Wind Mitigation and Flat Decks

Flat decks are the guerrilla in the room
When a flat deck is supported on top of the tie beam and the framing members for said deck are spaced 16" oc and attached to the beam with individual straps, the roof sheathing from the pitched roof does not connect to the deck, and the deck is larger than 100 sq/ft. is the roof geometry now considered a Flat Roof? I say no because it is not structually connected to the main roof structure.
What say yea?

I would conscider this section if it is above enclosed living space.

I would agree with your analogy as far as structurely attached. Often times visual inspection is difficult in the case of flat roofs. I’m sure there would be roof coverings torn off if the flat was uplifted during a hurricane and water penetration.

I should have been clear. what i was trying to descibe would be a open porch

I am trying to viualize the intersection of the porch roof that sits on the tie beam and the main roof that does not contact it. Is there an opening between roofs? My understanding is if it is stuctural to the home it would be flat, now if this same porch was just tacked to the fasica it would not even be counted

Mark I would disagree with your approach, although technically you are correct. I do not believe that was the intent. I believe that a re-inspection would claim it is structurally connected, they will not go the lengths that you do to verify one way or another.

The first consideration is to check the proportions to determine if the flat roof has any effect on the geometry whatsoever. Remember, the roof will be considered flat if the flat portion is greater than 100 sf or greater than 10% of the roof, whichever is **greater. **Just because the flat roof portion is greater than 100 sf, it does not render the entire roof flat unless it also is greater than 10% of the entire roof area. Once you have determined that it might classify the roof as flat based on this criteria, then check to see if it is also structurally attached. Now to answer your question ----

The flat roof portion needs to be considered if either one of the following conditions apply
1). If the roof is structurally attached to the roof (the pitched roof in this case) — or
2). If the space enclosed is living space.

You have already determined that the flat roof deck is not attached to the pitched roof, so condition #1 does not exist, even though the flat deck is by itself structurally attached to other components (ie the tie beam)

Soooo - If there is living space below, you still have to consider the flat portion and apply the greater then 100 sf or 10% rule.

Hope that helps


Thanks for your input that is the reason a wanted too float this balloon. The million dollar question is exactly as you stated. What is the intent? I don’t know and as far as I know the OIR does not have a source for interpetation.
It would be nice to know what an insurance company (being the building experts that they are) considers structurally connected