Deck footing and porch design questions

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mdnagel
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Joined: Thu Jan 06, 2011 12:39 am

Thu Aug 15, 2019 1:28 pm

I am working up some plans for a new deck (with porch).

I have a question on footings and on the general design of a porch.

Regarding footings, I'm wondering whether I need to change to having all posts resting on concrete piers (which are sunk about 2' [frost line is 12" to 18" here]) or whether I can use a mix of inner posts on the house's concrete pad (as is the current deck) and outer posts on concrete piers?

This footing issue becomes a bit more important when adding in a new porch. "Tying" (independently) the house's roof and the porch roof means I need the solution to provide as much synchronicity as possible. Utilizing the house's pad would seem to meet this requirement, but the outer posts would be independent and more likely to be out of concert with any movement. Would setting up small on-grade pads for the outer posts be more likely to match movement characteristics? (that's kind of how it is now with the current deck using concrete post blocks)

My other porch-design-specific question is how best to marry up the porch roof line with the house roof line. I am wanting to match the porch roof to the home's existing [faux] gable. As there is a bit of an overhang I'm wondering if I a porch roof can sit underneath; this would eliminate the need to splice in any transition material for the two roofs.

Here's a frontal view of the house:
HouseFront.jpg
HouseFront.jpg (223.23 KiB) Viewed 173 times
Rear of house (which more shows the concrete pad [I'm about to start my rim joist repair, door replacement, underbelly repair, maybe re-plumb and skirting work]):
HouseRear.jpg
HouseRear.jpg (233.53 KiB) Viewed 173 times


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Greg
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Thu Aug 15, 2019 6:08 pm

I think I would go with below frost line piers for support.
As for the roof I think you are almost going to have to continue the ridge line of the dormer, but if you are going to try to cover the whole porch you will have to change the pitch.

Greg
"If I can't fix it, I can screw it up so bad no one else can either."

mdnagel
Posts: 176
Joined: Thu Jan 06, 2011 12:39 am

Fri Aug 16, 2019 11:24 am

Greg, no, not going to try and cover the entire deck. I'd already set up sight lines on the "wings" and found that the existing roof line would drop too much if I extended out to the outside of the deck (except the gabled/dormer section).

I have not seen/heard of anyone mating up (in a float) metal roofing. That's why I was wondering if I could just situate the back edge of the porch roof under the house's eave (of the gable/dormer). Trying to get off with less work?

I agree that the deck footings need to be consistent. Just seems that the two structures having the same type of footing would tend to keep them more in sync. Seems that I could duplicate the float of the existing house pad for the deck footings. I may break down and consult an engineer and architect.

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Greg
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Fri Aug 16, 2019 7:57 pm

I was thinking that if you changed the roof pitch to cover the porch, you may be able to add a gable to the front of the new roof and hide the original roof lines of the dormer.

Greg
"If I can't fix it, I can screw it up so bad no one else can either."

mdnagel
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Joined: Thu Jan 06, 2011 12:39 am

Mon Aug 19, 2019 9:48 am

Greg, are you talking about changing the house's roof pitch? Current pitch is about the minimum that it can be, in which case I really cannot make it any less/more shallow.

The deck width will be about 25' and the porch's width will be about 15'.


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Greg
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Mon Aug 19, 2019 6:22 pm

No, but I question in my mind if you COULD do the whole porch and hide the difference between the pitch of the dormer & porch by adding a gable end on the porch roof. you would need to keep the same ridge line as the dormer. You may also be able to tie the roof line into the other roof line also and keep the dormer 100% visible but with a flatter pitch.

Greg
"If I can't fix it, I can screw it up so bad no one else can either."

mdnagel
Posts: 176
Joined: Thu Jan 06, 2011 12:39 am

Tue Aug 20, 2019 6:44 pm

Greg, I was going to take another guess but realized that I might once again fail to comprehend what you're suggesting. Any chance you could point me at an example, or perhaps scribble something down and insert here as a picture?

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