Roof - bought house - advice on wrong pitch and who is responsible

shefmarkh

Hello,

We bought a house last year that had a pre-existing extension. After moving in we have had problems with the roof leaking. A builder has told us the roof was built with the wrong pitch and needs replacing. We plan to get a second opinion to check we get the same advice or not. If we do - who is responsible for this mistake?

I would assume we can't go after the original builder (we never had any contract with them). But what about the council building control who signed off the building control regulations? Should the roof pitch have been checked as part of that? We also had a level 2 survey done by a RICS surveyor. Should they have noticed something like this and if so are they liable for the costs? The only thing they noted was that there was evidence of a leak in the past, but that this did not look current. The owner told us they had had this fixed (though now I doubt this given the roof still leaks and the builder says the fix is that it needs replacing) - are they in any way liable because they stated the issue had been resolved and it clearly has not been correctly resolved?

Finally is this something we could claim the cost of from the house insurance? If so, presumably this is is the simplest route to go down?

Thanks.

Mark

Section62

shefmarkh said:

But what about the council building control who signed off the building control regulations?

Should the roof pitch have been checked as part of that?

We also had a level 2 survey done by a RICS surveyor. Should they have noticed something like this and if so are they liable for the costs?

No, no, and possibly.

What is the as-built pitch, and what does the builder say it should be?  You probably need an architect or building surveyor to advise you, rather than just having a second opinion from a different builder.

One reason for people deliberately not giving the roof enough pitch is to keep the height (or volume) down below the permitted development rules. Is it possible this is what they have done in your case?  Or is there some physical restriction on the pitch imposed by the characteristics of the original building (e.g. position of windows etc)

shefmarkh

We'd have to ask the builder about the specific pitches, so don't know that right now.

The extension is to the side of the house. From the front if you only look at the extension you see a small room (with the problem roof). The roof goes up to a vertical wall behind that room that contains first and ground floor rooms that are also part of the same extension that was all built in one go. So the part of the extension behind this room goes much higher, so naively I don't think the height of the room at the front could have had any height restriction from planning rules. There are windows on the wall that this roof attaches to behind, so that presumably set a maximum pitch of the roof (assuming they could not have just sited those windows higher up, given this was all built together)?

stuart45

There are times when an inverted dormer can be used to increase the roof pitch when there's a problem with the cill heights.

ComicGeek

Is it a tiled roof then? All roof tiles will have a minimum roof pitch for installation, is the builder suggesting that the installed tiles are not suitable for the installed roof pitch?

There's a big difference between the whole roof needing replacing and the tiles needing replacing. The below is from Marley on their minimum pitches, so worth you checking the roof pitch and installed tile yourself rather than just relying on the builder.

Tucosalamanca

A roof cannot be built with the wrong pitch, it can however be defective if the wrong covering is installed after the roof is constructed.

Building Control wouldn't check the roof pitch (as it can be anything).
They also wouldn't have the knowledge to know if a suitable covering has been correctly installed.
A difference as minor as smooth or granulated can affect tile suitability for low pitch roofs.
Some tiles can go to quite low pitches if a larger headlap is used.
Again, Building Control are unlikely to have this knowledge and won't check.
As long as it looks OK and without glaring omissions, chances are that BC will sign it off.

Even a RICS surveyor might struggle to notice defects. Without physically lifting tiles, they wouldn't know if the tile headlap was correct and might also need to check the tile specifications.

As a rule of thumb. If a roof is less than 10degree pitch, it most likely needs a flat roof covering.

From 10 - 15 degrees, choice of tiles will be limited and will have specific installation requirements.

As you move into more typical pitched roofs (above 15 degrees), most tiles will be suitable.


Your roof might be a case of simply re-laying the existing tiles with an increased headlap (introducing an extra row of tiles)

The tiles might need to be replaced with something suitable for low pitch roofs, or if it's really low pitch (less than 10 degrees), the tiles will need to be replaced with a flat roof material.

I'd say that this is a frequently occurring issue.
Most people are unaware, as for the most part, the roof will remain watertight.
It's only in specific circumstances, such as prolonged heavy rain with the wind in the right direction, that faults occur.

shefmarkh

Yes, roof is tiled. By wrong pitch the builder means it should have been a "flat roof". He said he thinks changing the tile type may be an alternative option.

Measuring the angle myself I make the pitch around 11 degrees currently.

Section62

shefmarkh said:

Yes, roof is tiled. By wrong pitch the builder means it should have been a "flat roof". He said he thinks changing the tile type may be an alternative option.

Measuring the angle myself I make the pitch around 11 degrees currently.

Can you post a picture?

There could be some benefits if you can avoid converting to a flat roof - but it depends on the circumstances whether it is worthwhile.

shefmarkh

The leaking roof is the one above the left hand room at front.

gwynlas

The pitch of the roof is obviously impacted by the window above and the depth of the room. As other have said already it is most likely that the wrong covering was used in this instance. A flat roof would look wrong so you and your builder should look at a replacement product that would rectify issue, Chances are that original job completed with standard tile due to lack of knowledge.

grumbler

Tucosalamanca said:

Some tiles can go to quite low pitches if a larger headlap is used.

It's worth noting that with at least some tiles larger headlap can have the opposite effect as individual tiles become almost horisontal.