Question: Ready-Mixed vs. Dry Joint Compound
Q: "I will be installing drywall in my entire house--3 bedrooms, 2 bathrooms, kitchen, living room, dining room, and basement. Should I use ready-mixed joint compound or dry joint compound? Which is most cost-effective? I've heard that it's best to purchase a dedicated mud mixer, but am I justified in purchasing this machine just for one house?"
Types of Muds and Formats
The all-purpose joint compound, commonly called mud is used to adhere paper joint tape, fill joints, and to top paper and mesh joint tapes, as well as plastic and metal corner beads.
It can also be used to repair holes and cracks in drywall and plaster.
If you want to get fancy, you can use specialized muds. For instance, there is a mud just for embedding paper tape, another for setting a base layer to cover tape, and another one for topping the joints. But most homeowners stick with all purpose mud.
See Video: How to Mud and Tape Drywall
Mud comes in two forms: 1.) ready-mixed in buckets with the water already added; 2.) dry powdered form in bags, with no added water.
As with most things that come dry or wet, the dry form is cheaper. Dry drywall mud stores in smaller spaces; ships with less weight; requires less manufacturing, and has cheaper packaging (paper bags vs. plastic buckets).
Purchase Electric Mud Mixer?
Recently, I was speaking with Jason Swanson of TTI (the parent company responsible for RIDGID and Ryobi tools) about the RIDGID 1/2 in. Spade Handle Mud Mixer, which retails for $169 at The Home Depot.
A mud mixer isn't essential to mixing mud, but it makes life a lot easier. You can mix small amounts of dry mud with your electric corded drill. But a mud mixer has a strong motor and low torque for turning heavy compounds, even small mixes of concrete. Plus, it saves your drill for what it was made for drilling.
"I imagine this mud mixer would pay for itself," I told him, "because you can buy the cheaper dry mud instead of the more expensive pre-mixed mud."
Later on, I wondered how much dry mud you would have to mix with a mud mixer to justify the mixer's cost. So, I did what anyone else would do. I consulted a Ph.D. in Mathematics.
Calculating Dry vs. Wet Compound Costs
As it turns out, I should have been able to do the math. But probably all this hand-mixing of dry mud over the years has addled my brain, and I just couldn't do it. Assumptions:
- Five gallons of Beadex Joint Compound is $12.74 at The Home Depot and covers 448 square feet. Thus, one dollar's worth covers 35.16 square feet.
- BEADEX Brand Silver Set-20 18 lb. Setting-Type Joint Compound is $8.75 at The Home Depot and covers 346 square feet. Thus, one dollar's worth covers 39.54 square feet.
This means that dollar for dollar, dry compound covers 4.38 square feet more than the wet compound.
How Much Mudding Needed to Justify Mixer's Cost?
Okay, we kind of predicted that dry was cheaper than wet, but now we have exact figures. How much mudding with dry mix would you have to do in order to justify the purchase of a $169 mud mixer?
Answer: a lot.
It takes 55,229 square feet of mud to reach a break-even point for that $169 mixer.
In real world terms, you would need to skim-coat all four walls and ceiling of approximately 104 rooms sized at 12' wide, 14' long, and 7' high, in order to recover the cost of the mixer.
Skim Coats vs. Joint Work
Keep in mind, too, we said skim coating, which means covering every square foot of a wall or ceiling. Skim coating is part of a level 5 drywall finish, something that few homeowners will ever take on.
Since most drywall finishing confines itself to narrow joint strips (3" to 8" wide), I would triple or quadruple that earlier number. So, you might need to finish 400 rooms at a Level 4 finish to justify the cost of the machine.
As a homeowner, it's best to purchase ready-mixed joint compound in 5-gallon buckets.
Or purchase dry compound and mix with an old electric corded drill.
A professional contractor, remodeler, tradesman, or anyone who finishes drywall with regularity will find it worthwhile to purchase a mud mixer along with dry compound.
One bad thing about the ready-mixed compound is you are continually opening and closing the lid. This lets air in, speeding up the drying process inside the bucket (which you do not want). It can also introduce organic debris which will create mold in the mixture, requiring you to throw out the entire bucket.
A solution is to buy long, narrow metal mixing trays. They allow you to dollop out enough compound for this next 30-45 minutes' work-time. Additionally, drywall knives fit into these trays; they do not fit into round buckets very well.