Bubbles And Blisters On Painted Siding

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Estimated reading time: 5 minutes

Bubbles are fun in a bath but not on your freshly painted siding. Let’s break this issue down.

Bubbles forming under the paint can indicate poor adhesion, likely due to poor surface preparation. When paint doesn’t properly adhere to the surface, it can trap moisture. The sun heats the siding, and blisters form.

This condition eventually leads to peeling paint. It can be corrected, but the underlying cause of the problem must be addressed, or it will recur.

Here’s my short list of reasons the paint is bubbling.

  • You’ve painted a damp, dirty, or hot surface
  • Mistakenly applying oil-based or alkyd paint over latex paint
  • Improper surface preparation (most common cause)
  • Excessive moisture – poor flashing or siding installation issues
  • Exposing latex paint to moisture shortly after paint has dried – a rain event

You will need the following materials and tools to repair the paint bubbles on your siding. Remember, this article is meant to address outside paint issues, but the repairs should be similar when dealing with interior paint surface issues.


  • Paint Scraper or Putty Knife: To remove the bubbled paint.
  • Fine-Grit Sandpaper: For smoothing the surface after scraping, use 120 to 220 grit.
  • Mild Detergent: Clean the area before applying primer.
  • Sponge or Cloth: For applying the detergent and cleaning the surface.
  • Primer: Choose a high-quality primer appropriate for the siding material (rust-inhibitive for metal, plastic-adhering for vinyl).
  • Exterior Latex Paint: Select a paint compatible with your siding material and the primer used.
  • Painter’s Tape: To protect window frames, trim, and other areas not being painted.
  • Drop Cloths or Plastic Sheeting: Protect surrounding areas from debris and paint.


  • Safety Glasses: To protect your eyes during the scraping and sanding process.
  • Dust Mask: To avoid inhaling dust while sanding.
  • Paint Brushes or Rollers: For applying primer and paint. Use brushes for smaller areas and rollers for larger sections.
  • Paint Tray: If using a roller.
  • Ladder: If the repair area is out of reach from the ground.
  • Gloves: To protect your hands during the work.
  • Moisture Meter: To check for moisture in the siding before and after repair.
  • Caulking Gun and Caulk: If you need to seal any gaps or seams to prevent future moisture intrusion.
  • Extension Poles for Rollers: If you’re painting a larger area and have a roller.

How To Repair

Always start with safety in mind; use the ladder safely and wear your protective gear. Depending on the severity of the blistering and the size of the area you’re working on, you might not need all of the above, but this list should cover most scenarios.

Please note that this cost analysis is based on national averages and is only an estimate. Prices will vary by location and current market conditions. For an accurate quote, it is best to consult local professionals.

  1. Identify the Extent of Damage: Check the entire wall surface for bubbles and blisters. This will help determine how much area needs to be repaired and paint needed for the job.
  2. Prepare the Area: Before you begin, protect surrounding areas with drop cloths or plastic sheeting to catch any debris or paint.
  3. Remove the Bubbles: Use a paint scraper or putty knife to remove the bubbles gently. Be careful not to damage the underlying siding material. If the blisters do not reach the substrate, remove them by scraping and sanding. If the blisters go down to the substrate, you will need to remove the source of moisture, if possible.
  4. Sand the Surface: Once the blisters are removed, sand the area to create a smooth, flat surface. For metal siding, use fine-grit sandpaper to avoid scratching the surface.
  5. Clean the Area: Wash the sanded area with water and mild detergent to remove dust, grease, or debris. Rinse thoroughly and allow it to dry completely.
  6. Prime the Surface: Apply a high-quality primer suitable for the siding material. For metal, use a rust-inhibitive primer. For vinyl, use a primer designed for plastics to ensure proper adhesion. This is the important step and is where the failure occurs – preparation is key to your success in making this repair.
  7. Apply Paint: Once the primer is dry, apply a top-quality exterior latex paint appropriate for the siding material. Make sure the paint is labeled for use on vinyl or metal, as applicable.
  8. Monitor the Area: After the repair, monitor the area over the next few months to ensure the problem does not recur.
  • Safety Disclaimer: Take appropriate safety precautions when working on siding, especially when using a ladder or working at heights. If you are uncomfortable with this type of work or the damage is extensive, it may be best to consult a professional.
  • Cost Analysis: The average cost for repairing paint bubbles on siding can vary widely depending on the extent of the damage, the type of siding, and regional labor costs. For small areas, it might just be the cost of materials if you DIY, which can be under $100. For larger areas or if professional help is required, costs can escalate to several hundred dollars.

Remember, it’s best to consult a professional painter if unsure about the correct materials or methods for your specific type of siding.

If the issue persists or if you suspect there might be more serious underlying problems, such as persistent moisture intrusion or structural damage, it may be necessary to have a thorough inspection by a professional. In that case, I cover Metro Jackson, Mississippi. Contact me for a more detailed evaluation.

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