For the first time in 16 years, U.S. house prices have fallen, raising fears over the economy. This could in turn have a knock-on effect on the rest of the world.

This doesn’t seem to be an isolated incident, as the UK Land Registry is reporting a long-expected fall in the British property market — a 1.1 percentage fall last month, bolstered only by buoyant figures for London.

Standard & Poor’s/Case Shiller Index reports that American values fell 1.4 percent in the first quarter compared with the same period last year. They were also down 0.7 percent on the final quarter of 2006.

The OECD (Organization for Economic Cooperation and Development) warned that the spillover effect could be “more pronounced than generally expected”.

If you’re planning on remodeling your house to raise its market value, you’re less likely to recoup the cost of the improvements than you were a few years ago.

The reason is basically that the cost for making home improvements has risen faster than the degree to which those improvements raise the resale value of a home.

Before you launch into a remodeling project at your home, read the advice at Remodeling Online. They have regional maps and data with charts detailing cost vs. value of specific remodeling projects for various regions of the country.

For instance, in Massachusetts you can expect to recoup 79% of the cost of a deck addition but in Oregon you will recoup 91.1% of the project’s cost.

The Mortgage Bankers Association is reporting that more homeowners are falling delinquent on their mortgage payments. According to their report, 4.7% of loan payments were more than 30 day past due and 11% of mortgages were in foreclosure.

The trend is being blamed on high-risk loans with subprime rates and adjustable rate mortgages that are being affected by rising interest rates over the past few years.

More Americans Making Late Mortgage Payments

Former Federal Reserve chairman, Alan Greenspan, thinks that the current economic downturn is temporary, according to a report in the Toronto Star. The housing market in particular may not have bottomed out yet but he does not think it will get much worse.

“I think that while we are past most of it there are a lot of negatives … but it is no longer subtracting from the (gross domestic product) growth,” the former Fed chairman said.

For the broader economy, Greenspan offered tempered optimism, citing strong profit margins and capital goods data that are “showing some potency.”

“It’s hard to envisage those two key factors coming at the beginning of a recession,” he said.

He warned that some home buyers might have interest costs increase in the short term, however.