This is a rather complicated one to explain so it's going to be long with many pictures and sketches. Bear with me.
It is a single story residence located in Miami, FL. Concrete block exterior walls with wood framed roof. Monolithic concrete slab foundation. Built in 1955.
There is a sag on the roof. The sagged area is about 4-5' wide. Here is an overall roof layout. Most of the house is on an A-framed roof, but on the SE corner there is a flat roof section. The sagged area is just a few feet west of where the sloped roof and flat roof meet.
Here are two pictures of the roof above. The A-frame portion is shingle roof and the flat portion is flat deck concrete. You can see where the sagged area is at the bottom of the shingle section. I can't tell for sure, and it seems barely appreciable, but the roof ridge line may be off a little as well...but the amount is so little, it could easily be bad shingle work as well.
Next I went below to look at the location inside where it corresponds to the sagged area above, by transferring the measurements. You can tell, the sag is visible. The ceiling is sagging as well.
So this is not some roof deck getting wet and rot and bow, something is off.
Next I crawled inside the attic, to see what's up there. I can't get real close to the sagged area because there is just no head room. But with a flashlight I can tell there doesn't seem to be any roof leak or moisture penetration. The trusses look OK.
So the next step was I moved all the furniture out of the way and took down about a 30" wide strip of ceiling sheetrock where the sag is so I can see how the transitions look between the heels of the trusses and the flat roof framing. By removing the sheet rock in that room I exposed five trusses and I can see four of them have "dripped" at the heel where the transition is. The heel of the trusses and the metal brackets mounted on the flat roof 2X6s came apart a little. It appears out of the five trusses, one seem fine, the other four have dipped lower, from 1/4" to 1" or so. Not only the heels have dipped, the ends of the trusses have slipped off the metal brackets that attach them to the flat roof 2X6s, so that they are now at a "tilt".
]img]http://i173.photobucket.com/albums/w67/143house/11th/IMAG6430_1.jpg[/img]
Now the entire flat roof section is about 21' wide, the sag is only happening over a 5-6' portion of it. It turns out the room south of the sagged roof room, has a tie beam across that spot.
So it seems I need to jack up the trusses heels back to level, then install a beam across and under it?
I wonder how the trusses will behave as I jack up one end of it's heel for an inch. Would the 1"X6" roof deck pop and warp as a result? Can I use several bottle jacks across at the heels? Thanks for any comments and replies and sorry this got tedious.
It is a single story residence located in Miami, FL. Concrete block exterior walls with wood framed roof. Monolithic concrete slab foundation. Built in 1955.
There is a sag on the roof. The sagged area is about 4-5' wide. Here is an overall roof layout. Most of the house is on an A-framed roof, but on the SE corner there is a flat roof section. The sagged area is just a few feet west of where the sloped roof and flat roof meet.

Here are two pictures of the roof above. The A-frame portion is shingle roof and the flat portion is flat deck concrete. You can see where the sagged area is at the bottom of the shingle section. I can't tell for sure, and it seems barely appreciable, but the roof ridge line may be off a little as well...but the amount is so little, it could easily be bad shingle work as well.

Next I went below to look at the location inside where it corresponds to the sagged area above, by transferring the measurements. You can tell, the sag is visible. The ceiling is sagging as well.

So this is not some roof deck getting wet and rot and bow, something is off.
Next I crawled inside the attic, to see what's up there. I can't get real close to the sagged area because there is just no head room. But with a flashlight I can tell there doesn't seem to be any roof leak or moisture penetration. The trusses look OK.


So the next step was I moved all the furniture out of the way and took down about a 30" wide strip of ceiling sheetrock where the sag is so I can see how the transitions look between the heels of the trusses and the flat roof framing. By removing the sheet rock in that room I exposed five trusses and I can see four of them have "dripped" at the heel where the transition is. The heel of the trusses and the metal brackets mounted on the flat roof 2X6s came apart a little. It appears out of the five trusses, one seem fine, the other four have dipped lower, from 1/4" to 1" or so. Not only the heels have dipped, the ends of the trusses have slipped off the metal brackets that attach them to the flat roof 2X6s, so that they are now at a "tilt".


]img]http://i173.photobucket.com/albums/w67/143house/11th/IMAG6430_1.jpg[/img]

Now the entire flat roof section is about 21' wide, the sag is only happening over a 5-6' portion of it. It turns out the room south of the sagged roof room, has a tie beam across that spot.


So it seems I need to jack up the trusses heels back to level, then install a beam across and under it?
I wonder how the trusses will behave as I jack up one end of it's heel for an inch. Would the 1"X6" roof deck pop and warp as a result? Can I use several bottle jacks across at the heels? Thanks for any comments and replies and sorry this got tedious.