Painting Cupped Cedar Siding

Wobbly

The 50 year old very thick cedar siding on the west side of our house has damage in a number of places. Some of the boards have cupped noticeably. Climate is Pacific Northwest.

There are also knot holes, some splitting, and cracking. A few years ago, I got the bad idea to fair out all the cupping and smooth out all the surface imperfections with auto body filler. The worst cracks were filled with epoxy resin thickened with talc to prevent the epoxy from running.

Looked great for a few months. Then the Bondo developed massive cracking and large sections started to peel.

Some of the problem seems to be that the Bondo was put over a layer of weathered cedar. While it might have stuck to the weathered layer, that layer easily separates from the substrate. Another problem might be that Bondo didn't allow water to escape.

I'm now removing all the Bondo and paint down to fresh cedar using a Paint Shaver Pro, angle grinder with resin fiber disks, and a random orbit sander, and scrapers.

The surface will still be cupped and there will be areas where removal of the Bondo has left some ragged depressions.

Bob Vila's forum had this suggestion:

"When repainting your house, here's a way to restore that smooth original finish. After you've removed all loose paint and sealed the surface with a latex primer, use a water-based, exterior grade wood filler to fill in the rough areas that remain. With a four inch tool, spread an even layer of wood filler and smooth it out. When it's dry, lightly sand it, and apply a second coat the same way if necessary. When the surface is perfectly smooth, apply your finish paint."

On another forum, a contractor mentioned using a product called Flex Patch http://www.texcote.com/pages/fp-1297.html .

I've also thought of using thickened epoxy resin to fill in some of the gouges and splits. Using epoxy as a skim coat might prevent water migration through the siding, though. It's also pretty expensive to use as a fairing material.


Any thoughts?

Thanks

slickshift

Sometimes, one reaches a point where removal and replacement is actually easier (or at least more cost and time effective) than trying to fix what's there

mikey48

I also live in the NW. Sounds like it is time to replace the siding. Check around, we have a cedar yard in Chico that sells the cedar very reasonable

Wobbly

The existing siding is about 1- 1/2" thick at the base. Don't think they make it anymore.

lundybar

I too live in the northwest. My house is painted cedar with some blistering and cracking in the exterior paint. I am in the process of getting bids for painting the exterior and have received so many different opinions about which Dunn Edwards paint to use due to cracking and blistering.

Does anyone know which Dunn Edward exterior paint I should use "Evershield (flat) vs. Enduracryl (low sheen)? And how long paint should last?

Wisco

Dude, Yur in luck I have painted my large home(12 inch cedar) in wisco twice now in 5 years and the rough and split cedar is starting to look pretty good now. (I bet it was stained twice prior to that in 17 years maybe once) Suggestions Gorilla glue or Elmers urethane for the cracks and splits(spray a bit of water in the cracks and watch the urethane glue bubble into the grain like mount St. Helens at liftoff. Sand down the glue with lava rock or pumice stone.

Use DM ready patch on some of the open really weathered grain but it is not a cure all for really bad boards that just need replacing. It has been 5 years now and holding strong.Both at Menards.

I actuall oil primed the house when I bought it and then a solid stain. I now did a maintanence coat of SW Duration and knock on wood she is tight as a drum and looking good with urethane caulk to seal her up. Usually the cedar cups because it was not sealed on the backside and ends when installed with primer or paint/stain. Is real nice longlasting siding, with way more character than plastic(yah maintenance also) but this step is often neglected. Chow for now Morph

Wobbly

Looking at Zinsser and DAP sites. both say no to skim coating with their patch products. However, Zinsser says how to apply MH Patch as a skim coat! http://www.zinsser.com/PDF/TDB/ReadyPatch.pdf

I used way too much Bondo before , trying to completely fill in the cupping and make the boards perfectly flat amd smooth. Trying to get so much Bondo to expand and contract with the wood was asking too much. I also applied the Bondo in some places to the old topcoat instead of to sanded wood.. It seems the the previous painter slapped latex over the weathered cedar layer- with no primer. Even primer probably won't stick to the weathered cedar layer.


This time primer will go over bare sanded wood. I've been filling the splits and knotholes with epoxy resin thickened with talc, so that it doesn't run.
Gorilla glue sounds easier. I'm going to live with most of the cupping, but fill in gouges and defects to level of surrounding wood. Might use some MH Patch, or a latex wood filler. No skim coating, though.

Matthewt1970

I would sand the wood before I would put any kind of spackle or wood filler on the face of a board to smooth it out as it will never last as long as solid paint job.

I wouldn't trush Bob Vila's site as a few words into his suggestion he used the dreaded "Latex Primer" suggestion on bare wood.

Wobbly

I'm planning to use Zinsser Bulls Eye 1-2-3 water-base primer-sealer. http://www.zinsser.com/product_detail.asp?ProductID=11
This is what Zinsser recommends for scraped wood siding. Oil-base primer would soak into the wood, but I'm concerned how well it would adhere to the epoxy filler. However, after looking at Cover-Stain oil-base again, maybe I should go with it http://www.zinsser.com/product_detail.asp?ProductID=12



Bob Vila's skim coat recommendation seems to go against the application instructions for any filler product that I've seen.

Matthewt1970

That's exactly what I use except around here they just recetly changed the label to "Cover All" instead of "Cover Stain" but it's the same product. I would especially use it on epoxy. The day they make Latex Primer work just as well or better that oil, I will be the first to jump on board.

Wobbly

Just exchanged the Bulls Eye for Cover-Stain.

Thanks!