Engineers are competent to comment on structure or services in terms of building.
I know of none who deal with the weathering envelope of the superstructure, unless its a specialist curtain wall job, or repairing settlement cracking in an external masonry wall, for example - but I may stand corrected on this.
They'll advise on roofs that have blown off, but that's a structural issue involving wind uplift forces, wall plates, ties, purlins and fixing bolts - nothing to do with the deterioration of the membrane for example.
The effectiveness an engineer and this particular builder can be judged by their track record to date - 6 leaks in two years.
Please do yourself a favour and retain an architect to advise you on this, who will; -
- inspect when the opening up has occurred
- assess the trace of the leak
- conduct background research on the builder and the roof type
- inspect the Opinions of Compliance issued for this building by the developer's architect
- review the supplier's /manufacturer's guarantee / commissioning certificate for the roofing system,
- spot a pup if it turns out to be ponding asphalt without wedge pieces laid on timber with no separating layer, no solar protection and no flashing at upstands and
- issue a competently presented and comprehensive report detailing the non-compliance with the building regulations that will form the basis of any legal action you may have to take.
Otherwise you're going to be paying a solicitor a lot of money to write letters about technical matters he knows little about.
With an architect's Report to draw on he can use this to establish the terms of your claim as well as the proposed remedy.
Your house contents insurer may also need to be brought up to speed on all these goings on sooner or later.
In advance of any appointment ask around the development and see if anyone else has suffered leaks.
As regards the solicitor you have spoken with, he has already shown his level of experience.
His strategy appears inappropriate for this situation because the builder is not ignoring the problem.
The builder does not need to be reminded of his obligations, he appears to be discharging them, or trying to.
What both you and the builder need is competent technical advice on the source(s) of the leak and how to remedy it/them.
FWIW
ONQ
[broken link removed]