Newbie questions about prefab greenhouse

I am a newbie to this forum and I have never owned a greenhouse. My only greenhouse experience comes from 30+ yrs ago when I was in college and spent some time working in the college greenhouse for work study. But, my sister has spotted a redwood (or cedar) greenhouse that is 8 X 12 I believe...... the lower portion of the sides are wood, and then it has plastic or possibly fiberglass type panels up the top part of the sides and of course the roof. There is a small 'window' made out of the same material in the gable of each end that is on a thermostat controlled sensor to raise those small windows to ventilate the house to keep it from getting too warm.

The construction seems like it would be fairly simple to duplicate and I would think it could be built for much less than what they are asking but I had several questions that I thought some of your with greenhouse experience might could answer.

1. Where would one purchase these panels?
2. Are they fairly decent at insulating?
3. know of anyone who sells plans to build such a greenhouse?

and the biggie....
4. What are the big considerations that she should keep in mind when deciding if she wants this type of greenhouse.

I THINK she basically plans to keep it to overwinter plants and pots - and she would pull those items out when it got to be consistently warm temps, but in our area we can have some big temperature swings in the spring and fall - and actually even in the winter.

She likes this particular greenhouse because it is "pretty and not ugly like most greenhouses" - and I will agree that it is a very nice looking greenhouse, but I also know if it isn't reasonable functionable she will be disappointed in it, but I know feel like I have enough specific knowledge to help her.

Suggestions? Ideas?

My husband took a photo of the greenhouse so that he might could duplicate it for her, and I will try to get that from him and load it here for you to see which would probably help! It is being sold by several places in the area that sell the prefab wooden storage buildings.

Thanks for any input you can give!
Genna

Hi Genna,

I think the biggest problem with the greenhouse your sister is looking at is all that wood. By nature, greenhouses are wet and humid. The wood will rot in just a couple years and she will be left figuring out how to replace it.

Foundations and lower walls of concrete or brick are much more reasonable. Try to avoid wood in any part of your project.

The panels can be purchased online at almost any greenhouse supply company. Lookup "Polycarbonate panels". They are made up of thin walls of polycarbonate with baffles built into the "sandwich" layers. Twin wall (with one set of baffles) will suffice if your area doesn't fall below freezing or the plants you are wintering over don't mind those temperatures. The heavy duty panels are 5-wall, meaning they have 5 layers of polycarbonate with 3 sets of baffles.

On their own, the polycarbonate panels will only keep your greenhouse 5 degrees warmer than the outside air. That means a heat source is required. The more layers the panels have, the better they are at retaining heat.

Another consideration is wind. If it gets really windy in your area, the greenhouse will have to be anchored to the ground and built to withstand the winds. My California greenhouse was a twin-wall heated with half a dozen brooder lights. It stayed above freezing in 20* temps. My greenhouse here in Reno is a Super 5-wall Polycarbonate with 3-inch steel I-beam construction. The "Super" 5-wall panels are storm panels for wind and snow prone areas. It survived a 90 mile an hour wind last December and I manage to maintain about 60 degrees with a gas heater (low temps here are -5). If you do use a gas heater, ventilate it to the outside.

Air circulation is really important. In the winter, when all those windows are shut tight, keeping the air moving will keep the plants from mildewing. So access to electricity is important. I use clip-on RV fans that run continuously. I have 4 fans, all pointed in different directions, to keep the air moving. It doesn't have to be gale force - just moving.

Water and drainage. The simplest drainage is to put a sand and paver floor in the greenhouse. If the floor is not permeable, build in some drainage holes. Have water available - I have hose spigots that my husband built in while we were laying the floor.

The problem with greenhouses is that you find more and more things to stick in them. The the biggest one you can - you will never be sorry.

Google "greenhouse plans" and go to images. There are lots of plans and ideas there.

Daisy

Thanks so much Daisy! I appreciate the feedback.

I think that is why these are made of redwood (because they supposedly hold up well to water) and I know that cypress lumber is used a lot with water exposure so I figured it might work as well. I think she would be happy even if it just had a little wood trim on the front side...just something to dress it up a little - that might could even be put "outside" of the polycarbonate panels to only be for outward appearances and not function - although not sure what would support the panels in that case. I didn't know what those panels were called and had attempted to google them but with no luck not knowing what they were called or what they were made of..............

It definitely gets below freezing here - and we have ice and snow on occasion too. One of the biggest problems here is that one day it might be 20 degrees, and in a few days it might be 60 or more........... I would think that would make the temp inside difficult to regulate.

I am attempting to load a photo of what she saw - but it isn't giving me the option to load photos.........

Finally - had to refresh everything for it to ever give me an option to upload a photo.

This is a photo of the one she loves.............. they are available in different sizes.

Try to locate a plastics supplier they will be cheaper than a gh store. Spend the extra buck and use triple wall. Its a lot stronger and is clearer. Some day I am going to rip out all my twin wall and replace iit with triple wall.

Is the triple wall flat? Or corrugated like tin? Best I could tell from this one it was corrugated, but I didn't know how many 'walls' because I didn't walk up to it.

BTW, would she need to plan on lights in the greenhouse ?

Thanks for the info!

Genna

The polycarbonate panels are flat, not corrugated, but may appear that way from a distance because of the light refraction. Triple wall would have 3 layers of polycarbonate and 2 layers of baffles. There are also thicknesses of the overall product. Follow this link. It has good descriptions and photos:

http://www.charleysgreenhouse.com/193-247-Polycarbonate-Glazing---Poly-Covers.HTm

This company is in Canada (with a sales office in Seattle). Not the best prices but for information, they are great.

Lights are nice, especially if you plan to visit the greenhouse in the dark. Depending upon heat source, electricity may be needed anyway.

Daisy

Awesome! Thank you for the help!

You're welcome. Just be sure to keep us posted on your progress. And send photos!

Daisy