Semi Mortised

Semi-Mortised Automatic Door Bottoms

Semi-mortised automatic door bottoms are designed to provide a retractable seal beneath a door while keeping the casing partially recessed into the door. The casing is installed into a rabbet or prepared section of the door, allowing the exposed portion to sit flush with the door face for a cleaner installation than a fully surface-mounted automatic door bottom.

When the door closes, the automatic mechanism lowers the seal to close the gap underneath the door. When the door opens, the seal retracts, helping prevent the seal from dragging across the floor during normal door operation. This makes a semi-mortised door bottom useful for applications where both sealing performance and a less visible installation are important.

Benefits of Semi-Mortised Automatic Door Bottoms

Semi-mortised automatic door bottoms can help address gaps beneath doors where protection against unwanted air, light, sound, dust, and other infiltration is required. Depending on the product selected, available options may provide different levels of sound control as well as fire, smoke, light, and air sealing.

• Partially concealed installation: The casing is recessed into a rabbet in the door while remaining accessible for installation and maintenance.
• Retractable seal: The seal drops when the door closes and retracts when the door opens.
• Sound control: Certain models are designed for applications where reducing sound transmission through the bottom door gap is important.
• Air and light control: The seal can help close gaps that allow air or light to pass beneath the door.
• Fire and smoke applications: Select models are available with fire and smoke ratings. Always check the individual product specifications for the applicable rating.

Semi-Mortised vs. Surface Mounted Automatic Door Bottoms

The main difference between a semi-mortised automatic door bottom and a surface mounted automatic door bottom is how the product is installed on the door. A surface mounted model is installed directly onto the door, while a semi-mortised model is recessed into a rabbet or prepared area of the door with the casing positioned flush with the door face.

A semi-mortised installation can provide a cleaner appearance while still allowing the door bottom to use an automatic drop mechanism. The installation method should be selected based on the door construction, available space, installation conditions, and product specifications.

Where Can Semi-Mortised Door Bottoms Be Used?

Semi-mortised automatic door bottoms can be used on doors where the bottom gap needs to be sealed without using a fully exposed surface-mounted unit. They are suitable for a range of commercial and architectural door applications, depending on the specific product.

They can be used with hard flooring and, where appropriate, carpeted areas. When the floor covering does not provide a suitable surface for the automatic seal, a door threshold can provide a defined surface beneath the door bottom.

Semi-Mortised Automatic Door Bottom Installation

Semi-mortised automatic door bottoms require preparation of the door so that the casing can be installed into a rabbet or recessed section. Because this involves modifying the door, installation may require the door to be removed depending on the door construction and the specific product.

Before installation, check the product's required dimensions, mounting method, seal drop, door width, and clearance requirements. Proper measurement is important to ensure that the automatic seal reaches the intended sealing surface without interfering with normal door operation.

For help determining the correct product and installation style, see Which ADB is Right for Me and How to Measure for an Automatic Door Bottom.

Choosing a Semi-Mortised Automatic Door Bottom

When selecting a semi-mortised automatic door bottom, consider the following factors:

• Door construction: Confirm that the door can accommodate the required rabbet or recessed installation.
• Door width: Select a product that matches the width and requirements of the door.
• Gap beneath the door: Measure the actual gap to determine the required seal drop.
• Floor surface: Consider whether the seal will contact hard flooring, carpet, or a threshold.
• Sealing requirements: Determine whether the application requires sound, air, light, fire, or smoke control.
• Installation space: Check the manufacturer's dimensions to confirm that the automatic door bottom will fit correctly.

For additional information about automatic door bottom types and applications, visit About Automatic Door Bottoms.

Frequently Asked Questions About Semi-Mortised Automatic Door Bottoms

What is a semi-mortised automatic door bottom?

A semi-mortised automatic door bottom is a retractable door seal that is partially recessed into the bottom of a door. The casing is installed into a rabbet or prepared section of the door, allowing it to sit flush with the door face while the seal automatically drops when the door closes.

What is the difference between semi-mortised and mortised automatic door bottoms?

A semi-mortised automatic door bottom is installed into a rabbet or partially recessed area of the door, while a fully mortised automatic door bottom is installed into a deeper channel within the door. The appropriate installation depends on the door construction and the specific product.

Are semi-mortised automatic door bottoms good for soundproofing?

Some semi-mortised automatic door bottoms are designed for sound control and can help reduce sound transmission through the gap beneath a door. The actual sound performance depends on the complete door assembly and the specifications of the selected product.

Can a semi-mortised door bottom be used on a carpeted floor?

A semi-mortised automatic door bottom can be used with carpet in certain applications. When necessary, a door threshold or saddle installed directly beneath the door can provide a suitable sealing surface. Check the product specifications for the recommended floor conditions.

Do semi-mortised automatic door bottoms provide fire and smoke protection?

Some models are available with fire and smoke ratings. Not every automatic door bottom has the same rating, so the individual product specifications should be checked to confirm whether it is suitable for a specific fire or smoke control application.

How do I measure for a semi-mortised automatic door bottom?

Measure the door width, the gap beneath the door, and the available space for installation. The required measurements can vary by product, so review the manufacturer's specifications before ordering. See How to Measure for an Automatic Door Bottom for additional guidance.

Does a semi-mortised automatic door bottom retract when the door opens?

Yes. An automatic door bottom is designed to retract its seal when the door opens and lower the seal when the door closes. This allows the seal to close the bottom gap without continuously dragging across the floor as the door moves.

Do I need to remove the door to install a semi-mortised automatic door bottom?

Installation requirements depend on the door construction and the specific automatic door bottom. Because a semi-mortised model requires a rabbet or recessed area, the door may need to be removed to complete the installation properly.

Select a semi-mortised automatic door bottom above to compare available products, specifications, sizes, and sealing options. If you need help finding the right product, call Trademark Hardware at 845-338-1300.