We can see nailhead marks and slight staining where the wall studs are on the interior side of the outside walls and on the ceiling joists of our 35-year-old modular home. Any idea why? -Linda
It’s not uncommon to have a few drywall nail pops on the walls or ceilings of a house over time, due to movement from seasonal fluctuations in temperature and humidity. But if you have lots of popped drywall nails, accompanied by rust stains on the nailheads, you probably have a problem with excessive humidity building up either in your house or inside the walls and attic.
While you can fix the drywall pops, you need to address the excessive humidity issue first to prevent the problem from recurring, and to keep mold and rot from forming in your home.
Start by purchasing an inexpensive hygrometer and monitor the relative humidity inside your home, in the attic, and under the house (if you have a basement or crawlspace) to see if it stays within the optimal range of 30% to 50% throughout the year.
If you find you have a problem with excessive humidity in your house:
- Use vent fans vented to the outside in bathrooms during and for 10 to 15 minutes after bathing or showering (installing a timer switch or humidity sensing fan makes remembering simple).
- Run the stove vent fan vented to the outside when cooking.
- Check your clothes dryer to make sure it’s properly vented to the outside and the vent pipe is clean.
- Vent any gas fireplaces or gas space heaters to the outside.
- Run air conditioning during humid days in the summer.
- Seal up any cracks or gaps on the outside of your home with caulk or expanding foam.
- Check and repair weather stripping around doors and windows.
- Cover the ground in the crawlspace under your home with plastic, and make sure all foundation vents are unblocked and open.
- Check attic insulation for dampness, and make sure you have adequate ventilation in your attic through soffit vents, ridge vent, and/or gable vents. Power attic vents may be needed if humidity is too high in the attic.
- As a last resort, install a dehumidifier.
Once you have the humidity in your house under control, repair the worst of the drywall nail pops, apply a stain blocking primer to the walls and ceilings to cover the rust stains, and topcoat with latex wall and ceiling paint.
Good luck with your project,