(08-12-2019, 01:18 PM)Randy C Wrote: So you are saying that if I get a good tight joint between these two pieces of wood that this is bad and that I need a crappy fit so that I can fill it with caulk and that will solve the problem?
I guess I have been doing it wrong because I thought that a good tight joint was desirable?
Well, yes and no. A good tight joint that doesn't need caulk is better but it has to stay tight. If water gets into the joint and behind the paint the wood will be soaking in water and the paint, even with good primer, will lose its bond. I suggested the cleat behind the joint to help keep the joint tight.
However there are certainly times that purposely leaving space for caulk is the right thing to do. I was taught by an "old timer" to leave a "nickel space" at each end of every piece of cedar drop siding. We ran 3' wide felt paper up every corner before the fully primed corner boards were installed, and every butt joint in the fields had a small strip of felt paper behind it. (He made me leave them low so he could see every one was done, then had me go back up to trim them.) The Painter did his thing and totally filled each joint. All the nails were set and filled with glazing compound tinted to match the paint. Two decades later the paint was falling off the factory painted shutters but the house still looked great. (The paint was oil based Benny Moore with extra linseed oil)
There are also times where a 1/4" space is specified to be filled with 3/8" backer rod and flexible adhesive caulk. And there are some problem areas where leaving space for a quality caulk to do it's job is necessary but a small bead on the surface is all that's ever been done. I direct your attention to the joint between an aluminum threshold and the door jamb. The best the manufacturers came up with to stop this failure point is to finger joint a short piece of P.T. to the bottom of the pine. They sell more door units, and now I get to charge to replace the floor and framing down to the sill.
I think the best suggestion I can give is to stay on top of these problem areas before they become a big problem. If we inspect our own homes a few times a year, come up with a plan of action broken down into 1 or 2 hour segments, a lot of the repairs can be addressed before they are big problems. Your rake return is one of those problem areas that can be fixed in an hour or so. If you only want to do it once, I suggest P.V.C with the return splined to the rake and solvent welded together.
Sign at N.E. Vocational School Cabinetmaking Shop 1976, "Free knowledge given daily... Bring your own container"