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DIY has an unfortunate relationship with Safety: in hospital A&E departments across the country Easter Sunday - traditionally the most popular time of the year for DIY activities - is known as Bloody Sunday!

Of course nobody intends to have an accident and nobody thinks it can happen to them! When an accident does occur we can sometimes see with hindsight how we could have avoided it: preventing this sort of accident is a matter of cultivating better foresight - taking the time and giving the mental energy to thinking through the job (as not epitomised by Hoffnung's story about a builder and a barrel of bricks!).

However there are many dangers inherent in things in everyday life which are not at all obvious to those without specialist knowledge. For example how many people know that

  • dismantling a battery-operated disposable camera could kill them?
  • mixing toilet cleaners from two different bottles could do so?
  • a circular saw kicks backwards?
  • patio gas can cause a major explosion outdoors?

DIY (and Life in general) doesn't come with any foolproof safety guarantees, but we can stack the odds in our favour by:

  • understanding the science and technology around us
  • learning from the mistakes of others
  • being cautious, and knowing our limitations: sometimes it is more appropriate to get in a professional who has the skills and possibly equipment to do a job safety than to take risks by working outside our own competence. If you are accident-prone then maybe many DIY activities just aren't for you?!

General safety information


Most people know that mains electricity is more dangerous than batteries, and that voltages on overhead power cables are more lethal than household mains. Fewer know that some battery-operated equipment can contain voltages more dangerous than mains, and that some mains-operated appliances can contain voltages as hight as on overhead power lines.

There are also risks of fire and explosion if the contacts of high-power batteries (even as small as AA cells) are short-circuited.


By Law you must be competent to carry out work on gas pipework and appliances. Ed Sirett's Gas Fitting FAQ is a good guide to those considering doing their own. It is also a useful guide to what to look for and expect from a professional if you decide not to DIY, and explains the various warning notices which can be applied to dangerous appliances and installations.

Other building/DIY work

Even where you are not working directly on gas pipework or appliances there are gas-related safety considerations to:

  • running electricity cables or electrical fittings near gas pipes
  • removing walls supporting gas pipes, meters or appliances
  • changing the ventilation into a room or compartment containing a gas appliance, including
    • building an extension onto an outside wall which has a vent for a gas appliance
  • building near a gas flue, including
    • building an extension on an outside wall, enclosing the flue of a gas appliance (dangerous and illegal!)
  • creating a window or vent opening near a flue


Liquid Petroleum Gas - usually bottled, e.g. camping and patio gas - is heavier than air. Leaks may not be detected by smell since the source of gas is likely to be below nose height, and can accumulate in hollows and drains. Be aware of this when using gas barbecues, patio heaters etc.

Heat and Fire

Plumbing, metalworking and paint-stripping often involve the use of blowlamps. Naturally these involve the risk of setting fire to nearby combustible materials. Vacuuming away loose combustible material from the work area and possibly damping nearby materials with water lessen risks. There are particular risks to soldering pipes close to holes through timber since hot gases from the flame can pass into the hole and ignite the rough end-grain of the wood inside, unseen from the outside. If the air flow is through the hole to the far side smoke may not be seen from the smouldering or burning timber.

Using grinders on many metals also produces streams of hot sparks which can ignite some materials. Since the sparks can fly some distance care needs to be taken not to allow them to fly through gaps e.g. between floorboards where there may be combustible material underneath, out of sight and reach, which can be ignited.

Burning off paint can produce unpleasant and possibly toxic fumes, especially if the paint is old and contains lead.


Dry timber such as old floorboards, joists, laths etc can burn extremely fast and fiercely. If burning such material, especially if closer than 10 metres (30 feet) or so from buildings, trees etc., it is safest to start with a small amount and add more as it is consumed rather than making a pile of it all and setting fire to it. The radiant heat from a large fierce fire can melt plastic drain pipes and set fire to nearby brushwood. Check the surrounding ground: dry grass and twigs etc on the ground may spread the fire. A hosepipe or a sheet (of non-man-made-fibre material) soaked in water can be used to douse grass fires.

Plastics, rubber and other man-made materials emit unpleasant and possibly toxic, even carcinogenous (cancer-causing) smoke and fumes.

Using petrol to start or revive a flagging bonfire is - it is hoped - acknowledged to be hazardous, as petrol rapidly flashes to a burning vapour. However spirits such as methylated spirit are even more dangerous: they flash to burning vapour very rapidly, the flame can spread up an arc of spirit being poured or even thrown towards a fire, the flame is almost invisible and burns with great heat.

Chemical & Biological Hazards

Toilet cleaners

Common toilet cleaning chemicals are based either on bleach or on mild acids: if the two types mix they will generate chlorine gas which can kill in only few breaths! If you smell a strong swimming-pool smell get out into fresh air immediately!

Drain Cleaners

Drain cleaning chemicals are usually strongs acids or alkalis which are extremely dangerous.

Strong alkalis

Commonly known as:

  • Sodium Hydroxide
  • Caustic Soda

and found in:

  • Some drain cleaners
  • Oven cleaners

Skin contact can burn, but irritation occurs before damage, and as long as its rinsed off, no visible damage can be expected.

Contact between strong alkali and the eye is particularly dangerous: whilst acid causes pain immediately, an alkali can attack the eye without causing immediate discomfort. By the time discomfort occurs the alkali has entered the eye and serious damage can not be prevented. People have lost their sight this way.

Caustic boils and spits when added to hot water.

Safety eyewear is recommended when handling caustic soda, and water should be available for rinsing.


Lime is a weaker alkali which may irritate some skins, and is the component in cement that causes skin irritation. Note that some mortar mixes also contain other alkaline components such as fly ash.

When the job is over, applying vinegar to hands after washing seems to make skin comfortable again much more quickly.


Sewage works & pipes contain high levels of bacteria, some of which can be very dangerous to humans if ingested.

  • Observing good hygiene is especially important around sewage
  • When clearing a drain using a pressure washer, wear protection to prevent splashing to eyes, nose or mouth.

Falling Debris

Hard hats should be worn when there is a risk of falling debris.

Lifting When lifting heavy loads you should bend your knees and keep your back straight (don't bend over the load with your legs straight)

For factors involved in lifting to different heights and reaching out carrying loads see [1].

Steel toe-capped footwear is good when working with heavy loads: apart from reducing danger if the load is inadvertently dropped on a foot it can be useful to use the steel toe-cap as a support when manoevering the load (provided there is no sharp edge which can stray over the cap onto the unprotected foot. Grip-enhancing gloves can also make lifting easier and reduce the risk of dropping.