Roof ridge sags when looking at it from outside

Hi just purchased a home and doing a Reno. Looking at the roof from the outside the middle of the roof looks like it’s sagging in the middle. From the inside the beam doesn’t look like it’s bent. I would like to attach some videos and if anyone can tell me what kind of roof system I have and any tips please.

Long pieces of sheating and rafters are prone to sagging over time if not supported in the middle.

So if I jack it up in the middle and support it that might fix it?

What’s the beat way to support them in the middle ?

I can’t give you advice on how to fix it.

Any materials - wood, concrete, steel - when suspended between two points, will eventually relax and sag. It may take years. So these components needs to be properly supported. Old houses are prone to these things.

I would talk to a competent carpenter or roofer and see what he says. Imo, probably just best to live with it.

Got dizzy trying to watch the video. Get a laser level to determine where the problem actually is located. When the fly rafters are proud, the roof ridge appears to sag. The rafters might not have been crowned when it was built. Could be the bearing wall supports have no footer or support. Should be fairly easy to pinpoint now that it’s gutted. Did you cut out the rafter ties? Those are more than just ceiling joists… Check for the rafters separating from the ridge board where it’s sagging.

https://youtu.be/2C2vkiZN7xE Here’s a better video

Here’s a better video https://youtu.be/2C2vkiZN7xE

https://youtu.be/2C2vkiZN7xE

The ceiling joists are also rafter ties. They keep the walls from leaning out and keep the rafters in tension. You’ll notice the rafter ties/ ceiling joists have been removed where the ridge is sagging. You should see the rafters pulling away from the ridge board at the bottom, and the walls leaning out of plumb. Check those 2 points and see what you have.

So the walls that are on the bottom of the rafters are like 1.5 to 2 inches outward off level. I jacked up the middle of the ridge board it’s looks like they had 2 by 6 2 pieces ran across the home joining with no support the create the ridge. We jacked up 4-6 inches and put support but didn’t seam to straighten it. I mean who knows how many inches more. Plus there’s clay tile which is heavy as a roof

The person that cut the rafter ties is responsible. Not sure if you can cable the walls back to plumb with the dead load on the roof. You could be looking at collapse if the fasteners are all pulled free. Rafter Ties (constructionmentor.net)

Talk to a competent roof specialist. This is too important to be left to guesses and estimates.