A tennis club that shuts down four courts every November is throwing away six months of court-hire revenue. The fix isn't a permanent building with a foundation and a two-year planning process — it's an air dome: a single pressurized membrane that spans the entire court with no interior columns, goes up in days, and comes down when you want the summer sky back. The thing that decides whether that dome earns its keep — or collapses under the first heavy snowfall — isn't the floor area. It's the blower and backup system, the membrane spec, and how the perimeter is anchored to the ground.

What an air dome actually is (and how it holds itself up)

An air-supported structure stays up on nothing but a slight pressure difference. Continuous-running blowers keep the interior at roughly 250–500 Pa (1–2 inches of water column) above outside air — enough to hold a tensioned membrane in a smooth arch, but so gentle you barely notice it when you walk in. There are no poles, trusses, or columns inside. The whole span is clear, which is exactly what a sports facility needs: a full tennis court, a five-a-side soccer pitch, or a swimming pool with unobstructed overhead room for lobs and high balls.

This is a fundamentally different animal from a small frame or inflatable-beam structure. A metal frame tent or rigid-frame structure carries its load through an aluminium or steel skeleton, and an inflatable-beam tent stands on pressurized air-filled ribs. Both work well up to a point, but the clear span you can achieve without internal supports is limited. An air-supported sports bubble has no such ceiling — the entire enclosed volume is the structural element, which is why domes routinely cover spans of 30–40 m (100–130 ft) and beyond.

Clear span and clear height: sizing to the sport

The two numbers every buyer should lead with are clear span (the width the membrane crosses) and clear height at the apex. Sport dictates both:

• Tennis: a single court needs about 18–20 m width; a two-court dome runs 35–37 m. Apex height should be 9–12 m (30–40 ft) so a high lob never touches the membrane.
• Soccer / futsal: plan for the pitch plus run-off. A five-a-side dome often sits around 25–30 m wide; full training pitches go much larger.
• Pool enclosure dome: a pool enclosure dome can run lower at the sides but still needs generous headroom over the water for diving boards and lane visibility, plus humidity-resistant internal fittings.

Because an air dome carries no columns, you don't lose playable area to structure — the footprint you enclose is the footprint you play on. That's a real advantage over framed alternatives when every square metre of court is billable.

Pressurization, airlocks and the backup that matters most

The blower plant is the heart of an inflatable sports dome. A primary electric blower maintains working pressure; oversized systems add a second blower for peak wind. The single most important line item is the backup: a standby generator that fires automatically on a power cut. Lose pressure with no backup and the membrane deflates onto the court within minutes — with a generator, the dome holds through an outage without anyone inside noticing.

Entry is handled by an airlock so the dome doesn't dump pressure every time someone walks through. Smaller facilities use a two-door vestibule airlock; busier sites use a revolving door that lets a steady stream of players in and out while the seal is never fully broken. Vehicle access for pool maintenance or court equipment is handled by a larger inflatable airlock bay.

Membrane, insulation and keeping running costs sane

The skin is typically a PVC or PVDF-coated polyester membrane — PVDF top-coating resists UV, dirt pickup and hydrolysis, which is what keeps a membrane serviceable for 15–20 years rather than yellowing and going brittle in five. For year-round use in a cold climate, specify a double-layer insulated membrane with an air gap between skins; it cuts heat loss dramatically and stops condensation raining down on the court. Translucent panels let daylight in so you're not burning lighting energy during the day.

Operating cost is where domes get a bad reputation they don't always deserve. The three levers are the membrane (single vs insulated double-layer), the HVAC sizing, and the lighting. Get the insulation right and heating load drops; specify LED sports lighting rated for the lux level your sport needs and the electricity bill stays manageable. Treat heating, ventilation and dehumidification (critical over a pool) as a designed system, not an afterthought bolted on later.

Snow load, wind load and doing the engineering properly

This is the part buyers skip at their peril. An air supported structure resists snow and wind by internal pressure — the system is designed to raise pressure automatically as external load increases, and in heavy snow the interior heat plus a melt-management routine keeps snow from accumulating on the membrane. But that only works if the dome is engineered to your local snow and wind loads and operated correctly. Ask the supplier for the design load basis and confirm it matches your site's code requirements. Don't oversell it to your board as a certified permanent building — it's an engineered temporary/semi-permanent structure, and it needs to be specified, anchored and operated as one.

Anchoring and the perimeter seal

Whatever holds the dome down has to resist the uplift that pressure and wind generate. Common approaches are a continuous concrete grade beam the membrane bolts to, ground anchors, or a ballast system. The perimeter seal between membrane and slab is what keeps pressure in and weather out — a leaky base seal means the blowers run harder and the bills climb. On a pool deck or existing court slab, the anchoring detail is usually the single biggest bit of site prep, so scope it early.

Seasonal or permanent — and the ROI case

One of the quiet advantages of air-supported design is reversibility. Many clubs deflate and store the membrane through summer, then re-erect it in autumn — a seasonal cover that lets the courts breathe in good weather and pays for itself over the winter months. Others leave the dome up year-round as a permanent indoor facility. Both are valid; the seasonal model appeals to clubs that want their open-air identity back in July.

The ROI math is straightforward. Every off-season week a court sits idle is lost hire income. A dome converts those dead months into billable indoor hours — winter league play, coaching programmes, corporate bookings — typically at a premium rate because covered courts are scarce. For most tennis and soccer operators the added revenue pays back the structure within a small number of seasons, and the dome keeps earning long after. If you're weighing a lighter-duty option for events rather than sport, our guides to portable blow-up event domes that work in any season and commercial inflatable igloo and dining domes for hospitality cover those smaller, different use cases — they're not substitutes for a full sports dome.

When you brief a supplier, come with your span, clear height, sport, climate loads and whether you want seasonal or permanent operation. From there the membrane spec, blower and backup plant, airlock type and anchoring detail all follow. It's the same disciplined approach we bring to every large-span project, whether that's a commercial event tent or structure or a lightweight inflatable tent for temporary cover — right structure, right engineering, right load rating for the job.