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GH Floor

Posted by Hudson...WY 3 (My Page) on
Fri, Dec 27, 13 at 15:50

During the coming winter months I would like to finally prepare for a floor in our GH. Concrete seems to be our best option - but I would like your opinion for the best material to use for the GH Floor?

I was thinking of digging out the soil 6"s deep - screwing 2x4 redwood to the walk side of the 4x4 posts parallel to the raised bed on each side - installing perpendicular 2x4 redwood spacers at each 4x4 - then spreading gravel for a 3 1/2" thick concrete walk. There would be 3 1/2" of soil remaining between the concrete walk and the raised bed on each side of the walk. I would leave the 2x4 redwood forms in the concrete for appearance.

Does anyone see potential problems or concerns with installation of such a concrete walk in our GH from your experience with GH floors?

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Follow-Up Postings:

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RE: GH Floor

Your present floor looks fine to me. I would much prefer gravel to concrete for ease of operation, drainage and a less hazadarous walking experience.


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RE: GH Floor

I agree with bmoser. I'd like to see mine get built this year. We have salvaged a lot of red chimney brick. Thinking that might work for me for my GH floor. I'm always one to try and save a buck or two.


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RE: GH Floor

Is there a thermal mass benefit from using concrete on the floor? Presently - the dirt floor gets muddy when I over spray and it is hard to clean. We have considered gravel but gravel is not as comfortable when standing for several hours, pea gravel sticks in your shoes, 3/4 +- gravel is not comfortable kneeling, gravel is hard to wash and lacks some of the thermal mass benefit?

We have budgeted for concrete so the cost is not the concern - it is all about function. I don't want to pour concrete and then find out I wish I had used other materials that may have better functionality? we will place 3 1/2"s of gravel between the concrete walk and the raised beds on both sides for drainage. With concrete I can open both GH doors and hose it clean. I will have a flat surface for ladders and kneeling pads, wheel barrows - etc. It will provide a pad for the GH furnace, keep weeds/grass from growing on the floor and add to our thermal mass.

Am I missing something that I will regret for pouring concrete? Those of you that have concrete floors are there any reasons why you wished you hadn't or things I should consider before pouring?


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RE: GH Floor

Retired after 40 years professional horticulture. would never put in a concrete or gravel floor. GH floors should be mulched with organic material...sawdust, woodchips, etc. Gravel ruins drainage, concrete is cold, slippery, horrible. the whole greenhouse needs to be living and biologically active. Can say much more about this, but not now.


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RE: GH Floor

San_Mueller, I thought I read somewhere not to use anything for flooring if it is going to rot for it is a place for insects to hid and molds to grow. Myself I think it would be okay and would be the easiest flooring to install.


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RE: GH Floor

Indeed. Mulch is going to retain moisture and encourage rot in the wood. Even redwood rots....

You want drainage AND thermal mass. So use gravel as a base and concrete paving stones to get the best of both. In my greenhouse, I used about 10 tons of crusher run gravel; laid down landscape fabric to keep 1" of sand from disappearing into the gravel. More sand was swept into the joints between the stones.

Cheers


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RE: GH Floor

It is a common misperception that gravel improves drainage. the opposite is true. Gravel is packed down into your soil compacting your substrate. Since you are not growing in this floor the increasing water table underneath causes anaerobic conditions favoring eel worms and disease. Weeds that do grow are impossible to remove by hand. An organic floor loosens the soil beneath, encourages earthworms which make deep channels underneath your structure improving drainage. An organic floor captures leachate from your plants and eventually turns into a very useful soil itself. A dark organic floor is an excellent capturer of heat in winter and will cool and humidify in summer. Enough mulch on the floor provides a superior insulating floor particularly important in a cold climate where the ground freezes...don't let me start on the atrocity of a concrete floor in Wyoming. If you want to spend money and get fancy you can bury pipe beneath your floor and blow heat through that but 6 " of sawdust fantastic and by the way any weeds pull up with ease and a gentle raking lives a great appearance.


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RE: GH Floor

That's why I used landscape fabric above and below the layer of gravel: the gravel isn't going to migrate into the subsoil, while the sand won't fill the voids from above. In any solar structure, thermal mass is the key. Around here, sawdust is unheard of for 'flooring'. Too many wee beasties like to eat it.


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RE: GH Floor

It appears there are strong opinions! I appreciate your passion and knowledge/experience. You have definitely given me some things to consider in making a decision!
Thanks for your opinions!


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RE: GH Floor

I have never found soil biota to be anything but natural and beneficial. A grower can always control insects but can never eliminate them. thermal mass is very good and I like it myself, but it will do almost nothing to heat the air in a gh and if the temp inside falls to 25 degrees, I am going to lose all my citrus no matter how warm the soil. How much heat will gravel have after a week of cloudy freezing weather? How much heat does gravel pick up even on a sunny winter day? I actually think that insulation dollar for dollar is a better investment than solar mass...would love to have a giant American flag to drape over my house ant night. 6 " of mulch is a better floor insulator than gravel could ever be.


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RE: GH Floor

Insulating greenhouse floors is actually counterproductive. See attached references.

Here is a link that might be useful: greenhouse floor insulation


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RE: GH Floor

Great discussion!

I'd weigh in against poured concrete because of the permanence of it. What if you want to add a heated conduit underneath or a new irrigation line? Or change the layout of your beds? It's a total one-way street. If you want a concrete floor, I'd do pavers. Have you seen the big square 2 by 2 pavers they make nowadays? They are quite handsome. The re-used brick sounds lovely, as does the fluffy mulch.

Did you make a final decision yet?


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RE: GH Floor

Hudson, I think I would go with some type of paver, your choice. Pavers, properly installed on compacted, smoothed, compacted, smooth... did I mention compacted? Crusher dust (installed on top of 5/8" crushed gravel (also compacted - you will need this for poured concrete as well - rent a small compacter)). will give you a great floor, will be as impermeable to water as poured concrete, have about the same thermal mass, but as Karin says, will give you flexibility. I should add this disclaimer - I have no experience with gh floors, but I have with laying pavers.

You can also install Permeable Pavers, but they require a different substrate that I will leave to you to search out from your local paver supplier.


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RE: GH Floor

No - I haven't decided yet - I got to honest with you though - Pavers seem to be the best option and what you and LivelyDirt suggest makes sense but pouring concrete would be a whole lot easier for me and less - expensive. Most of the reason I don't have a floor yet is because I haven't convinced myself of the best option for our GH. Thanks for the info - there is plenty to do without worrying about the floor this year but we are tired of tracking mud - Now would be a good time to get it prepared !


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RE: GH Floor

  • Posted by bencjedi 6 - Central Kentucky (My Page) on
    Thu, Jan 9, 14 at 13:07

I went for something radical in my GH since I built mine on a raised platform deck. It's a design I've never heard of anyone doing. Basically a deck inside an outer shell of glass, so the two parts are independent. The deck was built in a standard way with spacing between planks to allow for expansion, but obviously all the open spaces can't be a good thing if you are trying to keep it warm in the winter, so the radical part involves using free carpet underlayment from some rooms in the house I replaced with laminate. I put the underlayment down and on that pinned down a waterproof canvas from a discarded screen house over it. I'm not done building the GH and have to install a rain gutter as currently rain water coming down at the end of the slanted roof drips right into the GH. Since the floor is now impervious to water it pools up on the slightly lower side of the deck (pitched to the same angle as the adjacent deck off the house). From there it very slowly evacuates the floor to the rear corner. In retrospect I should have designed the platform in a way where that side would have a gutter also so inside water had an easy way to drain. Maybe a cheap shop vac will be an interim solution. Anyhow thought I would share my experiment in flooring. As you can imagine it is bone dry beneath the GH on the ground.

Here's a couple pics


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RE: GH Floor

I can remember a similar thread on this forum nearly 20 years ago. I think I said pretty much the same things then.


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RE: GH Floor

It has been such sunny weather this week - nice day to work in the GH! Although there are a lot of good ideas for a GH floor - the best option for us IMO is a concrete floor. No better time than the present to get at it. The first tool to buy when you move to Wyoming (if you want to do any digging) is a Tamper Digger Bar - it is a must! I would have had a hard time digging out the soil today if I hadn't had it (had a hard time with it! - haha). The soil was really compacted after walking on it for 5 years. It almost looks like rocks - but no - that is dirt. I got a good start (one bucket at a time) - almost 1/4 (55 square ft) of what needs to be dug. It will take me a few days so I am glad I got started. I got the snow blower and blew out a trail to the garden so I had a place to dump the dirt. We don't have as much snow as usual for this time of year and it has been so cold - the snow is granular - like sugar.

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