• Welcome to The Building Code Forum

    Your premier resource for building code knowledge.

    This forum remains free to the public thanks to the generous support of our Sawhorse Members and Corporate Sponsors. Their contributions help keep this community thriving and accessible.

    Want enhanced access to expert discussions and exclusive features? Learn more about the benefits here.

    Ready to upgrade? Log in and upgrade now.

Porch roof attached to house at Fascia.

odd jobs

REGISTERED
Joined
Nov 17, 2020
Messages
5
Location
Lexington, KY
What is the building code for attaching a porch roof to the roof line at the fascia/gutter? What is the minimum desired pitch for the porch roof?
 
I Normally do not allow it without modifications
The new roof can generate significant uplift forces from wind and gravity loads.
How is the weight of the new roof and any live loads transferred to the supporting wall, reverse loads for wind uplift also need to be transferred and adequately tied down.

You may need a design professional to determine if the roof framing need to be strengthened.



1605619957187.png
 
If it is a stick framed roof (rafters), then you will need an engineer to review the reactions as described by Mark.

If it is trusses, you will need to reach out to the truss engineer, who will most assuredly tell you you it is a flat-out no, as it can alter the tension and compression forces within the truss chords.
 
Remove existing roof covering and decking far enough back to start your new rafters on top of the exterior wall.
 
Shirley it Depends

What is the overhang depth?
Rafter tails are 2x4....2x6....and how far apart?
Fascia is what 2x....1x....x4.....x6 bigger than that?
What do you plan on hanging on the fascia? Wood porch roof? How much wood porch roof?

If it gets engineered to hang from the fascia there will most likely be A35s from rafter tail to fascia. Everything would have to be 2x. If it's 2x4 rafters they can't be very long ......and there will probably be blocking required.....you'll see .... if you get it engineered. Of course if it's a small porch roof....the engineer will cost more than a small porch roof.
 
The proposed porch roof is to be attached to the existing roof rafters thru the fascia via a 2x6 ledger using 4" lag screws at 16" OC. The pitch is 3/12. The roofing material to be used is to be Ondura asphalt corrugated panels attached to 1x3 pickings that are sitting on 2x6 rafters. The rafters are attached to the ledger and beam with joist hangers. The over hang on the house is 18". A 15" soffit ladder or rake will be attached on the outside of the beam. The beam will be supported by 3-4x4 posts. The porch dimensions are 8'5"x 16'.
 
The IRC does not have a prescriptive design for roof slopes less than 3/12. If less than 3/12 it must be designed by an professional.
Roof pitch also is determined on what covering you are putting on it.
 
Not entirely true....

The IRC does not have a prescriptive design for roof slopes less than 3/12. If less than 3/12 it must be designed by an professional.
Roof pitch also is determined on what covering you are putting on it.

R802.2 Design and construction. The framing details required in Section R802 apply to roofs having a minimum slope of three units vertical in 12 units horizontal (25-percent slope) or greater.

The details don't apply, not the whole code...
 
The prescriptive rafter span tables in 802.4.1 apply to all roof slopes. The span is measured horizontally, not along the slope of the rafter.
 
The prescriptive rafter span tables in 802.4.1 apply to all roof slopes. The span is measured horizontally, not along the slope of the rafter.
Correct.

As Steveray pointed out, it is only the framing details in Section 802 that do not apply to roofs with a pitch less than 3:12. Where less than 3:12, roof framing must be done similar to floor framing with traditional ridge beam and rafter framing methods (i.e. no collar ties, ceiling joists, etc.).
 
In terms of building codes, it can vary depending on where you live. It's always a good idea to research and consult with professionals to ensure that your porch roof is built to code and will be safe and functional for years to come.
 
The attachment method and pitch requirements can vary depending on your location and climate.
It's always a good idea to check with your local building code department for specific requirements. If you want to update or repair your soffit and fascia, consider contacting a professional roofing contractor who can help assess your needs and provide recommendations. Best of luck with your porch project!
 
Aluminum design manuals have details for this including wood roof attachments. basically the fascia is a beam nailed in shear to the new. roof
 
Back
Top