how far shadow of trees should not fall on house

 in the bellow video he explains that shadow of any tree should not fall on our house.

in worst case when you can not keep trees 50 feet far from building you should make sure the shadow of tree should not fall on building up to some time like 3 jaamu.. 

the time is explained in the video.

he also explains how far the effect of shadow will be after the real shadow.