Anyone install / attach a structure through asphalt (i.e. car port base)?

[neo von retorch]

The Scenario
We have two cars and one full-sized car garage. (We have a second detached garage big enough for lawn mowers and tiny cars.)
Next to the detached garage is a parking area - this is where I park. It's all surrounded by trees.
The trees drop twigs, leaves and sap regularly. During storms, large branches fall. So far they've missed my car.

Proposed Solution
Use augur to dig reasonably wide/deep anchor holes.
Pour concrete with anchor hardware.
Attach anchors to footer beams securely.
Build a car port (i.e. roof) from the anchors up.

Educational Needs
I'm pretty sure I can do all the building of the carport, but I have no idea what the best way is to fasten the structure to the ground and keep it from blowing away.

What advice can you give me?

[Jack]

A thin layer of asphalt won't hold anything. You need a proper footing, which will involve removing the asphalt, digging down and pouring concrete.

Don't forget that you can't just consider the dead load of the structure pushing down on the footing; you also have to consider the wind load pulling up. You don't want the thing to blow away like a poorly-staked tent in a storm.

[neo von retorch]

Improved Solution
Use augur to dig reasonably wide anchor holes.
Pour concrete with anchor hardware.
Attach anchors to footer beams securely.

Does that sound about right? Any recommendations on good technique and hardware for anchoring?

[ncornilsen]

You really need about a 1ft square area for bearing, if you have posts about every 10ft.

So, rent a asphalt saw, cut those squres. Dig down to native soil 6-8" below the asphalt grade. Pour concrete in flush with asphalt.

They make brackets that can be cast in place in concrete, that will accept a 4x4. Use those, and keep the end of the 4x4 1" off the ground.  Make sure you have some lateral bracing at the top, since these brackets will not resist a rotating force (don't want it to fold up like a cardboard box)

Or, you could dig a 8" diameter hole, and set the post in 2ft deep and pour concrete around it.

http://www.lowes.com/pd/USP-Steel-G185-Post-Base-Common-4-in-Actual-3-562-in/3365740

-Nick

[Spork]

So, rent a asphalt saw, cut those squres. Dig down to native soil 6-8" below the asphalt grade. Pour concrete in flush with asphalt.

Alternatively, you can just put a cement cutting blade in either a circular saw or an angle grinder and just go to town.  You can zip through asphalt with one.  If you're worried about marring the bottom of your circular saw, toss a 1/4 inch bit of plywood down and run across that.  I cut a 30ft x 1ft sliver out of my driveway in under 10 minutes.

After you're done, you can patch any irregularities in the asphalt with asphalt patch.  Its in the cement aisle of your favorite box store.  Just plop it down in layers and tamp it in place.

[shuellmi]

No offence but it sounds like you have a lot to learn, better off hiring someone.  Couple issues mostly related to your particular location: wind load, frost depth, size/condition of trees, building setbacks/zoning ordinance, building permit issues, etc.

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[shuellmi]

If your just building a roof, no walls, you'll need a fairly substantial foundation to keep it from blowing away and causing serious damage, absolute min 3' deep, 18" dia. conc

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[Fishindude]

First high wind will take that thing for a ride, if you just anchor to the asphalt.
You will need some concrete foundations or piers to anchor that structure to.