GOODWILL AND INTANGIBLE ASSETS (Details 2) - USD ($) $ in Thousands	Dec. 28, 2019	Dec. 29, 2018
Newmark
Non-amortized intangible assets
Carrying value of trade names	$ 11,111	$ 11,111
Webforge
Non-amortized intangible assets
Carrying value of trade names	9,143	8,872
Valmont SM
Non-amortized intangible assets
Carrying value of trade names	7,966	8,155
Ingal EPS/Ingal Civil Products
Non-amortized intangible assets
Carrying value of trade names	7,454	7,233
Shakespeare
Non-amortized intangible assets
Carrying value of trade names	4,000	4,000
Walpar
Non-amortized intangible assets
Carrying value of trade names	3,500	4,300
Convert
Non-amortized intangible assets
Carrying value of trade names	8,378	8,580
Other
Non-amortized intangible assets
Carrying value of trade names	17,555	16,472
Trade Names
Non-amortized intangible assets
Carrying value of trade names	$ 69,107	$ 68,723