Still more valuable info from our acid stained concrete pro Joe Welsh, at Stained By Design!We recently covered Interior and Exterior Care of your Acid Stained Concrete Flooring. But it's probably a good idea to let you know how to put stained concrete floors down in the first place! So, let's cover the necessary steps to prepare your slab for stained concrete. Now, this can information for the do-it-yourselfer but if you're going to have a decorative concrete professional handle the job, it would be good to know the correct procedure. That way, if may be able to spot a problem before it arises. Joe pointed out this problem he saw on the Home Improvement Ideas site with info on stained flooring, where it says, "Basically it's when the concrete is colored as part of the mixing process (as opposed to being painted after it's laid and dried.)" According to Joe, "If you tried to add acid stain to the mix, you'd have concrete that would crumble like stale bread after a year." So, study his prep guide and show it to your concrete installer if you see something being done incorrectly:
Preparing a Slab for Stained Concrete
1) A quality batch of concrete should consist of at least a 5-sack mix with minimal fly-ash, no retarder, curing compounds or chloride accelerators. Do not pour below 40°F. Do not use fly-ash below 80°F. Use no more than 15% fly-ash above 80°F. The slab should be hard troweled by machine to a smooth finish. It is NOT necessary to burnish the surface to a slick, mirror finish. "Burning" the slab to an ultra smooth surface will close off the pours of the slab and cause the stain to sit on top of the concrete and not penetrate. A bit smoother than a garage floor is optimum. Make sure the Finishers don’t get "burrs", rocks, or debris caught under the blades which can cut swirl marks into the slab.
2) It is important that the concrete be thoroughly finished with hand tools, where needed, around the plumbing, risers, floor outlets, or any other element which is not accessible by the machine. Special care should be taken to blend in the areas at the exterior edges of the slab. If the finish is smooth in the center and rough-finished at the edges, there will be a noticeable difference of color and tone between these areas.
3) Silicone chalks should NOT be used, if at all possible. The red and yellow chalks are PERMANENT DYES. Red chalk should NOT be used for framing. White or blue chalks are okay. Do NOT use silicone sprays to "Hold" the lines. The sprays repel the stain and leaves harsh, permanent scars on the floor.
4) It is important that wood, sheet goods, sections of framing and the like not laid on the slab for extended periods of time. They can transfer resins and tannins into the slab. This will alter the moisture content in the slab which leaves a pattern in the finished floor. Cardboard should be placed between the slab and the stacked material to minimize any unwanted transfers.
5) The floor should be protected from the following: plumbers glue, foam insulation, bond release agents, flux, oils, grease, polyurethane, paint, markers (framers often write dimensions of doorways in marker on the slab - ask them to make that note on the wood framing the doorway), grease sticks, spray paints, crayons, muratic acid, and other chemicals both before and after staining. Also ask that locations of electrical and other outlets be marked on the studs and not on the floor.
6) The framers should brace the walls to the outside and not to the slab. Door plates should be cut away immediately.
7) The floors should be clean and the rooms empty, with absolutely nothing on the floors prior to the arrival of the stain crew. The best time to stain the floors is when you are Blacked-In with a roof on. The slab is at it’s cleanest at this point in time. After the Stain and Sealer, the floor should be covered with "Builder’s Paper" to protect it from the drywall mud and paint.
8) At the “Pre-Trim” stage, a refresher coat of sealer will bring the floors back to life.
9) It is extremely important that you do not tape the floor! When covering the floor, overlap sheets of builder’s paper (Roofing paper is a great covering item, too.) Tape the first sheet to the wall then overlap the second sheet to the first and tape it to the paper. DO NOT PUT TAPE ON THE FLOOR. Use no tape! Duct tape, masking tape, packing tape, strap tape, blue tape, green tape, stucco tape and electrical tape – there are NO exceptions. It alters the natural curing process and transfers chemicals to and from the slab. This will show in the finished product.10) When covering the floor, you may use sheets of masonite or single-faced cardboard on top of the builder’s paper. however, do not cover the floor with plastic at any time! It prevents the slab from breathing, which inhibits proper curing. It can result in efflorescence."
If you're in Louisiana, contact Joe about getting your interior floors resurfaced with decorative concrete overlays at (337) 316-4505 or you can email him. If you'd like to talk to a decorative concrete specialist in your area, you can find at ConstructionDeal.com.
