It takes almost nothing to block wifi signals. Your microwave oven runs at 1000 times the output power of a router on the same 2.4g radio. You can see though the front glass but a microwave oven is only allowed to leak much less than a router can transmit at. So the oven door is absorbing/blocking all that energy.
Now if you were very unlucky your radio beam might go directly through the microwave oven in the other house. The house itself absorbs huge amounts of energy. Anything in the path absorbs energy even the water vapor in the air which is partially what limits the distance. The other problem you have with a house in the middle is they likely have a wifi router. This router will interfere with your signals. Normally these ptp connections have rather narrow beams so no other radio can be in the path but if there is it will cause a large issue because the signal level are so low when you are trying to go distances.
So your best hope is to put a long pole on both houses so the signal can go over the one in the middle. If you have large trees in the way you need to find a way to get past though also. Pretty much if you can't see the other radio unit clearly with say binoculars it will not work.