Designing a breach-resistant entryway door.

[Packard]

This is simply a hypothetical and theoretical exercise.

I am reading an entertaining novel about the United States Marshalls’ Service.  In that book they are getting ready to breach an entryway door in an apartment. 

There was a surprising statement that they hoped that it was not a hollow core door.  Solid core doors were much easier to breach.

They used a breaching ram.  Two man breaching rams are typically 40 - 50 pounds and about 36” long by about 5” in diameter.

The theory put forth in the book, was that a hollow core door was so weak that you ended up making a bunch of 5” diameter holes in the door without ever breaking open the door. 

I suppose, if you make enough holes, you can eventually simply walk through the enlarged opening that they make.  But keep in mind that the breaching ram wants to make the impact at a fairly specific height.  It would be difficult to use it to make a hole at, for example, 4 feet high.

The solid core door is substantial enough that the breaching ram’s force would be transferred to the locking mechanism and the door would open instantly.

So, my thought is that the perimeter of the hollow core door be made from 2” x 1/8” steel and the lock set be mounted to that steel frame.  Likewise the hinges.

I am undecided if there should be some sort metal grid to eliminate the aforementioned enlarged hole from multiple strikes.  I am thinking 3/16” wire in a 12” x 12” grid pattern.  Or perhaps just vertically on that same 12” spacing.

I find this an amusing mental exercise.  Less amusing is that sold core doors are sometimes more vulnerable than hollow core doors. 

 

[woodferret]

That's weird.  Breaching etiquette says go for the lock   So much so, they manufacture knob and lock insert plates for training doors so you don't have to replace the whole door every time.

edit: clarified I mean training centers.

 

[luvmytoolz]

I wouldn't see the point to beefing up a hollow core door as it's extremely easy to kick it in, the skins delaminate from the cardboard core with barely any effort on impact. Even the lock block is usually only just long enough to cover the most common range lock placement heights.

So far as solid core doors being easier for law enforcement to penetrate, I'd say you'd have more chance being broken into by a crackhead than cops, so a solid core door will always be better in my opinion. Apart from the fact that most hollow core doors don't survive too well or long as exterior doors.

What people should always do for exterior doors is replace all the tiny 25mm screws with nice long 75-100mm screws, this adds so much strength helping resist the door being kicked open because the striker broke off the bit of door frame it was attached to.

I used to replace a lot of hollow core doors, and surprisingly most owners would replace it with another hollow core as they were cheap, one apartment I replaced the door twice over a couple of years. No cost savings there!

 

[woodbutcherbower]

Nothing is secure. The so-called 'impenetrable' Hatton Garden (UK) safe deposit vault had a £750,000 foot-thick steel door with four massive, NASA-level, unburstable security locks, each having six hardened steel crossbolts ten inches thick. So the thieves just stole a Hilti DD350 and core-drilled through the 3ft. thick reinforced concrete vault wall instead. They got away with £14 million, of which only £4.3 million has ever been recovered.

If they want it bad enough - they'll get it.

 

[dicktill]

I wouldn't see the point to beefing up a hollow core door as it's extremely easy to kick it in, the skins delaminate from the cardboard core with barely any effort on impact.

Not to hijack this thread, but is "hollow core door" generally a misnomer, i.e. is there usually a cardboard or foam core? Thinking about using a hollow core door as a torsion box on a project.

 

[woodferret]

I wouldn't see the point to beefing up a hollow core door as it's extremely easy to kick it in, the skins delaminate from the cardboard core with barely any effort on impact.

Not to hijack this thread, but is "hollow core door" generally a misnomer, i.e. is there usually a cardboard or foam core? Thinking about using a hollow core door as a torsion box on a project.

Depends on the style of door.  A single panel door will typically have the honeycomb.  Molded 3-lite or more will very likely just be hollow with some foam spacers if the relief is deep enough to be structural-ish.  There's a filler strip top and bottom as well as small blocking around the knob/lock area.

Cutting into doors for fun...

 

[Packard]

I wouldn't see the point to beefing up a hollow core door as it's extremely easy to kick it in, the skins delaminate from the cardboard core with barely any effort on impact.

Not to hijack this thread, but is "hollow core door" generally a misnomer, i.e. is there usually a cardboard or foam core? Thinking about using a hollow core door as a torsion box on a project.

Yes, then no.

About 40 years ago I made an ersatz desk top from a hollow core door which I had finished with shellac.  It worked well. I kept an IBM Selectric typewriter on it.

Fast forward to 20 years ago, I repeated that and it failed.

The older door had plywood skins over a honeycomb core.  The newer door had a wood veneer laminated to what can be described as a triple thick shirt cardboard.  It quickly collapsed under the weight of my computer printer.

If you look closely at the edges of the door you can determine if it is cardboard or plywood.  The plywood is OK, the cardboard is NG for a shelf. 

Note:  I later tried one of the cardboard doors as a door.  The water based paint apparently had too much water and the door bowed.  If you are using it for a door, use a shellac based primer like BIN from Zinsser first.

 

[jeh]

A 3-point locking mechanism along with longer jamb screws will slow the break-in down a little.

 

[Packard]

A steel door with a steel buck (door jam) will improve security, but will it resist a breaching ram?

My understanding is you can increase the strength of the door, just so long as the lock is stronger.

As long as the breaching ram penetrates the door before the locking mechanism fails, you are in good shape.

So you can make the door strong, as long as the latching mechanism is stronger.  But if the door is strong enough to transmit all of the energy of the breading ram, then the lock has to also.

If the lock cannot be made strong enough to defeat the breaching ram, then you are safer using a door that is slightly weaker than the lock.  In that case the door remains locked and there is a 5” diameter hole in the door.

The breach occurs at two minutes into the video.  The rest is all setup and aftermath.

 

[luvmytoolz]

Multiple locks (handle/lever lock + a deadlatch) will greatly increase resistance to general break-ins, and ramming to a degree, one of these Lockwood deadlatches for any front door really is the go with very long screws going into the frame/studs.

If you used a thin steel/brass plate under the key cylinder on the outside of the door you also then greatly increase the deadlatch holding power as it covers more surface area.

Of course the simplest way to make a front door more secure is to put a steel security mesh door in front of it!
Most have metal pins that fit on the frame to stop them being levered out of the striker, and it's far more difficult to pull out a door that opens outwards than it is to smash a door that opens inwards!

 

[dicktill]

Depends on the style of door.  A single panel door will typically have the honeycomb.  Molded 3-lite or more will very likely just be hollow with some foam spacers if the relief is deep enough to be structural-ish.  There's a filler strip top and bottom as well as small blocking around the knob/lock area.

Cutting into doors for fun...

Yes, then no.

About 40 years ago I made an ersatz desk top from a hollow core door which I had finished with shellac.  It worked well. I kept an IBM Selectric typewriter on it.

Fast forward to 20 years ago, I repeated that and it failed.

The older door had plywood skins over a honeycomb core.  The newer door had a wood veneer laminated to what can be described as a triple thick shirt cardboard.  It quickly collapsed under the weight of my computer printer.

If you look closely at the edges of the door you can determine if it is cardboard or plywood.  The plywood is OK, the cardboard is NG for a shelf. 

Note:  I later tried one of the cardboard doors as a door.  The water based paint apparently had too much water and the door bowed.  If you are using it for a door, use a shellac based primer like BIN from Zinsser first.

Thanks [member=72072]woodferret[/member] & [member=74278]Packard[/member], as I thought I'll have to build my own torsion box. Fortunately, I got a copy of "More Woodworkers' Essential ..." as mentioned in another thread.

 

[luvmytoolz]

While we're on the subject of breaching doors, a rapper named Afroman was raided late last year, and released a brilliant video mocking the police, of course they're now suing him for humiliation among other things:

 

[rst]

I’m pretty sure that no police will be able to breach my out swinging 18ga door and 16 ga door.  Even if they grind the hinges off, the hinge to jamb pins will screw them.

 

[Packard]

In the 1950s my grandmother lived in a high-rise apartment in The Bronx.  It was a prestigious neighborhood to live in when she moved there in the 1920s, but not such a good area 35 years later.

In addition to the deadbolt lock, which I saw used, she had a “police lock” which apparently she used when she was alone.

I believe the proper term was a “police bar lock”.

There was a socket in the floor to accept one end of the solid steel bar, and another mounted in the exact middle of the door. The bar itself was mounted to a pivot on the floor, and as you opened the door, the bar would slide up through a loop in the socket.  You can see that in the second photo.

The image I attached shows it mounted near the lock.  But I’m quite certain hers was set in the middle from both left to right and from top to bottom.

My impression back then (I was about 10 at the time) was that the police lock made the door impenetrable.

It was a heavy door.  It could have been wood or steel.  I never noticed.

The second image shows the door receptacle.