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Some of the lower boards of my 10-year old Hardie siding have become brownish. I am planning to repaint. What is the best approach?

Prime it again and then paint. Or just paint?

I suspect rain water splashing from ground. Even from grassy areas.

When I scrub it it becomes bright yellow. I wonder why. Even brighter than a fresh board.

I ended up priming it first. It looks fine now.

Realized painter's blue strip works 90% on Hardie as the texture is rough and some paint does get through. But still better than not putting the strip.

  • What is the brown ? Iron stain from well water a rust removal product may be all you need I have not used CLR for outside iron rich water but it may do the trick.
    – Ed Beal
    Jun 14 '20 at 1:00
  • @EdBeal not sure about the source. It happens mostly near grassy areas. Not where I have concrete flooring.
    – Maesumi
    Jun 14 '20 at 12:01
  • Grassy areas where you are watering the lawn, iron from well water is a source of brown stains this is what I am getting at, you might try a product called CLR do any of your sinks or bath tubs show brown stains close to the faucets?
    – Ed Beal
    Jun 14 '20 at 17:28
  • 1
    @EdBeal We do not have a well. If anything this looks like splash of rain from ground.
    – Maesumi
    Jun 14 '20 at 20:35
  • @Maesumi - thanks for coming back with your update. Please put that in as an actual "Answer", then click the check mark to accept the answer. That will tell future readers (who have a similar situation) that this question has a successful resolution and will have the added benefit of telling the system not to bump it to the top every now and then because it thinks it doesn't have an answer.
    – FreeMan
    Jun 18 '20 at 13:53

I ended up priming it first and then repainting. That was also suggested by an employee of the paint department of a major home improvement store.

Here are a set of suggested steps.

1- Clean from the very top near shingles so that debris does not get into fresh paint.

2- Pressure wash from a distant using a wide spray. Pay attention to the underside of overlaps. Wait for it to dry.

3- Make sure you have time to do a segment before it rains. Plan to finish an hour before sunset to be able to see missed spots.

4- Use painters blue tape to protect areas not to be painted. Press firmly to prevent paint from going underneath the tape. Cover the floor. Use a 4 or 6 inch roller with 3/4" nap for flat part of surfaces. Need small brushes for corners, edges, and under overlaps.

5- Prime.

6- Paint.

I ended up wiping the brown stain on the board with a rag. A bright shiny yellow surface shows underneath those browned spots. Brighter than a fresh board. Same thing shows around the home. Mostly in spots that does not get much direct sun. The reason for brown spots and bright yellow surface was not clear.

  • Excellent! Just make sure you come back (in 48 hours, I believe) and accept your self-answer!
    – FreeMan
    Jun 20 '20 at 14:20

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