Slight dip in roof

Hi , was just looking for abit of advice -
We are just buying a new house and the surveyor has advised us to get checked a slight dip in the rear roof … the house was constructed about 1960 and I think its the original roof -

I have a roofer coming round to have a look who says alot of the time its just the way the weight of the roof has lay and alot of the time there is nothing to worry about and the roof is sound …

Is a dip often nothing to worry about ??

Any help would be appreciated


You would have to look in attic to see the extent of reason its dipping, if its just a dip you would tear off old sheathing in that area and build back up level, don’t leave like some roofers who just roof over bowed sheathing, it will look more nice if leveled out.

Ok cheers –

Is this a big problem though you think ?

Im told alot of older houses have this quirk and it can be left without problem ?

It depends if the dip is between two rafters/trusses or between eave and ridge. And of course the amount of deflection. Between the rafters is a minor sheathing repair, between eave and ridge is MUCH more involved. Many older homes were “stick” built with lumber sizes that would not pass code now. However this type of dip is usually more of a cosmetic problem. More details and pics would help us steer you in the right direction.

This is the way to repair a slight dip in roof

These dips are notorious and are nationwide.Mostly in your older homes.I have seen them on homes from the 1890’s up to the 90’s and maybe newer.

Lots of things contribute to this structural anomaly.

Foundation settling,multiple layers exceeding the structures intended max weight load,multiple layers over shake roofs are also notorious for having truss/support issues…Improper bracing.,twisted or busted trusses maybe due to the home having had a tree or large branch fall on it.

It is not out of the normal for roof structures to be different measurements from rake to rake and in the center.

Meaning on a gable roof the rake on the left might be 20’ and the right might be 19’/10"
but the center of the roof is 19’.6".,so the center would be sunken on the ridge 6" from center rake to rake.

I have also seen this with dormers too.Steep roofs also have this problem.Generally from out dated structure reinforcement techniques.These occur mostly in the center of the roof.(Field)

These dips are generally simple to correct.I usually find the source of the problem then correct that.Then I will reset/reinforce the truss.Not finding the original culprit for the problem might have the same thing happen in the future.

Do I think it is a huge structural issue?.,Not a clue.It will depend on what actually caused the dip in the first place.But I can say.,the house is still standing. :badgrin:

That depends, if it is a dip in the sheeting between two trusses, then usually it is not a structural problem, just a cosmetic issue. These are usually caused by the sheeting being 3/8" plywood that has sagged over time and can be fixed by installing a new piece of sheeting or you could put a piece of 2x4 between the trusses to level out the sheet of wood (called “blocking”).

If it is a dip like A1SoCalroofer illustrated, then yes it is structural and should be fixed.

Can you advise if I should be concerned about the dips/humps in this supposedly 10 year old roof on a home I’m considering buying…

I respect your opinion!
Much appreciated!

Yes and that is not slight.

Wood Sheeting popping up in the middle,
It will be leaking soon if it isnt already.
Then about 4 feet below is the result of a bad
leak or a broken truss.
If it was a leak, it would surely be exposed on the inside.
I am strongly leaning toward a broken truss.

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