How to Seal Door Gaps and Save Energy

How to Know If Your Doors Are Properly Sealed

Take a closer look at the inside and outside of your doorframes to see if you have any gaps allowing air to come through. Properly sealed doors have caulk in any areas where unwanted air or moisture could enter your home.

A good way to test if your doors are properly sealed is to shut them on a windy day, turn on your exhaust fans, and light an incense stick. Bring the lit stick to each door, and if a draft is present, you’ll see the smoke move with it. This method can help identify areas to seal around doors and windows before winter. 

Why You Should Seal Your Doors 

You wouldn’t leave your window open in the dead of winter, or during a sizzling summer heat wave, yet many people never think twice about the insulation around their doors. Let’s review the benefits of sealing your doors:

• Decreased energy costs: Drafty, poorly sealed doors can let in cold air during the winter and hot air during the summer, dramatically increasing your energy costs year-round, no matter where you live. 

• Increased home insulation: A 1/8-inch gap under a door can let in as much air as a 2 1/2-inch hole in the wall. Sealing these gaps will dramatically increase your home’s insulation.

• Blocks pests from coming inside: A gap ¼ inch wide is also large enough for furry pests like mice to enter and take up residence. A little insulation is nothing compared to the cost of lost and damaged property you may lose through a pest infestation, let alone the cost of an exterminator.  

Cost to Seal Door Gaps 

The cost of sealing door gaps can vary dramatically, depending on how much insulation needs to be added and which materials you have on hand. If you do all the above steps, supplies could cost between $50 and $160, but not everyone needs to insulate inside the walls around their doors. If your doorframe is OK and you only need to add weather stripping and a door sweep, the project could cost as little as $10 to $45.

Hiring a pro to add new weather stripping costs between $130 and $450, depending on the material you choose and the number of doors and windows. A door professional can also install weather stripping in challenging areas, including around doors with automatic door sweeps. 

DIY vs. Hiring a Pro

If you don’t feel comfortable or don’t have the time to tackle these projects yourself, you can hire a pro. You can also do some of the tasks yourself and bring in an expert for other parts of the project. For example, you may be fine installing a door sweep, but if you don’t know how to replace weather stripping on the door, you can hire a professional to handle the rest.

How much you’ll save on sealing door gaps depends on what needs to be done and which supplies you already have. For example, hiring a pro to remove and replace door casings to add spray foam insulation costs between $130 and $225. If you DIY the project, you can get door casings and spray foam for under $35. Other door insulation projects are even less costly and time-consuming, so they may be worth the time and effort required to DIY.

Note that while it’s a good idea to insulate any front door, you’ll have to replace or repair it if it’s old or damaged. Modern door materials are more secure and better insulated than older ones—especially older doors with single-pane glass panels. If your door is older or in poor shape, fix or replace it yourself or contact a local door repair expert who can determine whether it’s better to repair or replace it.