Proper Join Design


Proper Joint Design

Believe it or not, caulking is more than just squeezing goop in and smearing a finger over it. Proper joint design matters! Not only will the finished job look neater, the caulking will perform better when applied correctly.
 
So, what is proper joint design?
 
The diagram below shows the ideal type of joint design for all sealants. This hourglass shaped, two-points-of-adhesion design allows for maximum sealant movement and favors cohesive failure (the best kind) if the movement is so extreme that failure cannot be avoided.
 
Some other tips:
  • Round backer rod is best, especially when substantial movement is expected, which means with new logs or“green” logs.
  • Ideally, when caulking and chinking between log courses, the caulking line should be no less than 15% of the log width. For example, with 10" diameter logs, a chink joint should be about 1-1/2" wide. If you choose to apply a smaller bead, expect more repairs.
  • Ideal sealant depth is half of the joint width, but no less than ¼", nor more than ½”.
proper joint design - blog

 Steps to Proper Joint Design

  1. A stained surface: Caulking and chinking actually adhere better to a stained surface than bare wood, so stain with a compatible stain first. If you aren’t sure if your product is compatible, contact us first.
  2. A clean surface: If your surface is already stained, make sure it’s clean, too. Remove all dirt, dust, oils, old caulking, peeling stain, bird poo, pollen, etc. etc. If caulk is applied over any of these things, it won’t stick properly.
  3. Insert a bond breaker: Caulk works like a rubber band. It stretches really well when pulled from just 2 sides. Pull from 3 and it won’t go as far and will break more quickly. A bond breaker, in the form of backer rod or clear packing tape, ensures you have just two points of adhesion - on the sides of the joint. You don’t want the caulk to stick to the backside of the joint.
  4. Tool to an hourglass shape: Round backer rod helps you accomplish this pretty easily. The caulk should be slightly (yes, only slightly) thinner at the center where it needs to stretch, slightly thicker and wider at the edges for good adhesion. 
  • TIP: Don’t wipe off more than you put on! A light touch with a slightly damp foam brush or a trowel will do the trick. You don’t want to starve the joint of caulk, either. 
 
Let’s face it: caulking and chinking is tedious. Follow the steps above to enjoy long-lasting caulking and chinking jobs and avoid having to repeat the tedium in another year.
 

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