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RE: Strengthening Ceiling Joists

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Ed,  to help get the sag out you can use a temporary beam perpendicular to the CJ's and a hydraulic jack and post in the room where the ceiling sags to jack up the sag a bit.  You can then sister a 2x6 or 2x8 and nail along side of the 2x4's.  If sistering them are too many, you can use a strong back.  I have jacked up floor joists before to install lintels (headers) in walls where homeowners wanted french doors and it worked fine.
Email me at tbodkin(--nospam--at) if you need more suggestions.
Tom Bodkin
-----Original Message-----
From: C Chan [mailto:seaint_list(--nospam--at)]
Sent: Friday, November 22, 2002 1:42 PM
To: seaint(--nospam--at)
Subject: Strengthening Ceiling Joists

I have strengthening existing 2x4 ceiling joists by sistering them with metal studs of similar depth.

 "ebosco(--nospam--at)" <ebosco(--nospam--at)> wrote:

I am renovating my two story 1912 dutch colonial which is balloon framed.
The ceiling joists on the second floor are 2x4 members (full 2x4 dimension)
which in some locations span as much as 15'. The mid-span deflection of
these members is 1/2" in some locations and the small depth of the members
gives me little room for adding insulation to the second floor ceiling.

In reviewing the alternatives for improving the situation it seems like a
very stong beam is produced by stacking a second 2x4 or 2x6 on top of the
existing joists. I would connect the two by lag bolting vertically through
the top member into the bottom one. A benefit of this plan is that I could
use the bolts to raise the sagging members slowly over a period of months to
reduce cracking of the plaster.

Has anyone ever seen this approach applied? Any recommendations for lag bolt
frequency? Would it be necessary to add a vertical plywood plate (or plates)
to the edge of the beam to help the two act as one?

This is a time when I wish my engineering experience covered more that
Mechanical, Electrical and Plumbing.


Ed Bosco, PE

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