Readers often ask me if now is a good time to buy a house. This question has appeared in my inbox for the past nine years, as the Housing Bubble reached its climax, burst, and an Echo Bubble arose in its place.

It's a tough question, as you know, for reasons that are inherent to buying and owning real estate, and to the uniqueness of every household's finances and needs. So I always start by saying I can't offer any advice or even suggestions, because everyone's situation is unique.

In many cases, readers are seeking reassurance that it's OK to buy a house for reasons other than financial: they're having another child, their parents need them close at hand, and so on.

This is the dual nature of housing: it is both an enormous financial commitment and home/shelter.

The problem with being an enormous financial commitment is two-fold:

1. The size of the financial commitment outweighs every other expense and risk of capital. mortgage, property taxes and maintenance typically consume more of the household budget than any other item.

2. Housing is illiquid and the transaction costs are high. If I want to sell $200,000 of apple shares, the cost is a trivial sum and the transactions is completed in a few seconds, as Apple stock, like most large corporate shares, is highly liquid.

If I want to sell a $200,000 house, the process typically takes months and costs between 7% and 10% of the asking price in commissions, closing costs and fees.

Should I buy a house in 2015? Rather than seek a yes/no answer, let's try to identify some key reference points to consider.

1. Length of occupancy. If somebody buys a house with a fixed-rate mortgage and has a realistic plan to live in the house for 20+ years, fluctuations in value and demand don't matter much.

2. The potential consequences of a decline in value if the Echo Bubble pops. If, on the other hand, somebody is buying a house that they plan to sell in a few years to fund their retirement, that's a very different set of risks.