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I recently bought a house and discovered that the rafters in the attic are separating from the ceiling. The roof does not seem to be sagging, and only the rafters on one side of the attic are separating. The rafters on the other side are fine.

Does anyone know why this is happening and how to fix it? Can I lift the rafters back into place? Thank you in advance.

enter image description here

enter image description here

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    Is your entire roof constructed like this or just some shoddy addition?
    – MonkeyZeus
    Commented Nov 9, 2021 at 18:17
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    Does look like a DIY job not done to spec. Those plates usually need to be attached property and not just hammered on.
    – crip659
    Commented Nov 9, 2021 at 18:20
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    How old is the house? The thickness of the rafters and the boards on the roof rather that sheathing make it look very old. Some of the common building rules and practices we are used to today may have not been followed then.
    – JPhi1618
    Commented Nov 9, 2021 at 18:23
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    The entire roof is constructed like this, and it was built in 1939. The house is shoddy construction throughout, but luckily, it's in central California, so there is no snow load.
    – Ace Ender
    Commented Nov 9, 2021 at 18:26
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    @MonkeyZeus Those strong-ties were added later. I don't know exactly how long ago that particular model was invented, but the house itself predates Simpson as a company altogether by about 15 years.
    – TylerH
    Commented Nov 10, 2021 at 19:39

4 Answers 4

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Your roof is missing a collar tie (very important) and a ridge board (less important).

In essence you need to pull your rafters back into triangle shape and install a collar tie. You cannot just lift the problem areas; your walls have likely bowed outwards. You need to bring it back into a tight triangle shape.

Anatomy of a common rafter


This picture shows you how gravity affects a roof.

Side walls of house being pushed out due to lack of collar tie


If you want a perfect roof line then you can look into converting it into a truss style roof.

Picture of a rafter roof versus truss style


Whether this is a job you can take on or need a professional is not something I can answer. Get a few quotes; my guess is $3k-$7k for a professional to fix this. Converting to trusses would easily double my estimate.

Start looking up "fix sagging roof", read a few articles, watch a few videos, and buckle up because doing things right requires hard work and tools which I assume you do not currently possess.

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    You might look into a chandlery supplier for a couple of boat winches to DIY this. Plate the walls & guy between. Been there, done that, but that was on a Victorian brick build. Drag the walls in gradually over a few months. Leave the winches in place for a few years afterwards, until the building settles into its new vertical form. Saves thousands ;)
    – Tetsujin
    Commented Nov 10, 2021 at 18:11
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    @Tetsujin I think adding a "How-To" answer for OP's problem would be an excellent addition here. I think it would be a better candidate as OP's accepted answer more so than my own.
    – MonkeyZeus
    Commented Nov 10, 2021 at 18:15
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    Thanks - I shall give it some serious thought… as it was a real wing & prayer job, involving a DIY steel girder, scaffold jacks & two 10 ton boat winches… all without ever lifting a tile.
    – Tetsujin
    Commented Nov 10, 2021 at 18:21
  • There's no reason to think that collar ties are missing. We don't even know the span of those rafters, and you can't see the lower portion of the framing. Many such roof were built with just a few rafter ties at ceiling level. Frankly, I'm not even sure there's a problem here.
    – isherwood
    Commented Nov 11, 2021 at 16:43
  • If the floor joists are properly fastened to the rafters, then the picture you showed of the walls bowing out cannot happen, unless the joists snap (highly unlikely). The rafters might bow, but now the walls. The forces acting on the wall with proper installed joists is strictly vertical.
    – SteveSh
    Commented Nov 16, 2021 at 20:12
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You say your roof isn't sagging, but there is some kind of disintegration going on that you need to have looked at by an engineer. Maybe there is more than just poor roof construction. Some of the apparent movement may be caused by subsidence in the supporting walls.

The last pair of rafters are prevented from moving with the rest by their attachment to the gable wall. So there you can see separation of the roof from the rafters, light coming in through that separation, separation of the rafters from each other, and a crack in the right rafter opening up where the end bit of it is prevented by the vertical support from moving with the rest.

enter image description here

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    Wow, good eye! It didn't quite register with me how messed up that gable wall is.
    – MonkeyZeus
    Commented Nov 9, 2021 at 20:51
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    The white line above the next closest rafter looks like it may have been a metal strap that was designed to go over the top of the the two rafters in an attempt to hold them together, possibly as a temporary brace during construction. It does help show just how much the rafters have sagged. Either that, or someone took (poor) advantage of the gap to run some 14/2 cable up there. :/
    – FreeMan
    Commented Nov 11, 2021 at 13:14
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After comments, this answer is an addendum to MonkeyZeus' post, based on the same method, but with a twist.

It's impossible to tell from your pictures whether those rafters have purlins to prevent spread, or whether they're just 'plonked on top' of the ceiling joists.

As an unsupported roof sags, it can push the walls out from the vertical as it drops.
Imagine a roof as a simple inverted V thus rather than a correctly-braced A. If you push down on the top the sides have no option but to spread out - pushing the wall with it.

Depending on how far this has all managed to move over the years, you may have to consider pulling the walls back in as part of the process.

I've done this before as very much a 'wing & a prayer' DIY task to save the many thousands it would have cost to strip the roof entirely & rebuild it all correctly.
We started with two 10-ton boat winches & 4 heavy steel plates. You may have seen these on old buildings & thought they were decorational. Known as patress plates, they were most definitely functional - see https://www.redgwick.co.uk - though we didn't go for pretty we went for functional, as they weren't going to be permanent. Though these are perfect for holding a wall in place permanently, they're not so good at dragging one back into line if it's gone a bit far.
That's where the boat winches come into play. They're ratcheted, so you pull them in a click at a time & they won't slip back. The idea is that you drag the walls in very slowly so they have time to get used to the idea, not try to wind it all back in in one go. We spent 6 months gradually pulling in - this was on a Victorian brick build. The winches were then left in place a further two years after completion.

You combine this slow, careful action with one or two 'portable' steel girders placed across the tops of the walls, spanning the roof space in the same way as your rafters. You then use pit props, scaffold jacks; or whatever they're called in your territory - basically two pipes, one inside the other with a method of screwing them up to support a vertical.

The jacks go on the girders, pushing up at the centre of the roof. The winches wind in the walls. Once everything is back in correct position [not quite as simple as it sounds], you then brace it all in properly - either turning the into an A or set trusses as in MonkeyZeus' image.

30 years later, the old Victorian pile still has vertical walls & its original roof, now correctly braced.

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    Is an "old Victorian pile" a sub-style of Victorian, or does "pile" refer to "pile of junk"? Honest question, as on this side of the pond, "pile" implies "pile of junk" (at least to me).
    – FreeMan
    Commented Nov 11, 2021 at 13:11
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    Pile in this sense means "large imposing building" & conveys no sense of its being in disrepair. It does tend to go hand in hand with the words Victorian or Gothic, just as a 'quick imagery' - lexico.com/definition/pile
    – Tetsujin
    Commented Nov 11, 2021 at 13:19
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    Thanks, I was unaware of that usage. #TIL.
    – FreeMan
    Commented Nov 11, 2021 at 13:22
  • This is how my garage is held together. Working pretty well for 15+ years.
    – Z4-tier
    Commented Nov 12, 2021 at 22:14
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I believe that all that can be done about this is to prevent it from becoming worse by adding the collar ties.Trying to fix it without removing the roof may not be possible because the wood is nailed to the rafters; it would mean cutting all the nails because you don't want to trouble the shingles. It would be a surgical proceedure.

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