Hello jba3fan,
There have been minor variations from person to person on how weÂve chosen to make modifications, so I donÂt think thereÂs been a list of materials posted that would work for all of us. As one example, many of us have used EMT to make braces, but the number and location of braces varies, as does the size (1/2" or 3/4"). Maybe we are all too creative or too stubborn to do it the same way. :-)

However, I remember that TroyKD included a list of his materials and costs in his blog:
(TroyKD) Building our Harbor Freight 10x12 Greenhouse

And, in case you havenÂt already found it, hereÂs a link to gardenerwantabeÂs thread on his modifications:
Modifying the HF 10x12

My blog shows what my husband and I did for ours:
(mudhouse) Building our Harbor Freight 10x12

Basically, we purchased pressure-treated wood (and bolts) for the foundation, EMT tubing and aluminum angle for bracing, extra glazing clips for the panels, screws and neoprene washers for the panels, and some extra bolts as needed to complete the construction of the frame. (I list a lot more specifics in the blog.)

If you want extra clips for the panels, itÂs good to get those ordered ASAP because of possible shipping delays. We purchased everything else locally.

Hope this helps a bit, and of course as youÂve found there are lots of other good posts (and good folks) here. I wouldnÂt hesitate to post questions.

I used top rail from a chain link fence for my bracing I had 100 feet or so of it left and I thought it would add more strength. I used a LOT of self tapping rubber washered screws. It does take some bracing to complete. I just finished mine
yesterday.

I will post some new pictures in a few days.

Thanks Mudhouse for the links. I have had your page book marked on this comp and the others were on the old comp. After checking over my parts (not the nuts and bolts bags) everything is there and no extras.

Your error allert....

Error Alert! Page 8, step 7, the manual says to "attach the Front Ceiling Plate to the inside of the two Corner Studs." This is impossible. The ceiling plate can only be attached on the outside of the two corner studs. It will be obvious it can only go on the outside, so donÂt worry. The photo above shows how the ceiling plate looks installed.

..... has been fixed on my instructions. Most of the revisions were 05/06 but on page 8 it is both 05/06 and 09/06. Sure looks like they have taken notice.

Now I have to decide what is better to have the door on the north side or the south side??? If I put the door on the north side I think I can modify the door to use a 36" insulated glass storm door so I can look inside from the house instead of looking at heavy insulation only.

Hey, I am glad to know that they have fixed at least one error in the manual. I'll update that in my blog so it doesn't confuse folks, thanks. I should keep an eye on the PDF file for the manual of the HF website to see what they change.

Glad you have all your GH parts. I noticed that they provide very few extras (even on the little bagged parts) so keep an eye on those little ones!

I'm not good about advice on door location. I put mine on the west side which was questionable since we do get some winds from that direction, and I've read that strong winds blowing on the HF doors aren't a good thing. However, it made the best sense in relation to our house. I finally decided that the door location might not be that critical on a small square hobby GH, so I should just put it where it would be pleasing. Others will probably have better advice for you.

Amigatec, looking forward to your pics!

When I built mine I spent about $ 70.00 in toll calls to HF tech I kept calling them and telling them about all the mistakes in the instructions.
Shortly after that some changes started to be made to the manual.
The very first one even had the dimension for the base WRONG !!

I have uploaded some new pictures, I plan to build a website with these pictures so if you do a slideshow they are out of order, The newest pictures are on page 4.

Here is a link that might be useful: Amigatec's Greenhouse

Wow, that is a TON of great photos! Great detail that will be helpful to a lot of folks.

jba3fan, take a look at image 57 in amigatec's photos. It shows how the diagonal braces have been installed (early) to support the corner posts. I totally missed this advice in my reading (duh) but it's definately the smart way to go, especially if you're working by yourself. Without attaching these braces early the corner posts are terribly wobbly. The diagonals have to be removed again later (briefly) but that's easy to do.

You used more screws in the panels than we did, amigatec. No way those panels are going anywhere! Looks good. It's so helpful to see what other folks have done.

If you notice in the picture I have the bolts in the wrong holes, but it was enough to hold it. I added a LOT of other stuff to it as well. I still have some cross bracing to add. I will probably add that within the next week.

Here the bolts are in the wrong holes
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Same corner, but here they are in the right holes.
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Now I will work on building raised beds inside, I have an old waterbed frame that is taking up space. I think I can cut it down and make 2 beds that are 3'w X 5'l X 8"h, place a waterbed heater in the bottom line it with heavy plastic, fill with potting mix, and place on top of 3' high legs.

I know I over did the foundation but I figure I will have a nice heat sink

First off I couldn't figure out exactly where I wanted this to be..I wanted it closer to the house but then it would have looked way out of place and here is too far away to run power..
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so I moved (by myself) the old hoop house I built last winter to the west about 20-30 feet

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I framed the foundation onf 4 x 6 treated lumber on 4 x 4 post sunk in concrete on all 4 corners and half way on all sides

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I dug out the inside to a depth of 14 inches or deeper from the top of the 4 x 6

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then added some chicken wire

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some landscaping cloth

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and some 2 inch styrofoam insulation board (I couldn't find 1 inch boards) the outside walls the insulation is cut at 12 inches and the floor is 24 inches

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I added a 3 inch pvc pipe to run in a gas or propane line and a 2 inch pipe to run in some electricity

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I added about 65 wheelbarrow loads of #26's AKA crush and run gravel

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Tamped the gravel..(harder to do then move about 9 tons of gravel)

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I used some 20 mill plastic flashing under the GH base
I think this was an excelent idea for a number of reasons:
1-- easy to use
2-- just go to any new home construction jobsite and ask for some you only need about 50 feet.As long as the framing crew is not running out of the flashing they will gladly give you some.
3--made it really easy to spread out the nuts and bolts and small parts where they were needed with out getting lost in the gravel or dirt.
4--kept dirt and gravel out of the base area.

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when adding the extra bolts in the upright studs I used a rubberband to hold them up out of the way while deciding how many extras were needed.. I put the nuts on the bolts that go on the braces as you can see in the pic.

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thats it for now

I have part of the page on line now.

Here is a link that might be useful: Amigatec's Greenhouse Webpage

Wow, that's a super foundation! I can only imagine what your back felt like after 65 wheelbarrow loads of gravel, but you sure will have a nice base for your greenhouse.

Your website is a really good step-by-step, and should be very helpful to lots of folks! I'm looking forward to seeing the rest of your progress. Great job!

{{gwi:306560}}

I had no physical help from anyone to put this together. The only help I had was from here on Gardenweb.

I see I will need more self taping screws and washers for the panals so I can connect the top and bottoms to the frame. I had a problme with the self taping screws being too long on the drill part of the screw where I couldn't use a spacer between the panals and the horizontal braces.

I somehow lost a screw for one of the door rollers between the back room of the house and the green house site.

One question tho .......... How tall do you have to be to open the roof vent windows?

now to add insulation.. exaust fan and decide what to heat this with.... vented or unvented propane????

DH and I are working on this project now. I can't imagine one person doing it alone! I just put the windows together this morning and am most upset with the way they are fitting now. The roof is not up yet, but the windows just slide around and it looks like they will fall out when opened. And I guess I would need a stepladder to get them open anyway. Somewhere someone mentioned using c-clamps to fasten to top pole. Guess we will do that as it just doesn't look right. Anyone else have problem with the windows and the way they open?

Here's my two cents...the roof vent windows are my least favorite part of my HF 10x12 (which I love.) I fiddled with them a LOT when we put them in, and got them so they opened and closed pretty well. Several months later we had a big wind, and one of the polycarbonate panels actually blew part way out of the window frame. (My window poly panels could slide up and down a bit in the frame, and it slid all the way up, so the wind caught the exposed bottom edge of the panel, and pulled it partly out.) I will admit that our winds here are worse than many places.

So, we took all four window vents off, and I caulked all the poly panels to the aluminum frame with clear silicone caulk on the outside. It doesn't show, and now the poly panels don't slide in the frame. Great. BUT, we did not pay attention to the order of the windows when we put them back in...and now they really don't open and close smoothly at all. I guess we put them back in a different order, and there were enough tiny variations in the fit from window to window to make a difference. ARGH.

I do still use them and I climb up on a 6 foot stepladder to open and close them. But I have to reach up and snug down the corners with both hands to get them to fully close...simply pulling on the center handle doesn't snug them in anymore.

Given my experience I'd consider caulking those poly window panels in place before you install them in the roof, but maybe other folks have had better luck than I have. :-(
Sheri

After throwing away my HF openers, I one day discovered that I could open the top vents by slipping the end of the handle into a 3/4" pvc pipe (without have to climb a latter) and then moving it into the slot I want. You can close them the same way. One of my vents won't close all the way if I let it down easy, so I let it sorta slame shut. I rarely open them at all except to let butterflies or birds out of the GH. I have found that open vents cut down on cooling when I have the big fans running.

Pat wrote: "I have found that open vents cut down on cooling when I have the big fans running."

That's what I've read too, and one of the reasons I'm hoping I won't have to depend on these vents year round. However, I am going to try your 3/4" PVC idea, and see if that works on mine. I bet it would have worked before I removed and replaced the windows to caulk them...I'll go work on them.

jba3fan,
thanks for posting your photos. Just one question- why the styrofoam insulation on the floor?. Since heat rises, there is almost no heat loss from the floor of a greenhouse. You also mention a "nice heat sink" from the insulated foundation, but would't the foam actually inhibit heat moving into the soil during the day?

cuestaroble,

I used stryrofoam not to keep the heat in but to keep the cold out from the ground. In the winter time here in central Virginia the ground can freeze solid as much as 12 inches deep, usually it is only about 2 to 3 inches frozen for short periods of time.

I figure since the gravel is at least 14 inches thick it would hold more heat then just sitting on the bare ground.

I hope that makes sence

Jim

Probably most people think in terms of keeping "cold" from coming in, but in reality , it is only heat going out. The 14 inches of gravel is a good idea and is a heat sink. The foam insulation under the gravel actually keeps the soil from absorbing heat during the day to release at night. You cannot keep "cold" from coming in, only heat from going out. If you look at the many formulas for heating greenhouses, none include the floor, as relatively no heat is lost through the floor. The most important factor is the 68% of the total heat loss in a greenhouse going out through the roof.

I know when I build a house and it is built on a slab of concrete instead of a crawl space foundation I have to insulate around all the exterior walls. It is kind of the same thing as how deep you have to dig a footer for the house. It all depends on where in the country you live. for example in my area we have to go 16 inches deep to have a solid base where any freezing of the ground will not destroy the footer. Now say you are in New York your footer would have to be allot deeper. In southern Texas you would not have to be as deep. I don't know what's needed in California I would imagine something allot different to keep safe from earth quakes that could do the damage.

I am not planing on using this greenhouse in the summer so I do not want to gain any heat from the ground. In the winter I do not want to gain any freezing temps from the ground.

The physics of side wall, perimeter, insulation, is much different than that of the floor. My comments were directed only to the floor issue. It is not possible to "gain any freezing temps from the ground" in a greenhouse. As I noted, only heat loss is the issue, and that is negligible through the floor. Earthquakes are not considered in my comments. Floor insulation in a greenhouse is counterproductive. The attached link says, quote " do not insulate floor".

Here is a link that might be useful: insulating greenhouse floors

That is a nice link you posted there. I am sory but I do belive the webpage title greenhouse.gov actually means "green"-house as in energy efficent not Greenhouse for storing/growing plants.

The only place I read where they say not to insulate the floor was if I was trying to cool the house. As I said earlier I am using this greenhouse for winter protection. The R values that they use in Austraila are measured differently then here. I can only imagin that R 1.5 would be close to the same as our R 13 for exterior walls and R 30 is normal for cielings here but they call it R 2.

Below is from the Department of Energy
link.....

Insulation Priorities

It is most important to:

Insulate your attic to the recommended level, including the attic door, or hatch cover.
Provide the recommended level of insulation under floors above unheated spaces, around walls in a heated basement or unventilated crawl space, and on the edges of slabs-on-grade.
Use the recommended levels of insulation for exterior walls for new house construction. When remodeling or re-siding your house, consider using the levels recommended for new construction in your existing walls.
Next Section - How Does Insulation Work for You?

Here is a link that might be useful: Department of Energy

Cuestaroble, perhaps a more informative link would be your study citing 2-3% heat loss through the perimeter and none through the floor.

Deep ground temps around here are around 50-55F so the differential between my ground and my GH is about zero in the winter...thus, no heat loss through the floor. The perimeter is insulated, the floor is not.

SB

Thanks SB. As you know, most state universities have publications on greenhouse energy conservation, and none show any appreciable heat loss through the floor. Here is one chart, note that the total is 100%, with no floor loss.

Appendix 4- Greenhouse Energy Conservation
Typical Heat Loss Distribution in Greenhouses
Roof - 68%
Infiltration (leaks) Â 21%
Walls - 11%

Here is a link that might be useful: greenhouse heat loss factors

How about throwing in radiant cooling. Any cold surface will radiate coolness same as a hot surface radiates heat and wonÂt radiated heat or cold convert to convection? They use a ton block of ice to convert to btus cooling effect. John