Looks more like a slate valley, the tiles do not have enough lap over the valley.
Remove the old brick, and fit a preformed concrete surround.
You state, the water lays at the edge of outlet.
Common problem, the outlet hasn't been recessed into the decking board.
The only way you will get a bond between the 2 roofs is, use a termination bar with cut of mastic. ( needs to be fitted correctly ).
Or fit an...
We cut straight through the centre line, remove all existing roof covering and boards.
Fit 8x2 x 18mm osb3 t&g boards.
Glue down epdm, lapping...
Hes worked it to brick.
Extra cost would be additional boards needed for the gluing of rubber down.
The board needs to be laid across the roof timbers, not between them.
Only need to go up the roof about 300mm, the rubber...
At a guess, Redland Delta ?
Glue a sheet of epdm on it.
Same as John, sit an eco fan on top, it will throw the heat out.
You can get a very fine flame, and far hotter and faster.
Turn it down for upright burning, but if you cant do flat burning you will never be...
Ive used a Pencil Burner fitted to a Siever handle, but your better of with Oxy Turbo.
If you have never done it before you will blow holes in...
Litho mix, and add pigment to match colour.
Available from lime stockist.
I think he means a flat valley, taking several roof pitches.
Rubbers perfectly okay, if the budget allows use Resitrix.
Looks like they have done more damage.
It seems as though they have foamed up the valley, and pointed over it.
Use the insulated boards with ply already glued to them, or fit t&g osb3 over the insulation.
Get yourself half a metre of form flash, and a small tin of primer.
For the neatest join use 75mm splice tape.
Any holes etc will show, use a 2 part filler.
Separate names with a comma.