How to DIY a Natural Stone Interior Door Threshold

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Either you are planning ahead or your new floor has hit a point where your problem is a difference in floor height in between rooms. Now what? Do you go for some sort of traditional metal, laminate or wood threshold?

Perhaps, but maybe not because you…

• Have an eye for detail.
• Are looking for a unique solution with natural stone.
• Want an interior door threshold with a type of stone you can’t find on the shelf at any store.*
• Want to thoughtfully use some of the leftovers from another part of the room, incorporating your previous choices (tile used on the countertop, shower stall, bathtub surround,  backsplash, etc.) into another part of the room.
• Need to cover more subfloor than a normal width threshold.

No, this wasn’t an oops. We opened up the width of the bathroom door. Being that it is the door to the only bathroom in the house and it was only 20 or so inches wide, we tried to widen it as much as possible, which meant the hardwood no longer extended the entire width of the new door frame. Custom width stone interior door threshold to the rescue to cover that up! Fabricating your own threshold gives you flexibility, covering whatever measurement is necessary!

Most importantly, you are looking for that extra pizazz!

A stone interior door threshold is the perfect solution for you even if your floors are the same height on both sides of the threshold.

Note: this is specifically for tile or larger pieces of granite, travertine or marble. Porcelain or ceramic tile do not have the same color throughout so the following technique is only for natural stone.

Fabricating and installing a custom DIY stone interior door threshold is a possible solution for you!

In my case, I definitely hit the problem more than planned…

The original floor was subfloor, plywood, and then laminate. Of course, we ripped out the laminate.

There was also an old gold metal interior door threshold between the kitchen and living room that did not exactly match with the new color scheme or style.

Unfortunately, after removing the laminate we found issue after issue. There was no plywood or subfloor by the time all the rotten wood was removed. By the time we rebuilt the subfloor and plywood and then added Hardibacker and tile we were a full tile and a little of the Hardibacker thickness taller than the wood floors in the living room.

The traditional route would have worked for the new threshold, but I had an idea. What if I fabricated a series of granite pieces to go across the entire width of the doorways and mitered the front edge going down into the living room at a 45 angle?

Key point: this has to be preplanned somewhat. I discovered the difference in height only after I laid the Hardibacker. It was at this “Oh $hit” moment when I had the idea and pre-planned by leaving room for the threshold BEFORE laying the rest of the tile.

Notice the pencil lines on the Hardibacker.

As you can see the field tile goes to the penciled in line for the threshold.

Choosing to fabricate stone interior door thresholds could not have gone better.

• It solves the height problem.
• Natural stone is very attractive!
• It ties the flooring in with the rest of the room since the same kind of granite is used on the countertop and highlights in the backsplash.
• Since it stands out guests look at it and notice the difference in height.

The only downside: it adds additional time on site to fabricate the miter on the wet tile saw and polish the new edge. However, it is well worth the effort and makes the first step into the room a glamorous one!

Here’s how to go about fabricating a stone interior door threshold:

First measure off all the doorways where you plan on fabricating a stone threshold. Gathering all the materials and fabricating them all at once will save you a lot of time. For example, I measured off each threshold for all the rooms getting this treatment: the two interior entrance to the kitchen from the living room as well as the doorways of the bathroom and laundry.

Really consider adding a stone interior door threshold in any room that needs a little extra pizazz. The more unexpected the room–like the laundry room–the better the WOW factor!

How surprised are you from looking at this laundry room floor?

Next, figure out how many full width and partial pieces are needed. Your design really drives this number. You could put for a grout line in the middle or a full piece in the middle. In either case, symmetry is key.

As you can see here I opted for a full piece in the middle. My logic is there will be higher traffic in the middle. Putting weight in the middle of a solid piece limits weight changes on a grout joint. If there is any flexibility in the subfloor the grout is more likely to crack (of course, this does not apply to you if you have a slab foundation). Second, shoes with incidental rocks and dirt lodged in shoe tread grinds into grout faster than the stone.

Once you determine your count you need to calculate the size of the outside partial pieces. Make sure you take the size of your desired grout line into account.

This grout line.

The rest of the steps are very similar to fabricating a bullnose edge as previously outlined here. Many of the tile trim tips/ lessons learned are also applicable.

Scrounge through all your desired color stone scraps before cutting into a brand new tile. It is yet another reason to save your scraps! In my case, there were some leftovers from tiling the countertops and diamonds on the backsplashes. Any piece that is a full twelve inches is pure gold. It is much easier to match partial pieces with your bone pile as determined by the measurements in the previous step.

Now it is time to pull out your wet tile saw! Set it up and cut it the width of the threshold. Keep the size of the grout line–the one in between the other same height flooring–in mind when coming up with your measurement.

This grout line.

Once all your pieces are cut lengthwise it is time to miter one edge. Adjust the wet tile saw at a 45 degree angle (or 33 if you want a more gradual slope) and cut one of the long edges on each piece of stone.

Break out your variable speed grinder and polishing pads. As you go through each grit of pads make sure you do not over polish past the finish on top of the stone unless that is the look you want.

Depending on your tile you may need to do a small miter on all the other edges. It depends…really, check out the tile trim tips! The part on “Sometimes you need a small polished miter.” is exactly what I’m talking about here so your grout lines look perfect and match with the field tile.

Set the newly polished stone pieces into threshold just as you would any other field tile.

Other considerations when choosing to fabricate a natural stone interior door threshold:

Depending on your design adding a different kind of tile for your threshold may or may not be one too many. For instance, if I were to put in a threshold for my master bathroom I would be cautious with throwing in yet another stone/ tile/ color in there. There is porcelain tile for the floor already in place. The counters and shower curb are all Blue Pearl granite along with some other details. The shower floor is a cut pebble. The walls are a very active grey travertine. A white marble could work for the threshold, but there are already another four kinds of tile going on in there. On top of all that, I have a whole bunch of scrap Blue Pearl from completing both the master bathroom and the shared bathroom. I would probably opt to use the Blue Pearl overage and install a granite threshold.

Too many tile choices can make a design look too busy. One more for the entry and closet doorways could make this bathroom, or it could detract from the overall look and feel.

In the years since completing the initial remodel in the many photos above, I have learned about the different Schluter interior door threshold edge products. Their purpose is to protect the front edge of the stone transition with a metal transition. My way attempted to do this with the 45 miter. Since mine is just stone it is more prone to chipping. In my defense it has outlasted a family of five in high traffic areas. The kitchen certainly is a busy place in any household and with only one bathroom, the bathroom threshold is also constantly tested. YMMV!

The Schluter products are definitely high quality. Quick and easy to install, they do provide a protective edge in a variety of colors. I recommend checking them out before you go through the effort of fabricating your own leading edge if you are on the fence with this project.

Another solution is a cross between fully fabricating your own threshold and putting a Schuter profile on the edge of the field tile. If you cut the pieces down to size without the mitre and put a Schluter Edge on the sloped side of the transition. This way you still have the beautiful stone transition, but you do not have to go through the extra effort of the miter or polishing the edge.

*You can buy a prefabricated natural stone interior door threshold at flooring stores. Only engineered marble is sold at big box stores like Home Depot. Real marble, a light color travertine, and black granite are the vast majority of the choices sold at more specialized flooring stores like Floor and Decor. If you want something different you are left to your own devices or you can work with a fabricator to get your custom look.