Veggie Garden On Top Of Carport?

[jyl]

When Threads Collide. I started a thread about my planned carport project. And I've been interested in the thread about our veggie gardens.

Gonna plant a garden this year? See drawing of my driveway and potential carport location.

Help Me Design Carport? See lots of great gardens - and my garden too.

So now I am thinking, why not beef up the carport and grow my veggies on top of it?

The basic idea is: the best sun on my lot is the south-side which is all driveway and garage. My veggie garden is currently stealing space on the side of the driveway, growing in planter boxes, cultivated "square foot" style. Works fine but I am limited to only about 25 sq ft of garden space. Yes, I have a miniscule lot with big shade trees everywhere else.

If I put the garden on top of a 20 foot x 10 foot carport, let's say raised planter boxes around the periphery of the platform, I could have (1) 100-150 sq ft of garden, (2) even more sun due to less shading from neighbor to the south, (3) reclaim the side of my driveway or keep growing there for another 25 sq ft of garden, (4) have a place to sit with a cup of coffee and read the paper, tucked away amidst the tomatoes.

The obvious downsides are that this now becomes a bigger project, maybe no longer a DIY job, and my driveway will now be in deep shade - no biggie in summer but maybe depressing in winter.

Any thoughts? Anyone done this or seen this?

[Gogar]

I think the weight would be your biggest obstacle.

Oh yeah, and having to climb on top of your house to tend to the garden.

[jyl]

Typical references say dirt weighs 120 lb per cu ft. That's for compacted and saturated soil. There are lighter mixes meant for rooftop gardening that weigh 50 lb per cu ft when saturated.

http://www.greenrooftops.com/Planning_Soil.aspx

So, assuming planter box is 1 ft deep, 150 sq ft of planter box = 150 cu ft dirt = 18.0K lbs if using regular dirt or 7.5K lbs if using light-weight mix.

Either way, this would become (IMO) something for a professional to design and maybe to build.

Access might be via stairs, or even spiral stairs. Certainly need better than a ladder. For water, could plumb to a hose bib on the platform and/or use drip irrigation.

[Tishabet]

Are you thinking of covering the roof itself with soil (i.e. Green Roof) or of using totally self-contained planters?

My wife and I grow lots of veggies on our roof (we have around 1200 s.f. of flat roof) using "earth box" planters which are totally self-contained and have a water reservoir. Very convenient for us. If you're considering having the soil sitting on the roof surface there is a lot of info out there on how to do this, but you will need a special roof membrane, must allow for adequate drainage, etc. The greatest concern IMHO is making sure the structure can bear the load of what you're considering.

[Danimal16]

Originally Posted by jyl

When Threads Collide. I started a thread about my planned carport project. And I've been interested in the thread about our veggie gardens.

Gonna plant a garden this year? See drawing of my driveway and potential carport location.

Help Me Design Carport? See lots of great gardens - and my garden too.

So now I am thinking, why not beef up the carport and grow my veggies on top of it?

The basic idea is: the best sun on my lot is the south-side which is all driveway and garage. My veggie garden is currently stealing space on the side of the driveway, growing in planter boxes, cultivated "square foot" style. Works fine but I am limited to only about 25 sq ft of garden space. Yes, I have a miniscule lot with big shade trees everywhere else.

If I put the garden on top of a 20 foot x 10 foot carport, let's say raised planter boxes around the periphery of the platform, I could have (1) 100-150 sq ft of garden, (2) even more sun due to less shading from neighbor to the south, (3) reclaim the side of my driveway or keep growing there for another 25 sq ft of garden, (4) have a place to sit with a cup of coffee and read the paper, tucked away amidst the tomatoes.

The obvious downsides are that this now becomes a bigger project, maybe no longer a DIY job, and my driveway will now be in deep shade - no biggie in summer but maybe depressing in winter.

Any thoughts? Anyone done this or seen this?

150 lbs per square foot?? that is heavy. The structure may not be rated for it.

[jyl]

Not a "green roof", trendy as that may be.

Thought is a fairly standard deck surface (but needs to be impermeable since it has to function as a carport roof), with raised and self-contained planter boxes around the periphery. Maybe a little space in the middle for a cafe table and a couple of chairs.

Had not figured out details of the planter boxes. What is an "earth box"? I was thinking basic wooden boxes, mounted at waist height, about 1 foot depth, filled with some sort of light-weight soil mix.

[jyl]

Originally Posted by Danimal16

150 lbs per square foot?? that is heavy. The structure may not be rated for it.

I was thinking 15K lbs load (take the 7.5K lb assuming light-weight soil mix and double it to include the structure, people, and fudge factor). On a 200 sq ft deck. So 75 lbs/sq ft.

[Danimal16]

Jyl,

It depends a bunch on the type of structure. I would not do it unless I had structural calcs done on the roof. This is a huge load increase and if the basic structure is not designed for such a surcharge, I would be very careful, especially in light of any seismic induced accelerations.

[trekkor]

Let's see some pictures of the carport.

It may be a matter of just beefing it up with some additional supports.

Maybe use large pots instead of big planter boxes. Save on the weight that way.


KT

[jyl]

Sorry, I was not clear. There is not an existing carport. I am thinking of building a carport, and am now thinking about making it strong enough to support a veggie garden.

[Danimal16]

Originally Posted by jyl

Sorry, I was not clear. There is not an existing carport. I am thinking of building a carport, and am now thinking about making it strong enough to support a veggie garden.

OK,

Gotcha now. I would think that the permits would require a structural evaluation.

Sounds like a cool ideal if ya ask me.

[trekkor]

As long as it is not attached to an existing structure, I wouldn't be surprised if they do not require a permit.

Don't assume, of course.

If you are building from scratch, you'll have no problem making it strong enough.
Consider steel posts set in concrete with wood beams ( 4x8 or 4x10 ). They make lightweight engineered joists or you could just use 2x8 or 2x10 on 16" centers.
You could park cars on that.

Plywood deck with a waterproof membrane.
You could get wild and do a perimeter wall for privacy, floor drains, planting tables, BBQ area.

Sounds like a really fun project.

A 'build' thread is required


KT