Sale deed mentions only plot. It does not have reference to building constructed on the plot. Whether the buyer would acquire title only on the land or land and building. As per Sec 8 of T.P. Act, when the land is transferred all the things attached to land also get transferred unless different intention appears. Therefore building also gets transferred along with land.

A per Sec 54 of T.P. Act and Sec 17 of Registration Act sale of immovable property of rupees hundred is to be registered. Building is certainly immovable property worth more than Rupees Hundred. Hence sale of building requires registration.

Moreover there is maxim Expressio unis est exclusio alterius

If Sec 8 is followed if building is not shown in sale deed, it leads to evasion of tamp duty

On the ground of equity the vendor can not sell the plot alone when there is house.

As per ec. 55 of T.P. Act the buyer is bound to disclose the true value of the property, of which the seller is not aware.

Consider these points and other point as you deem fit and render legal opinion.

Thank you