CANNY homeowners marking time until they can take the next big leap up the property ladder are always looking for ways to improve the investment they have made in their present home.

Thirty-year-old Telecom engineer Nick White regards the three bedroom Victorian cottage he shares with his girlfriend not just as a nice place to live but also as a nest egg for their future pension.

They've just added a £45,000 loft conversion. The scaffolding is due to come down next week at the end of the three-and-a-half month contract.

After a local estate agent viewed their house last week, the couple were delighted to learn the value had gone up £80,000.

The project has been a success because they went about it the right way.

"We got five quotes for the work," says Nick, "four from specialist loft companies and one from a small builder. We chose the cheapest estimate from the loft companies. The quote from the builder was cheaper but we decided not to go with him because there wouldn't have been the back up.

"Our mansard conversion has given us a large double bedroom with ensuite bath and shower room and a large balcony at the back of the house. We could have gone right across the width of the property but that would have involved gettting planning permission and we wanted to avoid that."

The loft conversion has drawn admiring comments from the neighbours.

"The front of the cottage really doesn't look any different from how it did before," says Nick. "We had the sides of the sloping roof at the back tiled to make it blend in with the existing roof. Our immediate neighbours are so impressed, they're both going to do the same thing themselves."

Russell Jervis, managing director of Haart estate agents says adding a room in the roof will certainly add value if it is properly carried out. But he warned: "It's far from a simple DIY job. Homeowners could be pouring a lot of money down the drain if they don't go about it the right way."

Follow this seven-point plan, advises Jervis, and you shouldn't go wrong: 1. First ask an estate agent how much value a loft conversion will add. The value will often depend on other houses in the area and whether they have a conversion or not. It is possible to over-develop the wrong houses. Even if your house is the best in the road, the location could limit the potential value.

2. Look at the shape of the loft. Is there enough room to stand. Will it be comfortable useable space?

3. Ensure you have the correct planning permission. You are allowed to extend the overall floor area of your home by ten per cent without consent although you must obtain a permit to build from the council. And if you live in a listed building, an area of outstanding natural beauty or a conservation area you will need specific permission.

4. Even if you don't go ahead with the conversion, having consent can be enough in itself to add value.

5. Get it built to a professional standard 6. Always get more than one quote, ideally three and ask to see finished jobs carried out by the firm.

7. To be classed as extra living space, a loft conversion must have a proper staircase, windows and comply with fire and building regs. Otherwise all you'll end up with is a glorified storage room.