12’ or 16’ Greenhouse Assembly (with video)

Caution:   Some parts of the greenhouse can be extremely sharp so please use caution – and gloves – when handling the sheet metal.

Tools Needed:

  • Step Ladder (can be done with one but two will make it easier)
  • Drill – electric or cordless
  • #2 Phillips and  #2 Robertson bits
  • Tape measure & Sharpie (if you are installing the optional shelf or hanging rod)
  • Tin snips (if you are installing the optional shelf)
  • Helper

Confirm that your kit includes:

  • 2 wall panels (8′ long, lexan sticks out 1.5″ on either end)
  • 2 wall extensions (4′ long if you bought a 12′ model, 8′ long if you bought a 16′ model)
  • 2 roof panels (8′ long, lexan sticks out 1.5″ on either end)
  • 2 roof extensions
  • end panel with door insert
  • end panel with gable vent insert
  • main beam (2 pieces for a 12′ model and 3 pieces for a 16′ model)
  • green corner trim package
  • green main beam trim and eave trim (two 8′ pieces and two extension pieces)
  • short metal self-tapping screws
  • long brown or green wood screws
  • 1 1/2″ steel “trim” screws


  • vent openers
  • wood for base
  • shelf with metal braces (5 braces for a 12′ model, 7 braces for a 16′ model)
  • L-brace for shelf


If you purchased a base from us, you need to lay the boards out and screw the corners together, using 4 long green/brown screws in each corner. You want to build on as flat a surface as possible. 

It is possible for two strong people to push the greenhouse into place once it is fully assembled.

If you are using a lumber base, you need to ensure it is square before you begin to build on it.


Start with the gable end panel (NOT the door end) and the wall extension panel (it has one edge flush with lexan and the other end has a 1 1/2″ overlap of lexan). Place the pieces on the base if you are using one. The bottom edge of the wall is flat and the top edge of the wall is angled. Place the extension panel so that the lexan overlap cover the edge of the gable panel. (We start here and work our way clockwise around the greenhouse: gable end – extension – wall – door end – extension – wall.)

Connect them in the corner and use the short screws to screw them together every 12-16″. Next, attach the wall panel that has lexan overlapping on both ends. Screw it to the wall extension piece using the short screws. Then install the door end to the other end of the wall and screw the frame together using the short screws.

Continuing around the greenhouse, screw the second extension wall piece to the door end.

Lastly, place the last wall section in place. If the bottoms of the panels don’t line up, you can simply use your foot to press one down while you screw the top in place. 

NOTE: Be sure to have your helper unlatch the top of the door before you screw the final wall in place otherwise you will be locked into the greenhouse. 

Main Beam:

On a flat surface, overlap the main beam pieces and screw them into place at the appropriate length.

  • 7 x 12′ – 142 1/2” main beam
  • 7 x 16′ – 190 1/2” main beam

Carry one end of the steel main beam into the greenhouse and up the ladder. Lift the opposite end up onto the door end and then place the end you’re holding up onto the top point of the gable end. 

Screw it into the corresponding metal lip of the gable peak using the short screws. 

Then move your ladder to the door end and screw it into place using the short screws. If you have a helper, they can stand outside the door end and gently press the upper area of the panel inward to ensure the main beam rests on both peaks simultaneously.


You will install roof panels starting with connecting the extension panel and the door panel and install them all as you move counter clockwise around the structure.

Place the roof panels on the wall panels so that the flat edge rests on the main beam and the angled edge rests on the wall edge (which is also angled). Together, the two angles form a straight edge.  

If you have a helper, they can pass you the roof panel from outside. Otherwise, you can carry it in through the door and put it in place using the ladder. Put the panel in place and use the short screws to secure it.

Screw roof to wall panels, end panels and to main beam every 12 to 16 inches using the short screws.

Screw from inside the top of the wall frame, up into the bottom of the roof frame.

Then screw the eave frames together at each vertical stud.

After the roof is in place, you can secure the structure to the base if you are using one.


Attach the eave trim on both sides of the greenhouse where the roof meets the wall.  Slip the trim under the lexan on the roof panel and over top the lexan on the wall panel.  

Screw at each wall stud using the long trim screws.

Now you should arrange the corner trim pieces and attach the four complete corner trim pieces (without cuts) on the bottom four corners of the greenhouse.  You only need to screw on the bottom of the trim for now.

The left and right pieces should overlap the corner trim and the eave trim that you have already installed.  Use the long trim screws. 

Using the ladder, place the remaining two peak trim parts on with the long trim screws.

Now place one of the ridge beam trim pieces on the top and screw at all the roof studs and at the two ends using the long trim screws.  

Move to the other end of the greenhouse and place the second ridge beam trim, screwing it into place with the long trim screws.

Lastly, install the door latch on the corner of the greenhouse to hold the door open and make any other door adjustments needed.



Decide which side of the greenhouse you would like the shelf to be on as well as the height you want it to be at.

Measuring from the bottom of the metal frame, mark your height MINUS 1.5″ which is the depth of the shelf. For example, if you want your shelf work surface to be at 35.5″, mark out 34″ on the stud closest to the door, both corner studs and the studs along the wall to which you will mount it.

Install the L bracket to the studs on the door end so that one side faces down and the other faces inside the greenhouse, creating a ledge. The top of the bracket should align with the marks you made. This will form a ledge for one end of your shelf to rest on.

The first shelf to place is the one with the non-perforated stud at one end. The second shelf will slip on to this stud, forming a continuous shelf.

Hold the shelf against the gable end of the greenhouse and align the bottom of the shelf with the mark you made. Screw the bottom of the shelf into the metal frame of the greenhouse corner. Then screw the bottom of the shelf to the metal stud along the back wall of the greenhouse. Continue moving along underneath the shelf, using the short screws to attach it to the metal studs of the wall, aligning the bottom of the shelf with the marks you made earlier.. 

You will have 5 shelf braces with a 12′ model or you will have 7 braces with a 16′ model. Place one brace underneath the shelf and slide it into the vertical metal stud closest to the free end of the shelf and screw the two pieces together using a short screw. 

Now place the end second shelf onto the L-bracket you installed earlier. Align it with existing shelf and slide the two together. This may take some finky work. BE CAREFUL as the metal on this shelf is very sharp. Once the shelves are conjoined, screw the sceam and then screw the second shelf to the wall studs and onto the L-bracket. Install all but one of the remaining braces into the vertical studs and attach to the base of the shelf. 

The final brace is installed where the two wall panels meet. Using tin snips, cut both sides of the brace about 2″ from the end and fold the brace in on itself at about a 90 degree angle. Place the brace into the horizontal stud on the bottom of the shelf and screw in place. The short piece you just cut, will be placed against the flat vertical stud of the wall and screwed in place using the short screws.

Hanging Rail:

Decide where you would like the rod to hang on the ceiling, using the horizontal lines of the lexan to help ensure level measurement. Use a sharpie to make a mark on the roof stud closest to the door and at the same distance on the roof stud closest to the gable end.

Screw the metal U-brackets to the roof stud at one end using the short screws. Insert the metal hanging rod into the bracket. Move to the other end of the greenhouse and gather the metal rod up using the U-bracket than screw it into place using the short screws. Place the remaining U-brackets over the metal rod aligned with the remaining roof studs and screw them into place.

NOTE: You may have to angle the screws so that they will grip into the frame of the greenhouse.  

Happy gardening!

If you have any questions or problems, please give us a call.