Well, there were fires as a direct result of the use of straw and thatch roofing. Fires that laid whole cities and towns low and that's why, also around this time, 15th century, in say Amsterdam for example, the government boogies mandated hard roof covering, which meant tiles. No more thatched roofs in the city - imagine that. And it went even further. Not only the roofing changed but timber framed structures were replaced by brick and even the timber houses that were left were given brick facades and enclosures. A lot of times you will see these facades which seem to be tipping out over the street. That's because the brick wall follows the jettied timber construction being held to it with iron anchors and pins. There are more timbered buildings around than is apparent, they are just hidden behind these facades.