Building a Greenhouse

[Lady tehMa]

We're hoping to build a greenhouse.

Yesterday my friend and I snagged a large pile of concrete blocks

About 68 of these (plus or minus, we kind of lost count)

Concrete block.PNG

and two of these

Concrete half-block.PNG

Took 3 of her little trailer loads to get to my place. They were offered on Facebook Marketplace for $1 a block. Only thing is that they were in a retaining wall at the time. The first load, the guy was pulling them out and moving them to the trailer, huffing and puffing the whole way. We asked if he could please knock the dirt (and roots) out of them as then we could take more in the trailer. He looked at us, looked at the wall and said we could have the rest for free if we would do the work. First load was 25 bricks and the trailer was plain squirrely with that much in it. Second and third loads behaved much better without all the extra weight from the dirt. It took us about 4 hours to get it done.

Greenhouse.jpg

It may end up looking like this - but we have enough bricks to make the foundation 2 deep.

Our friends and husband and myself are going in on it together. We all thought it would be really nice to extend our growing season, and have a place to start plants. My friend's husband is over 6 ft so we will probaby need the extra height the extra row of foundation bricks will give us.

So, has anyone done a greenhouse build? Any suggestions/ideas/advice? We're complete Newbies at this. Friends husband is great with CADD and mine is an electrician. Friend's husband has been doing a bunch of research so we're hoping we have the right idea, but I was hoping to mine the forum for information.

[oneh2obabe]

How big? Glass or polycarbonate? What's your budget (ballpark)?

[OldIslander]

Nice to see you using recycled building supplies, rather than the gentleman dumping his used blocks somewhere, and you buying new ones.

While I have never built a greenhouse, I have used them and have several friends with them. The thing that I recall from personal experience, and that all the other GH owners I know, say without exception, is that it's always a lot hotter in a greenhouse in summer than you'd ever have believed it would be. Be sure to make sure there is lots of ventilation in the roof and openings on both ends (and maybe even the sides...) for cross ventilation.

Some local friends built one a few years ago and used dark brown bricks on the floor, which seemed like a good idea at the time. But the bricks absorbed heat and that floor acted as a highly efficient 'heat sync' -- they finally had to remove it and go to white gravel inside.

Good luck with it...! Can we see pics when you're done?

[alanjh595]

Be sure to make sure there is lots of ventilation in the roof and openings on both ends (and maybe even the sides...) for cross ventilation.

You can buy venting that will open and turn on the fans when it gets too hot.

Green houses get way too hot in the Summer to be of any real practical value. They are best suited for early Spring use, to get a head start on the seedlings. (Seeds are much cheaper than buying seedlings from a retailer).

[Lady tehMa]

How big? Glass or polycarbonate? What's your budget (ballpark)?

Polycarbonate - buddy (friend's husband) - thinks it is a more viable option, that we have options with build kits. So far we're thinking it will be around $1200 plus tax. This is just the beginning. I probably will update the thread, assuming that we manage this :)

[oneh2obabe]

What size?

[Lady tehMa]

I believe we were talking 8x10

[Catsumi]

Oh goody! Black Krim tomato plant starter area.

[Lady tehMa]

Oh goody! Black Krim tomato plant starter area.

I have saved some seeds from mine already this year XD

I'm also looking at seed catalogues - though I'm not going to actually buy until I know we are for sure doing it soon.

[TylerM4]

A few tips:
- Instead of building up, consider digging down. Depends on the water table, and slope in the area. If you can dig down a couple of feet it'll greatly help moderate the temperature inside of the greenhouse. Keeping it warm when outside temp is cold or below 0 and keeping it cool when it gets hot.
- Consider a double wall design for maximum efficiency and heat.
- Consider your goals and where the sunlight will be at that time of the year.

The best performing greenhouse I've even seen was build with the above features. It wasn't fancy to look at with a 2x4 frame and 6mil plastic sheeting/vapor barrier walls, but wow did it work well. It was dug down about 30", and had 2 walls of plastic (layer outside and a layer on the inside of the studs). The double layer helped trap heat inside, and having it dug down really helped regulate the temp.

[Lady tehMa]

We definitely have enough blocks to go down a bit. That will probably be the hardest part - I'm in Rutland, aka "Rockland".

Before the blocks were available I had pondered a walipini https://www.peakprosperity.com/walipini-style-greenhouses/ but I don't think I could manage that without an excavator.

[TylerM4]

Spent many a year living in Rutland.

My experience over 3 different properties has been:

1st foot - fairly easy digging but it certainly ain't like digging in prairie topsoil.
12"-18" - Digging gets hard, constantly fighting rocks.
18"+ - The rocks have unionized and you have to find the week member to bring out the group. Very slow going.

Getting down 18" shouldn't be too hard tho it's probably still a day's worth of digging!


Believe it or not - I've found worse in my place in Lake Country. I'm sure it's local to my neighborhood but we're on a layer of clay and gravel that have mixed to form a sort of natural cement. After 12-18" it's rock hard, shovel bounces right off - only a bar or a pick will get you further and make sure you wear eye protection cause the flying bits are dangerous!

[Lady tehMa]

Sounds like it is now going to be mixed construction, as we just found a deal on a bunch of commercial-grade double-glazed windows. We're still thinking polycarbonate for the roof. We're also thinking we may adjust the pitch and reinforce it.

[alanjh595]

Digging down 18" for a greenhouse footing is overkill. (Just consider the weight that needs to be supported).

Double glazed is also a big overkill for a greenhouse. Double glazed is only required for a structure that contains humans and the heating and cooling costs to keep those humans comfortable.

Unless you really want to start plants very early, in a cold atmospheric area, don't bother. Rutland is NOT one of those areas.
The biggest issue in Rutland/Okanagan would be too much heat, not too little. Once the plants have reached a certain maturity, they will do best with warm days and cool nights. (They need a rest period). Too much heat will burn them, and too much sun will cause them to become pale and spindly.
Seeds don't need any light, seedlings need a small amount of light.
Just like water, Ph, and fertilizer, too much or not enough will stress out the plant and it won't produce your desired effect.

[oneh2obabe]

Double-glazed windows are perfectly fine for use in greenhouses. If they weren't, greenhouse builders wouldn't consider using them when designing and building them. Double-glazed windows allow for around 80% light transmission while single-paned windows allow roughly 95%.

Single-paned windows allow better transfer of sunlight and heat, but make it more difficult to control temperature than double-paned windows. Windows with UV-protection or low-solar-gain low-e glass may be a better choice when the gardener wants to limit the amount of sunlight plants receive, such as in summer months or in warmer, sunnier climates. As with polycarbonate, glass windows can make use of an automatic opener to provide ventilation.

https://www.wisegeek.com/how-do-i-choos ... indows.htm