Why aren't house prices included in CPI?

Swedens central bank recently lowered their prime rate to -0.25% from -0.10% in an effort to avoid deflation. At the same time, house and apartment prices are higher than ever, up 11% last 12 months, and up hundreds of percents the last 5-10 years. Measures are taken to avoid a housing bubble, like regulations on mortgage payments and so on, these are having an effect but the effects of a rapid rise in rate would be disastrous. As I've understood, and I guess this might differ from country to country, the measure of inflation, CPI, includes prices for services and goods, but not for houses and apartments, why is that? In Sweden, rent for apartments and the bank rate are included in CPI, but the consumer isn't paying rate, they pay rate * house prices. If house prices were included in CPI, we would definitely have inflation rather than deflation, so the right action would be to increase the prime rate, which would also lower house prices.