Step 1: Measure Your Working Humidity
Before you start, know what you're dealing with. Pick up an inexpensive hygrometer (under $15 at any hardware store) and check the room you'll be working in. In winter, you'll likely see readings between 12% and 25% relative humidity. In summer, anywhere from 20% to 40% depending on whether the AC is running.
This number determines how aggressively you need to adjust your technique. Below 20% requires significant adjustments. 20% to 30% requires moderate changes. Above 30% you can probably work close to normal.
Step 2: Mix Your Mud Slightly Thinner Than Normal
In humid climates, you mix joint compound to a stiff consistency because moisture in the air slows drying and gives you working time. In Salt Lake City, that same stiff mix dries on your knife before you can spread it.
Add an extra splash or two of water during mixing. You want the mud slightly thinner than what you'd use elsewhere. Test by lifting the mixing paddle. The peak should soften within two seconds rather than holding firm.
Thinner mud spreads further before it starts setting and gives you more working time. The downside is slightly more shrinkage during drying, which means an extra coat may be needed. That tradeoff is almost always worth it.
Step 3: Work Smaller Sections
The biggest adjustment is psychological. In a humid climate you can mud a whole 12-foot wall before going back to wipe it down. In Salt Lake's dry air, by the time you reach the end of that wall, the start has already begun setting.
Work in sections of 4 to 6 feet. Apply mud, immediately go back and feather it, then move to the next section. This pace keeps the mud workable and produces cleaner edges.
For ceiling work, even smaller sections. Three feet is a comfortable working area. The mud dries faster overhead because warm air rises and intensifies the drying.
Step 4: Add Humidity to the Work Area
For larger projects, raising the humidity in the work area pays off significantly. A console humidifier running for an hour before you start brings local humidity up to a more workable range.
For a single room project, a small humidifier with a 2-gallon tank is sufficient. For a whole basement or multiple rooms, you'll want something larger or multiple units. Set them to run while you work and during the drying period between coats.
The target is 35% to 45% relative humidity in the work area. This brings working time back to manufacturer-stated specifications and reduces pinhole formation.
Step 5: Mist Tape Coats Before Embedding
Paper tape needs moisture to bond properly. In dry conditions, the bedding mud loses its surface moisture so quickly that the tape doesn't get the contact it needs. The result is poor adhesion that shows up months later as bubbled or peeling tape.
The fix is to lightly mist the bedding mud with water from a spray bottle just before placing the tape. A few quick spritzes is all it takes. The water adds a few minutes of bond-friendly working time.
Mist again on the surface of the tape before applying your skim coat. This prevents the tape from sucking moisture out of the topping mud too quickly, which is what causes pinholes.
Step 6: Use Setting Compound With Care
Setting-type compound (the kind that comes as a powder you mix with water) has a chemical setting time that's relatively unaffected by humidity. This makes it tempting for dry climate work because you know how long you have.
The catch is that setting compound is harder to sand than premixed compound, and it's much harder to work in thin coats. In Salt Lake's dry air, the surface drying compounds the difficulty because the mud feels set before it actually is.
Dave's recommendation: use 90-minute setting compound for first coats and tape embedding only. Use premixed mud for second and third coats where workability matters most. This gets you the chemical reliability of setting compound where it helps and the easy sanding of premixed where it matters.
Step 7: Adjust Drying Time Expectations
Manufacturer drying times assume around 70 degrees and 70% relative humidity. In Salt Lake's dry winter, drying happens 30 to 50% faster than spec. This sounds like a benefit until you realize that fast drying means surface dry, not cured.
A coat that feels dry to the touch in 90 minutes may not actually be cured for several hours more. Applying the next coat over a surface-dry but uncured layer traps moisture and causes shrinkage, cracking, and adhesion problems.
For coats you're applying yourself, wait at least the manufacturer's stated time even if the surface feels dry sooner. Better still, wait an additional hour beyond spec. The extra patience prevents most of the problems people blame on the dry climate.
Step 8: Sand With Dust Control
Salt Lake's dry air means joint compound dust travels further and settles harder than in humid climates. There's no moisture to weigh it down. A sanding session in winter can leave dust in every room of the house.
Use a sanding pole with a HEPA-equipped vacuum attachment for any project larger than a single patch. The investment in proper dust control pays off the first time you avoid spending an entire weekend cleaning up.
For finer dust control during final sanding, lightly mist the wall with water before sanding. This is wet sanding lite, and it virtually eliminates airborne dust at the cost of slightly slower sanding. The University of Utah's Department of Family and Preventive Medicine has documented elevated indoor particulate levels during dry construction work, which is one practical reason to manage drywall dust carefully here.
Common Mistakes Worth Avoiding
The mistakes I see Salt Lake homeowners make most often when doing drywall work:
Heating with a kerosene heater during winter projects. The combustion adds water vapor but also adds particulates that can contaminate finishing work. Use electric heat for finishing.
Working with windows open in winter. Outside humidity is even lower than inside. Opening windows for ventilation accelerates drying problems rather than helping.
Skipping primer. In dry climates, the porosity difference between drywall paper and joint compound shows up dramatically when painted. Primer evens the surface and prevents flashing. Don't skip it.