Value Engineering for Economy
A basic understanding of the molding process used in the manufacture of Cast Stone can effect a tremendous cost savings in the masonry budget.
By including one major flat unexposed side in the design of the basic section and in return conditions, production time will be reduced to a minimum, many pieces can be made from each mould daily and curing moisture is received from the face of
“L” shaped, “U” shaped or “cored out” stones can be made; however, the designer should be advised that these specially shaped units must be hand moulded and will result in much higher costs. The key to optimum economy with Cast Stone is repetition of shape and profile. A great majority of jobs can be reduced to a fraction of otherwise prohibitive cost if certain standards are followed.
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|• Cast Stone is moulded in a casting machine like this:||. . . and turned over by the machine onto a pallet like this:|
|. . . before hydration of cement, for production economy and “face up” curing under dense fog and water spray. This process generally requires one major flat unexposed surface. For Economy:|
|• Where return legs are essential to the design, standardize depth of return at 6” or 8” to allow for stone turnover with core box.|
|• Do not assume that profiles when combined will reduce stone setting costs. Undesirable sections (shown above) will usually triple the manufacturing leading time and the number of truckloads required. Such profiles are usually more difficult to adjust during setting and often require a separate erection crew, which may only be familiar with precast concrete erection procedures. Such an arrangement will almost certainly be attended by disappointing results.|
|• Where radii are required, maintain lengths to less than 4’-0” whenever possible. The major unexposed back of this section, if made flat as shown above, will reduce manufacturing costs substantially. Provide sufficient clearance in the masonry wythe or structural wall section. A sill section generally presents no problem when designed with a radius front and rear because the major unexposed side is flat at the masonry bed joint.|
|• Small trim sections such as sills and band courses are the most economical to produce in Cast Stone when designed with two perpendicular unexposed sides.|
|A face pattern is inserted in the machine like this:||. . . and turned 90 º like this:|
|This type of sill (or a band stone) will generally cost about the same as for rowlock brick, provided that a sufficient quantity is required to offset machine set-up time.|
|• For optimum economy, standard building stone anchors should be used whenever possible. The allowance for a continuous relieving angle to support the masonry is the most economical support system. This eliminates the need to pinpont insert locations in stones to agree with field conditions; a common cause of confusion and delay. Where this is not possible, the shear weight should be support by two or more of the embedded inserts Embedded weld plates and haunches to bolts projecting from the backs of stones should be avoided.|
|• Allow for a minimum of 7º mould draft on face sections to minimize the number of piece required in the face pattern. A slight “draft” is incorporated into all relief sections where right angles are shown:|
|• Avoid “negative draft” profiles whenever possible:|
|• For optimum economy with trim stones, maintain the maximum quantity of lengths at the same size; use a short or long piece at control joints as shown:|
|• An alternative method to the above is to run expansion material through head and bed joints as shown with horizontal offset:|
|• Maintain the same spacing between control joints to permit equal lengths of stones whenever possible.|
|• Bridge copings over control joints to minimize the possibility of water intrusion. Set the long bridge section of coping in a full bed of mortar, and dowel holes in thin copings or on raked walls to allow for added security as necessary. Gun sealant into dowel hole in lieu of mortar.|
|• Because of the manufacturing process, lintels, panels or similar stones can be made with logos, reliefs or other motifs at minor additional cost when compared to precast concrete or cut stone.|
|. . . or with a logo or pattern like this:||. . . at minor additional cost.|
|A Plain keystone like this:||Costs only slightly less than one made like this:|
|• Stones that are 2”-thick are more costly to produce than 3”-thick stones due to handling, mould stripping and packaging costs. A 2”-thick stone costs the same as a thick 4”-thick stone.
• Avoid acute angles adjacent to unexposed side. This avoids a feather edge in the mould.
|• Do not allow your Cast Stone manufacturer to miter corners of coping or feature trim work in order to cut costs. Maintain the profile around the return corner at the depth of the section wherever desired. So long as the return corner at the depth of the section, no additional cost is incurred.|
On the above information, we have shown the methods and standards of Cast Stone detailing and various detailing which will enable all of your projects involving Stone to fit the masonry/facade budgets at reasonable cost.
Our staff of estimating, design and production personnel has more than 76 years of continuous knowledge. Please call upon us for any of your needs concerning your design.
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