Fastening ridge tiles

[frediaz]

The manufacturer of the roof tiles I am using says that we need to provide mechanical fasteners on the ridge tiles (half round) even if they are fixed with mortar (no fancy ventilation in the ridge tiles)

Is this true? as I have never seen any screws or brackets on the ridge
or hip tiles, embedded in mortar, of houses built recently

 

[noseall]

do you live in a wind vulnerable area? top of a hill? tornado alley?

i have expressed concerns over the adhesion of mortar to some natural slates in the past, though i've not seen anything that would make me rush out and clip them down.

 

[^woody^]

I wonder if they screwed them down, 50, 100, 200 years ago?

Ive seen mortar which has turned to powder on a 3 year old newbuild, and mortar which would take a kango to remove from tiles on properties built in the early 1900's.

My own view, is that a good mix will defy all but the most extreme (and rare) weather that we get in the UK. Its all about the quality of the work.

 

[frediaz]

No I live in a sheltered area but there are these British Standards BS 55341 and BS 8000-63, that state that hip-ridge or ridges should be
mechanically fixed for a distance of not less than two consecutive units
or a distance of 900mm, whichever is the greater, from the face of rigid
masonry supports such as gables, dormers, valley junctions, abutments
and separating walls where there is a risk that differential movement
may take place.

To make it more confusing they say that it applies to gables that support the ridge but my understanding is that it is the trusses/battens/top tiles combination that do this, especially if you have got a truss very near to the gable wall

 

[Roofer]

The key words here are differential movement

The recommendation to mechanically fix the last two ridges (or 900mm) came about because of the tendency for the end ridges to be blown off. It became apparent that this was happening because the mortar bedding was cracking when the rafters/trusses were settling/moving more than the gable/party walls and therefore becoming more susceptible to wind damage.

Although not all roofing contractors comply with the recommendation I would say that most new-builds are fixed as the NHBC tend to look out for it

 

[frediaz]

Thanks for the feed-back, but in that case, how are they fixed, with a long screw into the truss below for instance?

 

[Mw Roofline]

Ive seen mortar which has turned to powder on a 3 year old newbuild, and mortar which would take a kango to remove from tiles on properties built in the early 1900's.

Just slightly going off-topic. Our local church built in seventeen hundred and something. You'd need a JCB to get even a smidge of mortar out of it. Now they didn't have British standards, Super recipe portland cement, plasticisers, pva's or anything else like that.

So what the hell were they using?

 

[^woody^]

Perhaps it was overseen by the guy who it was built for?

But I always refer back to how stuff was built "in the old days". No British Standards and no NHBC etc (and no mechanical fixing lol), just common sense and skill - and buildings that will generally outlast anything that we build today