Start With Ceiling Height, Not Floor Space

Most hirers measure the floor first. That's understandable, but indoors the ceiling usually decides what you can have. A standard 12ft castle stands around 2.6 metres at its tallest point, and a child at the top of a bounce adds a little more. If the hall has beams, suspended lights, sprinkler heads, ceiling fans or a mezzanine, your usable height may be well under three metres.

As a rough guide, you want at least 30cm of clear air above the highest part of the inflatable, and more if you're expecting bigger children. Ask the provider for the exact inflated height of the castle you're considering, then measure the lowest obstruction rather than the average ceiling. A photo of a tape measure held against the offending beam is often enough for them to advise you properly.

If the ceiling is low, don't give up. Many providers carry low-height designs, typically 2.1 to 2.4 metres, and smaller 8ft or 10ft footprints. They won't take quite as many children, but they're far safer than squeezing a full-height castle under a beam.

Floors, Anchor Points and Weighted Down Systems

Outdoor castles are pegged into grass. Indoors, pegs are useless — and usually banned outright by the venue. Indoor castles have to be held down with sandbags, water weights or purpose-made anchor points at each corner, plus extra weight along the sides if the castle is long. Ask specifically how your provider anchors indoors, and be wary of anyone who says the weight of the children will keep it in place. It won't, particularly when eight of them bounce in the same rhythm.

Floor surfaces matter too:

• Sprung or wooden sports floors are ideal, but ask the provider to use non-marking mats under the weights so nothing scuffs the varnish.
• Polished vinyl or tiled floors are slippery, and the castle can creep. Heavy weights and a mat underneath are essential.
• Carpet tiles can ruck up and become a trip hazard. Tape down loose edges well clear of the castle entrance.
• Astroturf or matting is usually fine, but check it isn't hiding a slope or a drain cover.

Also ask whether the venue has underfloor heating with a weight limit, or a newly refinished floor with a no-shoes policy for the setup crew.

Insurance, Risk Assessments and the Venue's Paperwork

Most village halls, community centres, schools and sports clubs will want to see documents before you set foot inside. The usual requests are public liability insurance — commonly £5 million, occasionally £10 million — a written risk assessment, a PAT testing certificate for the blower, and a method statement covering setup and takedown. Ask your provider for these as a bundle before you pay a deposit, and send them to the venue at least a week ahead. Chasing paperwork on the morning of the party is miserable.

Check your own position too. If you're hiring the hall in your own name, the venue's terms may make you responsible for any damage. Some venues also insist you use a provider from their approved list, or charge a small fee for an outside supplier. Confirm this before booking, and get the name of the person who approved the arrangement in writing.

Age Limits and Numbers Are Often Tighter Indoors

Indoor castles frequently come with lower age limits than the outdoor equivalent. A 12ft castle that happily takes ten eight-year-olds in a garden may be restricted to six children aged five and under in a hall, simply because there is less room to fall and less air moving around them. Many providers apply a maximum age or height, and some will only allow mixed ages in timed sessions.

Mixing toddlers with older children is the biggest risk at any indoor party. A seven-year-old can bounce a five-year-old clean off their feet without meaning to. If you have a wide age range, split the time: younger children first, older ones afterwards. An adult beside the castle at all times, keeping numbers down and stopping somersaults, prevents most incidents.

Power, Access and the Practical Bits Nobody Mentions

A blower runs continuously, so you need a socket within reach of the lead and a cable route that won't trip anyone. Bring gaffer tape and a cable cover. Never let the blower be covered, and keep it well away from the bouncers and from any damp corner. If the venue has no suitable socket, ask whether a generator is permitted — many indoor venues say no, for noise, fumes and insurance reasons.

Access is the other common surprise. A deflated castle is a bulky roll on a trolley, so measure the narrowest doorway, any corridor turns, lift dimensions and whether there are steps. Confirm setup time — usually 30 to 45 minutes — and make sure your hall booking starts early enough to cover it. Finally, check the venue's rules on food, shoes and cleaning, and pass them on to your guests before the day.

A Quick Checklist Before You Pay a Deposit

• Inflated height of the castle, checked against the lowest ceiling obstruction.
• Floor type, and confirmation that weights rather than pegs will be used.
• Proof of public liability insurance, PAT certificate and risk assessment.
• Any age, height or capacity limit the provider applies indoors.
• Nearest power socket, cable route and permission to tape cables down.
• Delivery access, setup time and the venue's start and finish times.

Get those six answers in writing and an indoor bouncy castle booking becomes one of the easiest parts of the party to organise.