4 Simple Ways to Seal a Drafty Door

Sealing gaps between a door and frame with weatherstrip, astragals and gasketing is a simple solution for reducing heat transfer.

In a deep winter freeze or scorching summer heat, your building’s HVAC system works overtime to keep tenants, employees and customers comfortable. 

Climate control is a major operating expense for building owners, so it’s important to reduce heat transfer by selecting the right building materials and eliminating drafts.

Doors represent a problem for temperature regulation, since they are basically big holes in your building that constantly open and close, allowing air to transfer between the inside and outside.  Insulated doors and thermally broken frames are used at exterior openings and work well to reduce heat transfer from one face of the door or frame to the other.

But what about drafty doors that leak air around their perimeters even when they are closed? 

There’s good news:  simple-to-install gasket and weatherstrip can help seal a drafty door, keep occupants comfortable and keep more money in your pocket.

(Note – extreme gaps or alignment issues should be addressed before moving ahead with sealing.)

Adhesive perimeter gasketing

Adhesive gasketing is very simple to install and can be a very effective, low-cost solution for a drafty door. 

These gaskets are usually made of silicone or other flexible material and are shaped like a teardrop or set of fins.  They are applied around the perimeter of the door frame and are designed to compress when the door closes, creating a tight seal.

Not all gasket is equal.  When selecting a product, pay attention to the fire rating requirements at your opening.  Some products offer features like anti-microbial coating, mold resistance, or sound protection. Do some research so you choose the best option for your door.

Also, pay close attention to the installation instructions.  For most adhesive products, it is critical that the frame surface is cleaned with alcohol and that any paint on has fully cured before you install the gasket.  Nothing looks quite as shoddy as gasket drooping into an opening.

Aluminum Weatherstrip

This is another solution for the perimeter of an opening that is more robust, but a bit trickier to install, than adhesive gasket.

Aluminum weatherstrip is installed on the frame stop around the push side of the opening.   The aluminum housing holds a softer material, like neoprene, silicone or pile, that creates a seal with the face of the door.

There are many different styles, sizes, materials and finishes to choose from. 

Some models of aluminum weatherstrip are spring loaded and adjustable, which can help overcome minor door alignment issues, ensures a tight seal along the entire length of the opening and allows for seasonal adjustments.

When selecting aluminum weatherstrip, pay close attention to the dimensions.  Ensure the housing will fit on your frame stop and remember that the height of the weatherstrip will reduce your opening size slightly, which could affect you if your opening is already narrow.

Also take note of any hardware that could be affected on the push side of your door.  If sizing isn’t properly coordinated, weatherstrip can interfere with door closer arms, stop-mounted strikes other hardware.   You may need to cut weatherstrip around these items and supplement your seal with adhesive gasket.

 

Pemko S88 Adhesive Bulb Weatherstrip
Pemko S77 Adhesive Fin Weatherstrip
Pemko perimeter seal
Stop-mounted Weatherstrip by Pemko
Crowder W15 Weatherstrip
W15 Weatherstrip from KN Crowder

Sweeps and Shoes

For the bottom of your door, sweeps or shoes are another simple fix that will stop a draft. 

Sweeps have an aluminum housing that is screwed into the door face.  A brush, neoprene or vinyl insert covers the gap between the bottom of the door and the ground.

Be sure to note the size of gap that you need to cover and get an appropriately sized sweep.  If you’re in an environment that is prone to freezing, try a brush sweep.  They are less prone to absorbing moisture and freezing to the ground.

Door shoes wrap around the bottom of the door in a U-shape, with the seal underneath the bottom edge of the door.  Select a model that fits the thickness of your door and gap beneath the door. 

If required, shoes and sweeps can be installed on a slight angle to accommodate an uneven gap at a sagging door or uneven floor. Just be sure they don’t interfere with the door swing by bottoming out on the ground.

These items will eventually wear down if they rub against the ground and will need to be replaced.  Some shoes are available with replacement inserts, while others may need to be completely replaced.

Astragals

For pairs of doors, drafts can often seep through the gap in between door leaves. The solution here is an astragal that runs vertically up the length of the doors.

Again, there are many styles and materials to choose from. 

Surface-mounted astragals are easy to install and are screwed into the face of the door.  Other models can be installed on the door edge for a more concealed look. 

To ensure a tight fit, adjustable spring-loaded astragals work well, but these can be trickier to install and align correctly. Magnetic astragals snap shut when the door is closed to create a tight seal.

Be careful to ensure your astragal won’t prevent your doors from closing or interfere with your latching hardware.  Installing a strip of brush astragal on each door leaf with a slight overlap is usually a safe bet.

 

Door show with drip cap
Door shoe with drip cap by Pemko
brush astragal
W25 brush astragal by KN Crowder
W40 Astragal
W40 Spring loaded adjustable astragal by KN Crowder

Trillium Wholesale offers a huge selection of weatherstrip, gaskets, astragals and sweeps from KN Crowder and Pemko, and they’ll help you choose the right one for your application.

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