A homeless man caused more than $7 million damage when he set fire to several schools and churches during a four-year arson spree on Brisbane’s southside, a court has heard.

David John Dillon, 38, pleaded guilty today to seven counts of arson, three counts of attempted arson and nine counts of entering a dwelling with intent.

Brisbane District Court heard the man targeted five schools, four churches and a factory at Salisbury, Coopers Plains, Wellers Hill and Moorooka between January 2002 and November 2006.

Prosecutor Dzenita Balic said in each attack, Dillon had broken a window, poured petrol on the ground and used paper and a cigarette lighter to set the fires.

In one night alone, he caused more than $4.2 million damage by torching two schools, Ms Balic said.

The court heard Dillon started blazes at the St Pius Catholic School at Salisbury and the Wellers Hill State School on December 9, 2006.

Dillon was eventually busted after DNA testing was conducted on blood found at the scenes of two school blazes at Moorooka.

He admitted the subsequent arsons during an interview with investigators, Ms Balic said.

A psychologist’s report tendered to the court said there was evidence Dillon was suffering from a “personality disorder” and concluded there was a high risk he would reoffend without treatment.

Defence barrister Scott Lynch said his client could offer no real explanation for his actions, but described the man as a “loner” who lived a simple existence.

Dillon had lived on the street needlessly for several years because he saw himself as a “burden” to his family, Mr Lynch said.

Judge Tony Rafter SC said the offences were “extremely serious” but noted the man’s cooperation with police and his early plea of guilty.

Dillon was sentenced to eight years’ imprisonment and will be eligible for parole on August 26, 2009.