Frequently asked questions

  • Recanor - Impact sound insulation
  • Combifor floor system
  • DTS-G Impact sound insulation
  • Dovetailed sheeting
How to get watertight edge seals?
The edge connection is sealed with commercially available sealing strips impermeable to water in the corner area. The sealing strips are glued horizontally and vertically to the floor and the wall.
How long does the cement have to dry?
The floor can be entered cautiously after 3 days. The floor has about 80% of its final strength after one week.
Rule of thumb: One week per cm cement layer.
Can cement screed be used?
Yes, Duofor dovetailed sheets can be used both with concrete and cement screed (quality class at least C20).
How to cut Duofor® dovetailed sheets?
A commercial angle grinder can be used for cutting dovetailed sheets.
How to support Duofor® dovetailed sheets in cement works?
Axis of 1100 mm or larger need a support beam under the sheets for curing.
For safety reasons: a paving screed must be laid with laying the sheets.
How do Duofor® dovetailed sheets overlap in the longitudinal and transverse directions?
On beams: Longitudinal overlap between 50 and 100 mm directly on the beam. 
On wooden flooring: Longitudinal overlap can be made to choose between 50 and 100 mm.  Profiles are placed on top of each other only in the outside width, colour marking on colour marking.
How to connect Duofor® dovetailed sheets?
In length: The first and third plates are laid down with the sticker, the second and fourth sheets are laid with the sticker facing up.  
In width: Colour coding on colour coding.
How to install underfloor heating?
The underfloor heating pipes must be installed transversely to the profile direction. The heating pipes and hoses are fixed easily with the DuoKlips (Ø 16 to 22 mm)
How to glue tiles to the screed?
Tiles must not be laid directly on the screed of the dovetailed sheets.
Tiles must be laid on a standard mortar or tile adhesive layer.
Is there an additional need of reinforcement and grounding?
No, Duofor® dovetailed sheets serve as reinforcement.
No, you can ground directly on the sheets.
How many kilograms of cement are needed per square meter?
Cement screed on the dovetailed sheets:  
Quality C20, consumption 25 kg/m²/cm

Concrete on the dovetailed sheets:             
Quality C20/25, consumption 25 kg/m²/cm  

For filling the sheets: extra 20 kg/m² are required
How much cement needs to be applied?
Floors with planking:                      20 mm
Standard floors:                              34 mm
Soundproofed floors:                      34 mm
Floors with underfloor heating:       40 mm

At dimension with span size greater than 1500 mm at least 59 mm or more applied to dovetailed sheets.
Are Duofor® dovetailed sheets bolted or nailed?
The dovetailed sheets should not be screwed but only nailed. The sheets can be nailed with three nails on the wooden beam in a non-floating installation. 
The sheets can be fixed with only two nails per sheet width in the upper profile when a floor heating is installed. The sheets must not be attached to the structure for a floating installation.
What is the maximum axis dimension?
The maximum axis dimension is 2.5 m (from middle wooden beams to middle wooden beams).
Are the beams stable enough for this floor construction?
Duofor offers a free installation plan and panel optimization according to the width and height and the maximum distance between the wooden beams (from center-to-center)  

Further important questions:

- Which ceiling is attached to the beams?
- Are walls built in for apartment separation?
- What is the use of space (apartment, office, etc.)?
- What is the total thickness of the dovetail floor?
- What will the flooring look like?
What economic lengths are available?
The length of the panels of our standard Duofor® dovetailed sheets is economical and effective in use.
The standard lengths often coincide with the existing beam distances + 100 mm for longitudinal overlap.  

1300 mm: 2 x 600 mm + 100 mm / 1600 mm: 3 x 500 mm + 100 mm. 1
900 mm: 3 x 600 mm + 100 mm / 2200 mm: 3 x 700 mm + 100 mm.  

For the less frequent center- to-center distances of the beams, the lengths 1200 mm, 1530 mm, 1830 mm and 2000 mm are available.
How to install Duofor® dovetailed sheets?
In width: The profiles are superimposed with the outside, colour coding on colour coding  
In length: The sheets are laid alternately with the label up or down, colour coding on colour coding  

First, second, third sheet, etc. are laid with the sticker facing down. Then second, fourth, sixth sheet, etc. is laid with the sticker pointing upwards.

What is the fire resistance?
Duofor® dovetailed sheets have a fire resistance of 60 minutes. A wooden flooring or a wooden board is not necessary. The strength of the wooden beams is crucial for the fire resistance. The false ceiling is merely an additional, less decisive fire protection. Duofor calculates the overall construction for you.
Use and building regulations
Duofor® dovetailed sheets are produced EN1090-1 and are CE marked.  
Production according to NEN-EN ISO 9001: 2008  
Steel grade S320GD with at least 275 g zinc/m².  

Environmental class / permitted fields of application:
C1: Heated buildings with a normal atmosphere. Zinc quality Z100 (100 g zinc/m²)
C2. Unheated buildings with an atmosphere in which condensation can occur. Zinc grade Z275 (275 g zinc/m²)  

Falling below the permitted values shortens the service life of the reinforcement of the plates!
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