Rotting Joists of Garage

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Matakumoe

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I have a garage that is approximately 26’x26’. The roof is pitched 15 degrees. The joists span the width of the garage with no center support that goes to the ground. Judging by pics and diagrams on the internet, the trusses are what you call "gable end". Nearly half the rafters and joists are rotting on one side due to water damage caused by the previous owner’s creative gutter work. I believe the unorthodox gutter was due to the neighbor’s relatively recent construction of a garage less than a hand-breadth away. (I don’t recall the inspector actually examining the exterior on that side.) Some of the top plate is rotting also.
My plan is to cut the rotting portions off and splice in new wood with rigid mending plates.
• Which size mending plate should I use?
• How many do I per splice? How far out from the splice should my temporary support be?
• Do I use a 4"x 4" post(s) or a jack post(s)?
• How many joists should I jack up at once to get at the rotting top plate?
• Should I add permanent center posts for additional support?
 
Do you have rafters and joists (2x8 or larger) or trusses 2x4's?

Can you post a few pictures?
 
You have rafters and and 2x6 rafter ties, Not really strong enough to support a ceiling..
This is all fixable . So.
Have you poked at the lumber with a screwdriver to judge just how bad they are. Are the rafters in question too?
There is a sill plate on top the wall, what condition is it in?
Have you got a spay can of paint so you can just spay a line on the bad stuff and stop where it is good. and then show us another photo.
 
Out of curiosity, does the water from your roof run down between the two garages? It looks like your neighbor has gutters on his garage. Talk about zero lot lines.
 
No, Sparky. Some of it runs into my garage behind the gutter ON the roof and some runs through the "Rube Goldberg" gutter across the front and down the spout out into the street.
I don't know why the previous owner let the neighbor build so close. For that matter I don't know the municipality let him build so close.
The neighbor's garage is a little higher and has a proper gutter.
 
Nealtw,

I didn't want to do the paint thing, but took more pics with a real camera.
You don't need to poke at it with a screw driver. A hand or any type of blunt object will do.
Yes some of the rafters are rotting also.

2 corner.jpg

joist1.jpg

joist2.jpg

joist3.jpg

raft1.jpg

raft2.jpg
 
You roof structure is a "stick framed" carpenters truss, IE. two opposing rafters with rafter ties at 48"oc. with 5-16Ds nailing them together.

"Which size mending plate should I use?"
Where? If you are referring to the top plate that sit on top of the masonry wall, and there is more than one, standard lap is 48". anything shorter you can us a 36" plate strap or MST.

If you are referring to the rafter ties you need to replace them.

If you are referring to the rafters, you sister another alongside.

"How many do I per splice? How far out from the splice should my temporary support be?"
You'll need to support the roof by building a temporary wall down the center of the span, and individual 2x props under each rafter near the masonry wall.

"How many joists should I jack up at once to get at the rotting top plate?"
See the splice comment and judge from there.

"Should I add permanent center posts for additional support?"
That shouldn't be necessary.
 
Matakumoe said:
No, Sparky. Some of it runs into my garage behind the gutter ON the roof and some runs through the "Rube Goldberg" gutter across the front and down the spout out into the street.
I don't know why the previous owner let the neighbor build so close. For that matter I don't know the municipality let him build so close.
The neighbor's garage is a little higher and has a proper gutter.
Click to expand...

Most fire codes in the US require a 36" high firewall for a 0 lot-line structure is permitted.

The previous owner would have nothing to say about it, its the municipality.

If both structures were there when you purchased then there may have been a variance applied for.

None of which addresses your problem.
 
Matakumoe said:
Nealtw,

I didn't want to do the paint thing, but took more pics with a real camera.
You don't need to poke at it with a screw driver. A hand or any type of blunt object will do.
Yes some of the rafters are rotting also.
Click to expand...

So Yes we can see it is ugly. Would it be safe to say everything is rotting from the wall to about 4 ft. will that include sheeting, and what about the front and back gables.
 
All the sheeting needs to be replaced. About half the joists are rotting 8"-18" at worst. Front end joist and rafter seems to be okay. Then ones at the back end are not real bad. Less than half of the rafters are rotting. The worst one has about 36" real damage. One has relatively little damage 48" out.
In general the top plate only has damage where the damaged rafters and/or joists rest on it.
 
I'll let my handyman friend know of your suggestion. He's a friend, but it still will cost me more than I'd like. I'm doing some work myself in my house that has already put a strain on my budget.
 
Someone who's work you are familiar with is a good place to start.
 
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