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Self-supporting cantilevered roof

Sunshine&Snow

Registered User
Joined
Jun 27, 2021
Messages
4
Location
British Columbia
My house has a rotten balcony and deck but the roof is good. The roof is about 24' long and extends about 7 ft horizontally from the building (so maybe 9' diagonally?)

Actual picture

The roof is cantilevered into the opposite roof. The original city plans (poor quality) show that it appears to be supporting the balcony, which is attached to the ledger.

City Plans

We would like to remove the deck and balcony and either cut back the roof or leave it as is or possibly rebuild the entire deck/balcony.

Sketch of possible reno

We need to know if the roof is structurally strong enough to hang on its own, or would it need support braces back to the house?

Is there enough information in the plans to indicate that it can support itself, or if I need to have an engineer certify it, what information would they need?

The house is on a small island that requires a barge to get materials to/from the island. (Protection Island, near Nanaimo, BC)

From what I can see, the original plans show the cantilevered roof is VERY strong. What do you think?
 

cda

Sawhorse 123
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Oct 19, 2009
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20,966
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Basement
Not my area
But seems like if you leave the overhang,,, it would need support posts

Think about a foot of snow setting on it,,, unsupported
 

ICE

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Ca. concrete jungle
Pictures would help. A drawing of the original condition would help. A cantilevered roof supporting a deck would be interesting to see and understand.
 

cda

Sawhorse 123
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Oct 19, 2009
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Basement
Pictures would help. A drawing of the original condition would help. A cantilevered roof supporting a deck would be interesting to see and understand.
Did you click on the blue wording
 

ADAguy

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Sep 11, 2013
Messages
6,209
Location
California
So you will remove the balcony leaving the roof cantilevered 7' from the building face. If you introduce 45 degree braces at 48" o.c. back to the building face supporting a continuous beam supporting the roof and reducing the cantilever by 1/2 you might be able to do it, Need to verify with an engineer.
 

Mark K

Platinum Member
Joined
May 12, 2010
Messages
2,093
Hire a structural engineer. There is not enough information to understand the problem or to develop a solution and this information cannot reasonably be conveyed by email or by postings on this web site.
 

SDS

Registered User
Joined
Dec 30, 2020
Messages
51
Location
Washington State, USA
The city plans are clear enough...

...remove the beam supporting the roof above the deck and the roof comes down.

The roof cannot be cantilevered without support as it does not meet the definition of cantilever

Cut the roof back to eave-length

or

Leave the beam supporting the roof and replace the posts supporting the beam (remove the deck only)

Any engineer is going to tell you the same thing...
 

Sunshine&Snow

Registered User
Joined
Jun 27, 2021
Messages
4
Location
British Columbia
Thanks everyone for the insight. Originally I thought the opposing roof would be strong, but I realize it is only as as strong as the bolts (or nails) attaching the rafter. Keeping the roof would require rebuilding the balcony and deck, which is a lot of wood and work for a 6' deck that probably wouldn't get used much. I will probably cut it back to eave length or remove it and build a small awning over the windows. Then build just a lower deck.
 

Sunshine&Snow

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Jun 27, 2021
Messages
4
Location
British Columbia
I find it hard to believe the city plans were approved because the balcony looks like it is attached to the ledger board on the rim joist. The angled roof would be supporting a considerable load without posts to the ground.

City Plans
 

SDS

Registered User
Joined
Dec 30, 2020
Messages
51
Location
Washington State, USA
I find it hard to believe the city plans were approved because the balcony looks like it is attached to the ledger board on the rim joist. The angled roof would be supporting a considerable load without posts to the ground.

City Plans
I'd venture a guess that the approved foundation plan shows footings/piers where the (4) posts are located...I'd say the designer omitted showing the posts in that section view to allow for text and the balcony support is detailed elsewhere in the plans...based solely on the provided picture of the actual construction which shows (4) posts continuous to the ground.

I'd also agree with ICE...a balcony supported by a cantilevered roof would be interesting to study :)
 

tmurray

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Jun 10, 2011
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2,274
Location
NB, Canada
I find it hard to believe the city plans were approved because the balcony looks like it is attached to the ledger board on the rim joist. The angled roof would be supporting a considerable load without posts to the ground.

City Plans
A lot of the time, older builds were not subjected to the more rigorous review that we see today. Looking through my archives, there was a time where we did not even receive plans. It was just a box sketched on an application showing how big the house was (nothing inside). After this, we required plans, but the inspector had no qualifications to review or inspect. He was a utility superintendent and had next to no knowledge about the building code. It wasn't until the 2000s that we started to have qualified inspectors. Even then, my boss (he's at 30 something years with my municipality) says I am the first "real" building inspector we've had. So, I'm not really surprised that this got through a plan review without any apparent comments.
 

ICE

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Jun 23, 2011
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10,277
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Ca. concrete jungle
We used to meet at a restaurant and use place mats for sketching the basics. The next step was important.....deciding where it was going to be on the property. The lady of the house had to approve the view from the kitchen window. I don't know about permits and codes. We just did it the same way as we always did it.
A big difference from then to now is that I used to be able to find every stud through drywall with just a tape measure. Now they pull from every which way and layout is random.
 

ICE

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Jun 23, 2011
Messages
10,277
Location
Ca. concrete jungle
It wasn't until the 2000s that we started to have qualified inspectors. Even then, my boss (he's at 30 something years with my municipality) says I am the first "real" building inspector we've had. So,
Unfortunately, we are trending in the opposite direction.
 
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