How to Seal Heavy Wooden Beams

Updated February 21, 2017

Large wood beams contain relatively high amounts of moisture. Over time, the escaping moisture causes large cracks to form in the beams as the wood dehydrates. Prevent this occurrence by sealing the beams with the appropriate coatings. For best results, choose a particular type of sealer based on the location of the beams. Learn the proper application methods or you could end up with an undesirable outcome.

Apply sanding sealer to the heavy wooden beam, using a china brush. Sanding sealer is prone to heavy runs and you combat this by applying only a thin amount. Let the beam dry for two hours.

Sand the wooden beam until it feels smooth. Be careful not to sand through the dry sealer and expose the bare wood.

Apply two more coats of sealer. Be sure to sand between coats.

Wash the three-inch china-bristled paintbrush with pure white spirit.

Place canvas dust sheets beneath the beams.

Access the wooden beams, using a step ladder if necessary. Wipe dust from the beams, using tack cloths.

Apply gel stain to the wood beams, using a 3-inch china-bristled paintbrush. Wipe the wet stain from the beams, using rags. Let the beams dry for two hours.

Wash the 3-inch china-bristled paintbrush with pure white spirit.


You may use a sanding sealer on interior beams if you desire a clear finish.

Things You'll Need

  • Sanding sealer
  • 3-inch china-bristled paintbrush
  • 180-grit sandpaper
  • White spirit
  • Canvas dust sheets
  • Step ladder
  • Tack cloths
  • Gel stain
  • Rags
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About the Author

Ryan Lawrence is a freelance writer based in Boulder, Colorado. He has been writing professionally since 1999. He has 10 years of experience as a professional painting contractor. Lawrence writes for High Class Blogs and Yodle. He has a bachelor's degree in journalism and public relations with a minor in history from the University of Oklahoma.