Why do I keep getting cracks above my doors and windows? I've patched them twice.
In St. Louis, this is almost always clay soil movement. The expansive clay soils under much of St. Louis City and County absorb moisture in wet seasons and shrink in dry ones. That movement — even when minor — loads the structure in ways that translate into diagonal cracks at window and door corners.
The repair keeps failing because you're filling a crack in a spot that's going to move again. Rigid joint compound cures hard and can't accommodate the movement. The options are: use flexible caulk instead of compound at those specific corners (which accommodates movement), or have a foundation specialist assess whether the movement is within normal tolerances or something that needs addressing structurally.
If the cracks are stable — same size for years — flexible caulk maintenance is a reasonable long-term approach. If they're growing or new ones are appearing, that warrants a closer look at the foundation.
My older Soulard home has plaster walls. Can I just patch over them with drywall compound?
It depends on the condition of the plaster. If the plaster is solid — when you knock on it, it sounds solid not hollow, and it doesn't flex or crumble — you can apply joint compound over it directly for small repairs and finish cracks. Use a bonding agent like Plaster-Weld first, or use a setting-type compound for the base coat rather than pre-mixed. Pre-mixed compound doesn't bond reliably to old plaster without a bonding primer.
If the plaster is hollow (the knocking sounds like a drum), crumbling, or has separated from the lath behind it, covering it with compound won't fix it. You'll need to either remove the failing section back to solid material, or remove the plaster entirely and install drywall — which is common in St. Louis renovations and produces a more stable result if done correctly.
The transition between remaining plaster and new drywall is the tricky part in older St. Louis homes. The thickness difference (plaster is typically 3/4-7/8 inch; drywall is 1/2 inch) creates a step that requires careful shimming and feathering to blend.
What's the best time of year to do drywall work in St. Louis?
Spring (April-May) and fall (September-October) are the best windows. Temperatures are mild and indoor humidity is manageable — typically 40-60% without needing to run AC or heat constantly.
Summer is workable but demanding. July and August humidity regularly exceeds 70%, which extends drying times significantly. If you're doing summer drywall work, run AC or a dehumidifier in the work area and budget extra time between coats.
Winter can be done but avoid working in unheated spaces below 55°F. Cold temperatures prevent proper compound curing. In a heated home, winter is actually fine — just watch that you're not bringing in very cold, dry outdoor air that will cause rapid drying. Rapid drying can cause cracking just like high humidity causes slow drying.
I have paint bubbling on an exterior wall near the floor. What's causing it?
In a St. Louis brick home, this pattern — paint bubbling near the floor on an exterior wall, especially if it appears after wet weather — usually indicates moisture migrating through the brick. The most common causes are failed or deteriorated mortar joints, failed caulk around windows, or a missing/failed flashing detail.
Don't just scrape and repaint. That's a cosmetic fix for what may be an ongoing moisture problem. The cycle will repeat.
Start outside. Inspect the mortar joints on the exterior wall in the area of the damage — look for gaps, crumbling, or areas where the mortar has receded significantly from the brick face. Check the caulk around any windows near the damage area. If you find deteriorated mortar, a mason can repoint the affected area; this is not a full tuckpointing job in most cases, just spot repointing where the mortar has failed.
After the exterior is addressed, let the wall dry out (4-6 weeks, ideally with a dehumidifier running in the room) before doing interior repairs. Closing the wall before it's fully dry traps moisture and extends the damage cycle.
How long does joint compound take to dry in St. Louis summers?
In July or August with outdoor humidity above 70%, a standard coat of pre-mixed compound applied at typical thickness can take 36-48 hours to dry properly — compared to the 24 hours manufacturers suggest and the 18-20 hours it might take in spring. Surface-dry (white on top) can happen in 12-16 hours even in humidity, but the interior still contains moisture that needs to evaporate before sanding or recoating.
Touch test: the compound should feel uniformly hard throughout, not just on the surface. Press gently in the center of the patch with a fingernail — if it feels at all soft or gives slightly, it needs more time.
Running AC keeps indoor humidity lower and significantly speeds drying. Even dropping indoor humidity from 75% to 55% can cut drying time nearly in half. A box fan promoting air circulation also helps, but avoid pointing a fan directly at fresh compound — rapid uneven drying can cause surface cracking.
Do I need a permit for drywall work in St. Louis?
For cosmetic repair work — patching holes, fixing cracks, replacing damaged sections without altering structure — permits are generally not required in St. Louis City or County.
Permits are typically required when the drywall work is part of a larger project: finishing a basement, adding or removing walls, renovation work involving electrical or plumbing, or anything changing the use or square footage of a space. The St. Louis City Building Division and St. Louis County have online permit guidance, and calling to ask about a specific project is usually the fastest way to get a clear answer for your situation.
If you're hiring a contractor for permitted work in St. Louis City, they need to be licensed with the city. St. Louis County has its own licensing requirements. This is worth verifying before work starts — unlicensed work done under permit can create title issues if you sell the property.