Interior & Exterior Paint

Is Drywall Mud Flexible? 7 Facts You Have To Know

Drywall joint compound dries hard rather than flexible, so repeated movement at seams can cause cracking unless the joint, tape, framing, and compound system are handled correctly.

Published · Interior & Exterior Paint

Drywall mud is used on the drywall surface to cover gaps and cracks. It dries strong and adhesion hardly. 

Now you can ask, is drywall mud flexible?

Generally, drywall compound mud should not be flexible. It dries hard. So we can sand the mud surface and then use paint. A flexible mud surface can not be sand. But for weather reasons, some manufacturers add some flexibility to joint compounds. This type of compound mud has some differences compared with general compound mud. 

In this article, we will explore more about drywall mud flexibility.

Does the joint compound crack?

Joint compound can crack when it shrinks, dries too fast, is applied too thickly, bridges movement, or sits over weak tape, uneven framing, or poorly prepared seams.

You see a small crack line through the painted wall when it cracks. Sometimes it can be too long, like one side to another side. 

I already describe in another article reasons of joint compound peeling after paint, you can check.

However, you don't always see the problem. Manufacturers make joint compounds to deal with the issue. The good news is future crack issues are fixable. 

What causes drywall compound to crack

Common causes of drywall-compound cracks include thick coats, weak tape bonds, uneven joints, rapid drying, moisture changes, framing movement, and poor surface preparation.

Uneven drywall joint

It is a very common reason for cracking drywall compounds. If you choose manufacturer premade drywall boards, these boards are ready with corners groove. Every board attaches to each other very easily.

If you use ordinary boards for drywall, these are not ready with corners. So there has a very high chance of not being perfectly attached to each other. 

However, there are also uneven joint chances with premade drywall boards. There needs attention when installing the boards.

Weather Issue

The weather has a significant effect on the joint compound. When the season is winter, the weather is cold and dry. The dried mud can shrink. As well as humidity and wet weather, the mud can expand.

Generally, in too cold weather, the dry mud has a chance for cracks. For this issue, it is best to use some flexible compounds. 

Make sure your room has good ventilation always. It will protect your drywall from humidity and wet weather.

Too thick coat of joint compound

It would be best if you did not use thick coats of joint compound. It has a very high chance of mud cracking if you do it. 

A thick coat instead, you should use multiple layers of coats. However, the first coat needs to be thick but not much. After each layer is dry, sand it and apply new thin coats of mud. It is the best practice to follow.

However, if you already use a thick coat, sand it with sandpaper, make it thin and smooth, and then apply more thin coats of mud. 

How do you make drywall mud flexible?

Do not add glue or other improvised modifiers to joint compound unless the manufacturer specifically approves it, because additives can change drying, sanding, adhesion, and strength.

However, I suggest you choose premade flexible mud. It is perfectly ready for a flexible type of job.

I already describe premix joint compound vs dry compound, you can check.

How to add glue on mud?

If extra flexibility or adhesion is needed, use a compound or setting product designed for that purpose rather than mixing household glue into standard drywall mud.

This is a tutorial video. You can follow it.

https://www.youtube.com/watch?v=eLAGQpLg9cI

Is there flexible drywall mud?

Some joint compounds and setting products are formulated for tougher or more crack-resistant applications, but none turn a moving drywall joint into a flexible seam.

Generally, I divide fixable mud into two types. One is a little flexible mud that can be sanded, making the surface smooth before other coats of paint. It is suitable for indoor projects.

Another is very flexible mud. It can not be sanded after it dries, generally used on outdoor projects. 

Best flexible drywall mud

Choose joint compound by repair type, setting time, sanding needs, moisture exposure, and manufacturer guidance rather than looking for a universally 'flexible' drywall mud.

DAP INC 18743 Alex Flex Quart Spackling [Best Indoor Flexible Drywall Mud]

As a drywall manufacturer, DAP has a well-known and good brand. DAP alex flex quart spackling is come to fix any crack issue and is used as drywall mud for any type of mud project. 

It has the ability to protect against any type of shink, crack or shrink. You can sand and make your surface more smooth. 

Although I found some bad reviews online about this product, the mud cracked after use and failed for sand, but these review numbers are very few. 90% of people like this product.

Overall good product.

Here is a video of how you can use the mud.

https://www.youtube.com/watch?v=SFqfdzgVJq8

Dap 12278 ElastoPatch White Pro-Grade Elastomeric Patching Compound [Best Outdoor Mud]

For outdoor projects, DAP elasto patch white pro-grade is a good one. It also can use the Indoor project, but it is not recommended. This mud cannot be sanded after applying.

It has excellent adhesive ability. Give good protection from any type of weather, humidity, temperature, wetness, etc. 

This product can use different types of surfaces like brick, plaster, masonry, wood and more. 

I found some bad reviews online that it can not be sanded and hard to apply. This product has already been told before about sand issues. 

Overall good product for outdoor use. Good protection from the crack.

Conclusion

Drywall mud is not meant to flex like caulk, so lasting crack resistance comes from stable framing, sound tape joints, correct compound thickness, and proper drying.

If you think this article is helpful, share it with your friends and family who are curious about this topic.

Source

https://www.doityourself.com/forum/patching-plastering/451733-joint-compound-thats-flexible.html
https://diy.stackexchange.com/questions/91259/why-is-my-drywall-mud-cracking