بسم الله الرحمن الرحيم
Yes, as per the authentic and reliable hadith, the belief of “Vastu” is haram rather it is against Islam. As per the belief of “Vastu” it is mandatory to build the house in a particular way i.e. the main gate of the house should be in so and so direction, the windows should be in so and so direction and the kitchen should be in so and so place and the bed room should be in so and so place etc. And if the house is built differently then it is believed that someone shall die or some incident might take place etc. Thus someone other than Allah is believed to be effective and various directions are considered to be having misfortune and evil omen, which is strictly prohibited in Islam. (See Mishkat Sharif p. 391-394)
In fact this is the belief of Hindus which came from Vedas through their priests, and it is their belief. Now some people try to prove it a scientific theory which is totally wrong among the just persons. That is why so far no scientist has claimed it to be a scientific research. In short, the belief of “Vastu” is against Islam. Muslims should avoid such false beliefs.
Allah knows Best!
Darul Uloom Deoband