Why Is My House Paint Bubbling?
Hint: It’s Not What You Think
Some Reasons Your Exterior Paint May Be Bubbling
Moisture
A common misconception is that moisture is the cause of all paint bubbling on exterior painting of siding and trim. Wet raw wood can hold lots of water. If paint is applied over it, thin, pebble-like bubbles will form immediately. When you press on them, they feel like bubblegum.
Moisture-related bubbling is the mark of poor workmanship. At Build & Paint Portland, we take a science-based approach to painting. Our crews use moisture meters and laser thermometers to ensure that conditions meet manufacturer guidelines before applying primer or paint. If it’s too cold or too wet, we don’t paint. Additionally, the high-quality paints we use offer “early moisture resistance,” should a shower come through unexpectedly. Moisture trapped underneath the new paint, not moisture on top of the new paint, is the most problematic.
The bottom line with moisture-related bubbling: Our warranty covers it. If you have bubblegum-type bubbling, we’ll fix it for free. View our warranty agreement here.
Dirty Surfaces
On exterior house painting projects, we’ll powerwash your home to remove dust, dirt, grime, and mildew so that we there is a clean surface for paint to adhere to.
On interior house painting projects, we’ll dust surfaces such as sills and base trim, vacuum window casings and degrease kitchen cabinetry.
For interior remodeling projects, drywall dust is a common cause of bubbles. Whether small or big, they’ll feel like bubblegum if you press on them. We’ll clean and vacuum surfaces before sealing new drywall to ensure great paint adhesion.
The bottom line with dirt-related bubbling: Our warranty covers it. If you have bubblegum-type bubbling, we’ll fix it for free. View our warranty agreement here.
Substrate Issues
The original “substrate” is the surface underneath the paint. It’s the original surface such as raw siding or trim. (Most commonly wood.) Bubbles that form from the original surface feel rigid to the touch. It’s rigid because the bubble has pushed out from the earliest layer through every subsequent layer, like peels of an onion.
Substrate bubbles happen for different reasons and there may be a combination of factors in play:
- When newly applied paint is drying, it can pull up weak areas. Our paint crews will inspect the siding and trim after the first coat is put on and address any bubble formation right away.
- Temperature fluctuation. Seasonally, as temperatures change, the paint can expand/contract and those weak areas might bubble. It’s typical for us to receive a couple of calls in spring from homeowners who had homes painted the previous summer.
- Heat transfer. Moisture from inside the home needs a way out when temperatures warm up. It can push through the siding, especially in old homes with poor insulation. They commonly form on the south or west sides of the home or near a kitchen wall. The moisture finds the weakest area and pushes right through.
- Oil paints and stains. Oil-based paints were the standard by the 1970s. If your old siding or trim was originally stained or painted in an oil-based product and then painted over with water-based primer and/or paint, it makes for a super weak bond that could create substrate bubbling. This is also common on interior trim where paint will chip easily or come off in sheets.Crews are trained to identify this situation and can perform a quick test to see if an underlying paint layer is oil-based. If so, they can spot prime with an oil product which will better bond to both the old layer and the new coats.
- Dark colors are most susceptible to bubbling since siding and trim warms considerably during the day and cools at night. If you want to paint your old home black, expect some bubbles.
Our Prep Process
It’s impossible to know what sort of painting process was used on your house if it was built 50-125 years ago or longer. The common assumption is that the new painter didn’t prep well enough.
At Build & Paint Portland, our crews will thoroughly hand scrape your home, running scrapers over every inch of your siding, trim, window sashes, eaves, fascia, and doors. We scrape until we reach a hard, stable edge. The goal is to remove old paint, clean the surface, putty and caulk gaps and nail holes, and hand-brush a high-quality primer into the raw wood to create a solid surface to paint on. This is the time-honored prep process. Extensive prep is the key to a long-lasting paint job.
Despite thorough preparation, a small percentage of our customer may still experience substrate-related bubble formation after getting their home painted – most commonly within the first year.
How to Test
An easy test to tell if a bubble is substrate-related is to cut one open. If it’s hard, stable and you see raw wood or stain underneath, the bubble starts at the original surface and not from the newly applied paint. Our warranty does not cover substrate bubbling because they aren’t a workmanship issue. Your home has thousands of linear feet of siding and trim. We have no may to know where a weakness may be outside of what’s already been properly scraped.
The Good and the Bad
The bad news is that the only true way to avoid the possibility of substrate-related bubbling is to fully remove all of the previous paint down to bare wood. This is labor intensive and costly (we have a machine that can do it that meets EPA standards). Re-siding or using a chemical stripper are other avenues to consider.
Aggressive sanding around scraped areas is not a great fix. It can cause pits in the wood and does not result in a professional looking finish and may still allow bubbles to form in the areas that were resistant to scraping.
The good news is that substrate bubbling is usually limited in scale. There are typically only a few problem areas that can be quickly addressed within a two-to-four-hour follow-up visit. We will come out to assess the source of the bubbling issue. If it’s substrate related, we’ll provide a quote to fix it.
Conclusion
Build & Paint Portland specializes in repainting and restoring old homes. We’ll use time-honored methods of preparation to ensure the longevity of your paint job.
During our estimating process, we assess the condition of the exterior of your home, review our prep practices and advise on your options, including the replacement of siding. (We have a full-time carpenter who can replace siding prior to the paint project starting.)
Our 3-year warranty provides piece of mind. Workmanship is our #1 core value. If there’s a problem, we’ll come out, take a look, and craft a plan to fix whatever problem has arisen. Guaranteed.
Quality Craftsmanship
Reach out to schedule a consultation and let’s talk through your project.