V. GREENHOUSE STRUCTURES

A. Introduction

B. Selection - factors

1. strength & design

2. light transmission

a. intensity• inside greenhouse

b. factors determining

intensity

3. working conditions

4. initial cost

5. maintenance costs

6. flexibility and adaptability

7. insurance and taxes

8. environmental control

D. Structure components

C. Peaked roof design

a. roof slope

•26-28° on glass x fiberglass structures

–(6" vertical : 12" horizontal)

Light passing through glass at different sun angles

Date 260 slope

Angle of sun

Dec 21 37

Nov&Jan 33

Sep&Mar 24

Aug&Apr 1

Jul&May 7

June 21 10

Ridge height of houseGreenhouse width

(ft)260 slope

ft-in

18 11’ 9”

21 12’ 5”

25 13’ 5”

28 14’ 2”

32 15’ 2”

35 15’ 10”

42 17’ 6”

49 19’ 4”

D. Structural types

1. post rafter

• A-frame

• post-truss3.

4. rigid-frame

5. quonset

6. gothic

7. ridge and furrow

8. connecting pipe house

Designed by Dr. John walker, Agriculture Engineer. University of Kentucky

E. Structural materials1. Wood

– types

•Cypress, black locust, red ceder

• redwood, osage orange

–characteristics

• high maintenance

• light weight

• available

2. Treated wood• nontoxic chemicals

–Chemonite (NH4CuAsO4)

–Greensalts (CrCuAsO4)

–Osmose K-33 (CrCuAsO4)

• toxic chemicals–Pentachloro phenol–Creosote

• treatment method–Pressure not painting–Last 20-30 yrs

3. Steel• treatment–Galvanized–Painted

• characteristics–Longevity–Heavy

–Rust

4. Aluminum

• characteristics–little corrosion, low maintenance–light weight–strong–light reflectance–attractive–high cost

Ridge height of houseGreenhouse width

(ft)260 ft-in 630 ft-in

18 11-9 25-0

21 12-5 27-11

25 13-5 31-10

28 14-2 34-10

32 15-2 38-9

35 15-10 41-9

42 17-6 48-6

49 19-4 55-5