How To Insulate Pre Existing Walls of Old House : Interior and Exterior?

How To Insulate Pre Existing Walls Of Old House


Are you facing a temperature disturbance and noise problem in your city and you don’t have an insulated house yet. Then I am pretty sure you need some insulating materials that you can use to insulate your house.

But how can you get and how you can use those insulating materials? This is a normal question that most people are asking. 

According to the survey of the US Energy Administration(2009) for residential houses, around 90% of US houses are under-insulated.

It means, they are wasting their money and comfort. Based on the International Energy Conservation Code (IECC) if all the US houses use insulation in their houses then around the nation wise electricity and gas consumption will drop down by 5 to 10%.

That’s why I have insulated my house and I am pretty sure you are also interested to insulate your old or new house. So that you save some energy, electricity and gas bill as well.

In this article, I am going to share some best insulating materials, how to insulate walls in an old house, and how you can insulate a wall without removing drywall, and so on. So don’t skip any point otherwise you couldn’t solve this problem.

But before it, you need to understand what R-value, STC, and NRC, how these things help you to determine the best insulation material for your house.


What are R-Value, STC, And NRC

Let understand each of them and how you can configure this for the best insulation.

What is R-Value?

R-Value (Resistance Value) is the measurement of temperature that will allow us to check how this material is capable of reducing the heat and cold through the walls, floor, and ceiling.

A higher number indicates that this is a good temperature-resistant material that protects your house.

What is NRC?

NRC (Noise Reduction Coefficient) stands for sound absorption. This rating gives a clear idea about the level of sound absorption.

The higher the number indicates the best noise absorption level of the material. I mean if the NRC is 0.02 of the material then this can absorb only 2% of noise and 98% will reflect.

What is STC?

STC (Sound Transmission Class) is the number of how this material is capable to block the sound waves, it means the higher the number the better the insulation.

Most importantly a better STC score is 50+ otherwise this will not provide you a noise-free environment. I have already explained this topic earlier so you can check it.

Let’s jump to understand, which type of insulation best for your house and how this will protect it from all things.


What Are Types Of Insulations

How do you configure the best insulation material for your old house? Generally, this depends on your need and the budget that you can invest in your house.

But these are some of the best insulation materials that easily come into your budget.

1. Batts Insulation

Batts insulation is the mixture of various types of insulation materials such as miner wool, cellulose, and polyurethane.

But generally fiberglass and miner wool are the main ingredients that are used to make this insulation. Traditionally this batts insulation comes in the rolls but now manufacture provide it in a pre-cut size that easily fits into the studs.

Its performance is based on the material that’s used to make this insulation. For example, fiberglass gives up to R-4.2, miner wool up to R-3.6, cellulose up to 3.5 per inches of thickness.

Batts insulation is cost-effective and comes about 40 to 60 cents per square foot.

2. Cellulose Insulation

Cellulose insulation is used in the cavity between the roof ceiling and the walls to create better insulation. Generally, this is made of fiber that has great noise reduction power.

This comes into three forms spray based, stabilized, and low dust that you can use according to your need.

This insulation provides mass and damping that reduce the sound transmission coming from the roof and walls.

Additionally, this is three times dense from the fiberglass that will provide a world-class noise-free environment. Cellulose insulation provides up to R- 3.8 thickness per inch and the cost of around 50 cents per square meter.

3. Fiberglass Insulation

The fiberglass is also called glass fiber that has amazing thermal and sound absorption properties because of its porous material.

They are used to absorb the sound waves from inside and outside as well. Its structure is based on both stiff and strong tension that will block the noise and maintain temperature along with its axis.

Most importantly, this material is much heavier than any of these insulation materials and it provides faster installation compared to the wool and foam. Fiberglass insulation cost is around 38 cents per square meter.

This material works very well and can insulate walls in an old house but if your focus is only on the noise-free environment in your house then it is not the best choice. You need some soundproofing materials to block the noise for a popper noise-free environment. 

4. Mineral Wool Insulation

This is a non-metallic and non-organic insulation provided fire-resistant layer to protect your house. Moreover, This mineral wool has exponential acoustic properties that absorb airborne and structure-borne noise.

So that you can enjoy a comfortable environment but this is different from acoustic foam.

This is a very different material that can be manufactured to many different densities and create friction between air particles and sound.

That will allow air movement in the material but this converts into heat and also this material can’t absorb water. Its cost is around $1.5 per square foot. I know this is much expensive but this will provide much insulation to your old house.

5. Spray Foam And Injection Foam Insulation

Spray foam and Injection foam insulation is chemical-based material that expands up to 30 to 60 times after being sprayed on a place. It means this is easily fit in any type of cavity in your old house. This is the best option instead of fiberglass that does not provide much noise absorption.

Moreover, its amazing thermal resistant property typically provides up to R-6.7 per inch of thickness. That has the ability to seal the air block connectivity of heat transfer so that you can save energy.

Spray foam insulation easily can block up to 60 decibels of noise and the cost is around $1.36 per square foot. I think this is the best insulation for exterior walls

6. Rigid Panel Insulation

Rigid panel board insulation is made from plastic that works well in both climates such as hot and cold. In a hot climate, this board creates a vapor barrier to keep the heat outside. Secondly, In the colder climate, this board will block the moisture so that your house keeps warm.

You need to place it between the studs then cover the whole thing from foil-faced panels and don’t forget to seal it. Moreover, rigid panel insulation has an R-value of about 7.5 that prevents temperature and sound leakage in your house.

Extruded polyurethane (XPS) ensure the airtight seal and they are all water-resistant.

So you have understood about the best insulation that you can use to insulate your old house. Now, this is the time to understand how you can install insulation and which type of insulation is best for which type of walls, ceiling, or floor.

This insulation works very well to insulate walls from heat.


How To Install Insulation In Interior Walls

We know that all the above-listed insulation materials can’t be used everywhere in your old house; you have to use them carefully.

Because every place is different in your house that’s why we have provided a step by step guide on how you can install insulation on interior walls in your old house. 

If you want to ask “what kind of insulation is available for interior walls?” Then my reply is this depends more on your house structure so read down below and understand this para.

How To Install Insulation In The Attic

Instead of insulating the whole house, you can just install the insulation in the attic because it is the major source of heat and sound leakage.

Also, if you seal your whole house from insulation it will become a cause of excess humidity.

So this is the most effective and safest way to insulate your house. But before it, you need to check every crack and gap around chimneys, ceiling fans, ductwork, vents, and windows, and so on.

Use an acoustic sealant to fill in these gaps because it will cause leakage. Now let’s check what type of insulation is best for the attic. Wait,  Do not forget to insulate the cathedral ceiling in the attic.

Best Insulation For Attic

Now you have understood how you can insulate the attic in your old house but which insulation is best for the attic? There is 2 insulation that I think works well in the attic.

  • Batt Insulation
  • Cellulose Insulation

Wait, if you can’t remove the drywall, then you need a professional to do this work because this is very difficult work. But this is the way how you can insulate your existing walls cheaply.

How do you install batts insulation in the attic? This is very easy first, remove the drywall then secondly, fill the fiberglass batts insulation in it.

Don’t forget to seal every gap and hole so that your house becomes protected.

How can you install cellulose insulation in the attic? Drill small holes in the drywall and then blown cellulose fiber in the cavity but make sure not to overfill the cavity.


How To Insulate Room In Old House

So you have insulated your attic now this is the time to insulate your room so that temperature or noise can’t disturb your enjoyment.

Most Importantly, you need to seal all the windows, ceiling, floor, and walls in your old house. Don’t worry I have explained one by one so that you can understand properly.

1 Insulate Window in Old House

Windows are the major part that is responsible for leakage noise and thermal energy in our house so it needs to be sealed first.

It has some small gaps between the glass and shield that are left to pass the air and obvious noise. You must use these materials to seal your window then you can use these thermal and noise reducing curtains to block the noise

2 Insulate Ceiling in Old House

The ceiling plays an important role to make your house warm and noise-free so you need to install a perfect barrier in the ceiling.

I think Liquid foam can work properly because it has the ability to expend 30 to 60 times. That will be the best solution for you.

You can create a decomposing zone on your ceiling to trap the noise as much as possible. How can you do it? Just by applying Ceilume 12 pieces of acoustic ceiling tiles on the ceiling.

Now let’s talk about how you can insulate interior walls in your old house?

3: Insulate Walls in Old House

If you are still too cold in winter and too warm in summer then you have to insulate the interior walls that prevent the leak of energy.

I know this is much expensive and you have to hire a professional person to do this work but this is worth it.

I think when in the existing walls you can use blow-in insulation such as miner wool and cellulose insulation to make things easy.

Also, this insulation will provide significant air sealing in your old house.


How To Insulate Basement In Your Old House

Do you know proper insulation of the basement can save you lots of money? That you are spending on heating and soundproofing your house?

Yes, this is absolutely right according to the USA Department Of Energy people are in the USA saving $250 to $390 monthly worth of energy by just applying proper basement insulation.

Not just the interior you have to insulate it from the exterior. But you need to follow some guidelines to make things better.

  • Many insulations release a toxic gas that can be very dangerous for you so make sure to cover them from fire-rated cover sheets.
  • Keep in mind that interior insulation reduces your basement space by a few inches.
  • Make sure to use damp-proof paint in your basement before applying any insulation.
  • I think if the foundation of the house is poor then this insulation becomes the cause of moisture in the walls or basement.

Best Insulation For Basement

This is very great if your basement is connected with some other spaces in your house because it will make your basement walls insulate.

But if not then you can use these things to insulate your basement.

  • Batts Insulation
  • Cellulose Insulation
  • Miner Wool Insulation
  • Fiberglass Insulation
  • Spray Insulation

This is how you can insulate walls in an old house and you can use any of them that fits your budget and need. But keep in mind that moisture is the greatest enemy that you have to face in basement insulation.


How To Install Insulation On The Exterior Area

You have understood interior wall insulation. Now, this is the time to improve the insulation from outside of the home.

I know that in terms of new houses people have a plus point to plan and place some additional insulations such as insulated panels, insulating concrete forms, and insulated concrete blocks.

That will build superior insulation in your house. But If you want to insulate your existing house then you can check out below. I have compiled a step by step guide on how you can use different types of insulations to the exterior area;

How to Insulate Roof of Old House

As you know temperature is getting down everyday especially during the winter season exterior insulation always makes an important part.

Also, the roof exterior prevents the excess heat from entering the house to keep the temperature maintained in our old house.

According to Homeadvisor your roof can cost between $1700 to $2100 but do you know why this is so much high.

Most of the part is contractor fees that they charge to install insulation on your old house. This is an obvious thing but you can drop it down by applying cheap and valuable insulation materials.

Best Insulation For Roof

You can cut some of the unnecessary expenses while installing insulation on your roof so that you can get an insulated house at a cheap cost. These are some of the same that you want.

  • Shingle / Shake Sides
  • Fiberglass Insulation

Don’t forget to check the R-value provided by manufacturers if you desire a high level of insulation. Before it checks your roof and analyzes what kind of insulation you already have on your roof and why they are no longer working.

How To Insulate Exterior Walls In An Old House

When in exterior walls we have the majority of siding that can create problems after applying some of the insulation on it.

So first you need to understand what kind of exterior siding your house has such as vinyl and aluminum, double brick, and wood siding. This is better insulation to insulate from outside and inside

Aluminum and vinyl siding is a good alternative to wood siding but the standard aluminum and vinyl siding does not provide insulation.

You need to install rigid panels before installing these sidings. After proper panel installation creates a barrier between the main surface and siding.

When combining these resources the R-value increases from its level. I think this is the best insulation under vinyl and aluminum siding.

After world war 2 we are not using double brickwork on our exterior walls because this type of wall is held together by brick ties.

That’s why some of the gap left between them and insulation can’t create but we have a solution for that. If you have double brickwork on your exterior walls then you can use loose-fill such as cellulose fiber, mineral wool, and spray foam insulation.

Make sure the insulation that you use is waterproof that can protect your interior walls as well. Also, this is the best way to insulate existing walls.

Do you know your wood siding is the perfect way to insulate your house with less energy consumption?

Yes, this is right, but harsh winds, heat, and weather conditions affect the performance of your exterior walls. However, most of the wall siding is not offering to protect your house’s energy performance. 

Wood siding is in the same category that’s why you need some extra insulation to protect your house.

Do you know wood siding provided only a 0.87 R-value that is not a good signal? You can use fiberglass, spray foam, cellulose, and mineral insulation with them. These types of insulations are the best for walls and can be installed on underwood siding.


How To Insulate Walls Without Removing The Drywall

If you want to insulate walls without removing the drywall then you have to drill some holes in your interior or exterior walls to fill them with insulations.

As you know some of the insulation material can be blown and sprayed into the cavities to fill them. This will help you to save energy without spending a large budget. This will cost you around $650 to $1000 for average house drywall.

But you can save up to 15% of your electric bills so I think this is worth it. You can use loose-fill and spray foam if you don’t want to remove your drywall.

What is your electricity bill comment down below and how much do you want to save? This step by step guide definitely helps you to set this up.

1: Make Holes In Your Interior or Exterior Drywalls

In this step, you need to follow some steps. First, prepare yourself and wear a protected kit, secondly, use a pencil to mark off the drilling holes.

Lastly, drill almost 2 inches holes on your drywalls. Do not forget to check any wire connection in the drywall before drilling.

2: Blown or Spray The Insulation In the Cavity

You have drilled multiple holes on the drywalls, now this is the time to fill them with insulation. First, place the hose pipe into the holes and make sure insulation is blown and sprayed in tight.

Secondly, evenly distribute insulation as much as the hole fills. Don’t forget to wear a mask and glasses to prevent dirt and dust.

3: Use Duct Tape And Patch The Hole

Once you have finished the 2 steps now you need to patch the holes to save the drywall disc. You can use duct tape or drywall tape to patch insulation in place, cover the hole and let it dry.

When all the holes are patched then you need to put the walls at their places and make sure they look in uniform. This is how you can add insulation to existing walls.


Wrap Up On How To Insulate Pre Existing Walls Of Old House

You want to insulate your house that’s great because this is very important to save some electricity bills and energy as well. In the past year, I have also used these insulations in my house and now I am feeling good and noise-free.

That’s why I have provided some of the most useful and effective insulation that works well when in a new or old house.

This step by step guide works very well but don’t over insulate your house then it will become the cause of excess humidity.

Moreover, in some cases, you can insulate your house by yourself but you need any helper to do this work.

Lastly, I want to say these insulating barriers have reforesting properties and some of them release harmful gases that will be very dangerous for your health so you have to cover them properly with fire-rated cover sheets. 

Thanks for reading!. If you enjoyed our article then just comment down below so that other people got to know this useful information.

How To Insulate Pre Existing Walls Of Old House

Hey, I am Kirtish Vyas a YouTuber and believer in making life peaceful, a couple of years back I started soundproofing my house, bedroom, studio, and Car to reduce the unwanted noise, and the same experience I am sharing on SoundProofidea. Read More

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