Why do pre-finished baseboards have groove in the back?


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Old 09-02-17, 07:30 AM
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Why do pre-finished baseboards have groove in the back?

I was thinking about making my baseboard; however, I found that most if not all the pre-finished baseboards have a light groove in the back. What's the purpose of this groove? Do I need to duplicate this on my custom made baseboard?

Thank you.
 
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Old 09-02-17, 07:38 AM
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It helps the base/casing to sit flat on the wall. Most of the woodwork in my house was made from saw mill lumber [planer and router] and I didn't cut any reliefs on the back.
 
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Old 09-02-17, 07:44 AM
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As I understand it there are several purposes... you generally nail on either side of the groove, not directly through the center of it... the groove helps reduce cupping, allows air movement behind the trim. In the case of casing, it allows the trim to be tipped inward when the wall surface is slightly proud, keeping the trim tight to the wall.
 
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Old 09-02-17, 08:37 AM
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I see. Thanks a lot. So, any suggestion on how I would go about creating the groove/relief with a router?
 
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Old 09-02-17, 08:46 AM
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Most any type of bit that will make a plunge cut can be used to make a pass or two across the back side of the wood. Depending on how tall the base is you might want 2 grooves.
 
 

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