In our basement, water came up last summer and now we still have damp patches on the walls. We've tried various dehumidifiers, but it's not getting any better. Do we need a professional for this or can we handle it ourselves?
Dehumidifiers alone won't do anything if the walls themselves are soaked through - they only pull moisture from the air, but the water's stuck in the pores. Have you tried exposing the spots (so stripping off wallpaper/paint) and checking how deep the dampness actually goes? If it's just surface-level, intense ventilation and targeted heating (combined with a dehumidifier) can help, but honestly: if the walls are still noticeably damp after a whole year, you probably need a professional to properly diagnose it - could be a leak or capillary rise, and missing that just costs you more money and headaches down the road.
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