Can't seem to trim extra top off of roof

I am trying to trim the parts of the extruded walls that go past the roof surface… not sure if there is another tool to use but any help would be very appreciated… thanks!

Do you get an error message?
It’s not easy to tell from just the picture but it does look like the surfaces would intersect. A few things to try:
You could intersect the objects to see if there is an incomplete intersection somewhere.
You could try extracting a copy of the lower roof surfaces and just that to trim manually - if it doesn’t work on the walls as polysurfaces you can explode the walls and trim one by one.

not sure if you’re having a problem with the particular model or if you just need to know how to do it… upload the .3dm for more accurate help…

here are a couple of ideas though:

instead of extruding the surfaces past the roof first, ExtrudeSrf (or ExtrudeCrv) using the option ‘To Boundary’… choose the roof as the boundary… this will stop the extrusion when it hits the roof:

it’s hard to tell which exact state your model is in right now (or which parts you’re trying to get rid of) but maybe try the BooleanSplit command then delete the leftovers after:

Thank you so much for your help guys.
Jeff, the “extrude surface to boundary” option is exactly what I’m looking for but I cannot get it to work… I think my roof is not the correct type of object for the tool but I don’t know why… It won’t let me upload the file

Are you getting an error message?

No error, just that it is too large

I used the boolean split and it worked! Thank you both so much for all the help