Greenhouse Roofing

[carlyai]

I'm looking for polycarbonate roofing sheets for a green house. The ones I'm interested in block out the UV light and don't burn the plants, plus they resist condensation.

 

I'd like to go with polycarbonate type sheets rather than white insect cloth as we have torrential rain and strong wind here in my Isaan location.

 

I'm worried that a polycarbonate roof will make the green house too hot, but if I can get the type that are plant friendly, all good.

 

I know I can rig up shade cloth as a cover on top of the roof, or some horizontal shade cloth curtains inside the greenhouse, but I wanted to start with the correct roof material.

 

I have viewed some older threads, but the posters seem to have become inactive.

 

Any ideas? Thanks.

 

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[surfdog]

I was also thinking about the polycarbonate roof too, but wondering about the tints to filter light and which one would be correct. Obviously clear polycarbonate would be way too hot!

I have 50” industrial “gate” exhaust fans which run on 3 phase power, they consume very little energy, they only have 1/3 or 1/2hp motor pushing huge cfm. you would need to seal room except for a few controlled openings.

This would require concrete foundation and wall on one side of greenhouse.

On the other hand... perhaps just building the roof high enough and setting a few small exhaust fans on too top to push out hot humid air.

Local place that does lettuce, just does plastic sheeting, high maintenance tbough, any time a big storm comes through they lose it all.

The framing of the greenhouse could be done with aluminum or steel just like doing windows, glass also comes in 40% tint as well, maybe not much more expensive then the polycarbonate sheets.

In the meantime I just build high stone wall raised beds 1 meter high, the unmortered stone walls give good drainage and need to build in areas where natural shade from trees.

Some nurseries here I have seen build square frames flat roof and cover with shade cloth. Then plant trees and passion fruit and Gac, within 2-3 years have good shade from the vines, 5-6 years trees also break canopy well and provide fruit.

Edible bamboo is a good choice if other trees likely to fail. “Pai Ginsu” is especially hardy and edible, and not too large or tall.


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[carlyai]

I was also thinking about the polycarbonate roof too, but wondering about the tints to filter light and which one would be correct. Obviously clear polycarbonate would be way too hot!

I have 50” industrial “gate” exhaust fans which run on 3 phase power, they consume very little energy, they only have 1/3 or 1/2hp motor pushing huge cfm. you would need to seal room except for a few controlled openings.

This would require concrete foundation and wall on one side of greenhouse.

On the other hand... perhaps just building the roof high enough and setting a few small exhaust fans on too top to push out hot humid air.

Local place that does lettuce, just does plastic sheeting, high maintenance tbough, any time a big storm comes through they lose it all.

The framing of the greenhouse could be done with aluminum or steel just like doing windows, glass also comes in 40% tint as well, maybe not much more expensive then the polycarbonate sheets.

In the meantime I just build high stone wall raised beds 1 meter high, the unmortered stone walls give good drainage and need to build in areas where natural shade from trees.

Some nurseries here I have seen build square frames flat roof and cover with shade cloth. Then plant trees and passion fruit and Gac, within 2-3 years have good shade from the vines, 5-6 years trees also break canopy well and provide fruit.

Edible bamboo is a good choice if other trees likely to fail. “Pai Ginsu” is especially hardy and edible, and not too large or tall.


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The design idea I'm leaning towards is a normal type A frame roof, with the building orientation east wlest long sides. The A frame roof would have a larger south area than the north roof area, as the north facing section would be the chicken pen. A QCon block wall would separate the chicken pen from the greenhouse side. The greenhouse side would have inline window openings near the roof apex and at the bottom of the south facing wall.

I already have a 10 cm QCon built structure that can accommodate 6 1000L fish tanks and they would be connected to the growth beds in the greenhouse.

So my plan for my set up is starting to take shape, but being able to source correct roofing material needs to be sorted before I start to CAD out the greenhouse plan.

There are some Thai suppliers of polyurethane roofimg, but have not replied to my emails.

I have some info on an Australian product, but again the company has not replied to my email as to the products availability in Thailand.

Suntuf plus is the Australian brand and ECO- polycarbonate is the Thai brand.

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[surfdog]

At global house they have plywood sized sheets, need bigger than that?  They cost around 300-400 baht, so perhaps wholesale around 200+ baht if you ordered a lot.  I think that is what I paid for 4 mm thickness.

[carlyai]

At global house they have plywood sized sheets, need bigger than that?  They cost around 300-400 baht, so perhaps wholesale around 200+ baht if you ordered a lot.  I think that is what I paid for 4 mm thickness.

Thanks. I'll have a look next time near a global, but I'm not sure they would be the type required for greenhouse roofs. Did they have a peel away film on one side? This is the UV side. The ones I'm after diffuse the light, block the UV rays and are about 10mm in thickness.

I'll have a look. [emoji3]

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[surfdog]

I’ll take a picture of the ones I have, planned to do sound dampers from the rafters of my workshop, yes have peel off on one side and there are 3-4 thicknesses available, and 8 tints or so.

That was my original question to you, what tint would be good for a greenhouse, blue, green, black, etc? does it matter?


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[Thian]

Hot air rises, so any plastic/glass roof will stop the air from rising and the greenhouse will get very hot.

 

I don't understand the reason for greenhouse actually, people build them against cold...

 

We have a polycarbonate carport with black/brown plastic and it gets very hot during the day....it does block some light though but is still too hot.

 

I would do like the orchidfarms, shadecloth or even mosquitonet...or the plastic wire mesh...

 

A greenhouse from aluminium with aluminium mosquitonet would be my dream so no mozzies/snakes or flying insects can come in. But that won't be cheap.

[carlyai]

I’ll take a picture of the ones I have, planned to do sound dampers from the rafters of my workshop, yes have peel off on one side and there are 3-4 thicknesses available, and 8 tints or so.

That was my original question to you, what tint would be good for a greenhouse, blue, green, black, etc? does it matter?


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I haven't read about the tints in the brochures.

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[carlyai]

Hot air rises, so any plastic/glass roof will stop the air from rising and the greenhouse will get very hot.
 
I don't understand the reason for greenhouse actually, people build them against cold...
 
We have a polycarbonate carport with black/brown plastic and it gets very hot during the day....it does block some light though but is still too hot.
 
I would do like the orchidfarms, shadecloth or even mosquitonet...or the plastic wire mesh...
 
A greenhouse from aluminium with aluminium mosquitonet would be my dream so no mozzies/snakes or flying insects can come in. But that won't be cheap.

Do you think a roof of insect cloth would be strong enough against the rain and wind?
I did see a large one at the Khong Kaen agriculture show. Looked good.

Waiting for information from the company.

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[mick220675]

https://www.homepro.co.th/product/1039360

 

Have a look in homepro at the above, it could be a possibility.

[carlyai]

https://www.homepro.co.th/product/1039360
 
Have a look in homepro at the above, it could be a possibility.

Ok thanks.
I've got a homepro about 100km away so will have a look. Doesn't give the UV spec though.

I'm going a bit cold on polycarbonate sheeting as i think they will make the greenhouse too hot, even with insect screen walls.



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[Time to grow]

On 2/12/2018 at 1:39 PM, carlyai said:

I'm going a bit cold on polycarbonate sheeting as i think they will make the greenhouse too hot, even with insect screen walls.

Curious what you ended up doing. I am getting ready to build a greenhouse and I am also very concerned about trapping the heat. Considering a solar swamp cooler but with the humidity, I am not sure if it will help much.