How big of a gap can you fill with drywall mud?

Answered by Robert Flynn

When it comes to filling gaps with drywall mud, the size of the gap you can fill depends on the type of drywall compound you are using. There are two main types of drywall compound: the setting-type compound and the drying-type compound.

The setting-type compound, also known as the bagged kind you mix, is a versatile option that can easily fill gaps up to 1/2 inch without cracking. This type of compound comes in powder form and needs to be mixed with water before use. Once mixed, it forms a chemical reaction that hardens the compound and provides a durable finish.

To fill a gap with setting-type compound, you need to ensure that you load up the gap well before applying any tape. This means applying a generous amount of compound to completely fill the gap. It’s important to press the compound firmly into the gap to ensure proper adhesion. Once the gap is filled, you can proceed with applying your tape and finishing the joint as you would with any other joint.

On the other hand, the drying-type compound, which comes premixed in a bucket, is not as suitable for filling larger gaps. This type of compound is more commonly used for thin coats and finishing touches rather than filling large gaps. It tends to shrink as it dries, which can lead to cracking if used to fill larger gaps.

If you have a gap larger than 1/2 inch, it is recommended to use additional materials to bridge the gap before applying the drywall compound. For example, you can use strips of drywall or joint tape to provide a solid foundation for the compound to adhere to. This will help prevent cracking and ensure a smooth finish.

In my personal experience, I have successfully used setting-type compound to fill gaps up to 1/2 inch without any issues. The chemical reaction that occurs during the drying process allows the compound to harden and withstand the stress of larger gaps. However, it’s important to note that proper technique and application are crucial for achieving a seamless and durable finish.

To summarize, with the right type of drywall compound, such as the setting-type compound, you can easily fill gaps up to 1/2 inch without cracking. It is important to load up the gap well before applying tape and finish the joint properly. For larger gaps, additional materials may be necessary to bridge the gap before applying the compound.