6" Crushed stone under slab.

Use wire mesh in slab. 4" is probably fine for the slab. 6" is definitely fine (unless you'll be using machines and vehicles in there, doubt it.)

Radiant heat tubes must be pressurized before you pour.

Look into your greenhouse manufacturers specs and warranty. They will tell you what you need.

Sometimes slabs like that require a haunch or footing/wall to keep your warranty.

If you don't care about warranty, but want to be safe, use a 1' haunch along the perimeter of your slab.

Cut control joints ~10' on center. Not sure if you need poly vapor barrier with the radiant heat, maybe look into that?

What are you using for the heat source? (boiler/propane/electric/etc)

Not sure yet currently there is only electric at the property , with the radiant heat i think they use boilers though, and a dude i know up here who is doing just propane burners is going through $2000 a month for a 30x 96 with 8ft side walls were are going to do 12 ft so we can put gavitas in... any suggestions?

Have you thought about no slab and trying to use geothermal heat?its free.
This dude hawks plans for a system thats supposed to be easy to build,Slabs and boilers and propane sound expensive.
http://www.citrusinthesnow.com/index.html

Concrete is not an inexpensive option! It is a permanent solution, that if you do, you should do right.

Could also set up as a baseboard heat system so no need for concrete and can intergrate heating fan coils if needed

A standard 4" slab will be sufficient will need to insulate the slab if heating the space

Good call @blazer, with greenhouses you're dealing with heat issues. Would definitely put 2" insulation under slab.

Lol shem,can tell your a concrete guy!I was a concrete contractor for 30+ years and been around it my whole life,dad was VP of a large ready mix company and every company i ever owned (3) was focused on that industry.The way i look at it a greenhouse should be energy efficient and as low tech as you can make it,K.I.S.S..When you start pouring slabs especially the way your talking about doing it (right) concrete is very expensive per sq ft,now add in supplemental heating systems and the cost to run them and you lose the efficiencies of a greenhouse or at least give your competition a competetive edge.By getting too crazy and drastically sending costs higher you reach a point where you could just grow under artificial light/environment almost as easily.Greenhouses are so great because they are low tech and take advantage of natural light and enviro,start pouring reinforced insulated slabs with hydronic heating and you have huge costs per sq ft when you bid it out,take my word for it,i have built many a tilt up for refrigerated storage facilities.From strictly a business standpoint the cheaper you can achieve the same or similar result the better and faster you can reach profitability and the better off you are IMO.

I'm young, but I am getting there lol. Absolutely agree with you! Very high upfront costs using a system with concrete floors. I think unless the goal had large expansion in mind, with a highly technical facility, concrete floors won't be worth it.

If the goal wasn't radiant heat flooring, you could go with concrete walk rows with gravel under the tables. I've seen lots of professional set-ups like that. Can then put radiant heat tubes in the grow beds. That's how I've seen a grafting tent set up.

Again the concrete is going to be expensive for sure. I think it's benefits would mostly boil down to being "aesthetically professional" and long lasting.

blazer said:

Could also set up as a baseboard heat system so no need for concrete and can intergrate heating fan coils if needed

A standard 4" slab will be sufficient will need to insulate the slab if heating the space

Click to expand...

Back in the '70's I put over 500' of 1/2" copper tube under my basement slab with no insulation under it and pumped it through my wood stove. It proved to be a big heat sink and the heat was being absorbed by the ground. 500' was also not enough tubing.