Installing a transparent dome in your garden: permits, flooring, and comfort

Before thinking about curtains or where to place the table, a transparent dome raises three very practical questions: is a permit required, what surface should it be placed on, and how do you keep it cool in the summer? Here is what you need to check, in order, before ordering. To compare shapes and formats, also consult our guide Transparent dome or glass capsule: choosing your configuration.

Floor area determines the procedure

For urban planning purposes, a dome placed in a garden is an independent structure, just like a garden shed. What matters is its footprint, i.e., the surface area it covers when viewed from above. For a round dome, it is calculated based on the diameter: 3.14 × (diameter ÷ 2)².

These diameters are those of the Star Dome. Even the smallest one slightly exceeds 5 m², so at the very least, a prior declaration must be filed. For an elongated capsule, start with the dimensions of the chosen format (3.65 × 4.60 m, for example, for the reference Moon Series capsule) and ask us for the exact footprint if you are close to a threshold.

Prior declaration or building permit?

• Up to 5 m²: no formalities, except in protected areas (vicinity of a historic monument, remarkable heritage site, classified site, etc.).
• From 5 to 20 m²: prior declaration of works. The town hall generally has one month to process it, two months in a protected area.
• Beyond 20 m²: building permit.

In all cases, the local urban plan (PLU) of the municipality applies. It may impose a distance from property lines, cap the total surface area of structures, or set aesthetic rules. In the absence of local rules, the structure must generally be placed either on the property line or at least 3 meters away from it. If you live in a housing estate or a condominium, also reread the regulations: they may be stricter than the PLU.

The simplest approach is to visit the urban planning department with the diameter and height of the planned model: you will immediately know which procedure to initiate. Applications are most often submitted online. A removable structure left in place all year round follows the same rules as a classic building; only installations lasting less than three months are generally exempt.

Development tax

A closed and covered building larger than 5 m² is included in the development tax calculation, even if it is removable. Only the surface area where the ceiling height exceeds 1.80 m is counted. For 2026, the base value is €892 per square meter outside the Île-de-France region and €1,011 in Île-de-France. The rates voted by the municipality and the department—plus the region in Île-de-France—are then applied to this.

Example: for 6 m² of taxable area outside Île-de-France and a cumulative rate of 6.5%, the tax would be approximately 6 × 892 × 6.5%, or €350. Rates vary from one municipality to another, and some exempt garden sheds of 20 m² or less in whole or in part. The structure must be declared on impots.gouv.fr, under the "Manage my real estate" section, within 90 days following the completion of the work.

For professional use

Tourist accommodation (glamping, unusual overnight stays) is subject to other rules. A removable structure intended for temporary or seasonal leisure use may be considered light leisure accommodation: it can then only be installed freely in certain places, such as authorized campsites, residential leisure parks, or certain holiday villages. Elsewhere, ordinary building rules apply. If the dome hosts hotel or restaurant customers, fire safety and accessibility rules for public establishments also come into play. Have the project validated before ordering, and then compare in particular the formats of the transparent accommodation capsule.

Preparing the ground and anchoring

The dome must rest on a flat, stable, and level surface slightly larger than its footprint: a concrete slab, a wooden deck on pedestals, or a dedicated platform. Loose or sloping ground shifts with the seasons and puts stress on the structure. Also, plan for anchoring: a polycarbonate and aluminum dome is lightweight relative to its surface area and offers significant wind resistance. The method of attachment depends on the base (anchors in a slab, foundation screws, base plates); ask us for the anchor points of the chosen model before pouring a slab or building a deck.

Finally, check the path between the street and the site: the elements are bulky and must be able to be transported to the installation location.

Heat, condensation, and privacy

A transparent dome functions somewhat like a greenhouse. In full summer sun, the indoor temperature rises quickly: choose a semi-shaded location, sheltered by a tree or building during hot hours, rather than an open south-facing exposure. The data sheets for our reference models indicate windows and exhaust fans, in varying numbers depending on the format: open and ventilate as soon as the dome is occupied or if it remains closed for a long time.

In cold and damp weather, condensation forms on the inside of the panels. Airing it out daily, not drying laundry inside, and heating it moderately limits the phenomenon. For lighting or heating, have a compliant external power supply installed by an electrician.

As for privacy, the curtains indicated on the reference model data sheets allow you to screen part of the wall. Orient the entrance and the rest area away from neighboring views.

Maintaining polycarbonate

Polycarbonate scratches more easily than glass. Clean it with lukewarm soapy water using a soft sponge or microfiber, then rinse with clear water. Avoid abrasive products, solvents, and high-pressure cleaners used close up. In winter, remove snow with a soft broom rather than a shovel.

Lead times: take the opportunity to complete the paperwork

Expect 21 to 56 days between ordering and delivery. Submit your prior declaration or your permit application as soon as you have decided on the model: authorization and site preparation can progress during this time, and the dome will be mounted on a prepared base.

Frequently asked questions

Is a building permit required for a 3-meter diameter dome?

No. A 3m diameter dome covers about 7 m²: in general, a prior declaration is sufficient. A building permit is required for areas beyond 20 m², which corresponds to a diameter of about 5.05 m for a round dome.

Is a removable dome exempt from administrative procedures?

No, if it remains installed. Whether removable or not, a structure left in place follows building rules and is included in the development tax calculation beyond 5 m².

Who should I contact to find out if my land is in a protected area?

Your town hall's urban planning department. They will also inform you of the PLU rules that apply to your plot.

Discover the models in our collection of transparent domes and glass capsules.

Regulatory information updated in October 2026, provided for indicative purposes: only your town hall can confirm the rules applicable to your land. Sources: Service-Public, urban planning authorization for a garden shed, prior declaration of works, and development tax.