This contains an excellent list of resources on Vastu: What are the best resources for Vastu Shastra?
Vastu, like Ayurveda, is originally a supplement to Atharva-veda. Also like Ayurveda, there don't seem to be any surviving texts from the original vedanga. With the exception of a few Puranas which provide some details on Vastu (also on Ayurveda), all of the available references on Vastu are from later authors.
Are there mentions of the original vedanga text in any commentaries or writings? Is the original body of text from Atharvaveda truly lost or has any part of it survived?