Is it possible to get lateral entry admission in B.Arch after completing Diploma in civil engineering?

Yes, if you have diploma in civil engineering you can surely get lateral entry in B.Tech architecture but some colleges has some colleges on their own rules. Most universities usually take the lateral entry for civil engineers to the B.Tech architecture you can surely search for that.

If you had done Diploma in architecture then you are eligible for lateral entry admission directly in the second year of B Arch.