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June 23, 2008 7:14 AM   Subscribe

It seems to me that bricklaying would be more efficient if house bricks interlocked like Lego blocks. Why aren't they made like that?
posted by Joe in Australia to Technology (28 answers total) 2 users marked this as a favorite
Human labor is much less expensive then the costs involved in making building materials into legos.
posted by geoff. at 7:18 AM on June 23, 2008

Lego, geoff. Lego. It's a plural noun.

Also.. (real) bricks are totally interchangeable. Except for size (which seems to be fairly standardized) a brick is a brick is a brick is a brick. If you went with Lego-style interlocking bricks, you'd be beholden to particular manufacturers, not who gives you the best price.
posted by dirtynumbangelboy at 7:22 AM on June 23, 2008

Because it takes mortar to hold the bricks in place permanently, otherwise the entire wall can be knocked down with a bump.

Because Lego blocks are made out of plastic; plastic is a material with some amount of elasticity that allows for the peg to compress very slightly as it snaps into the socket (or perhaps the socket flexes slightly, I'm really not sure). Stone and clay and the similar materials that bricks are made out of does not have this elastic property, the material will have a strong tenancy to crack and break off instead of snapping into place.

Because, even leaving aside it's mechanical properties, the grout lines of the mortar adds an important part of the visual appeal of brickwork and stonework.

Then again, if you can develop and market a product that overcomes those and other hurdles, and can deliver the same or superior strength for less money after labor is taken into consideration, go for it.
posted by Lokheed at 7:25 AM on June 23, 2008 [4 favorites]

I guess your GI Joe figures never attacked your Lego towns. Lego walls are pretty easy to break through.
posted by poppo at 7:25 AM on June 23, 2008 [5 favorites]

Lego are made out of plastic, which bends significantly more than clay bricks, therefore enabling the useful "snapping" together effect that bonds the bricks. I know it doesn't literally "snap", but I always assumed that is in effect what happens. Of course clay just doesn't have that property.

I could be wrong though

Surely modern prefab housing kits like the Huf House are an attempt to speed up construction by having bits that fit together less labour intensively, though?
posted by munchbunch at 7:25 AM on June 23, 2008

SHould have previewed, Lokheed got their first. sorry
posted by munchbunch at 7:26 AM on June 23, 2008

The pegs and sockets (guzintas and grabsontas? Upper Lego, lower Lego?) wouldn’t be very strong and would tend to break. Mortar would still be required and the pegs would get in the way. You’d still need to use a line to stack them straight and level, defeating the purpose. Also, bricks aren’t always stacked in a straight line, there are often curved walls, etc.

LEGO bricks are strong and efficient because they’re made out of plastic, using a technique that results in very small tolerance. They’re designed to hold together until you take them apart, and when you do they come apart very easily. You ever use any imitation Chinese LEGO knock-off bricks? They suck, they don’t hold together. Real bricks would be worse.

Any plastic, LEGO-like bricks that were made for building real-life buildings would be very expensive and probably would be a major fire hazard.

It’s a neat idea though. I could imagine a set of giant-ass LEGOs for rich folks to build they’re own houses with, taking them down and rebuilding whenever they wanted a change.
posted by bondcliff at 7:26 AM on June 23, 2008 [1 favorite]

There are lots of interlocking brick-type things for landscape and civil use, mostly for retaining walls, where the interlocking feature adds to the strength, I imagine. Doesn't answer the question of why they don't have them for houses though.
posted by BinGregory at 7:29 AM on June 23, 2008

Legos work as well as they do because of the high level of precision in making them; the parts need to be very closely aligned to interlock well and have everything look smooth.

Bricks are not going to be a building material that can be easily formed with that degree of precision; they are lumps of clay that are fired in a kiln, making it very hard to get them to the perfectly uniform sizes you would need for the interlocking elements to match.

Also, bricks + mortar are a very strong system for bearing up under downward pressure. Interlocking parts would weaken this strength (by placing holes in the brick for the underlying brick to mate with). This would increase their resistance to lateral motion, but most brick walls aren't used for lateral resistance.
posted by jenkinsEar at 7:29 AM on June 23, 2008

It has been tried in a way, by brewer Alfred Heineken. Who thought that using beer bottles as bricks would kill tow birds with one stone, in poorer regions. The empty bottles wouldn't become litter, and the problem that building material is so expensive would be solved by using a waste material.

However, apart from some tests, nothing was ever done by this idea of the World Bottle [WoBo].
posted by ijsbrand at 7:30 AM on June 23, 2008 [3 favorites]

If the bricks interlocked like LEGO, it would be impossible to replace individual bricks when they failed or were damaged. This was an important consideration in early brick construction when using traditional lime mortars, which were soft and needed frequent repointing (digging out damaged or failing mortar and replacing it with new material). During the repointing process was an ideal time to replace bricks as well.
posted by Rock Steady at 7:32 AM on June 23, 2008

Some bricks do have some sort of similar- they have holes or indents where the mortar can get into and create a sort of key that locks the brick in. I'm thinking of cinder blocks and glass blocks specifically.
posted by gjc at 7:36 AM on June 23, 2008

Those nubs would break off and crack when made of brick material at human scale.

Applying mortar would be a huge pain with the nubs in the way.

Manufacturing bricks with those nubs would be more expensive.
posted by MegoSteve at 7:37 AM on June 23, 2008

Legos stick together through tension. Brick cant do tension. The underside of a plastic lego has little "grabbers" that keep the pieces together. If you try this with brick you'll just end up breaking the brick.

Moving to plastic brick (not to mention a new type of mortar) would be pretty expensive, especially with oil costing as much as it does. I also would imagine its insulation properties, shear, compression, durability, etc are well below brick.
posted by damn dirty ape at 7:38 AM on June 23, 2008

Making rectangular bricks is a pretty simple process. Putting knobs and holes on them would be way more complicated and more expensive. And what would the payoff be? You'd still need to mortar the layers to prevent wobble and leakage, so it doesn't cut out the bricklaying cost. Mortar by itself is a pretty durable bond, it just requires some maintenance in the form of repointing every 25 years or so. And that maintenance would not be eliminated by lego bricks, either, or you'd get crumbling mortar, crumbling bricks, and leaks.

Finally, interlocking the bricks might exacerbate damage when foundations shift, although, since a solid foundation is essential for a brick wall, that's really not a good reason. Still, a little settling inevitably happens over the course of decades or centuries. With standard bricks, cracks form along mortar lines because the mortar is weaker than the brick, so repairs can often be made simply by repointing. But with interlocking bricks, the bricks themselves might crack, making repairs costlier.

All that said, there are various kinds of interlocking bricks, mainly for paving (just Google "interlocking brick"). And something called QuickBrick was announced a couple of years ago for wall construction, but I can find no images or other clues as to how it works.
posted by beagle at 7:39 AM on June 23, 2008

Sometimes they are.
posted by Partial Law at 7:39 AM on June 23, 2008

Interlocking 'bricks' are used for retaining walls as well as paving. Too lazy to look for a link.
posted by signal at 8:07 AM on June 23, 2008

Regardless of what else is being said here, bricks aren't automatically solid rectangles of clay.

The majority of bricks in the UK (and probably elsewhere) feature a depression in the middle which makes the brick top look like a Pez sweet. Builder's here call the indent a 'Frog' - I have no idea why. Nearly as common are bricks with three holes going down from top to bottom - normally called engineering bricks.

I believe, but can't prove, that these features are so that the mortar gets a better hold on the brick.

Importantly, these keys go into the brick. The brick maker saves material (no matter how small an amount this is) and the brick remains brick shaped. This means they stack neatly and securely for transportation. Putting bobbles on a brick as keying involves extra material and stops them from stacking as easily.

Finally, you'd want to keep the mortar in the equation - from memory the mortar is often stronger than the bricks it's holding together. I'm thinking specifically of certain regional bricks (Cambridge Whites?) and Breezeblocks (basically cement that has had air blown through it before being poured so that a cut one has a texture like sliced bread.)
posted by twine42 at 8:21 AM on June 23, 2008

"Roman Stack" type retaining wall blocks have some amount of interlocking and are typically used without mortar.
posted by madmethods at 9:23 AM on June 23, 2008

Nearly as common are bricks with three holes going down from top to bottom - normally called engineering bricks. I believe, but can't prove, that these features are so that the mortar gets a better hold on the brick.

I've only ever seen those holes used to run reinforcing rebar through, and then the bricks are 'threaded' onto the steel lines. It's for both lateral strength (no shifting) and convenience, I think.
posted by rokusan at 10:14 AM on June 23, 2008

While everyone here has brought up a lot of good reasons, the best I think is the lack of replaceability. If all of the bricks were interlocked as well as mortared together, it would be impossible to change out a piece of the wall. This is often done in older facades, or whenever there is damage to a brick building (if it can be safely done). Since these bricks are all rectangular, replacing a given brick is as easy as removing some mortar and sliding it out. If they had interlocking nibs, this could not be done, and the entire wall would have to be taken down when only a piece is damaged.
posted by Xoder at 10:20 AM on June 23, 2008

Making rectangular bricks is a pretty simple process. Putting knobs and holes on them would be way more complicated and more expensive.

This is proabably a huge part of it--bricks are typically made from a large extrusion of clay that is then sliced up to make bricks. For lego-type joining capability, they'd have to be individually molded, which be a far more complex process.

Also, buildings generally need doors and windows, as well as other openings and changes to walls. As nice as it would be if all the doors and all the windows that anybody ever wanted to put into a brick building were "on module" with the brick layout, that just doesn't always happen. So bricks need to be cut. There's no way to effectively individually mold all the different size brick bits that a mason might need on a jobsite and have it the process be more cost- or labor-effective than the mason just cutting a brick. Bricks are also used for different purposes than just stacking up to form a wall--they can be arches, windowsills, copings, and a number of other building detail features, created just by installing the bricks in a non-standard manner. Lego-fying the bricks would totally ruin their capacity to do that. Of couse, a builder could have two different supplies of bricks on site, one set for details and another for wall stacking, but why bother?
posted by LionIndex at 10:38 AM on June 23, 2008

Nearly as common are bricks with three holes going down from top to bottom - normally called engineering bricks. I believe, but can't prove, that these features are so that the mortar gets a better hold on the brick.

From what I understand, that's more of a secondary consideration; engineering bricks have holes because they are made of a denser clay material, which would make them extra heavy. Holes don't change how they function under compression, but they do make them lighter, and more resistant to water and frost damage . Extruded or wire cut bricks have holes because of the dies used in the manufacturing process. The holes do help the heavier bricks not slide off the mortar; that's also the role of the frog (the indent goes on the bottom).
posted by oneirodynia at 11:16 AM on June 23, 2008

Actually, Lego sucks for walls. Just try building a Lego wall that's more than 5 layers tall, and then press your finger in the middle. It will buckle.
posted by randomstriker at 12:03 PM on June 23, 2008

Lego, geoff. Lego. It's a plural noun.

In American English, more than one lego are (normally) legos. Not five lego, and not five lego bricks, and not five LEGO bricks, but five legos. We also spell colour color and call a two-four a case.

Most simply, legos touch each other. Bricks don't, and are separated by mortar. You could build bricks like legos so you just piled them on top of each other, but why would you want to? The efficient choice over normal brick is not lego bricks. It's cheaper siding.
posted by ROU_Xenophobe at 12:21 PM on June 23, 2008

I live in a city where 99% of the buildings are made of concrete blocks, which is of course not exactly the same as bricks, but in terms of laying requires similar effort. The blocks are made by hand in several shapes (basic rectangles for walls, thicker rectangles for foundations, rectangles with overhanging lips for hanging between beams for floors and ceilings) using metal forms, and then they are placed by hand with more concrete for mortar. In addition, the forms are made locally. The reason I mention all of this is that if lego-style were some combination of faster, easier, cheaper, or possible, these people would be doing it. Because they are already made by hand, it would not be more labor to make the blocks, and because the forms are made locally they are easy to replace.

Mortar is required for brick and block walls, regardless of interlocking shapes. To do without mortar you need much bigger and much heavier blocks (see: pyramids) so you can use friction and gravity to keep everything together. Big heavy blocks are hard to work, require a lot of material, and make very thick walls. Since mortar is required anyway, using interlocking shapes actually require more effort, because the person laying the blocks would have place each block in a specific orientation and position.

In the end, a smallish basic rectangle with as little variation as possible and as much empty space as structure will allow is the cheapest to make and the easiest to work with. Interlocking is useful in some cases, as mentioned above, usually when there is a strong horizontal force, such as in the case of a retaining wall. But it requires more work, not less.
posted by Nothing at 12:52 PM on June 23, 2008

Because bricks work fine just the way they are.

Cutting clay into squares: super easy and cheap with virtually no defects = cheap reliable building material.

Forming clay into interlocking bricks: difficult, expensive, more defective pieces = higher cost.

And what is the benefit? Doubt if they would build faster since a knobby brick would be harder to apply mortar, they would have to all be faced the right way and cutting a brick to size would require more precision.

Have you ever watched a pro bricklayer work? Damn, they can lay that stuff down fast. They don't need anything slowing them down.
posted by Ookseer at 1:13 PM on June 23, 2008

And to you I introduce the Insulated Concrete Form. It's right there in the first sentence. ICF's RULE, but for a lot more reasons than just stackability.

Case in point: we rocking an 8' crawlspace on a current build, total time to stack all blocks: 1.25 hours, + pour time of ~3-4 hours. 2 person team. Total man hours 11 maximum to build an 8' tall block wall with an r50 insulation rating.
posted by TomMelee at 8:44 PM on June 23, 2008

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