With all the recent entries about blowing things up...

Just a general what-if...

If the local neighborhood bombmaker made some kind of miscalculation and blew up himself and his house, and you just happened to have plywood covering your windows on that side of your house, would the concussion from the blast still break the windows, or would the plywood have some kind of mitigating effect on it?

I'm thinking that the 'subsonic' or whatever effects would still break the glass, but I don't really know what I'm talking about.

Sue

Depends on distance from blast, direction from blast, force of blast.

If you are next door, it'll be much worse than if you were even one more house away (intervening house would catch a lot of the concussion). Directly across the street is even worse, as the blast wave will be like a cone and the three houses across the street or even out the back door may be in the cone - again the two adjoining houses will mitigate the blast effects to the sides.

You have to remember, TV booms are not real life booms. No flames, unless something in there is flammable. Mainly concussion, possibly some shrapnel. The force of the blast moves objects at high speed (shrapnel) and the air is moved from the area at a high speed (concussion wave).

Back to the original question - Would plywood protect a window - a qualified maybe. If the blast was next door, probably not. If shrapnel decides to come visiting (think toilet/oven/chair), probably not. Down the street, on the same side as you - maybe. Down the street, other side, but 5 or 6 houses down - maybe.

Distance and what is between you and the blast center are what will determine damages.

That's a weird combo for a neighborhood--a bombmaker and someone right next door who just happens to board up their windows for no good reason? Hmmm, actually, I suppose you could subsitute "meth lab" for "bombmaker" in this hypotethical, too, and the boarded up windows would actually make sense.

When I lived in San Francisco, there was a guy who was storing illegal fireworks in his garage. Somehow there was a spark, and the guy was literally blown through the wall of his house and inside the house next door, so depending on the blast you're talking about, yeah, it could certainly still break the boarded up window.

Okay, y'all are just doing this to mess with me, aren't you? :-)
-Blast

"That's a weird combo for a neighborhood--a bombmaker and someone right next door who just happens to board up their windows for no good reason?"

*snickering*

Okay, let me use a real-life explosion that Blast would be proud of.

When nearly 9 million pounds of ammonium perchlorate (used in solid fuel rocket boosters) at PEPCON blew up in Henderson, NV, it damaged homes within a 10-miles radius, wobbled a 737 that was landing at McCarren Airport seven miles away, ruptured a 16" natural gas pipeline, created a crater 15' deep and 200' across, and two of the seven explosions caused land movement measuring 3.0 and 3.5 on the Richter Scale.
PEPCON Big Boom

It probably wouldn't have been quite so bad if they hadn't been storing over 4,000 55-gallon barrels of ammonium perchlorate in the parking lot.

Anyway, since windows were cracked and shattered as far as 10 miles away, I am assuming that the concussion did most of the damage in the outer areas.

So, is everyone saying that the concussion/shock wave would have broken the windows even if they were boarded up because a house was vacant? I am assuming that, since the homes in the outer reaches wouldn't likely to have had any debris affecting them at that distance, so the concussion had been traveling THROUGH houses to get to them, so one lousy sheet of plywood wouldn't have made any difference at all, right?

Sue

"Some" windows destroyed at a distance...is not the same as "all or most" windows were destroyed at a distance. Differing qualities of windows and installation are just some of the variables.

I would think plywood would be of some help, depending upon the thickness, grade, and size of window. There are also transparent films which will morph plain glass into a sort of safety glass, so that at least flying shards will not be slicing through the air.

I've read it only takes .3-.5 psi to break a house window. I'm not sure how much protection plywood's going to offer against the shockwave, but it's going to offer some protection against shrapnel that used to be your nutball neighbor's house.