Best placed in the North-East
The north-east is where the pooja room belongs. It is the lightest and most protected corner, it takes the first sun, and every school agrees on it — this is the least contested placement in the whole mandala.
What the North-East governs
The north-east — Ishanya — is the most protected corner in the whole mandala. It carries water and belongs to Shiva, and every school agrees on the same instruction: keep it light, clean, open and low. Almost every serious Vastu fault is some version of loading this corner.
Where the Pooja room belongs
The pooja room belongs to the light half of the plan. The tradition puts it where the first sun falls and keeps it away from anything heavy, wet or waste-carrying — including sharing a wall with a bathroom, which matters more than the compass point.