Anyone know of a way... - Contractor Talk - Professional Construction and Remodeling Forum

rjconstructs · 10-13-2009, 07:50 AM

Anyone have a way to calculate a load on a column? It's a porch so I'm not too concerned. I'm curious if there is a rule of thumb number per square foot of roof load? Or does someone know of a website that is helpful in determining these things?

mics_54 · 10-13-2009, 10:33 AM

some people use "strucalc" or some other analysis software for their design requirements. It's like rocket surgery or sumpthin.

rjconstructs · 10-13-2009, 05:10 PM

I just thought there might be a rule of thumb weight per square foot that could be used as an average.

reveivl · 10-14-2009, 12:22 AM

that's pretty much like asking how long is a piece of string.

What column, where? What's it holding up? How many floors? What live loads, Dead?

I think the answer is 20 or maybe more or less...

rjconstructs · 10-14-2009, 08:37 AM

Well, like I said, it's a porch 18' x 18'...standard framing, 4/12 pitch, 30yr shingles, etc. Half the load would be on the house and the other on two columns.
I'm not asking for the length of a string, that would be way to complicated.

mics_54 · 10-14-2009, 08:39 AM

well yeah there is a rule of thumb...

the more you need it...the more it costs.

the bigger the roof...the bigger the beam is

and..here's where it gets tricky

if your wife askes if this dress makes her look fat.. SAY NO!

gregj · 10-14-2009, 02:07 PM

rj your best bet as always is to have an engineer spec it. Our building dept. around here does have some numbers they will let us use for covered decks without an enginneers stamp.
Deck only = 50 lbs/sqft
Deck with roof = add 40 lbs/sqft so 90 lbs/sqft total
Deck with roof and ceiling = 105 lbs/sqft total

If there will be a hot tub on the deck add another 50 lbs/sqft

We have a 30 lb snow load - yours may be a little less.

rjconstructs · 10-14-2009, 08:47 PM

Thanks greg. Yea, If I have any doubt about something I defer to the engineers. I was just curious if anyone had an idea about the amount of weight involved. It sounds like 200# per sq. ft. is way more than enough.
rj

RobQuillin · 11-03-2009, 08:53 PM

One thing to remember is that when you are dealing with load points you have to divide the weight between the two load points. So it the span is 18 feet then the column is carrieing the weight of 9 of the feet, and the other bearing point carries the other half of the load.

naptown CR · 11-03-2009, 09:05 PM

This ain't rocket science
You have a porch that is 18x18 feet
One side is supported by the house
that means 1/2 of th porch is sitting on the two posts.
Ok given that each post is supporting 81 square feet. (9'x9')
your dead load is probably calculated at 15 # sf
Live load is what ever your code calls for
Add the dead and live loads and multiply by the 81sft area of infuence and you have the loads on the posts.
so say the live load from snow or whatever is 20 pounds per square foot
Ok total load is 35 #sf x81sf = 2835 pounds