Wedi Board and Cement Board Compared

cement board under wedi board

One of the many wonderful characteristics of mosaics is their durability. Who knows how many generations can enjoy the art made from glass, china, ceramic, and stone tesserae? We do know that we can easily find mosaics that are 1,000 years older than the oldest paintings.

Choosing the right substrate for your mosaic is critical to its longevity. A mosaic that may get wet should be on a moisture resistant or waterproof backer. Cement board has been around the longest and may thereby be best known, but Wedi is becoming widely recognized as an alternative.

Yet there are still a lot of questions about how they compare. So we set out to find and report on the differences. But first, there are similarities. They are both:

  • engineered for wet areas
  • are usable indoors and outdoors
  • able to be scored and snapped or cut with power saws

Here are the differences:

Construction – Cement board is a combination of cement and reinforcing fibers formed into sheets of 3 feet by 5 feet or 4 feet by 8 feet. Wedi is made with a dense polystyrene foam core sandwiched between thin layers of concrete which are reinforced with fiberglass mesh.

Weight – One square foot of ½ inch thick cement board weighs 40 ounces and wedi is 11 ounces.

Water tightness – Cement board is water and mold resistant and wedi is waterproof.

Shapeability - Cement board is not shapeable and wedi is.

Dimensions – Cement board is available in sheets with a thicknesses of 1/2 and 5/8 inch; widths of either 3 feet or 4 feet; and lengths of either 5 feet or 8 feet . Wedi is available in sheets or panels with thicknesses 1/8, 1/4, 1/2, and more up to 4 inches; widths of 6 to 24 inches; and lengths of 6 to 24 inches. Wedi is also available in freeform shapes.

Availability – Cement board is only available from building material suppliers and must be picked up at the store. Wedi is easy available online from mosaic supplies websites and may be available in local stores. Most sizes of wedi can be easily shipped via USPS and UPS.

Cost – there is a large difference in their cost. Depending on the quantity differences it is purchased in, wedi can cost from 4 to 10 times cement board. Is wedi worth the price? That depends mostly on your project.

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