both units would like to expand. In this case the only restriction would be the city by-laws, which can be played around in committee, if the project you are planning is adequate and makes common sense.

Before you talk to anyone I would ask your real estate what you will gain in price if you accomplish such addition. It should make sense financially to start such projects, and if price will go up substantially then you persuade your neighbors to build this project together.

Other than that from construction perspective it is not complicated. Such additions are most common throughout GTA these days.

Hope this helps.


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