Basements can be designed for House which is on Mountain slope. For other cases according to Vaastu, Basement below the house should be avoided.

However, in case due to scarcity of space where there is no option left & basement needs to be designed then it should be done as last resort following certain rules.

Below are some of Do's & Don't for Basement.

Vaastu Tips for constructing Basement(only as last choice):

1. Basement should not be used for dwelling purpose. It should only be used for storage purpose.

2. For Height of 9 feet basement, try to keep at least 2'6" above ground level. And add windows to it so sunlight & fresh air can reach the basement.

3. Paint the Basement walls with light vibrant colors which can reflect light.

4. Overall Basement shape should be square or Rectangle.

5. Avoid Basement in Earth Zone. This means avoid Basement in South to South West side. This should not be part of basement. 

6. Basic rule for any house. Keep the Basement clean & tidy.

7. The Basement Entry can be from North or East Direction. Follow the Entrance rule of N3, N4, E3, E4

8. Don't clutter the NNE to NE side of Basement. Keep it with light items.

Below are some things to strictly avoid for Basement:

1.  Staircase leading to Basement(if any from house) should not be in North-North-East & North East.

2. In overall constructed area of house, Strictly no basement under South to South West part.

3. Avoid irregular shape of basement.

4. Don't use basement for living purpose. Avoid as well for recreational purpose.

5. Heavy copper wires(Electrical wires) should not be kept in basement.

6. There should be strictly no basement below Brahmasthaan.

The Below image is indicative for square constructed area. In case of rectangular constructed area, do the gridding of the house from https://app.shilaavinyaas.com/vastu-zones to find exact location of zones.