Cover Page - shares	3 Months Ended
	Mar. 29, 2025	Apr. 25, 2025
Cover page
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 29, 2025
Current Fiscal Year End Date	--12-27
Document Transition Report	false
Entity File Number	001-31429
Entity Registrant Name	Valmont Industries, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-0351813
Entity Address, Address Line One	15000 Valmont Plaza,
Entity Address, City or Town	Omaha,
Entity Address, State or Province	NE
Entity Address, Postal Zip Code	68154
City Area Code	402
Local Phone Number	963-1000
Title of 12(b) Security	Common Stock, $1.00 par value
Trading Symbol	VMI
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Smaller Reporting Company	false
Emerging Growth Company	false
Shell Company	false
Entity Common Stock, Shares Outstanding		20,070,978
Entity Central Index Key	0000102729
Amendment Flag	false
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	Q1