If you mean the triangle parts, meant to be attached to roofs, maybe you can use shift to avoid that, but it won't look as good from the inside... Why don't use also use angled poles from the outside to make it look nice? Most people do it like that, if you want to avoid that though, try using corners, so you cover it all with roofs, instead of angled walls..

I could explain this far better with a share screen lol