Digging footings for a greenhouse columns

[plants4u]

I'm going to be building a greenhouse that requires (26) 18"w X 48"d footings.
The soil is clayish with some rocks. I thought of hiring this part out to a contractor. Sure I got a backhoe but that would disturb too much ground.
Any suggestions?

Thanks

CM

[CJ4]

I'm confused......are you putting in piers that are 18" diameter and 48" deep?? Or are you digging an outside perimeter footing that is 18" wide and 48" deep????

I'm interested in building a greenhouse for my wife.......have any brilliant ideas?

[plants4u]

Picture 18" X 48" concrete cylinders in ground. Steel pipe placed 24" deep into the poured concrete and 24"s above ground. From there the steel arches will be placed into these columns. I think the footing specs are overkill, but I need to hold to the specs. as per UBC regs.

[plants4u]

Oh and as far as a greenhouse for your wife CJ4, some of the larger greenhouse mfgs. may have something for you at a much better value than the "hobby" greenhouse kits. We have built many wood frame greenhouse structures in years past and have found some of them to have usable lifespans of 20 years at lower up front costs than steel. You will have to determine what is best for you.

[MarkV]

Wow, that is a lot of footings! Tell us a little more about the greenhouse. I am thinking with that much footing it must be a good size structure covered with something more lasting than plastic sheeting.

You might check local rental shops for a skid steer with an 18” hydraulic auger on the front. It would make quick work of the holes you need. People that build fencing often use a skid steer with an auger. That might be another angle to look at.

MarkV

[plants4u]

That's a great idea, I didn't think of the skid steer with an auger. I'll check with some landscapers I deal with and the local rental yards. The structure isn't huge, 30x60' and 15' at the peak. It is a gothic arch style with natural draft ventilation. Initially it will be covered with two layers of six mil. poly and later I plan on covering it with a corrugated polycarbonate. In our county a structure like this is exempt from a building permit if it is covered with plastic sheeting (temporary structure). Put a rigid glazing on it like polycarbonate it is deemed permanent. Go figure.....good thing for poly sheeting!