The entire surface of the pavers and all of the joints between them need to be cleaned out and empty. The weeds and moss need to be removed. This can be done by hand, but the best way to do this is by carefully power washing - making sure to hit each joint line. Many times plain water will be enough to clean the surface. Occaisionally a mild detergent or spot cleaner is added to tackle the tougher stains. There are commercial stain removers on the market that are specially formulated for things such as rust, organic stains, oil and grease and efflorescence.
This is where all repairs are made to the pavers and surrounding walls or steps. For instance, correcting any pitch or settling issues, replacing broken pieces, realigning the pattern or border and replacing the edge restraint.
Once the joints are cleaned out and dry, new joint filler must be installed. This is structural for the paver system - so a very improtant step. In most cases a polymer sand is used. Here's how it's done... First the polymeric sand is swept over the entire paver or stone surface to allow it to fill up all joints. Then, with a very small amount of residual sand left on the surface, a vibratory rolling compactor is moved over the surface to compact the joint sand tighter into the joints. More polymeric sand is then swept over the entire surface to refill the space left from the compacting. One more quick pass is made with the vibratory rolling compactor for a final compaction before the surface is swept clean. A blower at low speed is then used to remove any fine particle traces of polymer residue from the surface. Finally, the surface is wet down with a spray of water, followed by a more generous soaking for 30 seconds directly following. It is recommended to allow at least 2 hours of dry time before any additional water meets the joints.
Other types of joint filler would include a clean masonry sand or a small grit stone like what would be used for permeable pavers. These sands do not have any binders or stabilizing agents in them, so will need to be replenished often.
So the repairs have been made and the new polymer sand has been installed. Now it's time to put a protecting layer on the surface. This will keep the pavers cleaner longer. It will also protect the surface from eroding and breaking down over time. There are 2 basic kinds of sealers on the market today... invisible penetrating sealers or film forming protective sealers. The film forming sealers can be clear or provide a tint or wet look to the over all installation. In either case the surface will be sealed to leave a water resistant, luxurious finish thus, sustaining and enhancing the look and life of your hardscape.
Sealers can also be applied to new installations. However, manufacturers recommend a six to twelve month waiting period before anything is applied. This gives the new pavers time to completely cure before the sealers are applied.
NOTE: Re-Sealing is not recommended any time before two (2) years from the date of original sealing. However; re-sealing every 3-5 years is optimal to maintain your investment. The process will be less involved the second time around - only a light surface washing will be required.