! New roof sagging !

GlitterQueen_2

Full re-roof completed February 2021. Today I noticed one side is sagging. I have called the contractor whose immediate response was "the tiles we used are the same weight as the tiles we removed". I never mentioned tiles and I didn't point fingers since I have no idea what could be causing the problem. He has agreed to come out and take a look at the roof at the weekend. What could have caused the sagging? Is it definitely going to be an issue with the contractor or could there be other factors at play? No issues were raised by the contractor while the work was underway. Are there any checks I can carry out before the contractor arrives so that I can verify what he says is correct?

grumbler

GlitterQueen_2 said:

I have called the contractor whose immediate response was "the tiles we used are the same weight as the tiles we removed". I never mentioned tiles and I didn't point fingers since I have no idea what could be causing the problem.

Heavier tiles is the most likely, if not the only possible reason if everything else remained the same.

Are there any checks I can carry out before the contractor arrives so that I can verify what he says is correct?

Compare the weight of the old and the new tiles if you know what sort of tiles they were and are. The weight also depends on the overlap.

GlitterQueen_2

grumbler said:

Heavier tiles is the most likely, if not the only possible reason if everything else remained the same.

The tiles that came off were pretty old. Don't know if that would affect the weight. I know that tiles wear over the years. Other possible problems? 

grumbler

I don't think they were replaced with exactly the same, but new.

Modern concrete tiles are heavier than old clay tiles and can absorb more water. However, if they are interlocking, the overlap can be smaller.

The only other reason I can imagine is wet rafters.

stuart45

This can happen when replacing clay with concrete and not checking the roof structure, but a roofer should know this.

GlitterQueen_2

pretty sure old tiles were concrete too not clay. roman ridge tiles. tiles removed were original roof tiles from 1955 when house built. 

GlitterQueen_2

under what circumstance would the contractor be able to refuse to put the problem right?

stuart45

If he just replaced double Roman concrete tiles like for like he will probably claim it wasn't his fault. You might have to get an independent report on the cause of the roof dishing.

daveyjp

What did Building Regulations say?

twopenny

When you say sagging is it between the rafters, the ridge, whereabouts?
Could you post a photo?
Have you been in the attic to see if all the trusses and battons are straight?

travis-powers

twopenny said:

When you say sagging is it between the rafters, the ridge, whereabouts?
Could you post a photo?
Have you been in the attic to see if all the trusses and battons are straight?

Agreed a picture would be good and a picture of your roof structure, a carpenter can strengthen your roof but you may need to involve a structural engineer to do the calculations.