A rainy-day sort of mood pervades Let’s Build a Roof, the third album by loose-knit Portland combo Lake. Eli Moore, Ashley Eriksson and Lindsay Schief each contribute tunes infused with whimsical ambiance, mysterious yet never threatening. Producer Karl Blau brings out the same jazzy colors that tinge his own recent work, embroidering the group’s minimalist melodies with rippling synthesizers and snappy horn lines. Quaintly spiritual lyrics add to the ethereal atmosphere of “Breathing,” “Sing 99 & 90,” and “Loose Wind,” while “Gravel” and “Winking Sign” have the naïve charm of children’s verse. Lake shakes its collective booty on the afropop-rooted “Madagascar” and the ‘60s-soul-styled “Remote Control Cars.” Eriksson is especially good at conjuring up a misty glow with her swooning lead vocals on “Acorn” and “Christmas Island.” Though the word “forceful” doesn’t often apply to Lake’s music, the band does muster up a degree of folk-rock drive on “Collapsing Homes” and “Don’t Give Up.”