If the Roof covers the Wall (the screen shot is dark and hard to read), use a Solid Element Operation (SEO): select the Wall as Target, the Roof as Operator, and the execute a Subtraction with Upward Extrusion.
David
David Maudlin / Architect www.davidmaudlin.com Digital Architecture AC27 USA • iMac 27" 4.0GHz Quad-core i7 OSX11 | 24 gb ram • MacBook Pro M3 Pro | 36 gb ram OSX14