How to replace low-slope metal roofing?

I am purchasing a home that has 3 low sloped metal roofs. One over the front porch, one over the back, and one over an addition. The addition and the back porch are leaking and i would like to replace all three of them. The slope is probably 3or4:12.

Any websites or advice would be greatly appreciated.

I have done traditional shingle roofing in the past, but was under the impression that this slope was too low for it.

Remove the old roof, then place Certainteed Winter Guard Ice & Water shield on the low-sloping roof. Then re-apply roofing.

I would recomend replacing roof with asphault shingles rather than a metal roof, because they are more durable and better looking.