Some homeowners planning to redevelop their houses will not need to get planning permission under proposals being worked up by the Conservatives

John Gummer, the former environment secretary who is heading the Conservative party's Quality of Life commission, said he was looking at taking some estates out of the regular planning regime.

He said: "We're considering whether to exempt from planning requirements housing estates built since 1945 so they would have deemed planning consent for doing things that would otherwise require planning consent."

Under Gummer's proposal, large numbers of homeowners who are seeking to redevelop or alter their dwellings would need to do no more than notify planners. He argued that such a move would ease pressure on hard-pressed local authorities and add variety to otherwise bland estates.

He added: "If you look at the balance of development, you have to say that we spend a huge proportion of planning officers' time. Most people would say housing built since 1945 has been pretty mediocre."

However, the Royal Town Planning Institute have criticised the plans, saying that the existing system provided a mechanism for easing the conflicts thrown up by development. A spokesperson said: "What may seem like a modest extension to the homeowner who wants to build it may feel like an invasive eyesore to their neighbours."

Gummer is also backing much tougher warranties for new housing as part of his wide-ranging review of the Conservative party's environmental policy.

Gummer said the commission, which is designed to help reshape the Tories' environmental policy, is going to examine the introduction of stiffer warranties than those currently offered by housebuilders.

We are considering whether to exempt housing estates built since 1945

John Gummer

"We are looking at the idea that we would have the sort of warranties that you have for motor cars. It would be better than the housebuilders' inadequate guarantees, something that would be a proper guarantee," he said.

Under the National House-Building Council warranty, which applies to 85% of new dwellings, developers are obliged to make good defects that show up within two years of sale. Gummer argued that making housebuilders sign up to make good defects that became apparent within 10 years would improve the quality of their product and service.

Inspector Home, the new homes watchdog, welcomed proposal to introduce stiffer warranties. A spokesperson said: "It's a great step forward. If you have the people building the homes responsible for the warranties you are going to have more stringent checks in the first place because people are going to be keen to protect their liability."

Recently published research by Inspector Home showed that the number of defects per property rose by 19% last year.

Judith Harrison, the Housing Forum director, said her organisation was discussing the issue of warranties. These will be part of the customer satisfaction strategy of John Callcutt, English Partnerships new chairman. He will outline this at a conference next month.