Measurement checklist before ordering a greenhouse, pergola or outdoor sauna

A reliable site survey considers more than length and width. This checklist covers the plot, foundation, heights, wall connections, doors, service routes, drainage and installation access.

Accurate measurements are the basis of a dependable order. For a greenhouse, pergola or outdoor sauna, two roughly measured side lengths are not enough. Heights, diagonals, gradients, foundations, roof overhangs, circulation space, service routes and access to the installation site also matter.

This guide helps homeowners, planners and installation teams record a site systematically. It does not replace product-specific drawings or checks of local requirements. Always follow the documents for the selected model and the rules that apply at the installation site.

Measure the site before choosing the final model

Do not start by asking which nominal product size will just fit in the garden. First record the genuinely usable area. This shows which design, orientation and size make technical sense.

Mark property boundaries, buildings, walls, paths, trees, beds, inspection chambers and services. Check the applicable municipal planning scheme and whether building-plan approval or other consent is required. The article Building-plan approval for a greenhouse or pergola gives an overview; for a South African project, confirm the proposal with the municipality’s building-control office before ordering or installation.

Consider more than the structure itself. Doors, roof edges, drainage, maintenance and installation all need room. A model may fit geometrically but still be impractical if a door cannot open fully or a side wall cannot later be reached.

Four measurement rules that always apply

1. Measure twice: Record key dimensions at least twice. Where possible, long distances should be checked by two people.
2. Do not assume square corners: Patios, walls and existing foundations are often not perfectly square. Measure both diagonals.
3. Record heights separately: A flat drawing does not show a gradient. Record level differences at every corner and notable intermediate point.
4. Separate actual and planned dimensions: Write measured values, intended positions and product dimensions in separate columns. This prevents assumptions being treated as existing measurements.

Do not round prematurely to a convenient measurement. A rounded figure may help with selection, but actual product and connection dimensions must be checked before ordering and foundation work.

Prepare tools and information

• sturdy tape measure and suitable distance meter;
• spirit level, straightedge or suitable levelling device;
• string, pegs, chalk or removable marking tape;
• square, plumb line and, where needed, a ladder for safely reachable height measurements;
• notepad, site-plan sketch and camera for documentation;
• product drawing, foundation plan and assembly instructions for the intended model;
• information about underground services, drainage and existing foundations.

Find further product areas and planning guidance under Useful information, in Greenhouses and conservatories and in the Sauna section. Before foundation work, use Contact to clarify which documents govern the selected product for project-specific questions.

Create a complete site plan

Draw the installation area in plan view. The sketch need not be to scale, but it should have a clear reading direction. Add north, every boundary and at least one fixed reference point, such as a building corner.

Record the planned structure’s distances from at least two permanent reference lines. Add side lengths, diagonals, door-swing zones and maintenance routes. A wall elevation is also needed where the structure connects to a building.

Plan content	Record
Property and existing features	Boundaries, buildings, walls, paths, vegetation, chambers
Planned structure	External outline, orientation, doors, roof edges
Heights	Corner levels, gradients, steps, thresholds and wall connections
Services	Service routes, outlets, drainage direction
Logistics	Access, transport route, pinch points and assembly area

Measurements needed for every structure

Whatever the product type, the following values should be available:

• total usable length and width;
• both diagonals of the marked area;
• heights at every corner;
• distances to boundaries, walls and obstacles;
• narrowest clear width of the transport route;
• available height beneath branches, roof edges or services;
• width and opening direction of nearby doors and gates;
• positions of chambers, pipes and cables;
• space for installation, ladder placement and later maintenance.

For irregular areas, measure additional intermediate points. An apparently straight wall may bow, a patio may be trapezoidal and an edging stone may project into the intended post position.

Choose the product type before fixing the footprint

The design changes the demands on the site and foundation. A wall-mounted pergola needs a suitable connection wall; a freestanding structure needs defined support points all around. The comparison Wall-mounted or freestanding pergola helps with this initial decision.

The roof function also affects drainage, clear height and adjoining façades. See Bioclimatic or classic pergola and the background article What is a bioclimatic pergola?.

For saunas, rectangular cabins and barrel forms differ in spatial impact, access and usable surroundings. Compare, for example, Elma S, Elma L and the HC150 barrel sauna using their individual product documents, not garden photographs alone.

Measurement checklist for a greenhouse

• Document the sun path, shading and orientation of the long axis.
• Check the footprint, including the foundation or plinth area.
• Allow for the door side, opening path and step-free access.
• Check eaves and ridge areas for branches, services and roof overhangs.
• Leave space for window openers, ventilation elements and cleaning.
• Plan water access, rainwater drainage and routes for planting soil.
• For wall models, record window sills, downpipes, plinths and façade projections.

Historically inspired or geometrically divided structures may have extra axes and connection details. The article about Victorian greenhouses shows design relationships, but only the drawings for the chosen model are binding for measurements.

Measurement checklist for a pergola

• Measure patio width and depth at several points.
• Check each intended post position on load-bearing ground.
• Consider roof overhangs and any integrated drainage routes.
• Check clear height against doors, windows and roller shutters.
• Allow for the opening and movement space of louvres, shading or glazing.
• Record rainwater run-off from the existing patio and potential splash zones.
• Document wind-exposed sides and surroundings for site-specific planning.

For selecting a size, the Pergola size guide is helpful. Material choice and use concepts are explained in Aluminium or timber . Where side walls are planned, also measure sliding routes, stops and ground levels; see Pergola with glass walls.

Measurement checklist for an outdoor sauna

• Record the full installation zone, including entry and maintenance access.
• Mark the door position, opening direction and safe area in front.
• Check foundation points or continuous bearing surfaces against product documents.
• Document service routes for the planned technical equipment.
• Clarify drainage and cleaning options for the location.
• Check distances to vegetation, buildings and other installations.
• Assess the transport route for width, height, turns and load-bearing capacity.

Different models must not be planned using one standard footprint. Check documents for HC 180, HC 225, HCF 225, HCF 300 and LC 225 individually. The article Choosing a timber sauna and barrel sauna provides a general introduction.

Measure the foundation and patio

An existing surface is not automatically a suitable foundation. Record its construction, edge distances, joints, gradient, visible damage and available information about the substructure. Whether its load capacity, frost resistance, anchoring and drainage suit the specific structure must be professionally assessed.

For pergolas, the Pergola foundation guide summarises key planning questions. Transfer drilling or bearing points only from the approved product drawing. Never estimate distances from a product photograph.

How to check the marked-out rectangle

1. Mark outer edges with string.
2. Measure both long sides and both short sides separately.
3. Measure both diagonals.
4. If diagonals differ, correct the corners and measure again.
5. Level the heights at every corner.
6. Then secure positions against a fixed reference point.

Equal diagonals are an important check, but do not replace checking every side. For complex footprints, check each rectangular section separately.

Additional checks for wall-mounted structures

Create a dimensioned wall elevation. Record façade width, usable connection height, windows, doors, roller-shutter boxes, lights, downpipes, vents, outdoor taps, projections and plinth offsets. Check the wall not only at ground level but also at the future connection-profile height.

The wall and fixing suitability must be assessed for the specific property. Insulation, cladding or unclear wall construction must not be replaced with assumptions. Involve a qualified professional early where necessary.

Plan doors, routes and interior space

Mark every door in its open position. Check for conflicts with garden paths, furniture, raised beds or existing building doors. A comfortable main route should not be narrowed by a post, bench or technical installation.

Plan the interior before fixing the final orientation. In a greenhouse, potting benches and wheelbarrow routes matter. Under a pergola, tables, chairs, a braai or outdoor kitchen determine circulation space. For a sauna, consider entry, changing arrangements and a safe route to the building. Find patio ideas under Pergola ideas for patios and gardens.

Services, drainage and site conditions

Add existing and planned services to the site plan, including electricity, water, drainage and other installations. Plan connections only against the selected product’s requirements and locally applicable technical rules. Before electrical work begins, use a registered local electrical contractor to confirm equipment compatibility and protection, and to carry out the required inspection and testing for any applicable Certificate of Compliance documentation.

Observe the site in rain where possible. Record flow directions, puddles and water running off the building. Also check shading, leaf fall, wind exposure and winter conditions. See Pergola in winter for seasonal-use guidance. Site-specific loads and local requirements must be checked separately.

Measure the delivery and installation route

The route from the unloading point to the installation area forms part of the survey. Record the narrowest clear width and height, tight turns, steps, gradients, soft ground, gates and low branches. Check whether long components can pass around corners and whether enough space is available at the destination for sorting and assembly.

Also document restrictions on shared areas or narrow driveways. A sufficiently wide garden gate does not automatically mean every component can pass the full route.

Practical measurement sequence: Anna Koku Skola

The Anna Koku Skola image sequence should be viewed as one connected installation sequence. It suggests a clear workflow for surveying: first record the complete site, then set out the structure, check foundation and connection areas, and finally keep the assembly surroundings clear.

1. Record existing conditions: Note fixed reference points and obstacles on a sketch.
2. Set out the outline: Make the intended footprint visible with string.
3. Check geometry: Measure sides, diagonals and heights independently.
4. Check connections: Compare wall, ground and drainage areas with the documents.
5. Simulate use: Open doors, walk routes and mark interior zones.
6. Confirm logistics: Complete a final check of transport route and assembly area.

The individual images must not be interpreted as unrelated projects. They show the same installation context from different phases or viewpoints.

Pre-order measurement worksheet

Check point	Actual value or result	Status
Available length and width	Enter	Open/checked
Diagonal A and B	Enter	Open/checked
Heights at every corner	Enter	Open/checked
Distances to boundaries and existing features	Enter	Open/checked
Door and circulation routes	Describe	Open/checked
Foundation condition	Describe	Open/checked
Services and drainage	Mark	Open/checked
Transport route	Enter narrowest point	Open/checked
Product drawing checked	Note document version	Open/checked

Final check before releasing the order

• The exact model and its configuration are clearly defined.
• All dimensions come from the actual site.
• Footprint, overhangs and opening zones are distinguished.
• Diagonals and heights have been checked.
• Foundation and anchoring were not assessed from the visible surface alone.
• Wall connections and façade obstacles are fully documented.
• Accessories and planned additions are included in the space requirement.
• The transport and installation route is feasible.
• Local requirements have been clarified with the relevant authorities.
• Outstanding technical questions are answered before approval.

Company information is available under About us . For additional garden structures relevant to an overall plan, see Garden shed.

Check drawings and instructions again after ordering

Once order-specific documents arrive, carry out a second comparison. Check the model designation, orientation, external dimensions, foundation points, door positions and connections. Do not start foundation or service work from an old sketch, similar model or unmeasured screen image.

Give the foundation contractor and installation team the same current document version. Site changes must be added to the documents and checked again.

Measure for later maintenance, not only installation

A structure can be installable yet difficult to maintain. Keep areas accessible for cleaning, hardware care, checking drainage routes and replacing reachable components. Do not plant vigorous shrubs directly beside parts requiring regular inspection.

Also consider ladder placement, window cleaning and access to roof edges. Required clear space depends on the model, surroundings and maintenance task, so no general clearance should be adopted as a binding dimension.

Frequently asked questions

Should I order based on the footprint listed on a product page?

No, not without checking. Establish what the dimension refers to and whether roof overhangs, fixing areas or circulation space must also be allowed for. The documents for the exact selected model are decisive.

How do I know whether a marked-out rectangle is square?

Measure both diagonals. In a geometrically correct rectangle, they are equal in length. Opposite sides must also match, and corners should be checked on the intended level plane.

Can an existing concrete patio be used?

Possibly, but not on the basis of its surface alone. Construction, condition, gradient, edge distances, load capacity, frost resistance and anchoring options must suit the project. A professional assessment may be needed.

How much space should remain around the structure?

There is no universal dimension. Clear space depends on doors, roof overhangs, cleaning, installation, drainage, site conditions and local requirements. Define it using the specific model.

What should be measured for a lean-to greenhouse or wall-mounted pergola?

In addition to the footprint, you need a dimensioned wall elevation. It must include connection height, wall width, plinth, openings, services, downpipes, projections and wall construction.

Must I measure myself if Bloomcabin provides product drawings?

Yes. The drawing describes the product, not the actual conditions on your property. Only comparing product data with a site survey shows whether installation, use and assembly are possible.

When should the installer be involved?

Preferably before foundation and service work, especially with gradients, tight transport routes, wall mounting or uncertain existing conditions. This clarifies assumptions before difficult-to-correct work begins.

What should I do with a sloping garden?

Measure the height of every corner and relevant intermediate point. Do not plan only from the average gradient. Suitable foundations and ground adjustment must be determined for the site and product.

Must planned accessories be included in the survey?

Yes. Side walls, shading, gutters, technical components, steps, furniture and later additions can affect space, connections or foundation areas.

What is the most common surveying error?

Often only a nominal length and width are measured. Diagonals, height differences, door movement, overhangs and assembly routes are overlooked. A complete site plan prevents this limited approach.