Footings or Not?

[NY_Yankees_Fan]

I want to add a canopy/roof, about 7 feet wide by 12 feet long to my shed, which is about 12 feet wide by 24 feet long, to store stuff out of the weather. The shed sits on about a foot of gravel that was mixed with fines and is compacted. The floor is six pressure treated 4 by 4 with ¾ plywood floor. My question is the two or three posts I will put in to hold up the end NOT connected to the shed, do I dig down 3 feet below the frost line and put the posts in the ground or just sit it on a concrete block? I have dug down a foot and will back fill with the same material as the shed is sitting on. The block will sit on the compacted stone. The connection to the shed will be a 2 by 6 nailed to the outside of the shed wall, with 2 by 6 2 feet on center. I figure if the shed moves with the frost then the canopy will also. What do you think? Footings or a block?

By the way the BX with a toothbar had the hole dug real fast today, could not believe the power of the little BX to dig the soil. /forums/images/graemlins/grin.gif

Thanks

 

[NIXON]

You can probably get by with sitting the outer posts on block as you described . But for piece of mind ( if it were mine ) I'd go down 2.5-3 feet . A lot depends on the ground you're on .
If it's clay , you also have to contend with it shrinking and expanding . (dry /wet periods ). I tend to hate re-doing things /forums/images/graemlins/smile.gif Make sure you have good drainage in either case
Having said that, I've seen no end of really old out buildings here (Western Pa . ) sitting on nothing more than field stone piers . The guys that put them up must have known something about building or the "sheds " wouldn't still be there /forums/images/graemlins/smile.gif

 

[yooperdave]

Hi Tom,

You have the big picture properly in focus.

If the original building was bearing on a frost resistant foundation, then the addition should also. I do not usually recommend mixing up the foundation systems.

The original building is already floating. Unless you locate a significant expansion joint between the two buildings, you will probably end up with more problems than you originally bargained for if you have two different foundation systems.

I am assuming that you do not have a concern regarding your building floating with seasonal frost heaving. Hopefully, you are not located over very expansive soils.

Good Luck

Yooper Dave

 

[Anonymous Poster]

The bigger consideration might be wind. While a floating foundation on the canopy would be sufficient to hold the weight of the canopy, unless there is sufficient tie down, a canopy can easily become airborne in the proper wind conditions.

 

[Soundguy]

Hurricane strapping and a couple mobile home tie downs ought to solve that ...

Believe me.. the truss strapping does make a difference... Our neighbor has a barn newer than ours by a year.. last year, his roof blew off.. mine wasn't touched... he had no straps.

No tornados or hurricanes.. just unseasonably high winds..

Soundguy