Code reference for greenhouses

[theory2code2practice]

Hi All,

I remember long time ago I came across a reference that I believe implied that green houses have lower load requirements. Now we are talking about the US building code so it was probably described vaguely and without the word greenhouse. Probably something a long the lines of "light weight glass clad structure, constructed of light steel members." Either in IBC or ASCE 7. May have been in the commentary section. I cannot seem to find it. Anybody know what I'm talking about?

Thank you all in advanced

 

[adamsmithh]

You might be thinking of ASCE 7-16, Section 29.4, which addresses "Partially Enclosed Buildings" and can sometimes be interpreted to apply to greenhouses, depending on their design and cladding. Greenhouses often qualify for reduced wind loads due to their lightweight construction and increased permeability.

Additionally, IBC Chapter 16 (Structural Design) references different load considerations for temporary and lightly framed structures, which may include greenhouses depending on local jurisdictional interpretations. The commentary sections of ASCE 7 and IBC might provide more clarity on this classification.

 

[ChorasDen]

I'd generally assume lower loads are due to lower risk category associated with a greenhouse. See table 1604.5 in 2018 IBC.

 

[theory2code2practice]

I'd generally assume lower loads are due to lower risk category associated with a greenhouse. See table 1604.5 in 2018 IBC.

I thought that too. But I specifically remember something about light steel framed structures and how it was clearly talking about a green house without saying the word.

 

[DanKile]

Snow loads has a specific thermal factor for greenhouses.

 

[JStephen]

Greenhouses could be Risk Category I, which would be lower loading than normal buildings.

In googling the question, I ran across one item (in Michigan) that pointed out that a specific state law there exempted many farm buildings from building codes altogether. You'd have to research that in your specific area.

 

[HTURKAK]

There are three risk categories related with greenhouses. The followings are copy and paste from IBC 2021

- 303.4 Assembly Group A-3. Group A-3 occupancy includes assembly uses intended for worship, recreation or amusement and other assembly uses not classified elsewhere in Group A including, but not limited to..
Greenhouses for the conservation and exhibition of plants that provide public access..

-309.1 Mercantile Group M. Mercantile Group M occupancy includes, among others, the use of a building or structure or a portion thereof for the display and sale of merchandise
Greenhouses for display and sale of plants that provide public access.

- UTILITY AND MISCELLANEOUS GROUP U
312.1 General. Buildings and structures of an accessory
character and miscellaneous structures not classified in any
specific occupancy shall be constructed, equipped and main.. ( Agricultural buildings ,Barns,Carports ...)
312.1.1 Greenhouses. Greenhouses not classified as another occupancy shall be classified as Use Group U.

 

[LOTE]

The National Greenhouse Manufacturers Association has a design manual that goes through the full design considerations specific to greenhouses:

Industry Information – NGMA

Just another WordPress site

ngma.com

 

[haynewp]

The National Greenhouse Manufacturers Association has a design manual that goes through the full design considerations specific to greenhouses:

Industry Information – NGMA

Just another WordPress site

ngma.com

That guide is using a 10 psf roof live load and it is 12 psf in newer versions. We recently got a greenhouse submittal requesting to use 12 psf, instead of the 20 psf reducible, as if the 12 psf is an industry standard for greenhouses. My question is how do you know the roof won't ever be subject to 20 psf?

In structures such as greenhouses, where special
scaffolding is used as a work surface for workers and
materials during maintenance and repair operations, a
lower roof load than specified in the following equations
shall not be used unless approved by the building
official. Such structures shall be designed for a minimum
roof live load of 12 psf.

 

[theory2code2practice]

That guide is using a 10 psf roof live load and it is 12 psf in newer versions. We recently got a greenhouse submittal requesting to use 12 psf, instead of the 20 psf reducible, as if the 12 psf is an industry standard for greenhouses. My question is how do you know the roof won't ever be subject to 20 psf?

In structures such as greenhouses, where special
scaffolding is used as a work surface for workers and
materials during maintenance and repair operations, a
lower roof load than specified in the following equations
shall not be used unless approved by the building
official. Such structures shall be designed for a minimum
roof live load of 12 psf.

That might be it, but I'm almost positive I saw it in IBC or ASCE or maybe NYCBC?

 

[haynewp]

12 psf min is in newer versions of IBC I meant, 10 psf min was IBC 2000. It’s mentioned right before the roof live load reduction equations.