How To Add Insulation To Existing Exterior Walls?

Regretting the decision of not insulating your home enough? Yielding high energy bills? Feeling too cold or too humid inside your house?

Well, all these problems can simply be resolved by adding an extra layer of insulation to existing exterior walls.

Is it possible? Surely yes! Just use the right insulation and follow the technique to do so.

In this short post, you’ll learn how to insulate exterior walls. Insulating exterior walls from outside might feel tricky.

You can do it with the help of a contractor or by way of Do-It-Yourself! Any kind of wall insulation is best when you’ve the right clues.

How To Add Insulation To Existing Exterior Walls

How To Add Insulation To Existing Exterior Walls?

There are different kinds of walls and types of insulation. While adding insulation to walls, you should use the most-ideal insulation.

How to add insulation with Standard Siding wall?

How to add insulation with Standard Siding wall

Standard siding walls are longer length panels that are arranged on outer sides of homes, horizontally or vertically.

To add insulation to walls, take a strip of siding off about halfway up the wall. Soon, you’ll see brick, wood, concrete, OSB, drywall backing, and stuff. After you detach one or two siding panels, you’ll need to drill in between the wall cavity. Before you do so, locate and pinpoint the distance of approx 1.5 to 2 inches in between the studs.

Attention ! : Never ever mistakenly drill into the studs or pipes! If done, you’ll weaken the stud support to your home. Pipes can get damaged.

Once done, it’s time to drill holes cautiously. After that, blow-in spray foam or injection foam insulation inside the wall cavity through the holes. Inject all the cavities from top to bottom. This way, you insulate an exterior wall.

Lastly, it’s time to put back the panel siding that you took off! You can easily do it with a wooden plug. Fill the holes by inserting the wooden plug tightly. Finally, you can put back the long standard siding panels.

Repeat the same process for all remaining siding panels. Sooner, you’ll be done with adding insulation to exterior walls.

How to add insulation with Brick walls?

House built with brick walls? Don’t worry, its existing walls can be insulated too! Here is what you need to do!

To begin with, divide the wall exteriors into three sectors – top, bottom, and middle. It’s where you drill the holes.

In the middle segment, you start drilling 1/4th inch holes in the mortar joints. Mortar joints are the spaces or gaps between bricks. It fills crevices in between the bricks. In layman’s terms, it’s where the corner of bricks meet.

Drill the holes where mortar joints are! These holes are way deeper inside. So, you need to insert a tube while insulating exterior walls. That’s how you reach the other end of the wall. Make the holes as deep as the mortar layer. Fill in the insulation inside using the tube.

Finally, add more mortar to seal open holes. As you only layer it with mortar, there won’t be great color differences in sealing. Just a little difference due to ageing and sun exposure of the older one.

Well, insulating exterior walls of brick constructions might feel tricky at times! Yet, tasks become easier when you learn the nitty-gritties!

How to add insulation with wood or drywall?

Houses, especially in colder regions, are built with wood. It’s easy to drill through wooden exteriors as well. Read further to discover how the process works.

First of all, you need to find where the studs are! Make sure that you do not drill into the studs as it directly damages the home support. To avoid it, you can mark where the wood studs are! Once marked, you’re ready to drill in between.

Start by drilling a 2-inch hole close to the top or middle of the exterior wooden wall. Follow the same process for all the remaining studs.

Attention ! : Never drill the middle and top of wooden walls both at the same time. Always fill one hole in the middle with insulation and then move to drill the second hole at the top.

Once you drill holes, it’s time to fill-in insulation. One can use the insulation as per their requirements. In other words, you can select insulation based on the type of insulation which is already there inside old walls. Along with this, consider climatic conditions, cladding type, air sealing properties, price budget, insulation permeability factor, etc too!

So, you can use spray foam, blow in, rigid foam boards, natural fibers, mineral wool, or any other kind of insulation. Say, the old insulation inside the wall exterior cavity is settled over time. In that case, you can choose to add more fiberglass as well. This way, you keep the insulation the same all-over!

So, it’s easy adding insulation to exterior walls of wood and drywall.

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Here are some energy-efficient retrofitting options for insulating exterior walls.

Larsen trusses with cellulose insulation or batt insulation

Under this setup, you install 12-inch engineered I-joists to the outsides of the old house or on exterior walls. It involves insulating exterior walls from outside.

The joists are attached to the old house from the ledger at the bottom aligned to rafters at the top. I-joists are also attached to windows. Simply, cut the joists using different kinds of saws and jigs. As you put all the joists, you’ll see a cavity created that can be filled with insulation.

In that cavity, you can add dense-packed cellulose insulation, rigid panels, batt insulation, or spray foam, if you find it right. Also, you can create Larsen truss walls in a variety of thickness levels. That’s an advantage here.

If it’s a wooden house, the wood acts as a thermal bridge but it’s not a great concern as well. So, Larsen trusses system is also good for old wood stud houses.

Larsen trusses system requires extreme air-tightness and high energy-efficiency. Meaning, you need to tape wall sheathing tightly. Anyway, this system is perfect for retrofitting old constructions.

Fiberglass thermal spacers or “Cascadia Clips”

Under this method, you attach the red clips to the exterior wall for about 3 inches. With this, you can fasten strapping or furring strips and cladding on exterior sides using its screws.

Fiberglass is not a heat conductor so avoids thermal loss to greater extents. So, this setup is good for continuous insulation needs. These Cascadia clips facilitate bigger gaps for existing exterior wall insulation.

In a nutshell, you have a thermally isolated system. To say it otherwise, you do not lose the insulation efficiency over time!

Add Insulation with Metal screws

Under this method, you attach two insulation layers with strapping and screws. In this method, you avoid thermal bridging cleverly.

To break thermal bridging, you add two insulation layers. While doing so, take care that you do not let the screws penetrate through wall assembly. Also, with double insulation, you do not let one screw reach directly to the entire wall assembly as you’ve got two screws. That’s a good thing!

The only con is that you need to work more as you do double insulation to insulate existing walls. However, the combined R value is greater and its energy-efficient and long-lasting.

ThermalWall PH panel

Under this method, you use a rigid EPS foam insulation panel of varying thickness. With this method, you can increase the exterior wall’s R value phenomenally. Say, improving standard code compliant R 24 to R 52. This way, you surely get the high performance envelope.

Inside the insulation panel, there is a galvanised metal rail. So, as and when you pull out the snap track, the metal rail is visible. This is where you can screw into the stud wall of a building or masonry. Thereafter, replace snap track and fasten exterior strapping to the galvanised metal rail.

Don’t miss:

Rockwool vs Mineral Wool Insulation
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Open-Cell vs Closed-Cell Spray Foam Insulation

Final Thoughts

So, it’s easy to add insulation to existing exterior walls. Just a matter of a few days! And, you get an added insulation system for lifelong! You cut down utility bills!

Do-It-Yourself or hire a contractor! Consider all other factors like type of insulation, pre-existing insulation, technique to add insulation to existing walls, and similar. Also, you can go for greenest insulation choices like Larsen trusses and Cascadia Clips. Adding metal screws to insulation can also be a smart way!

In conclusion, soon, you’ll learn the right ways to insulate an exterior wall. Anytime, refer to this short post to learn those ways faster!