Roof Plywood: A quick guide to when it’s necessary to complete a deck-over with new roof sheathing.

A Good roofing system must have solid deck also known as roof plywood. On this job Revived Exteriors has installed an extra layer of roof plywood in order to cover big spacing in the existing roofing decking. This installation of roof plywood is also known in the roofing industry as a deck-over or a re-deck on spaced decking.

In this video Revived Exteriors is completing a roof replacement in Arlington Heights IL. After removing the shingles, it was discovered that the roof had spaced decking. Spaced decking is space between each wooden plank. Asphalt roof materials like 3 tab or architectural shingles cannot be installed over quarter inch spacing (1/4″) per manufacturer guidelines and shear common sense since the nail will be driven in certain areas through a gap or hole and not hold down the shingles adequately.

Current roofing codes require a solid and nail-able surface. That surface can be 6 inch planks that are spaced at less than 1/4 inch. Roof plywood is the most commonly used decking for roof shingles. The requirements for roof plywood vary from city to city but generally need to be at least 1/2 inch thickness. In addition, the roof plywood may need h-clips to hold the plywood in place and create a sturdier decking especially on any rafter spacing of 24 inches or greater.