Mechanical fixing/dry ridge system for old angle ridgetiles?

[cjcoffin]

We are having a dormer loft conversion done, with a flat roof meeting the original ridge line. To begin with, the specialist company told us they would trim the back wings of the old Victorian ridge tiles so they would fit securely and refix them in mortar. I have taken one up to the roof to check and this looks entirely practical.

Now their roofing sub-contractors say it cannot be done and have instead fitted semicircular plain tiles bedded in mortar. The twin of this cottage and most of the other Victorian houses in the neighbourhood still have the original collared angle ridge tiles so the new ones look completely different and we have lost the distinctive stepped ridge line.

If they cannot bed the original ridge tiles in mortar does anyone know of a dry-ridge system which would be suitable for this application? Preferably it would also incorporate a 5mm ventilation gap as this would solve another problem as we want to avoid having slate vents if possible.

[The pitch angle of the slant face is 34 deg and the material is natural slate, renewed in 1993. The dormer roof is almost completly horizontal (fall of 1 in 60) and is finished in torch-on felt.]

All suggestions gratefully received!

TIA

 

[cumbrianroofer]

your the customer and if it looks fine t yo and thats what you want go back to the contractor and explain this what your saying sounds pretty simple to me and if the roofer is going to bed plain tiles on this is not right a picture might help

 

[SurreyRoofingEstimator]

I'm assuming that the back of the flat roof is at the same height of the ridge rather than slightly lower

The only real way to have a ridge at that junction is build a small false slope at the junction of the flat and pitched roof, the problem with this of course is that it will slightly lengthen the rafter of the sloping roof.

If the leg is being cut off the capped angle ridge it will be a very vulnerable point in high winds

A lead apron flashing would have been the best option at that junction to be honest.

The only Capped Angle dry vent ridge system as far as I'm aware is made by Hanson (formerly Redbank0 and is DAMNED expensive