What is the Difference Between Pre-Hung vs. Slab Door?

At Riverside Millwork Group we provide pre-hung interior doors to all of our customers who ask. Now we are writing this piece to let you know what the difference between a pre-hung and a non-pre-hung door are at Riverside because we differ from our competitors in what we offer. Once we break down the difference, we will explain why we do it this way.

Interior Slab Door

When looking at whether a door is pre-hung or not, we differentiate the two by a slab door vs. a pre-hung door. So, what is a slab door? Well as it sounds a slab door is the rectangular component of the door that is much like a slab of wood. This slab door would not have the mortise carved out for the handle, nor would it have the hinges carved out. A slab door can be used to replace an existing door without changing out the casing of the door, but the cuts for the hinges and handle will still need to be done prior to installation. The biggest difference between a slab door and a pre-hung door is having the raw materials ready to hang your door and all the work to make the door able to hang must be done by the person installing the door.

Most homeowners and installers prefer for the door to be pre-hung as many tools are required to carve out the door mortise and the hinges which can take away from installation time. So let us breakdown what a pre-hung door can include!

Big Box Store Interior Pre-Hung Door

Pre-hung door from a big box retailer

When you go to a big box retailer, they will typically sell you a pre-hung door that is already attached to the frame around the door and ready to be installed into the doorway. When purchasing a pre-hung door with this approach you are relying on the inlet you are placing the pre-hung door into, to be a perfect match with the door size you have purchased. In most homes this can turn into a very difficult process as the opening between the studs is uneven and balancing the door to open and close properly for long term use can become difficult. There is nothing wrong with this approach, but at Riverside we strive to continuously improve so we chose a different way of providing a pre-hung door to our customers.

Riverside Pre-hung Interior Door

At Riverside Millwork Group we work with 3 different types of customers. We offer product to home builders constructing brand new homes, those renovating existing homes, and homeowners looking to replace doors in their home.

Since we work with both new construction and renovation, we wanted to offer a pre-hang solution that worked on all door types and based on our carpentry experience, would provide the best installation and result for the homeowner. In the industry we refer to our way of providing a pre-hung door as a knockdown pre-hung door solution for your reference.

This means, when we sell you a pre-hung door, we are selling you the interior door slab that is then carved at the hinges and mortises pre-carved for you for where the handle will be, along with jambs that are also machined to match the pattern of the door.  We offer a knockdown pre-hung solution to our clients, as it can benefit you in the following ways:


At Riverside we produce a number of custom interior wood doors for our clients. Sometimes this is due to the size of door they are requesting not being a standard stock door and other times this is due to the material and deign of the door. By providing custom doors, we are better suited to have a knockdown approach to a pre-hung door, this way you can choose the frame material to align with the quality of your doors and other millwork in the home. Most big box stores will only sell pre-hung doors with an MDF frame, where we will sell you a knockdown solution with any frame you want from MDF to poplar. This also means you have the option to choose how many hinges you want on the door(typically 2 or 3) and what you want those hinges to be. While satin nickel or black hinges are the most popular options, you shouldn’t feel as though you need to stick to those when you buy doors from us. We can work with you to create door solutions that add design elements to the home and not detract from them!


In addition to the appearance of the frame of a knockdown door, made with a wood frame, being of higher quality, the higher quality jambs will also be the sturdier option over time. When installing doors, you invested in, and intend to keep for 15-25 years, a higher quality option for the frame is the way to go.


For carpenters(installers of interior doors), having the doors ready with hinges attached and the opening for the lock already carved out, the time to install a new door is reduced as well as the tools required to install the door since the carving of the hinges and lock can be more, which should bring the cost of installation on-site down.

In existing homes, having a knockdown approach to a pre-hung door can also make it easier to work with existing openings of a doorway which have likely shifted over the years of the home being built. Compared to a slab door, having a pre-hung door will save you lots of time, and because of our automated setup the cost to have the doors machined by us is almost always less than having it machined on site by the installer.

Lastly, having a knockdown pre-hung door vs. the big box store variation of a pre-hung door will allow the carpenter installing the door to ensure a high standard of quality on the finished install and be more in control over the end result.

Riverside Pre-Hung vs. Big Box Pre-Hung or Slab Door

If you’ve read through all of these explanations and you’re still unsure which option is best for your upcoming or current project, consider a few things:

1.      Who is installing the new doors –have they been consulted?

2.      Do you have a budget you’re looking to stay within?

3.      Is there a look you’re trying to achieve with the door style?

4.      How long do you plan to have these doors in place?

5.      Is the frame staying on or will it be replaced too?

The approach we are trying to take with the Riverside Pre-Hung Knockdown solution is to have our doors set up in a way that it will save cost and time during installation, but it still gives our clients the opportunity to customize and install them without jeopardizing the quality of the final product.

If you’re looking to tackle a simple door swap out without removing the casing yourself then we can retrofit the new doors to the specs of your old doors, have the hinges installed at our shop, and all you have to do when you receive them is take the old hinge pin off and put the new one in, an action that can be done by any homeowner and it doesn’t require a professional installer.

If you have a general contractor you’re working with, it is best to ask them what they prefer. While most will love a knockdown pre-hang solution for installation. Some may prefer a slab door depending on the project so you are always best to ask their opinion on this before moving ahead with a purchase.

If you are doing this project yourself and would like some additional guidance, the team on our order desk have helped thousands of customers with their doors, and can help guide you through the process.

The Alternative Approach

Lastly, not comparing to our traditional pre-hang approach to doors, we offer an alternative approach to pre-hung doors for installation that many of our high-volume builder clients love to have on-site.

For those builders looking to further improve the efficiency of installing doors on site, we recommend what we call our U-channels for the frame of the door. If you’re interested in hearing more about this option, check out our blog on U-channels to learn more.