Foam Series: Layering Foam for Mattresses & Cushions

Item # X-HT-300495

If your next DIY project involves foam, such as a boat cabin mattress, a patio cushion or a new sofa, you have some options when it comes to the feel of your application. Depending on your comfort preference, you can customize how your cushion or mattress feels by layering different types of foam on top of each other. Let’s get into it!

Layering foam.

Before we begin, you’ll want to make sure you have an understanding of foam terminology. Specifically, the terms density and indentation force deflection (IFD) and how they relate to your project. Check out our blog “Foam Series: 5 Important Foam Terms to Know” (#300052XHT) to get acquainted with these. You’ll also want to make sure you know the foam products offered at Sailrite. It’s a good idea to read our “Foam Series: Comparing Types of Cushion Foam” (#300053XHT) for more information on what type of foam is best for you.

When it comes to layering foam, you have some wiggle room to experiment. The layering process is subjective depending on how you want your foam to feel and what the foam will be used for. If you’re an absolute beginner, we recommend you first get your hands on our Foam Sample Box (#121658), which showcases every type of foam available at Sailrite and explains their recommended uses. It’s truly the best way to practice layering foam pieces firsthand and see what might work best for your project. It also breaks down every type of foam we offer in an easy-to-understand chart.

The concept of layering foam can be used to achieve a different foam thickness and/or a different firmness. Thickness is pretty self-explanatory, but firmness is how the foam feels to you. To adjust the firmness, you’ll want to use a firmer foam with a higher IFD and layer a softer foam with a lower IFD on top. This method works for cushions and mattresses. Think of the firmer base layer of your foam as a stabilizer, kind of like the box spring on a mattress. It gives you support even if the softer top layer of foam starts to bottom out over time. This will ensure your cushion or mattress still feels comfortable even after everyday use. It’s easy to secure layers of foam together using a spray adhesive, like our Foam Lock Spray Adhesive (#120464).

When it comes to sleeping on a boat, many people decide to layer foam to customize their interior cabin mattress so that it feels just right using two or three layers of foam. When this is done, the base layer is usually the thickest and the others are thinner. So, as we mentioned before, you would begin with a thick foam with a higher IFD and then top it off with smaller layers of something with a lower IFD. But as we’ve mentioned before, layering foam is subjective based on your preference, needs and living conditions. We have compiled several recommendations from the experts here at Sailrite to help you.

Matt’s Recommendation

Your mattress should be at least two to three layers of foam. This does not count the very base of your mattress assembly, which should be our Moisture Prevention Underliner (#121766) to promote air circulation and prevent moisture buildup beneath the mattress. Boat mattresses differ from the ones in your home due to space concerns. Most boats, even large yachts, don’t have a lot of overhead room in the sleeping berth so you do not want your mattress to be too thick, otherwise, you’ll be encroaching on valuable sleeping space. You’ll want to be mindful of your cabin dimensions when you choose your foam.


Here's another option which is simpler and involves underliner material, closed cell foam, and then a thick layer of high density foam on top, preferably a layer that is several inches thick.


Eric’s Recommendation

Your mattress should be at least two to three layers of foam and should have at least 3 inches of firm high density foam in it. In fact, the more often you intend to sleep on your mattress, the more you’ll want to use a thicker, firmer piece of foam. So if you’re a liveaboard boater, you’ll absolutely want a high density foam. This will help combat any bottoming out that occurs, especially if you’re going to be putting a lot of weight on the mattress. Putting Dry Fast Foam as the topmost layer isn’t going to be the most comfortable, and you should avoid it unless you’re really concerned about excess moisture and sweating. It's recommended that you make your mattress at least 4 inches thick, if not thicker.

For a firmer mattress, you may want to use two 4-inch sheets of high density foam (firm) and just one 2-inch sheet of high density foam of medium firmness. Another option would be to have one 6-inch layer of high density foam (firm) and another layer of high density foam (firm) of 4-inch thickness. Both of these would need the Moisture Prevention Underliner beneath them. If you're really concerned about moisture, you can also add a layer of closed cell foam with small holes drilled in it over your Moisture Prevention Underliner, but still have the closed cell foam underneath your high density foam, like in the image below.


Wrapping It Up

As you’ve probably gathered by now, the possibilities are endless when it comes to layering foam. It’s truly up to you! Even our experts agree that there’s a lot of wiggle room as long as you understand what each foam is capable of. If you still have questions, comments or concerns about your foam project, feel free to reach out. Our knowledgeable support staff is available through email, phone or the chat function on our website. You can also comment below and one of our crew will get back to you. We’re always ready to share our DIY tips and tricks with you.