Covered Porch Header design 20ft Span
Covered Porch Header design 20ft Span
(OP)
I am trying to size a header for a covered porch but I am having an inner struggle with how to determine the size.
Any span tables for this specific use?
IT is a 20ft clear span 6.5/12 roof pitch, shingled roof. 40-50 GSL. The designer has a double 2x12, but I am a bit hesitant on that being that garage door headers require 3 2x12 at 18ft clear span (As per SYP span tables).
Thanks all.
Any span tables for this specific use?
IT is a 20ft clear span 6.5/12 roof pitch, shingled roof. 40-50 GSL. The designer has a double 2x12, but I am a bit hesitant on that being that garage door headers require 3 2x12 at 18ft clear span (As per SYP span tables).
Thanks all.






RE: Covered Porch Header design 20ft Span
RE: Covered Porch Header design 20ft Span
RE: Covered Porch Header design 20ft Span
Watch your wind loading also, in my opinion most porch roofs act as big overhangs (or at least partially as overhangs) and thus you should consider using overhang uplift pressures for at least a portion of the roof.
RE: Covered Porch Header design 20ft Span
RE: Covered Porch Header design 20ft Span
RE: Covered Porch Header design 20ft Span
I am not the designer, but I am reviewing the drawings (So I end up the designer in the end when/if I stamp it). The drawings were wrong. IT is not 20ft clear span. more like 6ft supporting 20ft clear span trusses.
I got the same thing, failed in deflection horribly under my first calc, but the drawing was incorrect.
Thanks all.
RE: Covered Porch Header design 20ft Span
RE: Covered Porch Header design 20ft Span
RE: Covered Porch Header design 20ft Span
RE: Covered Porch Header design 20ft Span
Most people would be shocked if they really knew how this whole system worked and what gets built, since most homes have little actual engineering performed. I have seen some really, really bad "designs" that were obviously plan stamped. During the big real estate building craze in Florida a few years ago there were archs/engineers signing hundreds of drawings a week. You may guess about how much review and design they were doing.
I am not accusing the poster of doing one thing or the other, just saying in my experience that his is how the residential market works. I am a little concerned that the poster is not qualified, since they were just looking for some tables in regards to a very simple problem (one I had in my timber design class in college). That is not engineering, that is prescriptive design. BE CAREFUL!!! You are the engineer of record in the eyes of the law and you cannot blame the "designer", cad tech, or anyone else for anything you are signing and sealing.
RE: Covered Porch Header design 20ft Span
Mike McCann
MMC Engineering
RE: Covered Porch Header design 20ft Span
I do not "design" the building. I am reviewing the designers plans. In my definition of a designer, they are above drafters, with intimate construction and knowledge and experience with oprescriptive code, but not trained as an engineer. Very typical of residential type construction here. IF it were to be engineered in its entirety at over $100/hr bill rate it would never get built. Most of it is prescriptive code. This span caught my eye due to the long span of 20ft and only 2 2x12 header. I checked it for deflection first (FAILED). I wanted a gut check so I looked for some span tables. Closes span table I could find was for garage door headers.
It ended up being an incorrect dimension. It is more like 6ft span supporing some trusses over a cover entranceway.
Thanks for all of the help and consideration guys. I appreciate the help.