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HFGH 6x8 - observations and tips

13 years ago

Hi everyone, after much hemming and hawing, I built the Harbor Freight greenhouse to house plumeria, and wrote some tips and additions that others might find useful.


Harbor Freight 6'x8' Greenhouse (HFGH SKU 47712): Modifications, tips and cautionary notes.

In July 2010 we undertook a major effort to convert a disused corner of the yard to a greenhouse area. It involved tree removal, foundation building, and greenhouse assembly. I scoured GW and other sites for tips, but found that the actual assembly has different problems than others reported.

Site: a large 4 trunked tree was messy and dropped branches. We chain sawed and chopped the canopy and branches and left the stumps to dry for later removal. The soil is extremely hard beneath 2-3' of topsoil. After many weekends, we completely removed the canopy and created a level area for the GH. A termite infested fence will be replaced later. The neighbor's ash tree provides midday shade in summer.

Foundation: it took a full day to build the pressure treated wood base and floor the interior with pavers. Be obsessive that it is level, square, and properly fits the GH aluminum base.

- Clear and level the area, and remove all roots that might interfere with the floor.

- Assemble the GH base and corner uprights in order to measure the exterior edge: 6'3" x 8'3". This was a different dimension from other postings and different from the manual.

- PTW is not perfectly square, but try to make the foundation accurate and level.

- Line the interior with landscaping fabric after leveling the dirt, and place concrete pavers inside. I filled the excess spaces around the edges with loose stones to collect dirt and debris.

Tools and such for HFGH construction (not in kit)

- Nut screwdriver

- Foam sheets

- Electric drill / screwdriver, extension cord

- Philips screwdriver

- Aluminum tape (in Duct hardware section)

- Carpenters square

- Carpenters level

- Measuring tape

- Scissors

- Silicon grease

- Step stool

- 1 1/2" coated wood screws, approx. 30 to secure the GH frame to the wood foundation

- Remote temperature sensor

Kit: all parts listed were included, however a roller (parts 37, 42, 53) is in the parts list, not included in the kit, but is not used anywhere. Lay out all frame parts on a level surface in numerical order. 95% of the packaging is recyclable.

Important: keep the panels out of the sun! Even 10 minutes in sunlight bakes the protective film, making it extremely difficult to remove.

Assembly: overall, the HFGH instructions are easy to follow and most pieces fit only one way. However, the Door instructions are wrong. Total GH assembly was 10 hours with 2 people, including a half hour to unassemble and reassemble the door sides. The HFGH revised manual is dated 05/03; 12/05

Additional steps and cautions:

- Cut strips of foam as a leak barrier and to shim the GH base. Make sure the base is level and square. Do not attach the base to the foundation until assembly is complete.

- Assemble the entire GH without panels. Do not tighten any bolts until completely finished, and do not drill mounting holes or secure the base to the foundation until the whole frame is put together. If the frame is out of square, parts do not fit - use the carpenter's square to find problems and stretch, bump, lift and jiggle into position. Overall, the frame edges and holes are in the proper locations - if they don't line up, either the part is in the wrong spot or the alignment is off. This is most noticeable when adding the door and roof. Assemble with the nuts on the inside of the GH.

- Many of the steps after building the base and before the window assembly can be done in any order. If only one person is assembling the GH, change the step order to make it easier to build the roof frame. Suggest putting the corner brackets on early, although you will need to take nuts on and off at times.

- Window instructions are minimal - use the diagram on the GH box to visualize them. Install the panel when assembling the windows.

- Door instructions on page 14 have two significant errors. Either the door side pieces are mislabeled or the instructions have the two sides reversed. In our kit, part 28 is actually the door left side, and part 20 is the door right side. We unassembled the door sides and switched them, or the panel clips would not install correctly. In addition, the panels can only be installed during the door assembly. Grease the sliders after installing the door.

- Panels: apply aluminum tape to the panel edges to close the open channels. This helps the insulation, and hopefully keeps out mildew and insects. I used 2 1/2" aluminum tape cut in half - it has a red logo down the length, so apply the tape so the red ink isn't noticeable on installation. With one person taping and the other hanging panels, the installation went quickly.

- We will add more clips to prevent the panels from flying off in the wind - a major concern.

- Depending on the temperatures, may add a blind on the western end to prevent sunburn and excessive late afternoon heat. In winter, may add water jugs as heat sinks in cooler weather.

- Wish list: shelves, solar fan, temperature activated window control


- HFGH 6'x8' kit ~ $225 (sale and coupon)

- Aluminum tape $10

- 30 Cement pavers ~ $50

- 5 8' pressure treated wood 4'x4' (already owned)

- Screws, landscaping cloth $4 and foam from previous wood floor installation

- Remote temperature gauge (La Crosse Technology) ~ $30 from Frys Electronics

- Total: approx $320, not including foundation wood and assuming you already own the tools

Diana =^,,^=

Here is a link that might be useful: HFGH pix

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