An 83-year-old grandfather has a smashed skull after a brutal home invasion in Mandurah, south of Perth.

Barry Lawless was sitting at a table having a cup of tea when a man stormed through his front door and started bashing him with a home-made weapon, while his children watched on in horror.

Mr Lawless is a father of six and a grandfather of eight.

View photos Barry Lawless, 83, was savagely bashed by a home intruder. Source: 7 News More

He was bashed by a stranger in his living room when his 12-year-old daughter and 11-year-old son sprang into action.

"And my boy, trying to chase him out of the living room, he said: 'I'll get him dad", a tearful Mr Lawless said from hospital.

"Very traumatic, I can tell you."

View photos Mr Lawless described the bashing as More

The 83-year old has no idea why he was attacked and nothing was stolen from his home.

The weapon used "looked like a lump of steel", Mr Lawless said.

"He kept swinging it at me, I was lucky to be alive actually."

View photos The man used a home-made weapon in the home invasion in Mandurah. Source: 7 News More

On Thursday night Mr Lawless went into surgery.

He has two breaks in his head, is covered in cuts and bruises, and lost 1.5 litres of blood in the horrific attack.

It happened around 9pm Wednesday night on Truarn Street in Mandurah.

Most houses in the street have heavy security, but Mr Lawless' front door was open last night because it was hot.

View photos Mr Lawless had left his front door open because it was hot. Source: 7 News More

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