Painting question

[Michael Weber]

I have a hardboard or high density fiber board siding on a detached garage. I’ve replaced the lower 2 courses with a cement product due to deterioration. The siding is painted with what I believe is an oil based product. While the siding seems solid The paint is not. I’ve scraped a bit and when the paint comes off it brings a layer on the siding with it. This leaves a rough surface. Not sure how to deal with this. I don’t want to replace all the siding. Suggestions on how best to deal with this would be appreciated. 439180439181

[Jim Becker]

Sadly, it appears that the top layer of the existing siding is damaged and delaminating; perhaps from moisture. Your second photo really shows how the paint was failing with the siding surface. If it's only localized to a reasonably small area, you could try filling leveling the damage with bondo or some other appropriate filler, but if the damage is extensive, you may have no choice other than replacing the siding or living with the rough surface and continuing degradation.

[Ron Citerone]

Sadly, it appears that the top layer of the existing siding is damaged and delaminating; perhaps from moisture. Your second photo really shows how the paint was failing with the siding surface. If it's only localized to a reasonably small area, you could try filling leveling the damage with bondo or some other appropriate filler, but if the damage is extensive, you may have no choice other than replacing the siding or living with the rough surface and continuing degradation.

I concur with Jim on this one. Sorry to bring the reality check.

[Bruce King]

Look at the thick deck repair paints. Goes on with a roller and some are tintable.

[Andrew Seemann]

If you keep the siding and paint over the delaminated parts, make sure you use an oil based primer, you will get better "bite" on the wood than with just paint or latex primer. Also make sure the siding is completely dry. Those flaked off parts tend to get a little spongy and don't always dry quickly.

I have a couple places where I have had to paint over siding like that, since I won't be residing for another couple years. It worked reasonably well. It doesn't look great, but it looks better than peeling paint.

[Michael Weber]

Thanks for the suggestions. Replacement seems my best option. I think however, since the garage siding is not really visible to anyone not going down the alley, I’m going to try to salvage what’s there. As suggested, use Bondo on the few areas I damaged by scrapping. Use a pretty fine grit paper in my ROS and lightly go over all the siding. Oil base primer on any exposed undamaged bare spots. Then use a Zinsser product I found in my searches called Triple Thick Peel Stop Primer over the entire surface followed by top coats. The Zinsser product claims to seal the edges of peeling paint and bridge small cracks a thinner primer won’t. It gets favorable reviews. We’ll see how it goes on one side then go from there. Still open to suggestions.

[Mel Fulks]

Look up Gripper primer, I think it's better than oil based. Less mold and mildew.

[Ken Combs]

Probably Masonite or one of the copycats. Common problem and I think subject to a lawsuit years ago. I had the same issue on the back, upper story of a house years ago. There is no permanent fix, other than replacement. Good oil base primer, thinned a little for deep penetration and two coats followed by a good quality top coat will give you a couple of years, maybe more.

Really hated to see that stuff disappear though, made great concrete form material for curved walks. Use it once and throw it away. best use for it.

[Stan Calow]

AFAIK, they still sell Masonite siding. Maybe they did something to improve it.