1. Greenhouse
• greenｷhouse [green-hous] noun,
Greenhouse Construction plural greenｷhousｷes a building,
room, or area, usually chiefly of
glass, in which the temperature is
maintained within a desired range,
used for cultivating tender plants
or growing plants out of season.
Greenhouse Components
• Refers to a structure covered with a clear material • Frame- be mindful of load bearing requirements,
to allow in natural light for the purpose of growing the closer the bow spacing the greater the strength
plants but more expensive
• It is usually artificially heated • Glazing- different types, usually double layer
• End walls
• 2 or more greenhouses in the same location is
usually referred to as a greenhouse range • Cooling and ventilation systems
• Floor type- ranges from bare to concrete
• A building associated with the greenhouse not for
growing plants, usually for storage or potting is • Benches
referred to as a head-house or service building.
Location Topography
• Location should be the first consideration • It is best to chose a level site to reduce the cost of
grading
• Allow for room for expansion if possible • The site should be well drained, where drainage
• Non greenhouse space needs should be issues exist drainage tiles should be installed
considered such as service buildings, under the surface prior to construction
parking lots, storage. • It is advised to chose a site with a natural
windbreak, such as a row of trees or hills on the
north and windward sides.
• In areas that receive significant show fall trees
should be 100 feet from the greenhouse to keep
drifts back from the greenhouses.
1

2. Climate Water
• The primary limiting factor to greenhouse • Water is frequently overlooked when
crop production is adequate light in winter establishing a greenhouse thought it is one
• Areas with frequent fog, inclimate weather of the most important factors
and shadows from tall mountains are not • Before a site is purchased the water should
ideal for plants with high light be tested, cost of removing ions is
requirements. expensive
• Areas in high altitudes with high light levels • Well water is usually desired because
is not best for plants with low light municipal water is often expensive and can
requirements, such as bedding plants. contain harmful fluoride
Orientation Orientation
• The magnitude of the shadows cast by the
greenhouse depends on the angle of the sun • Single greenhouses located above 40˚N
and season of the year. latitude in the northern hemisphere should
be built with the ridge running E to W
• The effect is most seen in the winter when
the sun remains closer to the horizon and • Below 40˚N latitude, the ridge should be
shadows are longer oriented N to S
• All ridge and furrow and gutter connected
greenhouses should be oriented N to S.
Styles of Greenhouses Glass
• Only glass greenhouses existed prior to 1950s
• They have greater light intensity due to single
glass covering
• Tend to have higher air infiltration rate, leads to
lower interior humidity- good for disease
prevention
• Glass greenhouses have a higher initial cost than
film plastic greenhouses- cost of glass plus
structure to support the weight of glass
• Breakage is a major disadvantage
• Tempered glass is much more durable
2

3. Glass Film Plastic Greenhouses
• Light transmission of up to 90% • Polyethylene is what is most used today
• Heat, UV and wind resistant • Other materials include polyester and polyvinyl
chloride (PVC)
• Has low heat retention
• Popular because it costs less than glass and the
• Not flexible cost of heating is aprox 40% less than single layer
• In 2000 13% of greenhouses built used glass greenhouses.
glass • Light transmission is lower than single later glass
• Material coverings are shorter lived than glass
Types of film plastic Polyethylene
• Principal film of choice for greenhouse covering
in the world
• Almost always have 2 layers, outer layer is
typically 0.15mm thick, inner later only needs to
be about 0.1mm thick
• Double layer helps retain heat and extends life
• Has a UV protection additive
• Lasts up to 4 years
• Light transmission 87% single layer, 78% for
double layer
PVC ETEF
• Lasts 4-5 years, was an advantage until 4 • Ethylene tetrafluoroethylene
year polyethylene was invented • Most recent category of greenhouse film
• The cost is aprox 3 times polyethylene • Anticipated life expectance is over 10 years
• Vinyl films hold a charge which attracts • Light transmission of over 90%
dust which reduces light transmission • Much more expensive than polyethylene in
• PVC is seldom used in the US but is used the US
primarily in Japan
3

4. Film Plastic Greenhouse
Polyester
Designs
• Was used because of durability and price,
lasted 4 years
• Free of charge so it does not attract dust
• Light transmission equal to glass
• When other industrial uses were found the
price went up making it not practical for use
in greenhouses
• Still used in heat retention screens
Wood Frame Greenhouse
• Polyethylene made it affordable for growers • Wood requires frequent painting to prevent
to enter the industry rotting
• People who did not have funds for glass • White paint was typically used to increase
were able to build greenhouses interior light intensity
• Inexpensive frames were also sought • Only treat wood with approved treatments,
• Pinewood was used some can cause plant death or deformed
• A-Frame was very popular growth
• Scissor-truss frame is very strong
Quonset Greenhouse
• Today wood is rarely used in established • Price of wood is high compared to metal and
greenhouse because of the cost of upkeep metal does not have the burden of painting
and low levels of interior light • In the 1970s many greenhouses were Quonset
style
• Single layer plastic film was usually used
• They can be purchased prefabricated or
until the 1960s
constructed on site
• Due to fuel costs double layer plastic • Less expensive than gutter connected greenhouses
coverings were used after 1960s so are popular for those on a limited budget
• This gives about 40% fuel savings • Good when small isolated area is need such as
cold treatment
4

5. Gutter-Connected
Greenhouses
• Trusses are often constructed from water • Most efficient film covered greenhouse design
pipes bent to 180° arc • Cheaper and easier to automate because it is a
single consolidated space
• Quonset greenhouses are either freestanding • Management is more efficient when they are in the
or arranged in a interlocking ridge-and- same building instead of scattered among many
furrow manner buildings
• Single large interior is better adapted to • Cost to build and heat a single space instead of
multiple buildings is much less because of less
movement of labor and automation surface area to lose heat from
• Gutter-connected costs about $1.25-1.50/sq ft,
Quonset is as high as $3.00/ sq ft
Options
• Height
• New houses can be connected to existing houses  Height has been increasing in recent years to
• Many owners of gutter-connected and Quonset accommodate elevation of climate control equipment,
automation devices and hanging baskets
greenhouses use double layer polycarbonate
(sometimes acrylic) panels on the ends these can • Distance between gutter rows
last over 20 years  Ranges from 10.5-40 ft, wider spaces between rows are
weaker and need extra strong trusses
• Side walls are usually covered with double layer
of polyethylene film • Contour of the roof
 Traditionally were relatively flat, Quonset arch shape,
• Polycarbonate and acrylic are becoming more today can have gothic-arch or peaked roof
popular for side walls for passively cooled
greenhouses using side-wall ventilators • Active or passive cooling
 Passive cooling is offered with roll up side curtains,
roof and side ventilators, hinged and retractable roofs
Double-Layer Covering Rigid panels
• Dead-air space provides the best and • Today 16% of greenhouses are covered with
cheapest insulation for greenhouses rigid panels
• Space should be 0.5-4 inches
• More than 4” air currents can form in air
space which reduces insulation
• Almost all film plastic covered greenhouses
use double covering
5

6. PVC Fiberglass reinforced Plastic
• For the most part PVC is not used anymore • Was very popular in the past but is declining in
popularity and rarely used today
for rigid panel greenhouses
• Today twin wall polycarbonate panels are used in
• Life expectancy was much lower than was place of fiberglass reinforced plastic because it
once believed, as little as 2 years reduced heating cost by almost half
• Cost was 4-5 times of polyethylene film • Corrugated sheets are preferred because they have
greater strength
• FRP offered advantages over glass, more resistant
to breakage , uniform light intensity
• Disadvantages are that it is subject to etching and
pitting by abrasion and pollution
Acrylic and Polycarbonate
• Light transmission • Has been available for about 25 years
 FRP is roughly equivalent to glass • Acrylic is particularly popular with research
institutions because of high light transmission and
• Heat transmission longer life, 83-90% light transmission
 Easier to cool than glass • Acrylic is preferred by growers of plug seedlings,
• Fire hazard cut flowers and vegetables because of their high
light requirements.
 Fire is a concern in FRP greenhouses • Polycarbonate tends to be used for bedding plants
and perennials , reduces fuel costs lasts 10 years
81% light transmission
• The main deterrent to acrylic is the price • Polycarbonate is available in flat and
• Risk of fire corrugated single-layer sheets
• Advantage of acrylic over polycarbonate is • Trend is moving to twin-wall panels to
has about 2.5x longer life expectancy, reduce heating costs
higher light transmission, lower heat • Triple layer is now becoming available for 2
transmission and greater resistance to hail layers of deal air space
damage
6

7. Types of Greenhouses Venlo
• Low profile, known as the Venlo
Greenhouse, originated in The Netherlands
• Eves are 10.5 feet apart
• Lower profile slightly reduced the exposed
surface area, reducing the heating costs
Lean-to Even Span Greenhouse
• This is where a greenhouse is places up • Two roof slopes of equal pitch and width.
against the side of building.
• Minimizes the need for roof support
• Mostly used in the retail industry
Ridge and furrow
Uneven span
greenhouse
• Not used much because it is not adaptable to • Uses one or more A frame greenhouse connected to each
other along the legnth of the eave
automation
• The eave serve as a furow to carry rain or melted snow
• Has roofs of unequal width away
• The side wall is eliminated between greenhouses
• Reduces the cost of automation and labor
• Less cost to heat because there is less exposed wall area
7

8. Quonset Structure
• Metal frame • Wood
• Less expensive than wood and does not require • Need to be painted to prevent rotting
painting to prevent rotting • Rarley used today
• Popular among people entering the industry on a
low budget • Metal
• Trusses are often built from water pipes bent to • Long lasting
180 degree arc • Aluminum usually used
• Free standing or ridge and furrow • High stregnth
• Curved surface so flexable covering is needed • Low maintence
Benches and Beds Cut Flowers
• Cut flowers can be grown in raised benches or in
ground beds.
• Plants that get tall such as roses that are grown for
5 years or more are usually grown in ground beds.
• If crop is moderate height (snapdragon,
chrysanthemum) if raised benches are used, they
should be located close to the ground so plant is at
a practical height for maintenance
• In ground beds should be raised so the substrate is
separate from the external soil to allow for
sterilization of the substrate on a routine schedule
Cut Flowers Cut Flowers
• Most roses used a cut flowers are grown in in- • In recent years some crops including roses
ground beds because of their height and gerbera have been grown in rows of
• Walls of in-ground beds can be treated wood or individual containers filled with substrate
cement blocks • Containers are placed in a trough and
• Walls should be at least 8” deep and beds should watered with a nutrient solution via plastic
extend down into a well drained foundation tube on top of each container
substance, such as gravel • Excess solution leaches out the bottom into
• If foundation substance is not well drained, a the trough and is captured, pasteurized and
drainage tile should be placed under each bed reused
8

9. Potted-Plants Floor Options
• Raised benches are typically used for pot plants
• A height of 32-36” is best for working.
• They should not be wider than 6 feet if not next to a
wall or 3 feet if next to a wall to allow access from both
sides.
• Benches used for ebb and flow irrigation are water tight
• Movable benches can increase production space by up
to 90% of the floor space
• Some greenhouses use a porous concrete flooring and
grow plants in pots directly on the floor. This system
makes it possible to use up to 90% of floor space
Considerations Considerations
• Drainage- crucial in a wet environment like • Heat- heat retention is important in colder climates
a greenhouse. With a solid floor drains must materials such as brick and flagstaff retain heat,
be installed to keep mold away this can help reduce heating costs in colder month
• Decomposition- organic materials like • Comfort- standing on a hard floor like concrete
wood, bark, sawdust etc will decompose can be hard on your feet and back
over time and will need to be removed and • Traction- consider that the floor may be wet so
replaced consider traction
• Price- one of the most important • Weeds- be sure to put down weed blocking
considerations material under flooring material
Materials Materials
• Standard concrete- no drainage, should be avoided • Stone- durable, easily cleaned, individual
in growing areas stones so it can drain in the cracks.
• Porous concrete- allows for drainage, avoid using Expensive and may not be level
in seeding and propagation area because over time
particles will clog holes • Wood- planks across greenhouse floor,
attractive, cracks provide drainage but can
• Gravel/dirt- inexpensive but can not be properly
disinfected or cleaned, harbor more pests, plants be expensive
can not touch floors, not good for retail operation • Bark chips, wood chips, sawdust-
because can be hazardous and not wheelchair inexpensive but will need to be replaced
accessible when they decompose
9

10. Flood Floor Videos
• The flood floor is a non porous floor that slopes • http://www.greenhousegrower.com/video/c:99/str
form the sides to the center of each bay. A drain is uctures-equipment/
at the low point. When water or fertilization is
required the floor is flooded for approximately 10 • http://www.greenhousegrower.com/video/c:99/str
minutes and then the floor is drained. uctures-equipment/772/
• Water moves into the pots by capillary action
• Heat pipes under the floor allow for speedy drying • http://www.greenhousegrower.com/video/c:99/str
uctures-equipment/1170/
10