To me, ofta makes it sound a bit like the houses would change colors, which I guess they do sometimes when they're repainted, but still… It is however true that the typical house in the countryside in Sweden is red. This is because of Falu koppargruva, where copper has been mined since the age of the vikings, and using that copper, the typical color falu red is made.
Well, I didn't do too well understanding the Falu koppargruva article, so I tried Chrome's automatic translation button at the top. Here is one of the resulting paragraphs:
When in 1719 emptied a 500 foot deep reduction, marten mine, which for many years been under water, was found where the corpse of a miner Mats Israelsson, commonly called Fet-Mats , who 42 years earlier gone alone into the thin and then died. Upon resumption was the vitriolhaltiga water genomlakade body yet soft. He then became hard as rock and stored for many years as a great curiosity, but did eventually decompose and was then with great honor buried in Stora Kopparberg old church in 1749. [ 6 ] The rest did not last long, they would do if the church floor and was Had to move on Fet-Mats. His leg was put in a box as one moved up to the attic where he was forgotten. In the 1930s, they found the box with Mats when you did on the wind and he got his funeral year 1934th.
Late answer, but for those who are curious the reason that red is a rather common color in Sweden for houses (and barns, that's where the stereotypical red barn with white trim comes from) has to do with the historical prevalence of copper mining as a major aspect of the Swedish economy. The classic red color used is a pigment produced from the byproducts of the copper refining process and originally was produced mostly in Falun. See https://en.wikipedia.org/wiki/Falu_red for a bit more info.