House prices keep on moving upwards. Nationwide building society said on Tuesday that in April it had recorded its biggest monthly rise since 1991 - when it started recording monthly figures. What is going on?

How much have prices risen?

According to Nationwide's latest house price survey, the cost of an average UK home rose by 3.4% in April.

Over the past 12 months prices have risen by 16.5% - and by 90% over the last six years.

The Halifax bank's house price report is due later in the week.

What is keeping the prices of houses so high?

Housing may be expensive, but borrowing is still cheap.

Mortgage rates, which are based on the Bank of England base rate, are at their lowest for more than 40 years.

This means people can afford to borrow larger sums of money with which to buy properties than if interest rates were higher.

In the immediate aftermath of 11 September there were concerns about how the events would affect the world's economy.

But while there have been some job losses and economic jitters, it appears that British consumers are still willing to part with their hard-earned cash - and saddle themselves with increasing levels of debt.

What are the dangers for the market?

Unfortunately, there are a couple of worrying signs in the market - especially for first-time buyers.

With so many people determined to get on the housing ladder, there is concern that some people could be overstretching themselves - and could get into trouble if interest rates rise.

There have been reports that more first-time buyers are borrowing for deposits on a property, and that people are borrowing at higher levels - in some cases up to five times their income.

Frustrated by the expense of buying alone, more first-time buyers are clubbing together to purchase properties with friends.

And according to Your Mortgage magazine there is another worrying sign - first-time buyers are taking out interest-only mortgages which are not backed-up by any security or investment vehicle to cover the underlying debt.

It is not only first-time buyers, but people who have piled into the buy-to-let market.

There is evidence in central London, for example, that rental yields have been falling.

In some parts there are basically too many landlords chasing too few tenants, which is pushing down rents.

Is the property market going to crash?

Most people buying homes now can remember the boom and bust of the housing market in the late 1980s and early 1990s.

A quarter of a million homes were repossessed, and it took those hit by negative equity almost 10 years to get back on an even keel.

The difference this time around is that mortgage rates are very low, so borrowing is still relatively affordable.

There is also a shortage of properties. Experts predict that this could sustain the market for years to come.

How can I protect myself?

With prices rising so dramatically, investors need to be cautious - and remember a few important principles of property investment.

• Property is an investment, which can go up and down in value.

• It should be viewed as a long-term investment and is illiquid. Unlocking the value of your house is not the same as drawing money out of a cash machine.

• Investors should be cautious about overstretching themselves. There is now real fear that younger people, who have overstretched themselves, could be exposing themselves to real headaches in the future.

• Responsible mortgage brokers are now warning people who are concerned about higher interest rates rising to fix their mortgage rates, so that they do not get caught out.

• People may be tempted to take out an interest-only mortgage, because the monthly payments are lower than a repayment deal.

  But an interest-only mortgage covers only interest payments and not the underlying debt.

  People use an investment product, such as an equity based investment in an Individual Savings Account, to pay off the debt at the end of the mortgage period - typically after 25 years.

  But recent experience with underperforming endowment polices has shown that investment products do not always make enough money to pay off the underlying debt.

  Repayment mortgages may be a little more expensive, but they should cause less worry. They pay off both the interest and mortgage debt each month - and are not dependent on the vagaries of the stock market.

Are you worried that prices have spiralled out of reach or are you happily sitting on the best investment you ever made? You told us your experiences of the housing market.

As one of the victims of the 80's Repossession scam, I urge all prospective buyers to beware, as stated in other postings a 1% rise in interest rates equals a 25% rise in repayments. It may be cheap now ! but it will cost you !! Beware Beware Beware
John , London UK

Having over 30 years professional experience of property markets, I have rarely seen a market more ready for a serious fall. In the London area, much of the continuation of the boom has been fuelled by the "buy to let" fashion (I know a people who have bought 2 or 3 homes in this way instead of putting money into a traditional pension plan). With rents falling, a rise in interest rates ought to encourage people to cash in these investments. However, the ability to fix interest rates for a few years have delayed this "normal" market correction. When these rate fixes unwind, there will be a considerable amount of selling. With low liquidity, people who need to sell quickly or those frightened of losing everything will cut prices to ensure the limited demand will result in the purchase of their property. There is no doubt in my mind that we will see at least a 20% fall in values - perhaps as much as 40%. The questions are: (1) When ?(6 months or 3 years?); (2) What will be the social cost as consumer spending suddenly takes a dive with increased mortgage payments dominating and many people facing negative equity or the loss of their pension investments ?
Richard Lovell, London, UK

House prices will continue to rise until the chronic shortage in the SE is relieved..... which will be a long time as I do not expect 5 million new homes to suddenly appear within the M25 in the next 30 days....
Michael Turberville, London, UK/EU

Move up North. It aint grim ! And you get significantly better value for your money.
Liam, uk

A couple of thoughts that seem overlooked. Borrowing is cheap as interest rates are low - however the sensitivity of interest rates is far higher than when they were high in the 80s. A 1 point rise in rates is like a 25% increase or a 3 point increase in the late 80s. Also there may be a shortage of property which is partly fueled by buy-to-let demand. When the buy-to-let demand becomes saturated and rents fall further some of this property will come back on to the market.
Richard, Bucks

Yes, interest rates are at a historical low. But, if you have to borrow three times as much (which is the case in London, where property prices have trebled since the late 80s) to buy a property, the servicing costs is very much higher! It is because mortgage repayments (including the capital) is excluded from the RPI, that is painting a false picture of inflation. The problem with the decision makers in this country is that they do not live in the real world and carry the notion that everyone in London earns at least 100k p.a., hence the constant chanting of the mantra, "owning your own property is only costing the average taxpayer 20% of their pay".
Steve, UK

My boyfriend and I are first time buyers and are very confused as to whether to buy now or delay buying until the market slows.
Katrina Clark, England

I've been looking at buying a house for over a year. The prices are mad. I will be making the mistake of over stretching myself, as I need to get onto the property ladder. Last year there were reports that the bubble would burst, a year later it hasn't happened. So I'm now jumping onto the ladder, but who knows how long I will be able to hold on once the rates do decide to go up!
Usman Malik, London, UK

As a prospective first time buyer, the rising house prices are putting the prospect of owning my own home further out of reach. House prices, in particular, in the South East are not justified and salaries do not reflect the cost of living anymore. The areas do not justify the high prices and often, neither do the houses themselves. It feels that the only option is to rent, which is as good as throwing money away!
Kelly, UK

I decided to buy a house for just under �130,000 last month. The owner was made redundant two days ago, so pulled out of the sale. Now, in that time, house prices have risen �4,000 in the area I'm looking in! The whole market is insane, and I have lost hundreds of pounds on a failed sale. Those hundreds are utterly insignificant compared with the inflation in market values.
Andrew, UK

A couple of years ago we had a pretty dramatic stock market downturn particularly for the tech markets. No one seemed to foresee it and anyone that did was ignored. I wonder if this is a lesson that has not been learnt from?
Phil, UK

The bubble will burst as soon as interest rates increase. Remember only a one percentage point increase will put up interest rates 25%. The cost of borrowing is cheap at present, but with inflation rising, a rise will occur in the next two months. It will only take a small prick in the bubble to knock down the artificially high house prices. Remember the stock market three years ago? The bigger the climb the harder the fall.
BWatkins, UK

My husband and I are in the process of buying our first house. Having rented for nearly 12 years (since I went to university) I have been struck by several things during the buying process - 1. Mortgage lenders were prepared to lend us ridiculously large amounts of money. 2. We have had to miss out the 'starter home' range of houses as this now translates as houses that are affordable through the amount of work that needs putting into them, which neither of us has the time or energy to undertake. 3. As a result we have had to borrow more off the mortgage lender and get an interest repayment mortgage. 4. Which means we are now having to set up an ISA to run alongside it. 5. Which has meant that we need to borrow money to make up the 5% deposit 6. All the new properties are being 'bought to let' before they are even built which is pushing ALL the local property prices up. 7. Where we live at the moment, two bedroom flats are being sold (and then built!) for in excess of �200,000. CRAZY! What makes me cross is that, as always, there are people making an obscene amount of money, whilst I find myself increasingly worse off, about to own a home I may not be able to afford.
Kate, UK

My business is property development/letting.I am selling property now NOT buying. Most of my sales are to "but to let" buyers! The "tail is wagging the dog". A speculative "buy to let" boom that will crash when rates rise. A 2% rise in rates means a 50% increase in mortgage repayments.
Chris Jackson (CJ Property Ltd)

With house prices so astronomically high, low wage earners like myself find themselves in the unenviable position of being wholly unable to afford to buy a place to live. Single people like myself or Single parents trying to get on the ladder find the first rung to be so high you'd need a rocket to reach it. With inflation being low, wage rises are also low meaning the gap is widening constantly. Its very depressing really.
Simon Andrew, UK

It is crazy to set interest rate policy by the inflation rate that excludes mortgage repayment costs when this represents such a sizeable chunk of people's expenditure. Good luck to you all, I have had enough of being young, skilled and broke and am emigrating to the USA where for better or worse the citizens interests are taken care of!
Mark Arbon, UK

I live in the North East. Many people around the country think we all live in council houses and race pigeons for a living! How wrong they are - we enjoy a far cheaper cost of living and yet our salaries are not far off national averages. I'll try and sway people away from going South and move North East instead. I just bought a lovely four bed house with double garage, garden, and sea view in a green area that cost me the price of a cheap one bed flat in London. It's your choice!
Steven Tucker, England

I have a flat in London which I am letting while in New York. I have been shocked by the property's rise in value, but at the same time the decrease in rent. Due to the high number of properties bought to let, "renters" have greater choice and rents are falling. I imagine as the yield on buy to lets continues to decrease, interest rates increase and the stock market improves investors will stop investing in the property market and put their money elsewhere.
Claire, US