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Not so Simple Truss Repair

Note; This is probably one of the most dangerous techniques that I have posted. Unless you are comfortable with all of the suggestions and tools and techniques, farm this out to a professional.

Found a cracked truss at in a clients house. This is not normally a concern as engineered trusses are built pretty well. But things happen. This truss is underneath a HVAC roof unit. It was probably a combination of heat as temperatures in Arizona get insanely hot in attics, and vibrations from the heating unit.

The open crack tells us that the top chord of the truss has bent due to drying out and the extra weight of the HVAC unit. To repair we need to close up the crack and add some reinforcements. We will need to jack this up.
truss1

To straighten this I am using a 2 ton bottle jack found at the auto parts store. Any more than this, the risk of damage and or injury goes up.You don’t need any more power than this.

bottlejack

You need to be sure that you have a secure platform for doing this. I used a piece of 3/4” plywood spanning two joists to give me a solid jack point.  If you do not do this, you run the risk of bowing the bottom truss chord and causing nail pops on the ceiling below.

You want to perform a straight lift. It will also take some time. You need to jack slowly, let it rest before attaching the plywood reinforcements, and allowing time for the glue to set before releasing the pressure from the jack.

The diagram below shows the jack resting on the plywood, the jack, the temporary post, and a block of wood screwed to the rafter portion to prevent the jack post from sliding out while jacking.  To help my repair I am using PowerGrab in the crack before I jack it closed. Checking it with a level upon contact and before jacking will keep the jack and post from tipping over.

trussdwg

The left side of the photo below shows the wood post that is sitting on top of the jack for straightening and closing the crack. Notice that I cut an angle on the jack post so that it will contact my block and not tip the jack and post. Having jacked up my truss, I glued the back sides of my plywood and am using quick clamps to hold them in place before I screw them to the truss.

To repair this I cut 2 pieces of 5/8” 5 ply plywood,  3”x72” as reinforcements for either side. I am using 1 – 1/4” Deck Screws spaced about 8” apart staggered to attach them, taking care not to screw into the crack area we just fixed.
truss2

After about 30 mins., we slowly release the pressure on the jack, (it will sag a bit) and remove our jack and tools and materials. All Done.

truss3

Like I say, this is a dangerous repair due to being awkward, and is being presented for information only. You probably want to farm this out to a professional. This is only one method and I disclaim any responsibility for  injury or damage.

Yeah it really is that dangerous.