building-regulationsdeckfootings
I want to build a deck for my house but I don't really want to dig holes and pour concrete for the footings. Can I just build the deck on ground level using something like this to support the posts?
The location is in Wisconsin. The deck wouldn't be more than 2-3 feet off the ground at any point. Also, The deck would be free-standing and not directly attached to the house.
Around here, 4x4s are not uncommon. This table shows that a 4x4 pine post that is 6 ft or shorter can support a load area of up to 10 ft² assuming 50 lbs/ft².
Don't trust me or a random table on the internet; make our own calculations from tables in the building code or other trusted sources and consider having them checked by an engineer.
How deep is the frost line in your area? Deeper than that. You may also need to use post-footing-base flares to get adequate load capacity on the bottom of your footings, depending on the soil bearing capacity (what it can hold per square inch, in pounds) and the weight of the roof and any roof loads, such as snow.
This type of thing, possibly:
Image is from bigfootsystems, but lots of places make something similar, and the old-fashioned way is to pour a pad in the bottom of the hole and then set the sonotube on top of it (no fancy plastic flare required.) In "good" (from a load-bearing point of view) soils you may not need anything, if the area of the sonotube (about 50 square inches for an 8" tube) is adequate for the soil and loads. Bumping up to 12" at the bottom more than doubles the area, thus halving the soil loading.
Best Answer
So I was able to get confirmation on an answer from a local building inspector. As per Wisconsin Administrative Code SPS 321.15(2)(f)
SPS 321.15(2)(f)
So in essence, if there is a door that leads onto the deck it must have proper footings in the ground (as explained to me).