There will be an increase in serious building fires unless safety measures are given greater priority, London Fire Brigade has warned.
The brigade has made a number of recommendations to Dame Judith Hackitt's independent review into building regulation and fire safety, commissioned following the Grenfell blaze.
It said a "general lack of competence" is leading to "dangerous decisions" about building design or construction.
Inspections find serious problems with buildings including significant construction defects, critical fire safety system flaws and a lack of understanding of fire safety measures by building managers.
London Fire Brigade is calling for:
A loophole to be closed that means some fire safety elements can be designed without the involvement of a competent fire safety professional
Formal qualifications or accreditation for those who install life-saving systems like smoke ventilation, fire detection and alarms
Clearer definition of who is responsible for what under fire safety legislation
A clampdown on companies who act as a building control body as well as offering fire engineering design advice without clear separation between the two roles
A robust, independent on-site inspection programme that ensures the fire safety elements of a building's design are translated into the finished construction
Dan Daly, assistant commissioner for fire safety, said: "It took a tragedy for everyone to take fire safety seriously and listen to what the brigade has been saying for years about skills.
"Urgent action is needed to better regulate those who are responsible for ensuring a building's design, construction and maintenance are fit for purpose.
"There are countless points where a dangerous decision can be made about a building's design or upkeep and hardly any measures to ensure that the people making those decisions are sufficiently experienced and properly qualified.
"This means that potentially dangerous design flaws could exist within a building until we either find it at a later date, or in the worst case scenario, it is exposed by a serious fire.
"We don't have the legal powers or the resources to check the entire fabric of a building but we often uncover dangerous flaws that we can't ignore."
He added: "We recognise that this is a once in a generation opportunity to make buildings safer and are actively supporting the review process."