Unfortunately, tf_fastbuild builds instantly but only to level 1, but this functionality is there because i need it for my server ^^.
Yeah actually i'm quite surprised the sapper trick doesn't screw the server up.
As for the GetEntProp thing, i had tried GetEntProp(i,Prop_send,"m_hBuilder") but since it's an handle it was returning me weird numbers. The only workaround i found was the offset caching. But if you know a cleaner way to do that please, tell me