Conservatories and Building Codes: When You Need a Permit and What Not to Forget

It is often claimed that a sunroom up to 25 or 40 m² does not require a permit. Unfortunately, it’s not that simple. The key factor is whether the sunroom will be a standalone structure or an addition to the house.

The most important factor is whether it is an addition

If the sunroom expands the floor plan of a single-family home or recreational property and is functionally connected to it (typically, it will be accessed directly from the living room, kitchen, or another part of the house), it will generally be considered an addition. According to the Building Code , an addition is a modification to a completed structure in which the structure is expanded in terms of floor plan and, at the same time, functionally connected to the existing building. A typical sunroom attached to a single-family home is therefore generally not considered a separate small structure, even if it is only 15 or 20 m², for example. In such a case, it is important to recognize that this constitutes a modification to a structure intended for residential or family recreational use, and that it will be necessary to obtain a preliminary building permit from the building authority.

A different situation may arise if the glass-enclosed garden structure stands alone, is not directly connected to the house, and serves solely as supplementary space for residential or recreational use. Such a structure may, provided it meets the legal requirements, qualify as a minor structure not requiring a permit. The mere fact that the structure touches the house’s facade does not automatically mean it is an addition. The authority will assess the actual design, the connection to the house, and the manner of use.

Building Permit, Notification, or Neither?

Under the current Building Act, it is no longer common to choose between a “notification” and a “building permit” for new projects, as was the case under previous legislation.

In practice, there are two basic options:

• the project meets the criteria for a minor construction project and does not require a permit,
• or it is necessary to apply to the building authority for a permit for the project.

An application for a permit can be submitted via the Builder’s Portal or in hard copy to the relevant building authority. The scope of the required documentation depends on the specific construction project.

When Can a Freestanding Sunroom Be Built Without a Permit?

A freestanding sunroom or a glass-enclosed garden pavilion may qualify as a minor structure not requiring a permit if it meets the following conditions in particular:

• the built-up area does not exceed 40 m²,
• the height does not exceed 5 meters,
• the structure has no more than one above-ground story,
• it is located on the lot of a single-family home or a structure intended for family recreation,
• it is related to housing or family recreation,
• it is not used for business purposes,
• it is at least 2 meters from the property line,
• and, after its construction, at least 50% of the lot’s area remains capable of absorbing rainwater.

All conditions must be met simultaneously. Therefore, simply adhering to the 40 m² limit is not sufficient. It is also true that a structure built without a permit is not a structure “without rules.” It must comply with the zoning plan, general building requirements, fire safety regulations, and regulations for the protection of neighboring properties.

For example, if a freestanding structure does not meet the 2-meter setback requirement from the property line, it will no longer be possible to use this “small-scale construction without a permit” regime. The project will then fall under the “simple construction” regime, for which a permit is required.

How Far Must a Sunroom Be from a Neighboring Property?

The general rule stipulates a minimum distance of 2 meters between a structure and the property line. There are some legal exceptions to this rule, such as where placement on the property line is customary in a given location and consistent with the character of the surrounding development. In Prague, Brno, and Ostrava, specific municipal building codes may also apply. If the sunroom is to be built directly on the property line, there must be no openings in the wall facing the neighbor—specifically, no windows or doors. At the same time, measures must be taken to ensure that rainwater does not run off onto the neighboring property and that snow does not slide onto it.

In some cases, a location closer than 2 meters may be permitted as an exception. However, the building authority must assess whether this would jeopardize safety, health, the environment, or the rights of the owners of neighboring properties.The neighbor’s consent alone is not sufficient. It does not replace a permit or any potential exemption from the requirements for the location of the structure.

Do You Need Your Neighbors’ Consent?

For a minor structure that truly does not require a permit and meets all legal conditions, formal consent from neighbors does not need to be submitted to the building authority.For a permitted addition, the owners of neighboring properties or structures may be parties to the proceedings if their property rights may be directly affected by the project. For example, they may object to excessive shading, water runoff, invasion of privacy, or fire hazards. However, they do not have an automatic right to prohibit the construction without cause. The authority considers only objections related to a potential infringement of their rights. The consent of all parties to the proceedings is one of the conditions for issuing a permit under the expedited procedure. The builder must provide evidence of this consent, marked on the site plan in the documentation. If the conditions for expedited proceedings are not met, the building authority proceeds with the standard permit process.

Even though the law does not directly require a neighbor’s consent, we recommend discussing the planned construction in advance. Reaching an agreement early on is usually easier than a later dispute over shading, glare, construction noise, or water running off the roof. Furthermore, the Civil Code requires the owner to refrain from causing nuisances that intrude onto a neighboring property to an extent disproportionate to local conditions and substantially restrict its normal use. The direct introduction of nuisances—such as directing water onto a neighboring property—is prohibited regardless of their extent, unless based on a specific legal justification.

Land Development and the Zoning Plan

Even a technically small sunroom may not be permitted on every property. A zoning plan may stipulate, for example:

• a maximum percentage of the lot that may be built up,
• the minimum proportion of green space or unpaved areas,
• building line,
• the maximum height of structures,
• the shape and slope of the roof,
• the character of development in the given area.

The zoning plan is also binding for small structures that do not require a permit. Therefore, it is not possible to build a sunroom based solely on dimensional limits without addressing the zoning plan. When issuing a permit, the building authority assesses the project’s compliance with zoning documentation, the character of the area, construction requirements, and the protection of neighbors’ rights.

The often-cited requirement that at least 50% of the lot must remain capable of allowing water to infiltrate is not a universal rule for all sunrooms. It is one of the conditions specific to a particular category of minor structures that do not require a permit. For permitted additions, water infiltration, building coverage, and stormwater management are assessed based on the zoning plan and the specific technical design. Before ordering a sunroom, you can request preliminary information from the building authority. The request must specify the location, dimensions, distance from property lines, method of connection to the house, and intended use. The building authority will then inform you whether the project requires a permit and what documentation may be needed.

Project Documentation, Structural Engineering, and Fire Safety

When adding an extension to a single-family home, you must have project documentation prepared by a licensed designer. The documentation typically addresses the following in particular:

• the location of the sunroom on the property,
• floor plan, sections, and elevations,
• dimensions, height, and clearances,
• foundations, anchoring, and connection to the house,
• rainwater drainage,
• electricity, heating, and water connections,
• structural design,
• fire safety.

The documentation must allow for an assessment of mechanical strength, stability, fire safety, and the structure’s impact on the surrounding area. Therefore, when modifying a residential structure, it cannot be replaced by a simple diagram from the manufacturer alone. Structural engineering is important even for relatively small structures. A sunroom must safely withstand the weight of its own glass panels, wind, snow, and the effects of being anchored to the existing house. Large glass panels, frameless designs, mountainous areas, or connections to older structures require special attention.

Fire safety measures are assessed based on the specific design. The designer checks, for example, the distance from neighboring buildings, the materials used, the connection to the facade and roof, the potential for fire spread, and the maintenance of a safe escape route. An opinion from the fire department or a separate fire safety specialist is not automatically required for every sunroom; the need is determined based on the nature of the project.

Heating a sunroom does not in itself determine whether you need a permit. However, for a space that is heated year-round, there will be stricter requirements regarding thermal design, ventilation, safety, and, where applicable, energy efficiency.

Is a final inspection required upon completion?

A standalone minor structure that is not subject to a permit does not require a separate final inspection. For a sunroom constructed as a permitted addition to a single-family home, on the other hand, you must also expect the construction to be completed in accordance with the conditions of the issued permit and, as a rule, to receive a final inspection decision. The exact procedure will be specified in the permit and depends on the classification of the specific structure.

How to Insure a Sunroom

A permanently attached sunroom is usually part of the insured building. Therefore, it is not always necessary to take out a separate insurance policy. However, once construction is complete, it is important to notify the insurance company and adjust the insured value of the house. Some insurance policies explicitly classify permanently attached sunrooms as structural components of the building. At the same time, insurance companies recommend reporting the addition of a sunroom as a modification that increases the property’s value.

If the insured value does not correspond to the new value of the house after the addition, underinsurance may result, and the insurance company may reduce the insurance payout in the event of a major loss. A freestanding sunroom may be classified as an outbuilding under the insurance terms and conditions, and a separate coverage limit may apply to it. Furniture, electronics, and other movable items are generally covered under household insurance, not building insurance.

We strongly recommend verifying your glass coverage. Broken glass panels may not be automatically covered in all situations, and some insurance companies offer glass coverage as a separate rider or as part of a more comprehensive package. If the sunroom is to be used for business purposes, you must notify the insurance company of this fact. Standard home insurance may not cover business equipment or liability related to its operation.

Summary

For a sunroom, it is not only its size that matters, but primarily its design, location, and connection to the house. A sunroom that extends the floor plan of a single-family home and is functionally connected to it will generally be considered an addition requiring a permit from the building authority. A freestanding garden structure may be built without a permit only if it meets all the conditions set for minor structures, particularly the limits on built-up area, height, distance from the property line, and the preservation of a drainage area.

Even a structure built without a permit is not exempt from regulations. It must comply with the zoning plan, requirements for the location and safety of structures, fire regulations, and the protection of neighbors’ rights. A neighbor’s consent does not replace a permit or any potential exemption from building requirements.

Before ordering a sunroom, it is therefore advisable to verify the conditions of the specific lot, the method of connection to the house, and the required setbacks. For an addition, it is generally necessary to account for design documentation, a project permit, and subsequent final inspection. Consulting with a designer and the building authority early on can prevent costly design changes, disputes with neighbors, and problems with financing or insuring the structure.