How can anyone help you? Where is the warm country? What do you intend to grow in it?

A kit may be a better solution than a custom built job.

Is power available?

Is there all day sun in the spot where you going to build? Is it shaded in winter by tall buildings?

Do you want it to be fully automated?

And so on. A detailed 5000 word essay is outside the scope of this site.

As for the table and chairs? Every "orchid house" I have seen has no room for anything except orchids.

Here is more Stuff....

What are the weather extremes that you need to modify for your Greenhouse?

I know because I have been looking at temperature readings in the backyard for about 40 years.

Low about 5C

High about 42C

If there is a nearby AWS, you can a get a good idea.....

Some Climates are consistant others are all over the place. To the east is a nice warm Pacific Ocean. To the west is a very dry Continent.

Tell the readers here more and put the appropriate stuff next to your ID

Example: Micro-Climate, Zone 10b Sydney, Australia

Sorry arthur for any inaccuracies. Okay I live in Philippines... the temperature never goes below 15 degrees C. During dry season, the temp rises up to 40-50 degrees C. During wet or rainy season, 20 degrees is the minimum temperature. Generally, I want to grow orchids along with other plants that have same preferences such as aroids, bromeliads, etc. Power source is already available but I prefer a gh that won't consume a lot of energy. Location is actually our garage. It gets sun all day long, approximately 7 hours. As much as possible, I want to keep the environment inside the gh a bit cool or intermediate especially when dry season occurs.

The location looks like Pampanga, a province in the Philippines, about latitude 15 degrees north. Without knowing the exact location, the highest maximum temperatures are probably around 35C and lowest minimums not much below 20C.
A "greenhouse" wouldn't be a good idea as overheating would be a major problem. A "shadehouse" is a better idea but there is always a problem with balancing the right amount of sun or shade. And relative humidity is also a big question. You need to select the right species to grow.

Yay! Sort of like Darwin NT, Australia. With a bit more rain than Darwin in the dry season.

But, never ever a day with a Max temp of 42.5 C and humidity of about 8%.Yuk! That is why zone 10b has limitations because it only measures low temps.

OK that is 68 to 95 F for non metric readers. Is your location for the shade house in a sunny or shaded location? I use 50% shade Lexan for the roof. Made by General Electric. It is better to choose a sunny location as you can choke down the light to your needs with shade cloth. If it is too shady you can not make it brighter. Here we must protect against cold winters. Not your issue. It would be a benefit to have electric for fans and lights.And a water hose. Build your floor so that water drains through. My floor is concrete pavers. Gravel is good but the pavers are easier to stand on. Send pictures as you progress. Good luck.

I'm actually considering shadehouse instead as it will be much ventilated and sunny. But, my major concern is I cannot protect my orchids from excessive amounts of rain during wet season. Moreover, I grow vandas, phals, catts, den phals, and some oncidium, all of which are prone to rot. Although it would be windy during rainy days, the high levels of humidity won't allow my plants to dry out. Hence, even worse headaches to come.

Yes, you will need a polycarbonate roof with the appropriate amount of shading, maybe with an extra layer of shade-cloth appropriate to the latitude of about 15 North. This is so you can get out there and work on a rainy day.

Fibreglass is useless. Degrades in high- light.

My cold glass-house now has a polycarbonate roof after the frame started to rust after 40 years service. Polycarbonate rated at 85% light transfer. So i have 50% shade-cloth cover over that. Here is 33 something south, so it is hard to say what you need.

As for the climate there? Tropical Monsoon?

November - February, temperature is a bit cool due to northeast monsoon with occasional light rains, but tends to be hot during afternoon.

March - May, here are the most drastic period as temperature may rise up to 40 degrees C above. Heavy rains usually occur during nighttime due to heavy clouds that can last for an hour or two.

June - October, period when southeast monsoon commonly awakes along with strong tropical cyclones. Rains last for several days. Then weather will change and the place becomes dry. Cycle continues.

Is polycarbonate roof durable? Others said that it only last for a maximum of 4 years. How's the temperature? Perhaps I should also have to plan the air movement.

Jobert, Do not know what happened. Posts suddenly appeared even though you put them up ages ago.

Follow advice re. potting materials from Shaved Monkey and TropicbreezeNT.

People tend to use mounts and materials such as Lava Rock in places where the climate is warm and humid most of the year.

Temperatures are air temperatures recorded in the shade. It will never get to 50C.

As far as I know polycarbonate will last ages.

Re. Your design. Find out what the locals do. I have two glass-houses where fans run 24/7 because air movement is essential, but you have to have the fans installed so electricity and water do not come together.

I also have a shade-house which has the walls and roof just covered with shade-cloth. No fans or electricity there. But I think a solid roof is essential with

your continuous heavy rainfalls.

If you have a bit of Elevation where you live that will moderate the temps by about 3 degrees F for every thousand feet you go above sea level. Sorry for using this ancient system of measurement.

Some very desirable orchids come from the high Mountains of the Philippines.

Hope this helps!

Lexan, a polycarbonate roof, has lasted me for many years. It will tolerate minimal hurricane winds. But if you are prone to 80 plus mph winds you will lose your roof. Happened to me. Barring bad storms it will last a long time. Also use bug screening on your walls. I use to type with small holes that keeps tiny bugs out.

Large movable fans on automatic timer or remote controls that you can turn on from inside your home would help you with air flow, very important in high humidity locations; moving air will also help some with bug control. Extra layer of shade cloth that can be removed easily Aluminent highly recommended. It is made from material that is used for mylar shiny metallic balloons; it is lightweight but very effective. My GH has a double layer of polycarb with spacing between like cardboard box material. Some people use whitewash to cut down on the amount of sunlight that passes thru the roof and it washes off in rainy season.

tiarella, My fans stay on. The electric draw in minimal. I keep them on low...