[Edu.wes]

Hello, needing someone to double check my numbers on a 4 season addition.

14' long by 12' wide. Coming off an existing 2' kitchen cantilever and austerity the joists so the new joists will be a 16' span. Using 2x12 PT. Two piers are planned to be 4' deep with a 24" round by 12" deep footer on the bottom and a 12" pier on top of that. A 12ft 3x2x12 beam on top of stand offs on the piers. Piers cantilevered in by 1 ft on both the side and back

Anyone see any code violations?

 

[Edu.wes]

Austerity=sistering

 

[Edu.wes]

15' span with the 1' new cantilever, making 16' board length not span

 

[Edu.wes]

ground snow load is 30 psf here

 

[Daniel Holzman]

You don't note your location. You don't note what code and what version you are under. You don't note if there are any local codes that apply. I suggest you discuss the project with your local building inspector, they are the experts on code requirements.

 

[Edu.wes]

You don't note your location. You don't note what code and what version you are under. You don't note if there are any local codes that apply. I suggest you discuss the project with your local building inspector, they are the experts on code requirements.

2015 IRC in the Midwest USA

 

[Mingledtrash]

15' span with the 1' new cantilever, making 16' board length not span

is this your rafter span or floor joist span? and what is your joist/rafter spacing?
What species and grade is your pt wood?
Is this a deck that will have snow load or roof that has snow load?

if it is a deck with 30 psf snow load your 2x12 wont work even on a 12 in center you are way over span.

 

[Edu.wes]

is this your rafter span or floor joist span? and what is your joist/rafter spacing?
What species and grade is your pt wood?
Is this a deck that will have snow load or roof that has snow load?

if it is a deck with 30 psf snow load your 2x12 wont work even on a 12 in center you are way over span.

#1 Southern Yellow

3 season addition, the roof will have the snow load. 30 is my areas ground snow load stat. How do you calculate that I'm way over?

Deck span for a 2x12 says over 16' at 16" center. But that is for a deck and that is where I get confused.

Regular home joist span says over 17' at 40 live/20dead

 

[Mingledtrash]

#1 Southern Yellow

3 season addition, the roof will have the snow load. 30 is my areas ground snow load stat. How do you calculate that I'm way over?

Deck span for a 2x12 says over 16' at 16" center. But that is for a deck and that is where I get confused.

Regular home joist span says over 17' at 40 live/20dead

I initially ran it through the calculator as #2(most commonly used) lumber, pressure treated, incised and it came up somewhere around 14'. any way i punched in the new data you provided and you should be fine. One thing to note is that using pressure treated lumber that is incised reduces the strength of the lumber also if it is "wet" service the max span would decrease another thing is for a deck you are supposed to add the 30 psf snow on top of the 40 live load but where you have a roof over it, which i assume will be taking 100% of the snow load, you would just calculate your span as a normal floor.

so for your roof rafters if you use regular(non treated) #1 syp you should be able to go to a 24" o.c. 2x12 as long as your roof is dried in.

if your roof is not dried in you will need to drop the rafter spacing down to the 16" o.c. and use #1 syp treated lumber.

and to get pedantic deck span with your snow load 2x12 #1 southern pine PT 16" o.c. max span is 12'-10" :wink2:

I would recommend drawing up a simple plan and spending the couple hundred bucks to have an engineer review them because all these span numbers do not take into account the wind and seismic loading and where your floor would be near the max span for a regular floor joist it may not be strong enough. midwest usually = high wind = extreme shear walls and holddowns.