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Best Caulk for Hardie Siding (Reviews and Buying Guide)

As a homeowner myself, I’ve always liked doing small DIY projects. In fact, I’ve been doing these things for quite some time now. 

So, last summer I was thinking of caulking my Hardie siding. Everything was okay until a few months passed. Turns out, the caulk sealant was terrible. And as a result, I had to redo the project all over again. 

Later on, I thought why not write an article on it? So, here I am telling you about the best caulk for Hardie siding

In this article, I’ll talk about the caulk sealants I personally used. But most importantly, I’ll share my experience about what you should and shouldn’t do. 

Without further ado, let’s get on with it-

Comparison of Our Best Caulk for Hardie String

Product Type  Weight
DAP INC 18152 Silicone  10.1oz
GE Sealants & Adhesives M90015 Silicone  10.1oz
Dap 18001 Kwik Seal Caulk Silicone  5.5oz
Gorilla White 100 Percent Silicone Sealant Caulk Silicone  10.1oz

1. DAP INC 18152

Best Caulk for Hardie Siding (Reviews and Buying Guide) 1

Product Overview

First off, we have the DAP INC 18152. For those of you who want an overall best performer, this is the product for you. 

From sturdiness to excellent adhesiveness, this caulk sealant will do it all. Other than the excellent quality of the caulk, it has little to no odor. So, you’re safe there. 

The best part is, the cleaning process couldn’t get easier. All you need is some water and a rug. But just because you easily wipe it off doesn’t mean that it has a long drying time. 

In fact, the drying process only takes 30 minutes. You can paint it after that if you want.  


  • Doesn’t mess with other paints
  • Won’t release any horrible odor
  • Takes only 30 minutes to dry
  • Can be wiped off easily with water


  • Needs to dry properly to work 

2. GE Sealants & Adhesives M90015

Best Caulk for Hardie Siding (Reviews and Buying Guide) 2Best Caulk for Hardie Siding (Reviews and Buying Guide) 3

Product Overview

Next up, we have the GE Sealants & Adhesives M90015. I guess we don’t have to say anything more about GE as everyone knows about their brand reputation. 

And their caulk sealant holds up that reputation. The GE Sealants & Adhesives M90015 is 100% percent waterproof giving you protection from any kind of water damage. 

The seal is so strong that we’re quite sure that even a flood couldn’t penetrate it. So, obviously, that means it’ll keep out mold and mildew. 

Other than that, it has all the necessary requirements of a perfect caulk sealant. It takes only 30 minutes to dry but you should keep in mind that you really shouldn’t mess with it after 30 minutes. 

In my experience, it’s better to give the sealant at least 24 hours to dry. If you use this sealant like that, we’re sure it’ll give you excellent service for 


  • Stays 5 times stronger than other adhesives 
  • The neutral-core formula makes sure there’s less odor
  • Gets ready to face water in only 30 minutes
  • Protects from mold and mildew infestation


  • Can’t be painted over

3. Dap 18001 Kwik Seal Caulk

Best Caulk for Hardie Siding (Reviews and Buying Guide) 4

Product Overview

This product is quite useful in tight situations. We all know it’s not always easy to carry a big bottle of caulk sealant with you. Well, the Dap 18001 Kwik Seal Caulk will fix that for you. 

It’s a small size caulk sealant that has all the features of the big guns. You can take it anywhere you go and you wouldn’t even know it’s there in your toolbox. 

So, if you’re someone who’s always on the go, this product can come handy to you. 


  • Great value for the price
  • Acts both as caulk and glue
  • Great for any kind of projects
  • Creates a 100% waterproof seal 


  • Sometimes it can get hard to squeeze out of the caulk

4. Gorilla White 100 Percent Silicone Sealant Caulk

Best Caulk for Hardie Siding (Reviews and Buying Guide) 5

Product Overview

For our last contestant, we have the Gorilla White 100 Percent Silicone Sealant Caulk. Even though it’s at the end of our list, it’s one of our favorite products. 

From using it for the first time until now, it’s been giving us excellent performance. This is one of those few caulk sealants that work great for both indoor and outdoor projects. 

So, no matter what kind of project you’ve got in your hand, this is one tool you should keep with you. The service won’t disappoint that we can say for sure.  

This caulk might be the ideal one if you’re into closing the gap between tub and floor tiles


  • Infused with anti-yellowing technology
  • 100% waterproof
  • Keeps away mold and mildew
  • Great for both indoor and outdoor projects


  • Some users complain that the odor is unpleasant

Buying Guide 

When it’s about home improvement, caulk is surely one of the best things a homeowner can own. From interior to exterior, caulk can be used almost anywhere for anything. 

You can use it to fill out gaps such as a hole in your polycarbonate roofing sheets or you can connect two things. But mostly, a caulk sealant will definitely keep the moisture out of the place. 

While using caulk on the exterior isn’t really a tough job. But the caulk you’re going to use will be held responsible for how good of a job it is. 

That’s why I decided to point out these things for you. These things will be more than enough to get you started-

What to Look Out for When Buying Caulk for Hardie Siding?

When selecting caulk for an outdoor project, you need to keep a few things in mind as it’s going to face a number of elements. 

Moreover, it’s wiser if you don’t choose the inexpensive path. In this case, cheaper products aren’t usually that great. So, remember to choose quality over anything. 


Siding caulks are made from various kinds of materials. From latex, silicone to butyl rubber, they do it all. In fact, a lot of the caulk sealants are actually the mixture of these two. 

But they all have their different uses. So, they’re not universal just so you know. 

Although butyl rubber is becoming quite popular for exterior siding projects. However, you can also try any other caulks such as silicone. 

For a lot of years, people have been using silicone caulks for this purpose and the performance is great. But whatever you do, make sure to read the packaging and see if it’s okay for your surface or not. 


Ever heard of colored caulk sealants? Well, they are in the market that’s for sure. Even though most people like to paint over the caulk but just in case you ever need a colored caulk sealant, you know they are out there. 

In fact, you can choose different colored caulks and sidings too. That way you can make out a nice looking theme. Although you can use the same clear coat for the kitchen cabinets and the surface. 

Nonetheless, you should always keep in mind that no matter what you do, the texture of these two things will always be different. But if you’re okay then go for it. 

Where Should You Use Caulk on Hardie Siding?

You can use caulk on a number of areas of your Hardie siding. But in our experience, we saw that both of the corners and sometimes the crevices, also some butt-joints, door trim boards, and windows are quite common areas. 

When putting on caulk, most people decide where they want to put it. However, at first, you should select the areas you don’t want to paint. And most importantly, figure out how you want to apply it. 

You see, a misplaced caulk and a bad installation will look like a disaster. So, you know how important it is to ensure a proper installation. 

However, don’t go using caulk on wood sidings. And there’s a perfectly good explanation behind this. 

If you didn’t know, wood actually expands and contracts over time due to temperature fluctuations and precipitation. When you put caulk sealants on a big piece of wood, naturally, it prevents the wood from moving. 

After a while, you’ll notice that there are cracks here and there on that wood. In short, it’ll mess up the appearance of a wood siding. 

Moreover, you should also avoid using caulk on fiber cement sidings. But you can do it if there’s a metal flashing under it. Otherwise, the waterproofing capability will be completely gone.

Apart from that, trim boards don’t really need caulking. This is even more unnecessary if those just sit over the surface. In fact, that’ll do more damage than good. 

First of all, it’ll block most of the air circulation and create a damp environment. The worst part is, this type of environment is the perfect breeding spot for mold and mildew. 

Finally, you should avoid caulking underneath the horizontal sidings. You see, those things do one thing and it’s waterproofing the siding. But caulking those won’t allow them to move at all so avoiding is the wise thing to do here. 

Before We Go

So, that’s basically all we had to say about caulk sealants for sidings. Hopefully, by now you know which one’s the best caulk for Hardie siding that suits you. 

But if you don’t that’s okay. Let us know what issues you’re facing and we’ll sort it out in the comments section. Good luck!