Alan Knight, 51, admitted murdering David Bond, 50, in Worthing and was sentenced at Hove Crown Court to serve at least 19 years.
After the hearing, Sussex Police said the killing in August followed a row over the cleanliness of the house in Osmonde Close where they both lived.
Det Ch Insp Tanya Jones said the tipping point was the microwave oven.
Describing the level of violence as "horrendous", she said: "His reaction was extreme for something, which in reality, was very small."
Police said Mr Bond was last seen on 6 August in The Warwick pub, but an argument began after he arrived home.
Knight texted his friend to say his landlord had asked him to move out. He wrote: "Shall I just kill him and you find me somewhere to duck till we get a plan..."
Police said he later messaged the friend to say he was "only joking" but then sent six images of Mr Bond's body, which she did not believe.
The next day, Knight drove Mr Bond's car to Hove and withdrew Â£600 before abandoning the car in London and visiting a friend in Southend.
The friend later told Essex Police she believed he had killed his landlord.
Shortly afterwards, Sussex Police went to Mr Bond's house where his body had been seen.
Det Ch Insp Jones said Knight knew what he was doing and described it as "a cold and calculated crime". She said the pair only lived together for about six months.
In a statement, Mr Bond's family said: "David was a caring loving son and father to his two sons, David Jr and Christopher. Out of no reason, his life was taken away cruelly."

Ms Yellen said current valuations were "quite high", but added she did not see any bubbles forming.
Chinese shares saw the biggest falls in the region with the Shanghai Composite closing down 2.8% at 4,112.21 - marking a third day of declines.
Hong Kong's Hang Seng was down 1.3% at 27,289.97 - falling for the sixth day.
Several companies on the mainland have announced share offerings through the week, leading investors to pull funds from other stocks.
Investors were also worried about reported new moves by regulators to cool China's market, such as capping the size of margin financing and limiting the type of stocks investors can buy with borrowed money.
In Japan, the benchmark Nikkei 225 closed down 1.23% at 19,291.99 after being closed all week for a holiday.
Australia's benchmark S&P/ASX 200 index closed down 0.82% at 5,645.70.
Shares in Australia had suffered their biggest one-day fall in more than two years on Wednesday following disappointing results from Australia's biggest banks.
Investors are concerned about the country's big four banks facing slower growth.
National Australia Bank (NAB), the last of the big banks to announce their results this week, reported a 5.4% rise in cash profit for the six months to March.
It also announced a 5.5bn Australian dollar ($4.4bn; Â£2.8bn) capital-raising exercise which will involve the selling of new shares.
NAB wants to demerge and float its troubled British bank, Clydesdale, and shore up its balance sheet.
The lender's capital-raising announcement has been reported by some of Australia's media as being the largest in the country's corporate history.
Also weighing on investor confidence were the latest figures on Australia's unemployment rate, which showed a slight rise to 6.2% in April.
In South Korea, the benchmark Kospi index closed down 0.65% at 2,091.00.
A lodger has been jailed for life for stabbing his landlord 29 times after a row about cleanliness.
[NEXT_CONCEPT]
Asian shares fell on Thursday, tracking losses seen on US markets after Federal Reserve chair Janet Yellen expressed concerns over share valuations.