Line Extrude problem (see attachments)

[Anonymous]

I have made the front view of a building using line tool (picture 1).

When I extrude it I get picture 2. I have cheked the vertices and I'm sure my spline is closed. What could be the problem?

[Steve_Curley]

This is an old, old problem with extruded splines. The only real way to prevent it is to do it in smaller sections, convert them all to Editable Poly, remove any Polys which shouldn't exist (internal to the final structure), attach them all and weld the vertices. You could try using Booleans but they have their own problems.

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