Planning to build a greenhouse - seeking advice.

Hello everyone!

In the coming months I will finally be building a greenhouse/hothouse (still don't know what the difference is lol)

Construction will be of brick with large window inserts and a pitched roof with polycarbonate sheeting.
The reason for building with bricks is for 2 reasons, the first being to reduce temperature fluctuations and secondly because my best friend is a bricky so its going to massively reduce the build cost.
The flooring will be entirely concrete, I do not plan to have any cut outs or open garden beds in the greenhouse as I have heard they can be hit and miss and often lead to infestations of various nasties.
I will be having the roof trusses made up professionally as they are not that expensive and I want the house to look nice and not be a slap stick job.
Will also be having an electrician come out to wire up a ceiling fan for airflow.
Also plan to install guttering so the roof can catch the rain water and I will plumb up some water drums at the back so my plants can finally live exclusively on rain water which I am sure they will love.

The shape will be a long rectangle and eventually I want to build a patio on the long side that faces the yard, would like to cover this and have the larger plants live outside but just have to wait and see how much yard space I can negotiate with the other half (this intended build has already cost me dearly! ha ha ha)

I do however have a few blanks to fill in....

1. Is orientation all that important given how strong the sun is down here in melbourne?
(I would like to build it running along the fence so it doesn't cut into the yard too much as I intend to build it quite big)

2. If 1 side is facing the fence (the long side) is there any point in putting windows on this side or should I just leave it as a brick wall?
(if it is a brick wall it will be better as I can then put up shelving, the majority of the other walls will be all window)

3. In terms of the polycarbonate for the roof does anyone have any recommendations on what brand to use?
(i'd rather spend a bit extra and get some life out of it rather than having to replace it 18 months later)

4. Any suggestions for balancing the needs of cacti that love strong sunlight and their more sensitive counter parts?
(I wondered if putting up blinds on one end might help and the astro's and what not can live down that end?)

I'm assuming that with a completely clear roof there is going to be a hella lot of sun coming through coupled with the windows its going to be a pretty bright house but i'd rather it be too bright and then shade the individuals than have plants reaching for the light.

The build won't start until at least December but I am starting to do the groundwork now so that all my ducks are in a row before I start building, after all it is going to be brick and concrete so not like I can pick it up and move it if things aren't right!

Thank-you

Regards,

Walker87

Hi Walker. Sounds Like an awesome project. I work in the agri sector and am currently researching greenhouses for use as experimental and plant breeding facilities.

I would check your options very carefully as there are some seriously innovative and very cool professional greenhouses that can be purchased at a fraction of a cost of a brick building. So many options are available it is mind boggling and I haven't even begun to scratch the surface yet.  

Check these guys out:
Redpath Greenhouses
(excellent customer service and very helpful with design requirments)

Argosee Greenhouses
Check out their permanent research facility for ideas.

Hey sneaky,
Cheers for the links.
The brick build really isn't going to cost all that much as the bricks will be surplus from house builds and the window frames will be ones that are either slightly damaged or over order stock from builds as well.
As for the labor well a slab of beam is a great motivator for a bricky! Ha ha
The only thing that I will really have to outlay full cost for is roof trusses which will be getting built custom and the electrician to wire up the fan.
I have no plans to heat the house, don't think it's necessary in Melbourne and my plants do alright with a winter rest.
I'm itching to just start building this thing but have to be patient for a little while yet.
Also might take a while to source the bricks and windows as I'm not buying them off the shelf just have to wait until they come up but with the housing market the way it is I don't expect to be waiting all that long!

Haha cool! Best things in life are always free. Keep us all posted on your progress. It should be a damn good greenhouse when your finished and I am keen to see some pics!!!!

Sounds like a great project!

Couple of points - as I understand it, ideal orientation should be north-south. This allows the sun to cover both sides as it arcs across the sky. Going east west means you always have a hot side (north) and a cooler side on the south and may mean some plants are always shaded by others.

Light is probably the most precious commodity in the greenhouse (after space!!), so the more glass/windows the better. Even if it's diffuse light. If one side/area isn't as bright as the other, it might be a good seedling grow out area or a spot for Stapeliads etc.

Can't help much on the Poly, but have you looked at twin wall polycarbonate? Good for its insulation value..pretty exxy though...

Heating might be an advantage in Melbourne if you want to grow some of the rarer trickier plants, but not required for hardier species. Even if it's just to keep a bare minimum and to ward of morning frosts etc.

Thanks navajoa..
I'll have to suss out the direction of the yard and hopefully it suits the correct orientation for the house.
There's no way I'll get away with it going diagonally across the middle of the yard!