NF DTU 25.1 - Interior plaster coatings DTU 25 - Plastering
Batirama.com 11/29/2020
Following the DEPC*, the NF DTU 25.1 integrates the new methods used to produce interior plaster coatings, responding to the evolution of practices while preserving old techniques.
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Application domain
NF DTU 25.1 "Building work - Interior plaster coatings" gives the technical requirements for the implementation of plaster coatings carried out, on site, manually or by mechanical spraying, inside buildings, in all climatic zones or French naturals.
NF DTU 25.1 applies:
It does not apply:
The performance of the structures is not covered in this normative document. The current version of this NF DTU, at the publication of this sheet, is that of November 2010.
Targeted materials
The requirements that must be met by the materials necessary for the production of interior plaster coatings (plasters, coatings, mixing water, coating supports, fixings, protection of projecting angles, etc.), are given in part 1-2 "General criteria for the choice of materials" of NF DTU 25.1.
Implementation: the essentials
General provisions
Before carrying out the work, the following conditions must be satisfied:
Media characteristics
For a flat support whose flatness deviation does not exceed 5 mm under the 1 m rule:
For their part, the metal laths must be staggered, the opening of the ribs on the side to be coated. They are fixed using staples placed at each intersection between a main rib and the support.
Implementation of coatings
Interior plaster coatings can only be made between 5°C and 35°C.
It will sometimes be necessary to provide humidification of the support (prohibited for wood wool elements) or treatment using a background regulator.
Coatings can be applied:
Application of coatings
| Coatings | Plaster plasters with high hardness | Plaster coatings to be projected | |
|---|---|---|---|
Plaster used | B2 | B7 | Not indicated |
Mixing | 100 kg of plaster for 70 L of water | 100 kg of plaster for 50 L of water | 100 kg of plaster for 60 L of water |
Implementation | Manual: after the 1st casing, application in one coat on the support followed by dressing and tightening with a trowel or a knife | Application as soon as mixing is complete, in one or two coats | Application in one coat (two successive passes if the thickness exceeds 15 to 20 mm) with a ruler within 10 to 15 minutes of spraying, followed by tightening with a trowel or trowel |
Finishing | - by cutting the plaster with the berthelée with teeth then with the berthelée on the plain side for the cut plaster plasters - by smoothing with a smoothing trowel for smooth plaster coatings | Applies after straightening and tightening with a trowel then after re-wetting by smoothing with a trowel | Rewetting and felting of the coating before the end of setting followed by smoothing with a smoothing trowel of the laitance formed |
NF DTU 25.1 also deals with the implementation of the coating on specific structures such as:
Characteristics of the finished plaster
The characteristics of the expected finished coating are given in part 1-1 “Special technical specifications” of NF DTU 25.1, the main ones of which are listed in the table below.
Main characteristics of the finished plaster
Features | Expected value |
Theoretical thickness of the coating without bare or mark | 8mm |
Theoretical thickness of the coating with bares and marks | 12mm |
Surface appearance | No superficial pulverulence, no chapping, no cracking, no hole or streak deeper than 1 mm. No holes or grooves, systematically, depth less than 1 mm. |
Local flatness | Gap less than or equal to 1 mm, between the most prominent point and the most indented point, under a 20 cm ruler applied to the plaster and moved in all directions |
General flatness of the coating without bare or mark | Gap less than or equal to 10 mm, between the most prominent point and the most indented point, under a 2 m rule applied to the coating and moved in all directions |
General flatness of the coating on bare surfaces and markers | Gap less than or equal to 5 mm, between the most prominent point and the most indented point, under a 2 m rule applied to the coating and moved in all directions |
* European Construction Products Directive
NB: This sheet reports the essentials of NF DTU 25.1. It in no way replaces this normative document. For any further information required on this type of implementation, consult the NF DTU available from AFNOR or CSTB.
Source: batirama.com
