Red Cedar Treatment

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Forum topic by zipmac22 posted 06-20-2017 01:45 AM 773 views 0 times favorited 4 replies Add to Favorites Watch
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39 posts in 1625 days

06-20-2017 01:45 AM

I have some trim that borders around my garage door. The old trim is about 30 years old and the bottom has water damage. The trim size is 1 5/8” x 8” x 6’ and had to go with a rough cut of red cedar (2” x 10” x 12’) and will rip, cut, and sand it to fit.

My question is what would work best to treat the red cedar against water? Would I need to treat just the lower section or treat the whole length? I plan on painting it (Latex) once it is in place.

-- Chris, Central Texas

4 replies so far

View JCamp's profile


1180 posts in 1322 days

#1 posted 06-20-2017 02:06 AM

I’d cut it off mayb 8inches from the ground and replace with a 2x something treated board. Caulk it all up (mayb bevel the edge so it’ll flow good) then paint it to match. That’s a simple fast and cheap solution

-- Whatsoever thy hand findeth to do, do it with all thy might

View clin's profile


1113 posts in 1768 days

#2 posted 06-20-2017 02:16 AM

I don’t think anything other than paint is needed. The likely problem was lack of maintenance. Once paint cracks, water can get in. And once water gets under paint, the paint fails that much faster.

While Cedar is naturally rot resistant, I don’t think any wood is 100% immune from rot.

I would be inclined to caulk the bottom, where it meets the concrete, to prevent water from getting under the end of the board.

Probably be a good idea to paint all sides and the end of the board before installation. Or at least the lower foot or two. That way any water that gets under the end of the board won’t be drawn into the end of the board as easily.

Be sure to use a quality primer first and a good quality exterior paint. Paint the boards ASAP, don’t allow them to weather. Stay on top of the maintenance by sanding bad spots, priming the whole board, and repaint as often as needed. How often you’ll need to do that will depend on your climate and specific circumstances. But, I don’t think 5-10 years would be unusual.

The more often you do it, the smaller the job will be. Don’t wait for large cracks and peeling paint. Once you see hairline cracks and lifting of the paint along these cracks. Time to touch it up. Might only take some hand sanding.

-- Clin

View JBrow's profile


1368 posts in 1692 days

#3 posted 06-20-2017 03:15 AM


It is difficult to tell from the photo, but it appears there may be some rot to the jack stud. If so, repairing the jack stud could forestall a bigger future problem. The jack studs are asked to carry a lot of weight. If the jack stud is in fact rotted, the weight of a second story and roof are being carried only by the king stud.

Since the existing trim lasted 30 years, you could probably proceed as you described. However, hoping to avoid or at least delay some of the maintenance described by clin, I would approach the replacement a little differently from the method that was probably used to install the existing trim originally.

My approach to installing the new red cedar trim would be to first prepare the rough opening by applying some Self-Adhesive Butyl Window Flashing Tape to the rough opening. This step would be an effort to protect the framing from moisture should water get behind the trim.

Then, as JCamp suggests, I would cut a 5 or 10 degree bevel on the end of the vertical cedar trim pieces where the ends will meet the concrete. Once cut to fit, all six sides of the cedar trim would be primed with two coats of an alkyd primer. The two primer coats on all sides would help keep moisture from entering the wood and thus prolong the time before rot and peeling paint begins.

Prior to installing the trim but after installing the butyl flashing tape, the seam where the butyl tape meets the concrete could get a bead of silicone caulk (to help keep moisture from entering the rough framing). The trim board would then be installed keeping the end of the cedar with a bevel cut about 1/8” – ¼” above the concrete. The bevel would form a drip edge if placed so that the long face of the trim is installed outward. This gap and bevel would help water to run off and away and pooling water would be less likely to be sucked up into the cedar.

There is another option after preparing the opening. That is to use cellular PVC “lumber” rather than cedar. The gap where the PVC trim would meet the concrete would have to be preserved for expansion of the PVC, but the gap could be filled with caulk. Also, paint formulated for vinyl and PVC would be important due to the expansion and contraction of the PVC. If I recall correctly, Sherwin-Williams Sure paint is one such paint.

As clin stated, staying on top of maintenance would enhance the longevity of the trim and framing. I will add to clin’s comments that cracked caulking on the vertical seems suggest new caulking is needed.

View dhazelton's profile


2839 posts in 3068 days

#4 posted 06-20-2017 11:47 AM

I replaced a lot of garage trim recently with PVC lumber because of this issue. Scuff sand and paint with any latex paint (those were the directions right on the labels on the boards).

Cedar is pretty porous so I would caulk the end grain and smear it in well with your finger or a putty knife so water can’t wick upward.

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