Decorative Masonry Screens

CONCRETE BLOCK has emerged from the past ten or 15 years as a versatile medium that is stimulating architectural imagi­nations from coast to coast. Examples of the adaptability of masonry units can be found almost anywhere there is new construction— commercial or residential.

Pierced blocks made especially for the purpose, and even con­ventional type blocks with the cores used to transmit light and air, make it possible to design interior or exterior walls or screens with a visual lightness and character that is surprising in such a basically rugged and strong material.

Simplicity is often the keynote. It isn't necessary to use blocks with complex designs. Quite often it is the imaginative arrange­ment of simple blocks that results in a visually interesting pattern. If alternate blocks in a solid wall are allowed to project beyond the surface plane, for example, the wall takes on a new feeling with three-dimensional effects and shadow lines that are intriguing and pleasant.

Once you decide on the block pattern you wish to use, set up a few courses dry by stacking the blocks without mortar until you have a temporary structure that will give you some idea of what the finished project will look like. Most walls—solid or screen— require a footing, and this should be cast as level as possible to facilitate assembly of the blocks.

When wall is to be framed with wood or even precast concrete blocks, it's a good idea to lay out a first course of blocks very carefully using small strips of plywood as joint spacers. Do this horizontally to the full length of the wall and, in one area, vertically to the height of the wall. This step gives you an accurate picture of over-all height and length. Once the dimensions are established, work care­fully to maintain an even, uniform joint thickness. Remember that seemingly in­significant discrepancies can amount to a staggering total error.

Filigree touch with masonry? With new products available, beautiful screens are easy to build

STYLES OF PIERCED BLOCK

In addition to concrete block. Lacestone opens up new possi­bilities as the photo at left shows. This impressive, imaginative in­door screen is well within the scope of careful home craftsmen.

Intricate looking masonry screen below is actually a fairly simple job for amateur mason working-slowly and carefully. Drawings (r.) show the various styles of pierced block made by Besser Co.

Footing for screen above was poured as an integral part of patio slab. Square-block comer posts can be erected as the height of the screen increases.

Even ordinary brick can be placed in an open-work pat­tern for screen. Drawing (left) shows how this might be done.

This, however, shouldn't frighten you—it should merely prompt you to work cautiously and professionally. A regular mortar mix can be used with projects of this type or you can work with the new Threadline Mortar. More information on Threadline will be found in the chapter on concrete block.

Lacestone Units

Another material which is making big strides in the area of decorative masonry is Lacestone, a product of the Soapstone Duct Company of Oakland, Calif. Lace­stone is compounded of cement and micro-ground minerals extruded under tremen­dous pressure into the shapes illustrated.

Intricate-appearing design is actually straight­forward assembly of one type block. Blocks could be assembled on edge to create, another pattern.

The finish is smooth and mating surfaces are level-faced and precisely alike. The normal color is cement gray, but the units may be painted if desired or colors can be cast integrally on special order.

The blocks are relatively light, averag­ing about 12 lbs. per sq. ft., so that walls or screens under 6 ft. in height can be erected without a footing. This makes the material ideal for indoor use as long as the existing structure is sturdy enough to carry the additional load.

The best bet when planning a project is to make full-size cutouts of the shapes you plan to use and to work with these on a flat surface until you arrive at the pattern that suits you. Since a footing is not always needed, it is possible to encase the entire screen in a wooden frame. Vertical posts can be set directly in the ground with rails placed between, much as if you were mak­ing the framework for a fence. The rails must be solidly attached since they will be taking the full load of the blocks. If neces­sary, set extra short posts between the main verticals so that they sit beneath the rails and support them. The frame meas­urements must be very accurate and the vertical alignment of the posts must be perfectly plumb.

When a frame will be preassembled, the best method is to place the blocks on the ground (a smooth slab is good) in the pat­tern selected and take measurements from this to establish frame size. If you work with the special adhesive sold for assembly of Lacestone units, allow 1/4 in. for each 6 lineal feet of stone. Regular mortar may be used in place of the adhesive. In this case add up the total thickness of the mortar joints and make allowances accordingly. The easiest patterns to erect are those which have continuous vertical and hori­zontal joints since they mate on all four sides and thus support each other.

Masonry unit screen (left) was assembled by amateur using new Threadline Mor­tar. Project adds to appear­ance, privacy of the house.
Masonry screen (right) makes excellent divider and is as permanent as house. It also serves as a buffer between the various areas for recreation, living.

Pierced masonry units also make good boundary fences. Footing is concrete, cap is precast concrete blocks. This style of block is simple, has many uses.

Lacestone blocks can be preassembled in small squares for use in large screens. Align stones with a wooden square and bond them together as units.

-TEMPORARY WOODEN BRACE TO SUPPORT BLOCKS

Because Lacestone units are small, it is simple to create curved screens as above. Screen cuts off driveway traffic, lets light and air through.

Intricate open patterns can also be created with Lacestone. Drawing at left shows how to use brace to support the blocks while bonding them together.

Interior use of Lacestone is shown in the photo­graph at right. When the structure is large, check the weight-carrying capacity of the floor first.

When you do need a footing (or decide to use one), be sure that it is as level as possible. This will make block assembly much easier. Work with a long straight­edge to keep rows aligned. When the pat­tern you select places the joints at a 45-degree angle instead of vertically or horizontally, you must use particular care to space the first row very accurately and to maintain the spacing at all times.

When the pattern has open spaces be­neath a portion of any section, use tem­porary wood blocks to support the sections until the adhesive is set (24 hours). One way to speed up assembly, when the pattern permits, is to preassemble small sections on the ground. Allow these to set about 24 hours and place them as if they were in­dividual pieces. Lacestone can be cut with a hack saw or fine tooth crosscut saw.

Two sizes of Lacestone were used to create the in­teresting pattern shown at right. With designs like thìs. it's easier to preas-semble small sections and fit together against wall.

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