For architectural projects in Belgium, custom-made sills made of Belgian blue stone are available within 3 to 4 weeks, complete with a spec sheet, CE certification, and delivery directly to the construction site. At Renier, we quarry the stone from our own Vinalmont quarry and process it in our own workshop in Aarschot—a tradition spanning four generations. This gives you, as an architect, a single point of contact for material selection, specifications, production, and logistics. In this article, you’ll learn how our custom-made process works.
Standard sizes are sufficient for many projects. However, there are three situations in which custom solutions are essential:
Renovation of Historic Facades where existing window openings are non-standard. A Belgian home built in 1920 typically has window openings that deviate from the modern 100- or 110-cm standard. Custom work in Belgian blue stone respects the original and contributes to the overall look of the building.
New construction with non-standard window frames or asymmetrical windows. Architects who opt for wide sliding windows, corner windows, or glass facades require sills that fit to the millimeter. Standard sizes limit your design.
Balcony Finishing and Special Transitions. Whether between a patio and an indoor space, or as a transition between surfaces of different materials, a threshold serves as both a functional and aesthetic element. Here, custom work makes the difference between “good enough” and “a perfect fit.”.
| Type | Application | Standard sizes available | Custom Solutions | Finishes |
|---|---|---|---|---|
| Flat door threshold | Passages, sliding windows | 100×20, 110×20 cm, thickness 5+1 | Yes, upon request | Sanded, polished, antiqued, blue-tinted |
| Door sill with raised edge | Exterior door, moisture-sensitive | 100×20×6 cm, 110×20×6 cm | Yes | Sanded, polished, distressed |
| Flat window sill | Standard windows | Various standard sizes | Yes | Sanded, polished |
| Window sill with upstand | Moisture-sensitive windows | Miscellaneous | Yes | ditto |
| Window sill with drainage | Best Water Drainage | Miscellaneous | Yes | ditto |
| Garage threshold | Wide passageways | Various widths | Yes | Sanded, polished |
| Tussendorpel Interior | Between Departures | Miscellaneous | Yes | Sanded, honed |
Each type is available in any standard size and finish. Our standard drip groove is 0.6 × 0.6 cm, located 2 cm from the front edge and ending 2 cm before the machined ends. Other drip groove configurations are available upon request.
Five steps, transparent and with clear turnaround times.
Step 1: Send the specifications or construction drawings. A PDF, DWG, or even a sketch sent by email is sufficient. Please include: length, width, thickness, angle of inclination, finish, drip groove position, and quantity. Our technical department will review your submission.
Step 2: Technical advice and a quote within a few business days. We'll check whether your specifications are feasible, suggest improvements where necessary (e.g., a thicker version for heavy-duty use), and provide you with a quote that includes the delivery time.
Step 3: Production at our own workshop in Aarschot. Saw cuts, bevels, drainage grooves, and finishes are all done in-house. We do not use subcontractors for the primary work.
Step 4: Quality Control and Spec Sheet. Every custom-made threshold is inspected for dimensions, finish, and visual quality. The spec sheet lists the material (Belgian blue stone, Petit Granit, sourced from Vinalmont), specifications (density, compressive strength, frost resistance), CE conformity, and date of manufacture.
Step 5: Delivery to the construction site or pickup in Aarschot. Shipping via Renier truck or freight forwarder, with protective packaging materials. Pickup is available in Aarschot by appointment.
A Renier spec sheet contains all the information you, as an architect, need for the bid documents and construction site supervision:
Material: Belgian blue stone, certified Petit Granit
Quarry of origin: Vinalmont, Province of Liège
Technical properties: density, compressive strength, and water absorption based on certified measurements
Frost resistance according to EN 12371
CE Conformity: EN 1469 for facade elements, EN 12058 for interior flooring
Finish: sanded, polished, distressed, or as specified
Dimensions: as ordered, with tolerances in accordance with the EN standard
Drip groove: position and dimensions as ordered
Date of manufacture
Batch Identification for Traceability
The spec sheet is provided digitally (PDF) and is signed by our technical department.
Our blue stone bears the CE mark for the applications in which it is used. The relevant standards:
EN 1469: natural stone exterior cladding, such as exterior baseboards and facade elements
EN 1341: paving elements for outdoor use, such as stairs and exterior thresholds
EN 12058: natural stone flooring and stair treads for indoor use
EN 12371: Determining the Frost Resistance of Natural Stone
Petit Granit, the official name for Belgian blue stone, has been recognized by the European Commission as a designation of origin for the Belgian product. Our Vinalmont quarry has been supplying this certifiable material for generations.
Standard sizes Items from our product range are usually available immediately from stock. Please allow 1 to 2 weeks for delivery, including shipping to the job site.
Custom Solutions It typically takes 3 to 4 weeks from quote confirmation to delivery. For highly complex orders or large volumes, a longer lead time may be required; we will explicitly state this in the quote.
Transportation We provide service throughout Belgium. We deliver directly to the job site using our own trucks or a partner freight forwarder, with protective packaging to prevent damage during transport. Pickup in Aarschot is available by appointment. Shipping costs and terms can be found on our page pickup and shipping costs.
What is the lead time for custom-made thresholds? For custom orders, please allow 3 to 4 weeks between confirmation of the quote and delivery. Standard sizes are often available immediately from stock, with a 1-2 week lead time to the construction site.
What kind of spec sheets do you provide for architectural projects? Our spec sheet lists the material, origin (Vinalmont), technical properties, CE conformity in accordance with EN 1469 and EN 12058, finish, dimensions, drip groove specifications, date of manufacture, and batch identification. PDF, signed by our technical department.
Can you work from a blueprint? Yes. Please email us a PDF, DWG, or a detailed sketch. We’ll review the technical specifications and send you a quote with a delivery date within a few business days.
How is the threshold protected during transport? Our custom-made pieces are packed on pallets with covering material and protective corner guards. We are responsible for any damage that occurs during transport until delivery to the construction site.
What finishes are available for Belgian blue stone? Sanded, polished, aged, blue-glazed, bush-hammered. Other finishes are also available upon request. For advice on which finish is right for your project, please contact our technical department.
What is the difference between your custom thresholds and standard thresholds? Custom-made products are made entirely to specification: length, width, thickness, drip groove position, finish, and angle—all according to your preferences. Standard sills are pre-manufactured in fixed sizes and available for immediate delivery. For unique architectural projects where the design does not fit standard sizes, custom-made thresholds are the right choice.
Can you work with the contractor on the installation? Yes. We facilitate coordination between the architect and the contractor regarding installation details and can Levelit XL Installation System recommended for faster installation of larger areas. Our technical team advises both parties upon request.
Send us your specifications or blueprints, and you'll receive a quote with a delivery date within a few business days.
Our Vinalmont Quarry, where Belgian blue stone comes from
Door thresholds for structural work, with technical explanations for each type
Structural Work on Window Sills, including drainage variants
Custom Garage Sills, for wide passageways
Levelit XL Installation System, for expedited installation
Which threshold for your door or window?, general guide