Prehung vs Slab Door: What are the Differences?

What’s the difference between prehung and slab doors?

The difference between pre-hung doors and door slabs is obvious if you’re familiar with the terminology. Prehung doors are made as a set which includes a frame and slabs are just the door without the frame.

In this article, we’ll explain when you should choose prehung doors and when slabs are a better option.

Parts of a Prehung Door

A prehung door is one that is already assembled. The door unit includes the slab on hinges connected to a frame with casing around it.

The prehung door unit has three main parts:

Frame
Door
Hinges

Mortises, the threshold, weatherstripping, and the pre-cut hole for the handleset may not seem as noticeable but they are important because they complete the door and make it easier to install.

Mortise

A mortise is a type of cut that allows something else to fit into place usually locking together. In this case, we’re talking about mortise cuts for the door hinge.

On the prehung door, a mortise has already been cut and the hinges are installed. With a door slab, a mortise has to be cut so that the hinge is mounted flush with the jamb and the door, this allows the door to close properly.

A mortise can be cut with a router or by hand with a chisel and hammer.

Threshold

Thresholds are installed on exterior doors. The threshold bridges the gap between the ground and the bottom of the door and helps improve the energy efficiency of a door.

Not only does the threshold keep drafts from entering the home from beneath the door it also guards against pests and water. Generally, you won’t find thresholds on interior doors because weather and pests aren’t a concern inside.

Weatherstripping

Weatherstripping keeps the door weathertight, again, this is a concern with exterior doors. Prehung doors are typically already weathertight and fitted properly into the door frame. If you try to install a slab you’ll want to make sure you add durable and efficient weatherstripping around the door.

Pre-cut hole for the handleset

Prehung doors will arrive with a pre-cut hole for the handleset, this isn’t always the case with slabs.

If you ordered a handleset from the same manufacturer that made the door unit, the handleset won’t be pre-installed. In fact, handlesets are sometimes sold separately and some manufacturers design their doors to only accept certain types of handlesets and locks. You’ll want to know this before you purchase a handleset from someone other than the door manufacturer.

Pros and Cons of Prehung Doors

Pros

The door is ready to install
Speeds up the installation process

Cons

May need minor adjustments to fit properly in the rough opening
Is heavier than slabs and more difficult to manage alone
More expensive than a slab

Parts of a Door Slab

The slab. (Haha) But seriously, as I mentioned above, if you want a door slab that’s really all you’re getting. This is a great choice if you’re looking for something super custom and the existing door frames are in good condition, it just takes more work to get the door ready to attach to the frame.

Pros and Cons of Door Slabs

Pros

Less expensive than a prehung unit
Allows design flexibility

Cons

Requires more work, including extensive carpentry
Costs additional time and money to get it ready and installed

So, when should you choose prehung and when should you choose a slab?

Choose a prehung door if:

The door’s rough opening is exposed (new construction or remodel), especially if there are multiple doors that need to be installed. A prehung door will save installation time because you won’t have to build the frame from scratch.
You need to replace an exterior door. Exterior doors are part of the building’s envelope and should be energy efficient, you’ll get the best results with a door that’s manufactured for efficiency.
The existing door frame is rotted or damaged. You’re more likely to run into this problem with exterior doors, especially if the door is original to the house. A damaged frame shouldn’t be reused because it will continue to waste. Installing a prehung door allows you to take out the existing frame and inspect for further damage that may also need repair before installing the new door.

Choose a slab if:

The frame is in good condition and the door slab is being replaced with another of the exact same size.
You have a vintage door that you want to repurpose in your home. A project like this may require rebuilding the door frame but it can be done.
You are replacing interior doors and don’t mind extra work to save some money on material. If this is a DIY project, new slabs are easier to work with than antique or salvage doors.

If you decide to go with a new slab you can find them at big box stores or lumberyards.

For prehung doors, you can work with a door dealer or find a door at a big box store and find a contractor. If there is a specific brand that you are looking for you can visit the manufacturer’s website to see what is offered and then find a trusted dealer and installer directly through them. The benefit of this is that you know you’re getting the exact type of product that you want and having it installed by experienced professionals.

To learn more about some door brands check out our related posts below or visit our Doors product offerings.