The homeowner wants to transform this plain brick fireplace wall using stone or river rock. (Martha Sullivan)

I have a large painted brick fireplace that we want to resurface with real river rock or something similar. My husband and I are not interested in veneer or ledge panels. Will the mortar be strong enough to hold the stones? Do we need to use a special mortar? Or is an additive helpful? What kind of masonry expert can transform this dated brick fireplace wall of mine and do the job right? — Martha S., Lewes, Del.

It’s always exciting to embark on a major interior remodeling job like this. Based on the fine photo you provided, you’re about to change the look of the room in a major way. If you choose the correct stone, the room will become warmer and friendlier.

The first thing I think you should do is to go to my AsktheBuilder.com website and read a detailed past column titled “Adhesive Chain.” Just use the search engine. When you understand the concept of how layers of things that stick to one another depend on the strength of each layer, you’ll know that it’s vital this job be done the right way.

Mortar is quite strong, but I’d never depend on it to lock the new layer of stone to the painted brick. You need to mechanically fasten the stone to the brick using corrugated metal strips and masonry screws that are driven into the brick. These metal strips are often referred to as wall ties by masons, remodelers and builders.

They are used on just about all brick veneer homes to keep exterior brick walls from falling to the ground. In a frame home, the wall ties are nailed to the wood wall studs with hot-dipped galvanized nails that should penetrate into the wall studs at least 1½ inches.

Before you choose the stone, I urge you to look at large samples of it on a panel at a showroom or purchase a small amount of the stone and bring it home. If possible, you want to stack the stone next to your fireplace and look to see if you like the size and the color of the stone. Some stones are easier to dry stack than others. If you’re going for rounded river rock, it’s going to be very hard to dry stack them.

Real stone is very heavy. Some can approach 150 pounds per cubic foot. The brick you now see around the fireplace undoubtedly is bearing on a masonry foundation, or it could be on a concrete slab. Your new stone must be supported the same way. It’s unacceptable for it to rest on a wood floor, if that’s the case in your home.

If you have only a wood subfloor, then you’ll have to install a steel angle iron that transfers the weight of the new stone to the masonry foundation under the brick. This angle iron will be invisible once the job is complete, and you can help make it so by painting it a color that matches the mortar before you install the stone.

The steel angle iron needs to be anchored to the brick with half-inch expansion anchors that penetrate a minimum of 4 inches into the brick wall. To be safe, a structural engineer should specify the size of the angle iron, the size of the anchors and the spacing of the anchors. You never ever want to hope a structural solution is going to work. Investing in a structural engineer’s advice is the best money you can ever spend on a job.

You don’t need to use any special additive in the mortar because the mortar is not going to connect the new stone to the brick wall. You may want to consider using a one-to-one mixture of hydrated lime to Portland cement as the binder with the sand you use. Hydrated lime is a magical material that gives the mortar more adhesive qualities; it’s usually easier to work with and it has self-healing characteristics if the mortar should ever develop tiny cracks.

Finding a pro to do this job will require a small amount of work on your part. The pros are out there, and most of them rarely advertise. Most pros have a backlog of work, and the last thing they need to be doing is answering phone calls from advertising. Pros often get lots of their work from referrals and word of mouth.

Professionals almost always purchase the best products. They know that material failures are the fastest way to drain profits and to create bad feelings with customers. For this reason, most pros tend to buy what they need at businesses that specialize in their trade. If I were you, I’d visit several places that sell stone and brick.

Visit these businesses mid-morning or mid-afternoon. This is when they are usually slowest and the manager or owner can speak with you. You want to quiz the general manager or owner; ask them the following:

• Can you give me the names of masons who have been buying from you for more than 15 years?

• Who are the masons who always buy the best products you sell?

• Who are the masons who pay their bills before they’re due so they get the 2 percent discount?

• What’s the short list of masons you’d get bids from to work on your own home?

Once you have the names of the contractors who fit the above profile, you have the list of the best masons in your city or town.

Need an answer? All of Tim’s past columns are archived for free at AsktheBuilder.com. You can also watch hundreds of videos, download Quick Start Guides and more, all for free.

Catch up with some of Tim’s previous columns:

What you need to know before knocking down that wall in your home

Will exposure to rain hurt home’s framing lumber?

How to redirect water around a damp garage