What Caulking to use on the Exterior of House

Accept it. You’ve been one of those lost souls standing in the caulk aisle, dumbfounded by the vast array of caulk options. Let’s look at the different types of caulk, its uses, when not to use it, and other important information regarding the use of exterior caulk. Our company has been the leading caulking Melbourne company for over 5 years, so we are sure we can clear up all your questions.

What is External Caulk Used For?

Caulking materials are a sealant that fills nail holes, cracks gaps, and other surface imperfections. In other words, caulking prevents moisture from penetrating and causing leaks and deterioration.

It is a finishing material that is difficult to beat. This material can be used to fill gaps, cracks, and breaks on various surfaces. By caulking properly, you will save money on heating and cooling bills. It prevents heat loss around doors and windows. Furthermore, caulking used on the house’s exterior can also seal up cracks in the foundation and driveway, which can lead to costly repair bills if left unchecked.

External caulking is a substance that is specifically designed to seal the gap between two surfaces. It is also used to fill small surface holes. High-quality caulks, such as Multibond SMX25, can withstand extreme weather conditions with frequent temperature changes.

However, before using caulk to seal joints or fill holes, make sure that the manufacturer recommends caulk for both materials. For example, if you want to paint over the caulked surface, make sure you get paintable caulk like Multibond SMX25. If you are unsure which caulk to use on your exterior, you should consult with the label to determine what is recommended.

Why Is Caulking Necessary?

Caulking is essential during the winter months because keeping moisture out of homes is essential. During the winter, one must contend with a large amount of snow and water. This can damage your home’s exterior and interior surfaces without our knowledge. Caulking the surfaces is one of the most important and safest steps to protect your exterior surfaces from harsh weather conditions. After scraping, sanding, and priming a surface, caulk it. Caulk typically adheres to the primed surface the best.

Caulking the Exterior of a Building

Caulking the exterior of your home is important because it protects the exterior surfaces from water and insect damage. The most common areas that people use caulk is in the openings and cracks between joints along with windows, doors, and siding.

Caulking aids in the preparation of the surface before painting. It aids the house exterior by protecting it from extreme heat, cold, and moisture. Paint is undoubtedly important, but to protect your home, you must also invest in high-quality caulk such as Multibond SMX25.

In fact, a professional caulking job can save you money in the long run. As it also increases the insulating value of your home. Caulking is essential because it protects the wood and substrates on the inside and outside of your home at the same time from moisture and insects.

Many small cracks on the outside of a house appear insignificant at first. But be careful as they can quickly become a significant issue. Caulking can be useful in preventing these issues from becoming out of hand. However, the caulk aisles of home improvement stores can quickly become overwhelming due to the vast selection. Selecting the right caulk for a specific job can be extremely difficult.

What Factors Influence the Material Type Used?

To begin, narrow the range of caulking to use on the house’s exterior based on three important factors related to where it will be used: foundation type, season, and location.

Type of Foundation

If foundation cracks are not addressed promptly, they can lead to structural integrity loss and high-cost repairs. Keep the type of foundation in mind and carefully read the label before deciding.


The caulking area’s exposure to various temperatures should also be considered. Not all caulks are resistant to high temperatures. Some materials, for example, may have difficulty setting up initially in extreme heat, whereas others may not be suitable for homes in extremely cold or windy environments.


There are numerous areas on the outside of a house that may require caulking, and the specific location should determine the composition of the material you use. Different types of materials are required to successfully gutters, roofs, driveways, windows, doors, and seal foundations.

What kind of exterior caulking should I use on my house?

Exterior caulking is available in various materials, some of which are easier to work with than others. The following are some of the most popular exterior caulking options and where they work best.


Hybrid caulks are an excellent choice when both silicone and polyurethane properties are required. They will not necessarily have the word “hybrid” on their label but will be identified by their material mix and higher price. Although hybrid caulks are easier to apply than polyurethane caulks, they are not as simple to use as acrylic latex caulks.

High-quality caulk is essential on the exterior of your home because it seals out water and protects your home from rot and peeling paint. We recommend hybrid caulks for their superior adhesion and flexibility. Our highest recommendation would be Multibond SMX25 for this type of work.

The most common reason for using material, is to get the UV resistance of silicone with the strength of a polyurethane.. That’s why it’s usually a good idea to spend the extra dollars on high-quality caulk when possible and needed.

While we recommend Multibond SMX25, we wanted to look at the other types of exterior caulk on the market.


Silicone is one of the go-to materials due to its wide range of caulking applications. It is resistant to weather, chemicals, water, and temperature. This makes it an excellent choice for both exterior and interior applications. Silicone caulk is better at UV protection than you will find in a simple polyurethane. However, polyurethane is marketed to have good UV ratings. It is not one of our recommendations.

Solvent-Based Exterior Caulks

Solvent-based exterior caulks have a consistency that requires some skills to apply neatly. They are ideal for roofing and gutter jobs because they have excellent UV resistance.

Acrylic Latex Caulk

Acrylic latex is a good choice for inexperienced caulkers. This is because it is one of the simplest types to apply and create a smooth finish with. It’s also the only type that can be cleaned with water. When painting, acrylic latex is the best caulking material to use. When selecting acrylic latex caulking, look for silicone-containing versions that provide greater flexibility and adhesion.

Polyurethane Caulk

Polyurethane caulks have a gooey consistency that makes them difficult to control and are known as poly caulks. These are considered tougher than other options by some. This makes them ideal for trim, driveways, and areas of the home that are exposed to the elements. It is important to remember, however, that polyurethane caulks are often marketed as being UV resistant. However, there are better caulking materials out there for the job.

Areas to Caulk:

Now that we have discussed the types of caulk and our caulking recommendation of Multbond SMX25 for external applications, let’s take a look at the areas of the home where you should be using exterior caulk. We will also look at the areas that you should not.

Corner Caulking

This is a must-do for every home. Moisture prefers to hide in corners, along edges, and beneath ledges. We can use high-quality sealants to keep it from penetrating and causing structural damage.

Garage door trim – but never the garage door itself.

While a novice painter or DIYer may attempt to create a cleaner look by sealing all gaps on wood garage door panels and garage doors, these are designed to move. The panels on your garage door require some wiggle room. Caulking them is a bad idea, and the caulking will most likely fail prematurely.

Butt joints

Butt joints are where two pieces of siding come together. Should they be caulked all the time? The answer is dependent on the manufacturer, and the method of installation used when the siding was first installed.

NOTE: Butt joints on cedar siding should not be caulked. In the elements, natural wood dining is designed to expand and contract. We don’t want any adhesive to get in the way of that. When there is no metal flashing behind the fiber cement boards, they are caulked. Also, butt joints on cedar siding are only caulked if they were previously caulked. Because some manufacturers do not require metal flashing, we caulk the butt joint to keep the pieces together while preventing moisture.

Surface Flaws on the Siding

Surface flaws are gaps, cracks, failed knots, and so on.

Anything that could allow moisture to enter in the future should be sealed. Pay special attention to corners and crevices, as well as to trim boards around windows and doors. It’s also good to have a cloth or rag on hand to wipe up and smooth any excess caulking before it hardens on the siding.

Trim and Wood Windows

Almost all trim joints must be sealed. This is done to keep moisture out of the crack/joint, but it also improves the overall appearance of the surface.

What you should never caulk!

Now that we have discussed what to caulk, there are things that you should never caulk, and this is important as well. Let’s take a look at that really quick.

Caulking should not be used on garage door panels.

While a novice painter or DIYer may attempt to create a cleaner look by sealing all gaps on wood, garage door panels and garage doors are designed to move. The panels on your garage door require some wiggle room. Caulking them is a bad idea, and the caulking will most likely fail prematurely.

The weep hole in a window should not be caulked.

These small openings are designed to let water out of your windows and should never be sealed.

Trim boards that are installed on top of the siding.

In most new homes, the trim is installed after the siding, leaving a large gap that should not be caulked. We need air circulation behind these boards, and the opening serves as a water exit in the event that water gets behind the boards.

Siding board bottoms should not be caulked.

Water is supposed to escape through the bottom of each board. While paint helps to hold these pieces together, caulking is never recommended and can cause permanent damage. Avoid caulking tongue-and-groove siding boards together as well. Other areas to avoid caulking are:

  1. Caulking should not be used on metal flashing (or any metal-to-wood joint).
  2. Any other water exit route that should never be closed.

Caulk Should Not be Used on Siding Nails.

Siding boards, for example, require space to move around. The nails that hold the siding in place should not be caulked. A novice painter or DIYer may attempt to achieve a cleaner look by caulking the siding nails, but the nail will inevitably push the caulking material out of the way after a few months. Click here Find more details on our caulking Melbourne company.

Check out our blog on What Is Caulking?