Vicgcy

Struggling to get hold of them due to covid... Thought someone here could answer

Apologies in advanced for my lack of knowledge but ww are gaving a house build with a lean to added to the kitchen. I want to design the kitchen within the lean to but the plans include two wall either side about 2foot outbfrom the original perimeter wall. Normally if it was built after original construction i would assume they are supporting? But its all being built together. Im having bother adding an image so hope this makes sense. Thanks