There were two main locations for hearths: in the middle of the room, well away from the walls, or next to a brick/stone wall. The walls were at little risk, since wood is not that easy to ignite.

The two main protections for a thatched roof were:

• Cooking with a modest fire, rather than a big roaring fire.

• No chimney or smoke-hole.

The lack of a chimney/smoke-hole is important for many reasons:

1. It stays warmer in winter - the warm air heated by the fire doesn't escape.

2. Without an updraft through a chimney/smoke-hole, any embers won't be blown up to the thatch.

3. The warm air under the thatch will help keep the thatch dry.

4. The smoke will deter insects from living in the thatch.

A high roof will keep the smoke high enough to not trouble the occupants too much.

For the type of fire best for cooking over, see these modern examples:

• https://i.pinimg.com/564x/92/22/82/9222823d1ebbd6ac035f5e78f535e559.jpg

• https://i.pinimg.com/564x/92/54/6d/92546de1aa5973ed667800fa170e97d6.jpg (this is an old building - you can that smoke has blackened the timbers (but not the thatch, which has been replaced))

• https://commons.wikimedia.org/wiki/File:Tabu,_Myanmar,_Family_in_the_kitchen,_village_life_in_rural_remote_area_of_Shan_Hills.jpg

While these are modern examples, reconstructed kitchens (e.g., at living history sites) are quite similar:

• https://i.pinimg.com/564x/13/94/cd/1394cdfdc93b7a98be31df12a92f7d6b.jpg

• https://i.pinimg.com/564x/d5/de/39/d5de392dd0811816b190b2dcfbc57ab5.jpg

• https://i.pinimg.com/564x/f5/36/31/f5363127ba2ff002dfa2d0caa7bfb3c5.jpg

There is a third safety factor: the hearth is a focal point of social activity, so people are usually around.

Finally, thatch itself. Thatch will burn, and if it catches fire is difficult to put out, even with modern firefighting equipment - it's designed to repel water, so firefighting water tends to not penetrate into the thatch. However, it isn't too terribly flammable, especially from the inside. The air under a thatched roof is still, so there is little chance of a breeze making a small ember hot enough to ignite the thatch. Generally, small embers will cool safely, even if they reach the underside of a thatched roof. The lack of strong updrafts means that only small embers can reach that high.

A bigger risk was outdoor fires, such as bonfires, which could be quite large and produce large embers. A large ember on the outside of a thatched roof, if it is dry, can ignite the thatch, especially if the wind blow the right (or wrong?) way. Similarly, if a nearby house burns, the fire can ignite nearby thatched roofs (recall the Great Fire of London).

In England, there are still thatched roofs in use. Open hearths are very rarely used, and these thatched houses usually have fireplaces with chimneys, or enclosed wood-burning stoves. Both of these have a higher fire risk than an open hearth. In both case - fireplace and stove - hot air rises through the chimney, heating the chimney. Stoves are more dangerous than fireplaces - they cause the majority of modern thatch fires in English houses. Stoves get much hotter than fireplaces, and if there is a strong updraft, the fire can get very hot (if the stove has a steel/iron chimney, it is quite possible to have more than a metre of the chimney glowing red). Since the chimney passes through the thatch, this puts something potentially very hot next to the thatch.

Fireplaces are safer because a lot of relatively cool air from the room moves up and mixes in the chimney with the hotter air from the fire (which also means that a fireplace is not an efficient way to warm a room, since the warm air from the room gets sucked out). The main thatch risk from fireplaces is from spark arrestors installed in the chimneys. Spark arrestors are intended to stop embers from being blown out of the chimney. If the spark arrestor is not cleaned, it can greatly reduce the airflow, which reduces the amount of cooler air from the room entering the chimney. This increases the temperature in the chimney, and the outside of the chimney can (and sometimes does) heat the adjacent thatch to its ignition temperature (about 200C).

This is contrary to many peoples expectations - it is common to think that stoves are safer than fireplaces, in turn safer than hearths. However, rather than being safer, they are progressively more dangerous. Sometimes, the old ways are actually best!