Dry verge over mortar ?

[rileystadgu]

Can anyone explain why you need to remove mortar / undercloak when fitting a dry verge?.
Is it because of ventilation (Why if the ridge is currently mortared and ventilation is not an issue) or to fix the dry ridge (into mortar, but if the batten is behind it it will be secure using suitable screws .

How does the dry verge unit 'seal' to the tile to prevent water seepage between the plastic of the verge and the tile?.

If the dry verge unit covers the top of the tile and laps under the next tile plus covers any undercloak and id flush to the (UPVC) barge board what is the point of spending time removing mortar (and possibly damaging tiles) ?

 

[rileystadgu]

Any help would be appreciated

 

[Barthy]

I try to steer clear of dry verge systems personally there are exceptions though
You can retrofit if you have some sound material to fix each individual unit to... assuming your current overhang is suitable to the units you've purchased
It's good practice to remove tiles expose 1.2m of batten to the nearest rafter, renew felt and batten and fit accordingly
That said if the gods are with you and you have correct current overhang you can do it. For the cost of X amount of gable tiles it's worth doing properly...
If you are going to pay for a scaffold I'd go for undercloak and a mortar verge in my preference.

 

[Barthy]

And by sound material I mean bargeboard not existing mortar and hoping to hit the battens assuming they're close enough which they shouldn't be on a mortar verge

 

[rileystadgu]

Thanks, If you know where the battens are why not drill through the mortar and use long screws to fix into them if the tile overhang is sufficient ?