Good insulation plays a big role in creating an energy-efficient and comfortable living environment for your family, and investing in it can be beneficial and practical to homeowners. It helps keep your home warm in winter and cool during the summer by resisting airflow or drafts and heat energy losses through surfaces of the house. Aside from cutting energy bills, it decreases the use of energy, which also makes your home ecologically sound.

One of the ways you can enhance your home’s overall energy efficiency is to insulate your doors, and if you currently have hollow interior doors installed in your home, there’s no need to fret.

In this article, we’ll walk you through the relevant information you need to know about hollow interior doors, including their pros and cons. We’ll also introduce you to various comprehensive methods you can do at home. 

What is a Hollow Interior Door? 

A hollow interior door, also known as a hollow-core door, is comprised of a honeycomb cardboard core enclosed by a veneer wood or fiberboard, acting as its interior. Its edges are commonly made of Medium-density fibreboard (MDF), which is an engineered wood created from wood fibers of softwood or hardwood. 

Due to their lightweight core, hollow interior doors are a good door alternative for homeowners who prefer a more budget-friendly material compared to solid core doors.

They are excellent doors to use in parts of the house, such as pantries, kitchens, closets, bathrooms, and playrooms.

Pros and Cons of Hollow Interior Door

Hollow Interior Doors are much more affordable than solid wood doors, which makes them a good door choice for budget-conscious homeowners planning to replace or upgrade a large quantity of old interior doors.
The average price of a hollow interior door ranges from $50 to $100, a much cheaper price than solid wood doors that costs around $200 to $700, on average. 
Hollow interior doors also provide ease of handling and installation due to their lightweight material, which can be a huge benefit DIY homeowners such as yourself. They also offer minimum privacy and basic thermal insulation.
A hollow interior door is also much stable, as it is less susceptible to warping, expansion, or contraction. They are also available in a wide range of decorative choices.
Hollow Interior Doors are for interior use only because they easily damage when impacted with adequate physical force. They provide less security compared to solid wood doors, making them an unsuitable choice for exterior door applications. Intruders can readily break through a hollow interior door using a hammer or any type of tool. 
Once damaged, they are also much harder to repair and don’t offer weatherproofing features as they are not specifically designed for exterior use.
Moreover, hollow interior doors provide minimal noise reduction properties due to their honeycomb cardboard core, which tends to allow sound frequencies to pass through.
Read the comprehensive guide on how to insulate the hollow interior door to improve the efficiency of its thermal insulation properties. 

How Do You Insulate A Hollow Interior Door?

There are two common methods you can do to insulate a hollow interior door—glue foam insulation sheets externally and fill the hollow-core door with spray foam insulation.

Glue Foam Insulation Sheets Externally

Gluing foam insulation sheets externally is an easier and cheaper method. To do this, you have to measure the hollow interior door’s height and width to know the estimated pieces of the foam insulation sheets you’ll use.

Next is to cut a portion of the foam insulation sheet using a craft knife according to the height and width measurements. You can glue pieces of the foam insulation sheets together to form a large insulation board. 

Then, apply a layer of epoxy adhesive to the surface of the door, where you will attach the foam board insulation. It is preferred you attach it where it is the least noticeable.

After applying the epoxy adhesive, press the foam board insulation and keep it for a minute or two until the adhesive sets. Before you decorate the door, let the epoxy adhesive cure for about 24 hours.

Fill the Hollow-Core Door with Spray Foam Insulation

The first thing you need to do is to drill holes, for about every foot, in the sides, top, and bottom parts of the door. Start drilling from the bottom and work your way up.

Make sure that the holes should be able to fit the straw of the spray foam, or you can make the holes a bit bigger than the tube. Next is to start injecting the spray foam from the bottom holes and let it expand.

You can use a long straw or tube to better fill the door much easier. Take note that when you finally see excess foam coming out of the holes, that means the cavities of the door are already full, or the foam has already expanded.

You can also try to remove the doorknob and lock mechanism temporarily to check the progress of the expansion of the foam inside. Don’t forget to wipe the excess foam and cover the holes with tape or a strip of vinyl. 

This method is more expensive than gluing foam board insulation because you will have to use large quantities of spray foam until the cavities of your door are filled, especially if your doors are large.

Before You Insulate Your Interior Door…

Hollow interior doors are gaining ground as an interior door choice for modern new homes nowadays. They are cost-effective, lightweight, easier to install, and are less susceptible to warping, expansion, or contraction than solid wood doors.

And if you’re in the process of choosing to insulate your hollow interior doors, doing it yourself can be a more convenient and less expensive option than hiring a professional.

Use the above two comprehensive steps we provided for you on how to insulate your hollow interior doors properly—you can either attach or glue the foam insulation sheets externally or fill the hollow interior door with spray foam.

Editorial Contributors
avatar for Matt Greenfield

Matt Greenfield

Matt Greenfield is an experienced writer specializing in home improvement topics. He has a passion for educating and empowering homeowners to make informed decisions about their properties. Matt's writing focuses on a range of topics, including windows, flooring, HVAC, and construction materials. With a background in construction and home renovation, Matt is well-versed in the latest trends and techniques in the industry. His articles offer practical advice and expert insights that help readers tackle their home improvement projects with confidence. Whether you're a DIY enthusiast or a seasoned professional, Matt's writing is sure to provide valuable guidance and inspiration.

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