roof truss repair question

[MiamiCuse]

Hi I am repairing some stained ceiling sheetrock in my garage, and after removing some sections of it I realized there is more damage.

First the leak in the roof has been found and repair, so there should be no more water penetration.

Now I can see the water leak has been there for a long time as the end of the truss were severly damaged. The end of the joist and rafter meet and they rest on the concrete block wall as shown below:

there is a truss every 24" or so but one of them directly below the leak is damaged very badly. If you look at the image attached, the section labeled "C" in green when I pushed it just crumbled. Now the good news is that the roof is still up and it has been like this for years this truss has not been supporting it's share of the load for a long time now. The ends where it is rotted away is about 12" or so in length.

I went up to the attic and tried to see if it's possible to remove "A" and "B" completely and put new lumbers in but this is going to be near impossible with all the AC duct work running across, electric conduits nailed along it, ceiling hi hats and fans etc...and very tight space.

So what I plan to do is to get two 12' 2x4s. I plan to put one adjacent to the rafter and one adjacent to the joist for almost the entire length. The question is now should I attach the two?

Should I drill a hole every 18" or so and insert large (1/2") bolts through both and tie them together?

Or should I use some sort of structural glue/epocy to glue both together?

Or should I use those galvanized steel tie/straps to nail them together?

Or all of the above?

I also plan to insert some vertical wood members between the new sister rafter and joist.

Or this is all wrong?

Thanks in advance,

MC

[steve robinson]

Cut back the rot treat the timber

bolt your timber either side , between the truss and timber insert spike washers / timber connectors

Fit a 18mm ply gusset over the repair

before you do any of the above check the truss for alignment with the rest of the system and prop it in place

[MiamiCuse]

Got it, except for one part - what is a 18mm ply gusset? Are those the metal plates with lots of holes in it for framing nails?

Thanks.

MC

[DanG]

Homemade trusses were and are made with plywood gussets glued and nailed instead of the gang press plates used at truss factories. You and I have no way to press those plates into the lumber. The suggestion was to use plywood gussets that you can glue, nail, bolt, etc.

____________________________ Keep the whole world singing . . . . DanG (remove the sevens) [e-mail]

[DanG]

Brace, jack, shim, shore. Do whatever to get everything straightened out. Check the roof line and the ceiling joist line. I am a bit surprised if there are no signs of the rotted out portion.

Remove and replace any wood that has active rot - cut back to good sound wood.

If you can put in 12 footers, do it. If there are any other truss members, duplicate them also. Sister the new members on using plenty of panel adhesive and a generous nail pattern using common nails alternating a high/low nail pattern. If the existing truss is old and well seasoned, you may need to use a nail gun or pre drill a lead hole. Air gun nails are thinner and do not generate the same sheer numbers that common nails do.

Custom cut a plywood gusset for each side of the damaged truss that fits fairly well from the bottom of the bottom chord to rafter top, from outside plate line to whatever 4' plywood would cover, keep the grain vertical. Use good marine grade 7 ply. Glue everything. Throughbolt ply to ply with 3/8 bolts with fender washers. The sandwich will be about 4 1/2" thick.

[MiamiCuse]

OK. So to create plywood gusset in the end like in this picture:

make it as big as possible to reach as far back?

Since my sister timber will be right next to the existing one with the last

12" rotted out, how will this help? so instead of a 2x4, with my reinforced timber it will have a total of 4x4 in size, how would a gusset along the "side face" help? I must not be visualizing something correctly.

Thanks, MC

[MiamiCuse]

Nope. What happened was the water ran down the rotted wood member (since it's sloped) and at the end there drip into the block wall. The block wall has furring strips on them, then sheet rock. Then a custom floor to ceiling book case was mounted on the studs. So most of the staining was on the sheet rock and furring strips and the book case blocked everything. It was not until I ripped the book case out then the sheet rock I saw this.

Done that.

Yes existing lumber there is 35 years old.

OK you mean to use the gusset on one side which is the damaged wood, the other side will be over the new sistering wood right? Making the total width 4 1/2".

What is the reason to use a gusset on the good side which is new?

The other problem I see is I would like to use a piece as large as possible like up to 4' you suggested. However a big issue is there are AC ducts running through there, and that would limit how far back I can go. Also there is no way I can cut a piece this big and get it up through the 24" hatch access and pass it through other trusses. I would have to cut an access hole over 6' in length right where this is happening to get it in there and still the AC duct would be in the way.

Can I use a gusset on either side of the AC duct?

Thanks,

MC