What is Wall Insulation

When we talk about wall insulation we refer to the idea of making an interior of a space warmer during winter months, and colder during summertime. Wall insulation is what brings energy efficiency to a higher level, it’s what reduces cooling and heating costs. No matter how the building is built, the wall insulation can dramatically increase the level of comfort in the interior space, which is why this type of insulation is highly recommended no matter if the property is designed for residential or commercial usage.

Insulation for walls

There is no doubt that adding interior wall insulation is the smartest decision you can make, especially since this endeavor will not only prevent the heat loss in winter or make your space pleasant enough during hot summer days, but it will also improve its acoustic performances and add protection regarding fire risks.

Now, what’s essential to know when it comes to wall insulation is how thick the insulation for walls should be in order not to create the opposite effect. The more the merrier approach is not something that can be applied in this matter. According to professionals, if you install too much insulation you can end up with a colder house since you risk losing small tiny pockets of air, which are the thing that keeps the warmth inside the walls and therefore the space.

In most cases there are two wall types all houses are built from, and they need different insulation. Older homes are usually designed with 2x4 interior walls, and the best insulation option for them are R-13 and R-15 fiberglass rolls. On the other hand, the best insulation for walls in modern buildings that are usually 2x6 thick is R-19 and R-21 fiberglass, since they can make sure that the insulation on interior walls is not too tight nor too loose.

Best insulation for walls

After we established two main types of interior walls it is important to say that there are two types of interior walls - separation walls that are separating adjoining houses and flats, and partition walls that have one purpose only, and that’s to divide rooms. They can both be insulated in several different ways, but we will now focus on partition walls and their insulation.

When it comes to what’s the best insulation for walls of this kind you should know that you have several options. However, they are different regarding the cost, energy efficiency, and complexity of installation.


One of the most popular house wall insulation is definitely open-cell or closed-cell polyurethane foam. It can be in a liquid or soft foam form, and after it’s applied it will expand and stiffen creating a great insulation barrier. This option can be pretty expensive given it’s usually applied by professionals.


If you are looking for acoustic wall insulation, one that will provide not only heat loss but sound isolation, Prodex HYBRID is a way to go. It is capable of creating maximum thermal and great acoustic comfort. Its price is pretty affordable and it can be applied by a homeowner.

Fiberglass batts

Fiberglass batts are sort of blankets that are shaped in pads or rolls and should be placed between wall studs. Even though they are the most common type of batts, there are also cotton and wool batts you can use for the same purpose. Their price goes from 40 cents to one dollar per square foot.


There are large panels made of foam or extruded polystyrene that can go inside the interior walls in order to create a special moisture barricade. They are ideal for homes located in cooler climates given these boards will stop hot air from breaking out. They are ideal for 2x4 walls and they go from R-5 to R-8.

Dry bits

Another interesting way of installing insulation in walls is by using dry bits. They require a specific blow technique that places them inside the wall cavities, and these dry bits can be made from cellulose, fiberglass, or mineral wool. The tricky part is to properly patch the holes through which you will insert the bits, and this solution can be pretty pricey.

Prodex Total

Here is one more Prodex product you can use for properly insulating your home. This material is ideal for the purpose of interior insulation given it provides an air barrier, vapor barrier, radiant barrier, all in one, and it has an improved tearing resistance which is another plus. Many people suggest using it for attic wall insulation.

How to install insulation in walls

If you would like to insulate your walls by yourself and you are wondering how to install insulation in walls properly, here is what you should do:

Get all the information

First and foremost you need to be well informed if you plan on executing this process correctly. Make sure to consult with the professional about all the details you need to pay attention to. For instance, you have to check the areas that can be overlooked easily and block all air gaps.

Learn what’s the best way to seal openings around pipes and what’s the best insulation solution for your particular property.

Choose the material

After you study all the possible material choices, and after you do the calculations, decide on which one is ideal for your needs as well as your budget. Bear in mind that not every insulation material could or should be installed by an amateur. And learn how to insulate walls without removing the drywall.

Do the math

It’s not only about how to install insulation in interior walls but how to calculate exactly how much filling you will need. You will have to establish the exact length, depth, and width of an area you need to insulate. And you have to consider all the wires and pipes and how they affect your calculation. Also, bear in mind that there is a difference between metal building walls insulation and houses built from wood and other natural materials.

Apply the insulation

Depending on which material you decide to go with, the insulation appliance can be more or less complicated. When it comes to the most common fiberglass insulation, all you need to do is to lay the insulation parts inside the wall construction and then staple them firmly. With foam, you will have to spray it from a proper distance and an adequate angle, and then wait for it to tighten.

What to avoid when placing wall insulation?

When someone asks us what is the best insulation for walls, we often say the one that’s not excessive. And we meant it. For instance, the majority of people use fiberglass insulation because it’s good enough and one of the most affordable materials for this purpose, but they tend to exaggerate with its thickness believing more insulation will provide them with better climate efficiency of the space. And that’s where they are wrong. This is what you should avoid doing by any means.

The fact is fiberglass insulation is based on a structure that has the ability to trap small air pockets and use them to cumulate the heat. When people add too much insulation on a wall that’s pretty thick, it results in air pocket reduction, and therefore reduction of thermal resistance you counted on.

Also, when deciding on how to add insulation to walls, especially one made out of fiberglass, make sure not to place too thick batts behind pipes and cables. If you do so you will compress the insulation too much and lower its efficiency by creating a void between drywall and insulation. And finally, remember not to place full-width insulation in extremely narrow wall spaces because there is a great chance you will crumple it and therefore create air pockets that are uninsulated.

Calculations and savings

As we already mentioned, one of the steps regarding how to put insulation in walls is to do the calculation on how much the whole endeavor will cost in the end. There are several factors you should take into account here, but the three main ones are: one - the size of your property, two - the number of walls that need to be insulated, and three - the preferable wall thickness.

Here is a calculator you can use in order to get a close assessment of your insulation costs, but the fact is some of them you can do on your own. If you decide on the material you will use, and on insulation thickness, all you have to do next is to measure the wall studs and find out the precise cost of foam, panels, or any other insulation option per square foot.

Also, make sure you can do the insulation on your own. If not you will have to calculate the price of professional help which will dramatically increase the expenses. And finally, take into account the cost of equipment and additional gear you will need in order to do the job correctly.

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