GOODWILL AND INTANGIBLE ASSETS (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 28, 2014	Dec. 28, 2013
Webforge
Non-amortized intangible assets
Carrying value of trade names	$ 18,389	$ 17,787
Valmont SM
Non-amortized intangible assets
Carrying value of trade names	12,059
Newmark
Non-amortized intangible assets
Carrying value of trade names	11,111	11,111
Ingal EPS/Ingal Civil Products
Non-amortized intangible assets
Carrying value of trade names	9,705	9,387
Donhad
Non-amortized intangible assets
Carrying value of trade names	7,322	7,082
Industrial Galvanizers
Non-amortized intangible assets
Carrying value of trade names	4,257	4,117
Other
Non-amortized intangible assets
Carrying value of trade names	14,907	14,685
Trade names
Non-amortized intangible assets
Carrying value of trade names	$ 77,750	$ 64,169