Erecting the Greenhouse

Erecting a commercial-sized greenhouse is not for the faint of heart. There are thousands of pieces, some come pre-cut but many are cut on site, and every one is handled a minimum of three times – unloading the truck, sorting into staging piles, and attaching to the structure. There is definitely efficiency gained by a crew who has erected at least one of these before.

A lot of pieces

I bought my greenhouse directly from the manufacturer who does not offer an installation service. They did, however, provide contact information for an experienced installation crew. We were fortunate that crew was able to slot my project into their schedule in about the right timeframe relative to my contractor’s schedule for building the house. The original estimate to erect the greenhouse from start to finish was 2-3 weeks. Between the crew getting sick, waiting arrival of missing pieces, difficulty maneuvering the lift around the house foundation and around my property, and weather delays, the actual installation is just short of 5 weeks.

This will give you a sense of what’s involved in the installation process.

Receiving the Greenhouse Package

In a previous post I described the delivery and off-loading of the greenhouse package, which was daunting enough in itself.

As the person who wrote the check for the materials and the shipping, I would have liked to inventory and examine the materials to be sure I received my order and everything was undamaged.

Before leaving, the driver handed me a folder that contained the material shipping list – it was 9 pages long! Although the list was broken down into sections for the Frame, Covering and Fasteners, Doors, and Roof Vents, it would have taken forever to decipher the cryptic parts descriptions and count each piece. The best I could do was check that I had the right number of shipped bundles and there wasn’t any obvious damage. See more on YouTube E6 The Greenhouse Arrives

Erecting the Structure

Posts First

Preparing to stand up the posts

The manufacturer of my greenhouse package offers 2 options for standing up the posts – sink them into concrete or bolt them to pre-poured concrete pads. As the order was placed before meeting with the installer, in our naivete we chose the first option. This was the wrong decision given how long the gable-end posts are (18’ to 21’) and how challenging my site is with the house foundation already in place and little room to maneuver a lift. If we’d chosen the bolt-down option, we could have poured the concrete pads before the installers arrival and the pour day may have been an hour or more shorter, saving hundreds of dollars.

Instead, on concrete pour day we stood up only the sidewall posts but did not have the ability to stand up the gable posts and reverted to ‘Plan B’ which was to order brackets for the 8 gable-end posts to bolt them to the pads poured that day. See more on YouTube E6 Starting the Greenhouse

Not having the gable-end posts in place changed the build order while waiting for the brackets to arrive. This is another advantage of an experienced installer – knowing where they can make progress while blocked by this kind of issue.

Frame and Trusses

The purlins and trusses went up quickly and their installation appears to be straight-forward. I’m impressed by how solid the structure is and by the ingenious design that allows the installers to adjust for out of square, level, or plumb issues.

However, this was when the installers noticed we were missing some pieces that were marked on the shipping list as included. Fortunately the installer was able to request those from the manufacturer without me in the middle. Also fortunately the manufacturer had the pieces in stock and was able to quickly ship them. But add another blocking issue for the installers to work around. See more on YouTube E9 Greenhouse Framing


The covering for my greenhouse is 8mm twin-walled polycarbonate panels, not glass (although I sometimes refer to these panels as “glazing”). There are 3 different coverings – 11 pieces of “opal” (i.e. opaque white) for the north side wall for privacy from the neighbor’s view; 54 pieces of clear for the other 3 walls and the north roof face and ridge vents; and 21 pieces of “solarsoft” (I.e. a semi-opaque light-diffusing white) for the south roof face and ridge vents.

Although more pieces are included than absolutely needed, this is another area an experienced installer can make a difference worth hundreds or thousands of dollars.

The opal material and solar soft material both cost more per square foot than the clear and are less available than the clear (although supply chain issues can make it hard to get any and all materials). My installer was efficient in using off-cuts where less than full sheets were needed.

This saved, in addition to partial sheets, a full sheet of clear and a full sheet of solar soft in case a future repair is needed.

These panels come with a protective film on both sides. For installation, the film is removed from one side, a foil tape is applied to the top and bottom edges, and a foam washer slides onto the top edge. The top of the panel inserts into a metal channel and the long vertical sides are held in place by aluminum strips. Four evenly spaced screws attach the panels to each purlin. Rubber gaskets between the screw head and panel and between the panel and purlin protect from leakage and reduce wind vibration and noise. See more on YouTube E10 More Framing!


Protective film still attached

My greenhouse has a single, hinged door on the east gable end and double doors that roll on a track on the west gable end. These come pre-formed as metal frames with polycarbonate panels set into the frame. They are definitely an industrial aesthetic.

The single door was specified as a right hand swing in the contract but a left hand swing is on the shipping list and that is what I received so we’re investigating what it will take to change that in the field.

The double doors were specified as inside sliding assembly but, apparently, the parts are identical for installing as inside or outside sliding. After the installer explained the pros and cons of inside versus outside sliding I agreed to have them installed as outside sliding.

Ridge Vents

The rack and pinion ridge vents are approximately 54” wide and run the entire 60’ length on both sides of the ridge. There are 2 electric motors and a controller that will be controlled by a thermostat. The greenhouse manufacturer provides all the parts except the motors but they arrange for the motors to drop-ship directly to the buyer. They don’t supply the thermostats.

Although the contract stated the motors would drop-ship directly to me, the shipping list listed them as included with the package. We received the controller with the greenhouse package but no motors. The motor manufacturer had delivered them to the greenhouse manufacturer who ‘missed’ putting them onto the truck. Fortunately they were able to include those with the other missing parts. But add a third blocking issue for the installers to work around.

Cable Braces

There are also 4 different (20 pieces) brace cables. Cable runs from each gable end post to its twin on the opposite end. These help prevent the ends from bowing outward. There are also cables from each corner to the nearest roof truss. Also 2 sets of X-cables on each sidewall to prevent sheer.


I intend to collect rainwater from the greenhouse and garage roofs for irrigation in the greenhouse and to fill and maintain the lap pool’s water level. There is more than 2,100 square feet of roof surface so there needs to be sizable gutters to capture that much water flowing with momentum.

Compared to residential gutters, these gutters are massive!

As it will be some time before my contractor installs the rainwater collection tanks and piping from the gutters to the tanks, we need to provide some form of temporary downspout and/or run-out to divert that much water away from the structure. This we did not do before the first rain. It was only a moderate amount of rain fall but captured from that much roof and directed to a single outlet from the north face and one from the south face, it flooded that end of the greenhouse and made the ground soft and difficult for the lift to maneuver. Lesson learned.

All in all I’m very happy with the quality of the structure and installation and my contractor can’t wait to start building the house inside a dry space.

NOTE: This page includes affiliate links. If you click and buy, I may receive a small commission without additional cost to you.

Leave a Reply