Sagging Roof on Shed Dormer


#1

Hi All,

Our house (Built ~1929) passed inspection with a bit of sagging over a upstairs Shed Dormer. The ceiling appeared to be sagging before and after we purchased the house. The sagging (inside and out) hasn’t changed in the 18 months we have had the house, however one of the projects in our list was to pull down the plaster & lathe ceiling upstairs in the sagging area to see what is going on and hopefully be able to repair or at least stop it from getting worse for the long haul.

First, I was hoping that changing the plaster and lathe to Sheetrock may light the load pulling down on the Shed Dormer rafters. Will this help any?

Also, I am no expert, but I noticed several things that appear to be wrong, at least by todays standards (and possibly by 1929 standards!) It looks like the shed dormer rafters are 2x4, the collar ties are 2x4s, they aren’t spaced evenly in the dormer area (two are ~22" OC and one spacing is ~30" OC), also there is no ridge beam.

Wow, that is a lot of stuff. My question is:
Can I jack up the current rafters and collars, then sister everything with 2x6s? I can angle cut the rafter sisters and I can go back all the way to where the collar ties end for both? Will this be enough?

Since pictures are far better at explaining everything, I will attach a link to a few: members.cox.net/jr.due/shed_dormer_pics.htm

Thanks for the help guys!
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#2

lokks like there was a heavy ceiling fan rite in the middle.
just try to jack it up.
see what happens.

gweedo.


#3

[quote=“gweedo”]lokks like there was a heavy ceiling fan rite in the middle.
just try to jack it up.
see what happens.

gweedo.[/quote]

Hi Gweedo,

the ceiling is plaster & lathe and that was very heavy obviously. However, we only had a small light fixture that weighed less than 5lbs.

thanks for the help,
JR


#4

First, Attach a string underneath the first rafter pull it tight and attach it to the last rafter where you ended the plaster cut out.

Run the string down the center but right beside the light.

Remove the nails in the 1x4 supporting the sagging 2x4.

With a floor jack and a 2x4(cut to fit) jack up the 2x4 untill the string is flush.

Renail or screw the 1x4 into the 2x4.

If you are still uncomfortable and want more support,
add an additional 1x4 near the existing ones.


#5

This is tricky, definetly pull off all the plaster and lathe. Looking at the pictures, those are called “jack rafters”, they are tying the 2 sides of the ratfters together. Yes a 2X6 will work, even a 2X8 will work. What I would do is start at the begining rafter and install a 2X6 or 8 on the first rafter, nailing it to the side of the roof rafter. Then pull off the old one if it is there. Then do that to every rafter in the ceiling. jacking up the rafter will not help anything, because what you will be jacking up is the main house roof. and that is a whole nother issue altogether.

At least doing this will make your ceiling straight.


#6

Hi,

Would have been nice to see this before you ripped it apart.

All this framing and drywall you want to do will weigh the same if not more then before you started.

Half the houses built today have no ridge beam and the rafters are 24" on center. They are made out of 2x4’s.

It was probably an easy fix before you started this. If it needed anything done at all.


#7

[quote=“Lefty”]Hi,

Would have been nice to see this before you ripped it apart.

All this framing and drywall you want to do will weigh the same if not more then before you started.

Half the houses built today have no ridge beam and the rafters are 24" on center. They are made out of 2x4’s.

It was probably an easy fix before you started this. If it needed anything done at all.[/quote]

Hi Lefty,

Thanks for the help.

The only thing I have done is take out lathe and plaster that was sagging about 4" in the center. It appeared the sagging was partially due to the collar ties and roof sagging, the other cause was the lathe pulling away.

How could I have fixed the sag easily?

The rafters being oddly spaced seems weird. As mentioned before one space is roughly 30" OC.

Thanks,
Phiz


#8

[quote=“roof-lover”]First, Attach a string underneath the first rafter pull it tight and attach it to the last rafter where you ended the plaster cut out.

Run the string down the center but right beside the light.

Remove the nails in the 1x4 supporting the sagging 2x4.

With a floor jack and a 2x4(cut to fit) jack up the 2x4 untill the string is flush.

Renail or screw the 1x4 into the 2x4.

If you are still uncomfortable and want more support,
add an additional 1x4 near the existing ones.[/quote]

Hi Roof-Lover & G-Tape

What if I use some of both of your suggestions.

What if I replace the 2x4s with 2x6s one at a time and use the string method to make sure they are straight? I know this wouldn’t fix the sag in the roof but at least it would straighten the inside and keep it straight.

BTW, you guys are very helpful. Thanks for taking the time to help out!


#9

You would have to put the string up inside the attic space for it to work that way.Putting it below, into the room, you would have to remove all the rafters first.


#10

Gotcha. I will try it out, take pictures along the way, and give you guys an update along the way.

Thanks again everyone that helped. If anyone has other ideas, the bulk of the work will probably take place tomorrow so please let me know as soon as you get a chance!


#11

Please dont buy any wood yet.

Play with the strings first.
play with them in different directions if you wish.
Then you will know what to do.

They look straight to me…

but the strings wont lie.