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Commercial Flat Roof Replacement

Muckin_Slusher

Well-known member
Joined
Apr 1, 2017
Messages
465
Location
Abitibi
I own a warehouse in Northern Ontario. I bought it dirt cheap and have been repairing it as needed over the years. It had three separate flat roofs when I bought it. I have converted two of them to pitched roofs and installed shingles.

It's time to do something about the third one, which is also the largest.

First of all, there are no commercial flat roof companies near me (within 100 miles, maybe even further).

What are my options and where the hell do I start?
I'll most likely bring in some type of contractor, but I would like to do my own research first and learn as much as I can to make a good decision.

Roof is 73x44 feet. 24 inch tall steel trusses (welded angle iron) space 9 feet apart. Trusses run the 44 foot distance and are clear span (no posts).
Roof is decked with painted steel decking. The bottom ribs have severe corrosion and holes. Some of it has visibly started to sag between trusses.

There are pitched roofs adjacent to this one (see first pic).

I need to look into the pitched roof conversion options. From what I've seen you can add supports and purlins on top of the existing trusses. Peak and eaves would have to be like the adjacent roofs (eave would be over the garage doors). Seems like this should be the correct option since I'm gonna have to replace decking anyway.

The pics below are the worst of the roof. You can see the janky fixes that got done when the adjacent apartment building was demo'd after it burned. Some of the blocks fell through the roof. It was fixed with wood and has the silver roofing tin underneathP9270257.JPG



RIMG4635.jpg



RIMG4637.jpg



RIMG4641.jpg.
 
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budget76

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Joined
Jan 19, 2016
Messages
502
I'm interested to follow along, no good advice tho. Remember watching you buy the place on the old must-not-be-mentioned 4x4 site.
 
OP
M

Muckin_Slusher

Well-known member
Joined
Apr 1, 2017
Messages
465
Location
Abitibi
So, that McElroy Metals pitched roof conversion is only available in the USA. I'm in Canada.

Anyone know of a company that sells a conversion system up here?
 
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readhead

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Joined
Dec 8, 2012
Messages
6,181
Location
Durango, Co.
Keep it mind that the bar joist system you have is only designed to support itself and some snow load. I have installed something similar to the sloped retrofit system you showed. It involved extra support in the original roof to support the extra weight per the engineered plan.
 

mikedodge

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Joined
Jun 27, 2017
Messages
2,815
I agree that your current roof structure probably wasn't designed for that much extra weight. You'd need a structural engineer to come up with something or maybe a contractor who builds commercial up there can convert it.

Its very surprising that there's no company up there that deals with flat roofs. That's the standard for commercial pretty much everywhere in Canada. I'd prefer peaked too.
 

pbon

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Joined
May 14, 2017
Messages
3,498
I just spent about $70k replacing a roughly 60x100 flat roof. Did not consider turning it into a peak roof because adding the structure would have added to the roofing cost. I agree the extra weight of a bunch of steel beams could also be a problem.
 
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