Greenhouse Flooring

[Brina A]

I am part of a club at my High School that has put together a group of over 100 students to build a greenhouse and we are still trying to figure a few things out. My main question at the moment is if I need to have some kind of material as our flooring to lay on top of our black top concrete foundation because we are located in southern California and the black top can really heat up. Thank you.

 

[MoonShadows]

That's a tough one, not only because you definitely need to lower the temperature of asphalt, but you also want drainage on a greenhouse floor, and asphalt will not provide that. Asphalt can absorb over 90% of the sun’s radiation, storing it there for hours, even overnight. This is not good for a greenhouse, especially in Southern California. You are going to wind up cooking your plants.

I guess my first thought is to abandon building the greenhouse on asphalt. Isn't there a grass area the school could let you guys build the greenhouse on? Since I imagine the school has sanctioned this greenhouse build and wants to see you succeed, perhaps you can approach the administration and lay out the reasons why building a greenhouse on asphalt could doom this project from the outset.

If that fails, and the only area you can build on is the asphalt, you will need to find a way to lower the temperature of the asphalt. A white gravel base over the asphalt will help to lower the temperature and provide some drainage. The white gravel will not absorb as much heat as the black asphalt.

I don't know your budget, but you could also paint the asphalt floor with a light colored, durable paint. This will not provide drainage, but it will help to reduce the pavement's ability to absorb the sun's radiation.

Brainstorm with your classmates for creative ways to lower the floor temps and create some drainage. (The floor temperature issue is more important than the drainage issue.) I would also recommend whatever you decide upon that you also extend it out around the perimeter of the greenhouse as well to keep the adjacent asphalt as cool as possible.

I would love to hear back about how you guys cope with this "problem", and see pics as your project develops.

Great to have you with us!

 

[Greenhorn]

Hi there Fun project you all have started. What size is your greenhouse going to be? Oh and if your surface is black it would typically be asphalt, white then concrete. If it was concrete you would be fine, if it is blacktop then yes very hot. I am in a similar zone and have a small greenhouse. Also, will it be for winter use only?

 

[DrCase]

A few bags of mulch would cool it down .

 

[MoonShadows]

A few bags of mulch would cool it down .

Very good idea, @DrCase . I never thought about that. The only thing is it might harbor all types of bugs. They might have to treat it with something...hopefully something natural.

 

[Robert Cummings]

Would coconut she'll be a viable alternative?

 

[Gemma]

Question: does cement absorb as much heat as asphalt?
We have a nice basketball court that our kids no longer use, we were thinking of building our greenhouse on that

 

[Robert Cummings]

A major consideration when deciding on structures for the greenhouse is cleaning, Asphalt will hold plant pests and diseases much more so than.say concrete or gravel which can easily be washed down. Of course a lot depends on how the greenhouse is going to be used, for example if you are going to create planting beds either side of the path through the centre of the greenhouse then you could use asphalt but in california I would opt for gravel on top of a weed control membrane. If there are no planting beds just shelving paving gravel or even sterilised woodchuck may be an option