Generally, both types of fire are common so the best form of protection would be to choose at least one smoke alarm of each type. You can buy smoke alarms at DIY stores, hardware and electrical shops, and at some supermarkets. Always buy an alarm which conforms to the British Standard. Smoke alarms should meet BS 5446 Part 1, and carry the well-known Kitemark. The number of smoke alarms to fit in your home depends on your particular circumstances.
Fires can start anywhere, so the more that are fitted, the higher the level of protection.
You should choose the type most suited to the risk in each room. If your home has more than one floor, at least one alarm should be fitted on each level. In this case a combination of optical and ionisation alarms, preferably interconnected, will give the best protection. Do not fit an alarm in the kitchen or bathroom , as cooking fumes or steam may trigger the alarm. Similarly, do not fit an alarm in a garage where exhaust fumes are likely to set it off.