Greenhouse construction considerations

Special Section - Growing Under Cover

If you’re considering adding greenhouse space to your nursery, the National Greenhouse Manufacturers Association offers these tips for designing and building a greenhouse.

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October 5, 2012
Garden Center

If you’re considering adding greenhouse space to your nursery, the National Greenhouse Manufacturers Association offers these tips for designing and building a greenhouse.


What should a grower do first before purchasing a greenhouse?

The first thing, before purchasing a greenhouse, is to contact the local authorities. Because zoning varies from one county to the next, one greenhouse may have a totally different situation then a greenhouse just across the street. Simply put, each location is different and there is no one answer. While the United States recognizes 50 state governments, there are more than 87,000 local governments. The possibilities of code and zoning combinations are endless. Zoning codes and building requirements can be any mix. The laws are becoming stricter and the negative consequences of noncompliance worse.


What authorities do I contact before purchasing a greenhouse?

First check with your zoning authorities for your specific location’s setbacks, building material requirements, and allowed businesses. Secondly, talk with the planning commission regarding building codes. Ask them what code body they recognize and for which year. Also determine if stamped and licensed drawings, by an engineer, are required. If applicable, also ask what the wind and snow loads requirements are for a greenhouse. Then check with the fire authorities on what they require for greenhouses. While greenhouses are unique, they often are not treated as such. Find out all their fire codes, specifically sprinkler system and covering requirements. The tough questions should be answered before designing a greenhouse, not after. While these questions may seem overwhelming to the new grower, there is help available through any of the National Greenhouse Manufacturers Association’s structural members.


Does it matter what materials I build a greenhouse with?

Yes, zoning also includes building materials. Government regulators can dictate exact specifications for such items as brick, coverings, glass, and what the overall building must look like when erected.


Are greenhouses insurable?

Yes, look into the insurability of a greenhouse before purchasing. Ask whether your insurance company will provide replacement cost coverage for the structure. What perils do they insure? Some companies will only provide a very limited number of insured perils and may exclude those of most concern. Do they offer coverage for plant material and how will they value the crop should there be a loss? Like with purchasing an automobile, insurance information allows you to make an educated decision.


Do I need a licensed engineer to stamp finished greenhouse drawings?

Yes, some states require that a licensed engineer stamp your drawings. If this is a requirement of your state, the engineer must be licensed in that state. An engineer can be licensed in numerous states, not just where they are located. To be licensed they must be tested and /or pay a fee.


Do setbacks affect greenhouses?

Yes, they can, depending on your location. A setback which is more common in larger cities, is the amount of feet from the street or property line a greenhouse must sit to be built. For example, a building may be required to set back 50’ from the curb for what they call ‘street appeal.’ Zoning setbacks are also lot specific and can vary from one lot to another.


Are there any fire-code issues with greenhouses?

Yes, there are fire codes specific to greenhouses and they vary depending on the area. Many growers have elaborate drawings made up only to find out that none of the fire codes have been addressed. Before you invest in drawings, find out what fire codes affect a greenhouse at your location.


Does the crop determine the type of greenhouse needed?

Crop is important when choosing a greenhouse, but seldom does a grower start and stay with the same crop. We often see growers completely change or add to their existing crop line. When it comes to type of crop, make sure your greenhouse is designed to be flexible.

 

For more: www.ngma.com