Changes to plans were approved on Thursday (October 19) which could see the store relocate to Unit 11 in Teesside Park.
A two-story extension is planned in the rear area with the installation of a mezzanine, a new shop front and the associated systems and machines.
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It also includes proposals for rear and front parking, including public areas, landscaping and associated infrastructure works.
Primark had previously received planning permission to expand the former Mothercare unit, which is ready to open in 2024.
Plans for a pedestrian zone with a “high quality, usable urban space” have been “adapted” to suit Primark.
Retailers including Lush and Flannels submitted planning applications for potential new sites at Teesside Park in Thornaby last year.
They are joined by popular food giant Wagamama, which submitted a planning application in August and recently put up signage for a new site.
Companies like Tim Horton’s and Victoria’s Secret have already made their way into the mall.
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Frasers Group, which has a stake in Teesside Park near Stockton and Middlesbrough, announced in August that two new leases had been signed for the shopping center – involving major moves for four individual retailers.
Under the plans, Sports Direct will double in size to 40,000 square meters and offer both a GAME and Evans bike, as well as Flannel bikes.
The B&M Garden Center and Store has also applied for planning permission for a garden center which is still awaiting approval.