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Question DetailsAsked on 1/5/2014

Can vinyl siding be painted?

We have dark stains in the "cedar look" vinyl in our gable areas that looks like mold/mildew but would not come off with a professional power wash.

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4 Answers

Voted Best Answer

Quite likely is - power washing alone will not remove mold/mildew - heck, except with very high pressure on concrete and stone (6-10,000 psi, which will cut right through siding), it does not even remove all the dirt, especially if it has not been presoaked with a detergent solution. Most contractors, if they use detergent at all, just use a siphon mix that mixes in with the pressure washing water and they do one pass with that - which is the worst of both worlds, as it does not sit long enough to soak in and release the bond of the dirt to the surface, but it does loosen the unwashed dirt sitting there, and it then leaves soap and loosened dirt on the surface so the following paint does not bond correctly. People have gotten WAY too dependent on power washing - it is good to get the worst of the dirt and to apply soapy water over a large area, and good for a final rinse to remove soap, but rarely comes close to a good hand scrubbing in dirt removal, and does not come anywhere close to a hot water wash unless the pressure washer is a "Hotsy" or similar that uses hot water for the washing and rinsing.

Your situation requires treatment with a mold killer, then vigorous hand or power brush scrubbing with a strong detergent or siding cleaner designed for vinyl, followed by a light sanding along the plank direction to provide "tooth" for the paint, followed by good primer designed for vinyl, and finally 1-2 coat of non-glossy finish coat, then the final "skin" coat (best if a stain or semi-gloss for weather and dirt resistance) of finish paint.

Most exterior painters are NOT qualified to paint vinyl or metal siding - just takes too much care and attention to detail for most to care enough to do right. You should base your painter selection on in-place samples of paint jobs he has done at least 3 years ago - because it commonly takes a couple of years for a bad job to start blistering and peeling.

Unfortunately, you can figure a proper job costing about $2.50-3.00/SF if done right, about 50% more than a wood house, which is more tolerant because it has more grain to hold the paint and resist blisters and peeling.

Answered 6 years ago by LCD


LCD, thanks for your very thorough and thoughtful reply. Would something like good old Tilex Mold and Mildew remover do the job? I have found it to be a great product on other mold and mildew issues in and out of the house. Thank you.

Answered 6 years ago by Guest_93686122


Tilex will work but most good home washes and mildewicides will work.

Look for some home wash with some TSP.

Answered 6 years ago by WoWHomeSolutions


lot of people have good luck with Mold Armor House Wash - but appears to work well only at about 60 degree surface temp and above, and you have to be sure to follow instructions and let it sit long enough for the bleach in it to work before you rinse off.

A good heavy-duty cleaner like NAPA Purple Power MultiPurpose Cleaner preceded by 25% bleach-water mix works good for me.

Answered 6 years ago by LCD


I have not tried Tilex - don't know if it would pull the paint or not - test in some small inconspicuous spot first. I would be suspicious, because it is made for use on tile and baked enamel paint surfaces, which are a lot tougher than house paint.

Personally, I like scrubbing with the NAPA Purple Multi-purpose Cleaner after a 25% chlorine bleach solution soak to kill mold and mildew. A lot of people use a 10% solution, but for the $50 or so extra bucks for a whole house I prefer to go for the overkill and have confidence the mold actually is totally killed - roots and all. To get the bleach to work well, you should not do it in the direct hot sun, because mold takes from 5-30 minutes contact time with the bleach to be killed, so if it evaporates too fast you may not kill it all, especially the roots.

Some other people swear by spray on and wash off Mold Armor, though I have heard it does not work well below about 60-65 degrees surface temperature or with very cold water if you use the hose-attached spray bottle.

The key is a bleach to kill the mold/mildew - both on the surface and its roots, then SCRUBBING with a good detergent or TSP to remove the killed mold and the dirt that dupports its growth - without the scrubbing you will not get rid of the staining and grayish look enough for finish coats to cover it up.

Of course, priming with a mold killer primer like Kilz greatly enhances the confidence that it will not come back, but unless you cover the entire wall you run a good chance of a shade or sheen variation between the Kilz section and the other areas. My preference, unless the problem was so bad you had no choice but to use Kilz, is to add a packet of mold killer powder per gallon of exterior (and bathroom and kitchen and basement and attic) paint, except with bright white where it can cause slight discoloration. This will inhibit (but not guaranteed to prevent) mold growth, as that upper gable area sounds like a shady area prone to future regrowth.

Washing (preferably pressure washing or scrubbing and rinsing if you are up to it, but just a detergent dispenser on the hose working from a ladder, or even a hose with jet nozzle from ground level to let you get all the way up the walls it better than nothing) your walls every year or two can reduce mold growth too - just be sure to keep the duration of water contact short to limit infiltration at any leaky spots, always have the water directed or spraying down rather than longitudinally or up so it does not penetrate under the siding, and do it on breezy or sunny days where it will dry quickly. The washing removes dirt which acts as a substrate (like topsoil) for the mold and also help retain moisture for the mold growth, and of course washing also removes the mold spores that are always in the air and land on the walls, hoepfully before they are able to take root.

Good luck

Answered 6 years ago by LCD

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