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Short Summary
Main recommendation: Temporarily support a sagging old-house beam with a jack and temporary posts, then slowly raise it over several weeks while a structural engineer is consulted. The speaker repairs a sagging ceiling beam in an 1880s farmhouse, where the middle of the house had no support and the beam was cracking. He also stresses that a jack should be used only with proper tools and careful handling.
Key Points
- Support is needed for spans over 16 feet; the speaker refers to the house's span as both 25 feet and 20 feet at different points, and it lacked a post down the middle, causing cracking and stress.
- Shore up the beam with temporary posts before the structural engineer proposes a permanent fix, so the structure does not fail in the meantime.
- Lift gradually, never in one big push: lift a small amount, set the temporary post right away, then continue over about six to eight to twelve weeks, usually with a half-turn adjustment per week.
- Secure each post with two shear pins, one on each side of the post, rather than relying on a single pin.
- Fix the top and bottom plates in place (here, with a Ram Set nail into concrete and structural screws) so the posts cannot be knocked out of position.
Details Worth Noting
- Concrete instructions:
- Use a car-type jack (the speaker's is rated three tons), and learn which turn direction engages lifting and which releases it, so you do not collapse the post by accident.
- Place a four-by-four post with a base plate under the beam, then raise the jack until the post gently carries the load.
- Listen for moaning or groaning sounds from the house as the load shifts, which signals movement.
- Do not lift only the middle of a span, because that can load one beam and disengage the other posts.
- Assemble the post's two sections, aligning the holes in an alternating pattern and inserting a pin on both sides.
- Set the top plate in its cradle as close to level as you can get, then tap it into the bracket with a hammer and block if needed.
- Secure the base plate by driving a nail into the concrete with a Ram Set, and fasten the top with structural screws, one on each side in the corners.
- Check beam thickness with a square against the ceiling and level, since tree-based beams vary in size.
- Turn the jack's threaded rod about a half turn per week, or in small amounts, so the wood can stretch and relax between adjustments.
- Caveat: the speaker notes that old houses vary and that his method is shown in the context of his own project; a structural engineer should still design the permanent fix.
- Caveat: overtightening or lifting too much at once can snap posts, so move slowly.
Bottom Line
Temporary jacking and posts can stabilize a sagging old-house beam, but they should be installed carefully, lifted slowly, and checked with a structural engineer before any permanent repair.
