We give you the opportunity to choose a beautiful patio door that matches your folding doors. Our patio doors are made according to the same principles as our folding doors, ensuring top-quality craftsmanship.
TMT Composite® (Thermally Modified Timber) is the term for Lacuna’s advanced heat treatment, which we apply to beech for our folding doors. The process involves no chemicals whatsoever—only heat. After the TMT® treatment, the wood achieves durability class 1, similar to teak, and a moisture content of approximately 5.5%. This makes the modified wood highly suitable for folding doors, where dimensional stability is crucial for a tight, well-functioning product that does not require adjustment in changing weather conditions (humidity/dryness).
TMT Composite® also provides significantly better insulation, as the wood cannot absorb moisture like untreated timber. The result is a folding door built to last for many years.
FSC-certified sapele mahogany and European oak are also available, oiled in a wide range of color tones without TMT Composite® treatment.
In line with our principles, we use only environmentally friendly, proven durable, and water-based paint products.
You can choose from a wide range of RAL and NCS colors.
For elements that are not particularly exposed, no repainting is required for the first 25–35 years.
For oiled mahogany or oak, we use cold-pressed linseed oil, which protects the wood better than water- or turpentine-based oils.
Oiled products should be treated with oil at least 3 times during the first year to saturate the wood and reduce the risk of shrinkage cracks. After that, maintenance is recommended twice a year, depending on how exposed the element is to the weather.
We also offer a transparent UV surface treatment for sapele mahogany and oak. It functions like a painted finish, meaning the elements do not require surface treatment for the first many years.
In modern buildings, darker frames and sashes are often used on the exterior. Inside, a lighter color—often white—is typically chosen. We can paint our folding doors in two or three color combinations, including options such as oiled mahogany combined with a white finish.
We can also apply various textured finishes as well as a clear coating, similar to a lacquer.
Lacuna manufactures several different types of glazing bars and mullions. Most of our customers choose 25 mm palace glazing bars with what we also refer to as a farmhouse profile on the interior side. This design is also available in widths of 20, 36, and 42 mm. For all widths, an interior softline profile is also available, offering a simple and modern look that matches the style of new-build homes.
All of our glazing bars are mortised into the outer frame (not bonded onto the glass) and therefore cannot fall off.
As an alternative to traditional glazing bars, we also offer Helima glazing bars. These are integrated between the panes of glass, meaning there are no bars on either the exterior or interior of the door. Helima is a cost-effective option and offers a significant advantage when it comes to cleaning. The bars are available in several widths: 18, 26, and 45 mm.
See glazing bar profiles, dimensions, and sizes below.
If wider glazing bars or mullions are desired, we also offer horizontal transoms in 55 mm, 75 mm, and 110 mm. These are continuous and therefore divide the glass within the door. The transoms are, of course, fully integrated into the frame design.
Lacuna also offers panels, including flat and framed panel options. The panels are not solid but are laminated with highly insulating material to ensure optimal insulation. Panels are supplied in the same color as the rest of the door.
As an alternative to traditional glazing bars, we also offer Helima glazing bars. These are integrated between the panes of glass, meaning there are no bars on either the exterior or interior of the door. Helima is a cost-effective option and offers a significant advantage when it comes to cleaning. The bars are available in several widths: 18, 26, and 45 mm.

Lacuna doesn’t settle for standard testing. Our folding doors are tested at the Danish Technological Institute, in our own extreme tests, and by independent third parties abroad for moisture absorption, dimensional stability, and insulation. This ensures full documentation and helps make Lacuna folding doors the world’s most airtight.

At Lacuna, care for the environment is an integral part of everything we do. Our raw materials are carefully selected, and our folding doors are developed with a focus on high insulation, reduced heat consumption, and a lower CO₂ footprint. With a Uw value of 1.0–1.2, they can help reduce energy consumption by up to 30%.

Lacuna’s products combine energy efficiency, durability, and a refined finish with a revolutionary patented top-frame system. Here, the running track is integrated directly into the top frame, allowing for more precise installation, fewer materials, and an even better-looking result.
We know that visiting Denmark isn’t possible for everyone, so we’ve created a short video to give you a quick visual tour of our showroom and show Lacuna’s folding doors in action. It’s an easy way to experience the product and feel more confident in making the right decision.
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