How to over-grout a stone fireplace – an easy DIY

With a super brightening effect

Over grouted and whitewash fireplace makeover
(Image credit: Liz Hartmann)

Fireplaces can make quite the statement, but many seem dark and outdated. The idea of changing out the stone on a fireplace can seem daunting, but do not fret! There is another alternative... And knowing how to over-grout a stone fireplace can make a huge difference.

Transforming a dark, heavy stone fireplace to light and bright is a way to really lift a room, or even the entire house. The process isn’t as difficult as one may assume, either and as far as fireplace ideas go, it's very impressive.

I recently worked on our two-story stone fireplace in which we completely transformed it, elevating the space entirely.

The fireplace before

Brick fireplace hearth before over grouting

(Image credit: Liz Hartmann)

The over-grouting method

For this process, we used a method called 'over grouting,' and then we also whitewashed the fireplace stone afterwards.

The process of over grouting makes a huge difference in the appearance of the stone, and by adding mortar to the existing grout lines, you can brighten up the gaps between the stones which gives the entire surface a smoother look. 

The idea of mortar seems intimidating, but I can assure you that it is really as easy as working with wet sand like you did as a child in the sandbox...

What you'll need for an over-grouted stone fireplace: 

  • Mortar
  • Water
  • Electric mixing drill attachment
  • Piping bag
  • Gloves and eye protection
  • Paint and a large brush (if whitewashing afterwards)

DIY: Over-grouted stone fireplace

1. Mixing the mortar

Bags of mortar can be found at any home improvement store, and the mixing process is as easy as following the directions on the bag. Water and stirring are all you need to create the mix, but an electric mixing attachment for a drill is going to be the best bet at ensuring that the mixture reaches the appropriate consistency.

2. Application

Once your mortar is mixed, you will want to add it to a piping bag (similar to a baking piping bag, only bigger). The next part of the process is where you will really feel like a kid. Application is as simple as squeezing the mixture between the stones and smoothing it out.

Top tip: It’s important to remember that the process is called over grouting, so don’t be stingy when applying the mortar mixture. It is better to have too much as opposed to too little, and if there is overflow between the stones, you can always smooth it on to the existing stone.

There are all kinds of tools that can be used for this, but I have found that the best method is just wearing gloves and smoothing with your hands. This is one DIY project that will be a labor of love, but it is so worth it in the end. Slowly but surely, the fireplace will completely transform.

3. Drying time

Once the mortar is smoothed between the cracks and has had time to dry, a whitewash is a nice way to further brighten the fireplace.

By mixing water and paint together, a mixture called whitewash will form, which is just what it sounds like: watered down paint. Thinning the paint in this way will ensure that the color of the existing stone still shows through a little bit, providing dimension and keeping the natural stone appearance intact. 

The application process of whitewash is quite simple as well. Using a large brush, simply dab and brush the whitewash mixture on to the stone and brush away any drips that might develop. Again, this is really an incredibly easy process. The whitewashing shouldn’t take too long at all, and it usually starts beautifully transform its piece in no time at all.

The results

Over grouted and whitewash fireplace makeover

(Image credit: Liz Hartmann)

It is guaranteed that this two-step over-grouting and whitewash process will completely transform any fireplace that it is applied to. As a DIY alternative to completely ripping out and replacing the stone of an outdated fireplace, the time and effort will be worth it in the end.

It’s amazing what a statement the bright fireplace stone can make and brightening up a room in this way can easily transform the feeling of an entire home. Not only that, but every time you look at your beautiful accomplishment, you will know that lots of love went into your home. That’s really the beauty of DIY. So, get to grouting!