PS: I think wards are three dimensional. And a strong enough one would just reflect a dropped satellite.
It might be something which needs to be specified when setting up the Ward. While the example in Turn Coat is not a perfect one...
The crystal which Molly activated in the ruined cabin on Demonreach was setup as a sphere. My understanding of the crystal was that is was effectively a one-use Ward using a potion item slot. Ancient Mai specifically mentioned digging underneath the effect to get a Molly and Morgan when Harry regained consciousness and Harry specifically said not to, that the effect was spherical.
I think part of the issue a number of us have is that some of us get some very different numbers when sit down and work out what we consider as 'realistic' in terms of the number of shifts which a mortal wizard could raise and put into a Ward. Given what Jim has stated in various books and short stories like in Curses, which mentions a curse afflicting a certain sports team for ~60 years which if it was still the same spell, would've required enough power to survive that many sunrises to have actually cracked the crust of the planet, tends to give some a different view of the amount of power spellcasters can manage.
It all has to do with what one's group/GM will accept or allow though, to each their own.
Now, from canon, the only instance I can recall of a mundane, physical object coming into contact with Harry's apartment was the roman candle which was thrown through the window in Day Off. Everything else which would have come into contact with the Wards,
(the frog-demon in Storm Front, the zombie horde in Dead Beat, possibly Cowl's mental attack in White Night, for the FBI and Chicago PD in Changes)
was either a living being/creature, and/or a magical entity or construct.
So far, there hasn't been a specific example of something like a car crashing into a Warded structure and either going straight through, or bouncing off, getting blown apart by a 'landmine' or doing a bad impression of an accordian after crashing straight into the magical equivalent of a solid rock face.
In order words, absent more specific word from Jim, Fred, or someone else at Evil Hat, it depends on just how one's group interprets the RAW.
Now, regarding those who suggest some sort of gas attack against a Warded location, that would seem an effective method, and there is a suggestion within the novel Dead Beat that the Red Court has already successfully used just such a tactic, given that I would consider any White Council installation would have at least some sort of Ward to defend it against intruders.
I'm referring to the hospital which the White Council had setup in the Congo, which the Red Court attacked using a nerve agent, most likely sarin. The attack was estimated by Luccio to have cost the lives of several thousand people, both Council members and ordinary 'vanilla' mortals.
-Cheers