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roof sagging


zurg99

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Hi and welcome. 

Have you had the property long ? Looks like natural sag, so I don't think it's about to cave in any time soon ;)

16 minutes ago, recoveringacademic said:

Indulge us with a little effort, please.

Ian's gentle encouragement is so we can get some background and additional info. :)

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Are you trying to remove the sag from your roof ? Or just prevent it sagging anymore.

If you want to remove the sag you will need to re,build it as it has taken 40 odd years to sag to the degree it has and trying to straighten it will be a non starter. 

 

This looks like a relatively easy fix by transferring the roof load directly down to the wall below

 

BUT

 

You need to make sure that the wall can take the load, look at what the wall sits on, if it is just built off the top of the floor boards then it is just a partition and should not really have any additional load placed on it. 

 

If it passes through the floor and continues down  stairs then it can probably take some more additional loading. 

 

You need to do some poking around. 

Alternativly you can make up a truss type arrangement by adding a spreader tie with a vertical member from this. 

A spreader tie would be a timber probably a 4x2 that would run from side to side bolted to the rafters on either side, from this spreader tie you can run a vertical timber to prop under the ridge. 

As I said you will stop it sagging anymore but you won’t push it back up straight. 

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5 hours ago, MikeSharp01 said:

For it to sag like that the rafters must be moving over the perlins and / or the wall plate are the perlins / wall plate bulging out at the 100mm sag point? If they are then the problem might be bigger than you think. 

 

rafters are not moved over perlins ( fixed on 4 inch's, no signs of moving), and the perlins are not bent(from load) both sides, bent/sagged are only from perlins to ridge board and only in the middle of the roof itself .

 

monday i will try what Simplysimon and Russell griffiths recommends and i will update this post with results, the goal is bring it at least half way back to initial position and stop from future sagging.

thank you all

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1 hour ago, zurg99 said:

rafters are not moved over perlins ( fixed on 4 inch's, no signs of moving), and the perlins are not bent(from load) both sides, bent/sagged are only from perlins to ridge board and only in the middle of the roof itself 

That's odd. The geometry of the sag seems to limit the possible outcomes either: 1. as the ridge sags the ends of the rafters must move out, or 2. They slide up the ridge board or 3. they get shorter or 4. they buckle longitudinally to shorten the end to end distance. As 3 seems implausible only 1, 2 or 4 remain, 1 is ruled out by your observations so 2 and 4 are left. If it is neither of them then the only other explanation, 5., is that it was built that way! Intriguing or what?

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