September 2015 Job of the Month:
When we were contracted to refinish concrete on this patio deck, we arrived to find that the existing deck was not in the best shape. The roof had protected it from rain damage, but scratches, blemishes of different colors, and chips had all left their marks. The deck also had a dull, boring surface. Next to the house's brick walls, the hot tub's attractive stone walls, and the bricks around the pool, the deck's plain concrete floor just didn't look good. The homeowner was ready for a change. He wanted a surface that would draw the eye and complement the other features in the backyard.
When we refinish concrete, we either make changes to the existing surface or we lay down an overlay. If the patio deck's exiting floor had been in good condition, we could have transformed it into an attractive, eye-catching surface without placing a new concrete layer on top of it by just acid staining it. However, given the damages, an overlay was the better option. It would be free of the old blemishes, dents, chips or scratches and would create a smooth, clean slate to start from.
The surface of any project where we refinish concrete needs to hold up against future wear and tear. One way we strengthen the new concrete overlay is by making sure it sticks to the existing surface. We do this by grinding the existing concrete which creates an abrasive surface that helps the overlay "bite" into the existing floor. Grinding can also remove dirt and other blemishes.
Grinding is possible with the help of a few tools. Buffers with grinding attachments are useful over large areas of concrete. A metal disc, which we attach to the 17" buffer, does the actual grinding. The disc is has carbide bits which, when the disc spins, make direct contact with the concrete and grind it.
The chips spin so fast that the ground-up concrete creates a dust cloud. To prevent it from going everywhere we use a shroud, a metallic case that surrounds the grinding disc. The shroud covers all parts of the disc except for the side that comes into direct contact with the concrete surface. The concrete dust trapped by the shroud is then sucked into a vacuum.
We used a buffer to grind the large middle section of the patio deck. Once that was done, we switched to hand grinders. A hand grinder has a 7" grinding wheel that consists of multiple segments. Each segments contains diamonds in a metal matrix, which do the grinding.
Hand grinders are useful over small areas and in tight spaces as they are easier to control than the large buffer. The operator has to kneel down to use it on floors and decks. It came in handy near the bricks walls of this home where we needed to be extra careful so as to not damage them. The hand grinder gave us all the control we needed. In even tighter spaces, we can switch to a 4" grinder. That wasn't necessary to refinish concrete at this house. The patio deck butted against a pool deck. We wouldn't be laying a new overlay on the pool deck, so we were careful not to grind its surface by accident. The hand grinder came in handy here, too.
Once all of the grinding was done in this refinish concrete project, we laid down a skim coat layer. This filled in the chips in the patio deck's existing surface. The skim coat also acted as a bond coat that helps adhere the next coat of overlay tightly to the existing deck which is the one that has a decorative texture we call a trowel down. The homeowner really wanted the surface to pop, so we scored a stone-like pattern and added a colorful stain to do the trick. We used hand grinders to cut into the surface and create the custom-made shapes of each stone. We applied a stain to give the surface an orange-brown color. The last step we took to protect the new concrete from damage was to apply a sealer. The finished deck looked great next to the brick walls, the pool deck and the stone hot tub. It was just what the homeowner needed to turn his patio deck from drab to delightful.