A material as versatile as concrete masonry encourages innovation. The National Concrete Masonry Association's Block Shapes & Sizes Manual has drawings of over 2500 different units, most of which can be produced in a wide variety of colors and textures. Special blocks are available for purposes ranging from sound abatement to flooring.
There are, in fact, so many innovations that we must limit the scope of this article. It will not discuss units with integral insulation, mortarless wall systems, sound-absorbing units, or units intended to keep water out of a wall.
The following are some of the most interesting and unique applications we've seen recently. Some of these units are widely available; others are either not in full production or have limited distribution.
Roofblock creates the roof overhang, soffit, and fascia at the top of a masonry wall. Roofblock bedded in mortar at the top of the wall seals the cavity, protecting the wall insulation, the structural wood wall framing, and the wood roof joists. Along a sloping gable, Roofblocks minimize the need to cut brick to match the roof slope since the unit covers the ragged brickwork edge. Roofblocks are not currently being made in the United States.
- VOBB Blocks is a mortarless system based on a lightweight dry-stack wall unit aimed primarily at do-it-yourselfers and home builders. Designed completely on a 6-inch grid, these units are structural only--an exterior coating of EIFS or stucco is typically used with an interior covering of drywall. John Guy, president of VOBB, states that since a wall can be built so quickly with unskilled workers, the labor cost to install a VOBB Block is 20 cents, compared with about $3 for a standard concrete masonry unit.
- Novabriks, mortarless units, are more concrete siding than masonry wall. Stacked up in a running bond and tied back to the building frame, Novabriks create a masonry facing that has the look of a standard clay or concrete brick wall. For a Novabrik wall, furring strips are installed on the structural wall. Manufacturers of Novabrik are located across the country.
- Air Crete Blocks, although not yet in full production, are a promising innovation. These units are manufactured on patented machines that resemble standard block machines but that, according to the developer, produce units with tolerances so tight that the units can be dry-stacked and will remain plumb up to 10 feet high. The units, which interlock on all sides with tongues and grooves, are then grouted.
- Block Joist floors, installed very successfully in a number of homes over the past few years, have a 2- or 3-hour fire rating, depending on the thickness of the topping. Pat Ellison sees concrete masonry as the ideal material for a concrete roof or floor slab. He's been able to accomplish this by using a 7-inch-deep steel joist with wide bottom flanges to support standard 8-inch lightweight CMUs in 16- or 24-inch lengths. Building a floor with this system is as easy as positioning the joists, laying in the blocks, filling the joints between the blocks and the joists with a fluid grout, placing transverse reinforcing wires in the spaces between the blocks, then spreading a final thin coat of grout to form the floor surface.
- Flowblox incorporates a drainage system and weeps as part of the shape of the unit to overcome the weakness created by through-wall flashing in a single-wythe wall. A course of Flowblox units are installed anywhere flashing would normally be installed. Plastic diverter shields are placed atop the head joint between blocks to divert water into the coated cavity of the block then out through slots in the center of the block's face.
- Pentstar CMFU Building System looks like any other masonry wall. The Pentstar System allows the designer to mix or match any pattern or texture of concrete or brick face shells since keyed-in plastic webs connect them. The Pentstar System provides a wall that has no thermal bridges and is sound-absorbent and fire-resistant. The plastic webs result in a unit that has ergonomic advantages for the mason: it weighs about half as much as a standard 12-inch unit, and the middle plastic web serves as a balanced built-in handle.
- Rapid Building Systems units are currently being made in the United States on a custom basis only, but they will become more-widely available this year. The units that were developed are EcoBloqs, FooterBlock, SpanBlock, Biaxial Block, and FlashingBlock. All of these units are matched to form a complete building system.
The three EcoBloqs are structure, drainage, and insulation--all in one architecturally faced unit. The cubic units are assembled in a nearly mortarless way--some mortar is used in the head joints to maintain level and plumb.
The FooterBlock is a segmental footing system composed of 4x8x16-inch blocks that key together to form a wall footing over a gravel base that is just as capable of carrying building loads as a poured footing.
SpanBlock is a two-part system of arched coffer units and joist units that are used to create a suspended slab.
Biaxial Blocks are used to create walls that have vertical and horizontal chases through all blocks for electrical and mechanical systems and knockouts for electrical outlets.
FlashingBlock is a block with integral weep slots at 8 inches on center and built-in slots in the back face shell to hold the top flap of a preformed metal flashing.