If you want to add a cobblestone wall to the exterior of your home, then you may want to protect it against water damage by adding a waterproof coating. As cobblestone walls are usually built from a combination of stone and concrete or cement, you will need to add a sealant that will work well with both stone and concrete, and also one which is fully protected against all of the elements. Adding this coating will ensure that the wall stays solid for many years, and will improve the longevity of any cobblestone wall that you have in your garden.
Step 1 - Clean the Cobblestone Wall
Before you can place any sealant over the surface of your cobblestone wall, you will need to make sure that it is completely clean. This is vital, as most sealants are completely clear, and will pick up traces of dirt and debris and highlight them, rather like varnish on doors or window frames. Take a soft brush, and run it over all of the cobblestones, both on the top and the sides. Inspect the wall for holes or chips which might affect how the sealant forms on the wall, and use caulk to fill in any large areas. Leave this to dry before continuing.
Step 2 - Prepare the Sealant
You should be able to purchase a suitable waterproofing sealant from your local home improvements store. This type of coating is flexible and bonds with most surfaces, so you will likely be able to get one that is suitable for use on a cobblestone wall. Take the sealant, and pour it into a suitable tray. A paint tray can be used, but if you don't have one, or don't want to use it for this coating, you can also use plastic food trays.
Step 3 - Add the Sealant
Take your small paintbrush, and dip it into the sealant. You should not take too much onto your brush, as this can easily cause the sealant to run down the wall, leaving a residue behind. Using the brush, put the sealant onto the cobblestone wall in even, steady strokes. You should apply the coating slowly so that you cover all of the wall without gaps. You should also push the brushes down between the cobblestones in order to seal the wall completely. Remember that any small areas which are not covered by the waterproofing could be vulnerable to water damage.
Step 4 - Add a Second Coat
Leave the first coat of your sealant to dry overnight, protecting the wall using a suitable tarpaulin or tent. Once the sealant has dried, you can then add a second coat, or apply some self-polishing wax to the surface of your cobblestones as the latter will give them an extra shine. Remember to check the coating regularly, and replace it with a new coat every 12 to 18 months.