GOODWILL AND INTANGIBLE ASSETS (Details 2) (USD $) In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013
Webforge
Non-amortized intangible assets
Carrying value of trade names	$ 17,595	$ 17,787
Valmont SM
Non-amortized intangible assets
Carrying value of trade names	11,285
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	9,286	9,387
Donhad
Non-amortized intangible assets
Carrying value of trade names	7,006	7,082
Industrial Galvanizers
Non-amortized intangible assets
Carrying value of trade names	4,073	4,117
Other
Non-amortized intangible assets
Carrying value of trade names	15,380	14,685
Trade names
Non-amortized intangible assets
Carrying value of trade names	$ 75,736	$ 64,169