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Building laws background

Good reasons for anchoring an ETICS
         
Safe installation on old facades
         
Highest structueral stability
       
Highest security against hygrothermal impacts
         
Highest security against wind loads
 

Ways to perfect anchoring
         
Judging the substructure
         
Determinig the anchor type for the substrate      
    
Further criteria for choosing the perfect anchor
         
Additional plates depending on the application
         
Determinig the necessary anchor length
         
Determinig the necessary number of anchors
         
Correct processing is crucial for the function of the anchor
         
Drilling methods

Building law background

To harmonise the EU single market the EU Commission issued a directive on construction parts (89/106 EWG). It determines which building parts need to comply with the following essential requirements regarding their intended use:

• mechanical resistance and stability

• safety in case of fire

• hygiene, health and the environment

• safety in use

• protection against noise

• energy economy and heat retention

Working groups of the European Organisation for Technical Approvals (EOTA) have elaborated criteria on how to precisely prove these requirements are fulfilled for ETICS. These criteria and corresponding testing methods are stated in the European Technical Approval Guidelines (ETAG). For ETICS the following guidelines are relevant:

• ETAG 004: external thermal insulation composite systems with rendering
  
• ETAG 014: plastic anchors for fixing external thermal insulation composite
  systems with rendering

• CUAP according to the relevant ETAG

These guidelines are mandatory for all member states of the European Union (EU) as for well as those states of the European Free Trade Association (EFTA), that have signed the agreements of the European Economic Area (EEA), Iceland, Liechtenstein and Norway. The guidelines form the base for awarding European Technical Approval (ETA) for individual products. Construction parts with ETA and certificate of conformity may carry the CE mark, which enables the free movement of goods within the member states of the EEA. This way a uniform appraisal of construction parts and their fundamental technical specifications is ensured. Therefore each member state can assume without further testing that the construction part is generally suitable for the intended use if planning and construction are done correctly. Nevertheless, the CE mark may not be regarded as a quality mark.

The guidelines assume a prospective useful life of ETICS of at least 25 years. In accordance with current practical experiences, the actual useful life may be much longer without having to fear fundamental quality impairment. In spite of that, a guarantee towards the system owner or single components cannot be inferred.

When processing the products, national requirements are to be regarded. This way, member states may explicitly incorporate specific national or regional requirements (e.g. different wind loads, safety factors, countryspecific construction methods).

In terms of the EC guideline on construction parts, external thermal insulation composite systems are kits. The producer whose system receives an ETA is responsible for carefully choosing the single constituents. In accordance with ETAG 004, components of an ETICS are:

• adhesive

• insulation product

• rendering system (including mesh reinforcement)

• mechanical fixing devices (anchors, holding rails)

• ancillary materials (e.g. corner strips and base profile)

The approval lapses if components of various system owners are used. This constitutes a breach of the building code that leads to the loss of the warrantee by the owner and may have legal consequences.

EJOT advises: Buy all system components exclusively from the holder of an approved system!

An ETICS itself does not contribute to the structural stability of a building. Especially in renovation the stability of the wall construction has to be checked if an ETICS shall be installed. Since it has to carry the dead load of the insulation system after renovation, the stability might have to be rebuilt before attaching an ETICS. In particular this effects wall constructions of multiple shells (buildings with a prewall shell and precast concrete slabtype constructions).

Good reasons for anchoring an ETICS

Safe installation on old facades

ETICS are often used for energetic insulation of old buildings. Do you know how much load the old render can actually carry? For decades it was exposed to weather and emissions. Soot, dirt and old paint reduce the bearing strength of the glue. Or single components are not compatible with the composition of the glue ("saponifying"). After installing a new ETICS building physics can change the bearing capacity of the old render (failure of old render) even after years. Regarding new buildings residues of release oil on concrete may cause difficulties. Cleaning a facade is complex and costly. Contaminated waste water has to be collected and professionally disposed. Moreover the old render is imbued when thoroughly cleaned.

But if insulation boards are additionally anchored, usually no special treatment of the facade is necessary. Only loose parts of the render, efflorescence and paint flaking off need to be roughly removed. Possible holes are filled. Eventually anchors provide safe support.

When insulation boards are solely glued, the deadweight of an ETICS is passed onto the wall through shearing forces. The used glue is therefore the only connection between wall and insulation. Thanks to their specifically solid anchor plate and high characteristic loads, ejotherm plate anchors

give your facade safe support. Through contact pressure the frictional bond between facade surface and adhesive as well as between adhesive and insulation board is steadily increased. This results in a higher stability of the whole system. Moreover anchors with steel screw or steel nail offer higher safety reserves. Safe is safe!

Impact of anchoring:

• dead load of the system is passed onto the substructure via adhesive and insulation
  
• plate anchors provide additional contact pressure

Advantages:

• highest stability for the hole system
  
• anchor plates divert wind load
  
• highest security in case of wind loads

Good reasons for anchoring an ETICS

Highest security against hygrothermal impacts

Hygrothermal influences like temperature changes and shrinkage lead to fluctuating material expansion that effect the inelastic adhesive joints. If solely glued there is a latent danger of the insulation boards to bulge due to lacking expansion possibility at the joints. The additional anchoring in the area of the joints as well as in the centre of the board results in a mechanical fixing of the system onto the wall and therefore reduces the risk of cracking plaster.

  warm outside                                                               cold outside

Therefore:

Additional fixing of the insulation boards with ETICS anchors by EJOT

Wind loads affect in the opposite direction of the deadweight. They provide for a vertical tensile load onto the adhesive joint. Special importance is attached to the intersection of wall/adhesive (new buildings) and of old render/adhesive (renovation) respectively as well as of adhesive/insulation.

Particularly high wind loads exist

Consectetuer adipiscing

• at higher buildings
• at building edges
• at free-standing buildings
• in exposed areas
• in coastal areas
• in stormy weather

Ways to perfect anchoring

Judging the substructure

The expansion zone of an anchor has to perfectly fit the wall substrate found at the building. It is the only way the anchor can optimally fulfil its function within the ETIC system. This is why carefully assessing the substructure is highly important.

ETAG 014 (guideline for anchors in external thermal insulation composite systems) distinguishes standard substrates according to socalled use categories in order to facilitate the assignment of the matching anchor.

Substrates

	Use categorie A:                                                                    Normal weight concrete
	Use categorie B: Solid masonry
	Use categorie C: Hollow or perforated masonry
	Use categorie D: Lightweight aggregate concrete
	Use categorie E: Autoclaved aerated concrete

Ways to perfect anchoring

Determining the anchor type for the substrate

After the substructure is determined, the proper anchor can be assigned with its approval since anchors with ETA are tested and approved for specific use categories. The following cases are possible:

The anchor is approved for the determined building material category. The identified substrate is mentioned in the ETA of the anchor.

The anchor may be used on the building without further testing. The loads given in the approval can be used offhand for calculating the necessary number of anchors. Where required, national safety factors need to be observed.

Solid lime sandstone was determined as wall substrate. This corresponds to use category B. The anchor has an ETA for use categories A and B. For solid lime sandstones, the ETA mentions a characteristic load of 1.2 kN. National rules require a security value of 3 for use category B.
Therefore the anchor can be calculated having a design load of 1.2 kN : 3 = 0.4 kN without further testing on the building.

The anchor has no approval for the determined building material category.

If the determined substrate at the building does not belong to a use category for which the anchor is approved according to the ETA, the anchor may not be used on this object. In this case, the usability of the anchor cannot be proven through pullout tests.

Vertical coring bricks were determined as wall substrate. This corresponds to use category C. An anchor only approved for use categories A and B may not be used.

The anchor is generally approved for the determined building material category. But the identified substrate is not explicitly named in the ETA of the anchor.

The anchor may be used if its usability is proven through tests on the building. The object specific characteristic loads are determined through pullout tests as described in the ETA. When deducting the design load national safety factors need to be incorporated.

Example:

Perforated lime sandstone was determined as wall substrate. This corresponds to use category C. The anchor has an ETA for use categories A, B, C and D. Nevertheless, perforated lime sandstone is not explicitly named in the ETA. Pullout tests with this anchor on the object result in a characteristic load of 1.5 kN. National rules require a security value of 3 for use category C. The anchor can be calculated having an design load of 1.5 kN : 3 = 0.5 kN.

The anchor is generally approved for the determined building material category. The identified substrate is already mentioned in the ETA of the anchor, but the gross density or the compression strength of the stone differs from the declaration of the approval.

In principle this case corresponds to case 3. The usability for the substructure can be proven through tests on the building.

Special case:

Weather shells of concrete (precast concrete slabtype construction) are assigned to use category A. With any ejotherm anchor the loads may be calculated employing tests on the building.

Ways to perfect anchoring

Further criteria for choosing the perfect anchor

If in principal several anchor types are applicable in the found building material, further assessment criteria can be employed.

Ways to perfect anchoring

Additional plates depending on the application

Depending on the application, our ETICS anchors are combined with additional plates. The additional plates are very simple to use and are available in various diameters. They are put on the plate anchor like a washer. The further installation is processed as usual. In which case a specific additional plate is applied, depends on the used insulation and the system configuration. Crucial are the specifications of the system owner.

Note: Additional plates are system components of the anchor. They are tested accordingly and described in the approval of the anchor. Therefore plate anchors may only be combined with the matching additional plates by the same manufacturer.

Ways to perfect anchoring

Determining the necessary anchor length

The correct determination of the anchor length is an important prerequisite to obtain the highest fastening safety possible. The object specific preconditions always have to be taken into account. But determining the necessary anchorage length itself is easy:

   nominal anchorage depth h_nom

+ tolerance compensation t_tol

+ insulation thickness h_D

= necessary anchor length l_D

Notes:

If no other specifications are given, the nominal anchorage depth h_nom matches the effective anchorage depth h_ef.

The tolerance compensation is composed of:

thickness of the old render (if existent, the old render often has approx. 20 mm)

+ thickness of the adhesive joint after pressing the insulation boards against the wall (as a rule approx. 10 mm)*

+ additional compensation of facade unevenness*

= tolerance compensation t_tol

If during the energetic renovation there is a larger facade unevenness to compensate, it may be necessary to employ different anchor lengths.

* Facade tolerances are eventually compensated through the actual total thickness of the adhesive mortar.

Ways to perfect anchoring

Determining the necessary number of anchors

The necessary number of anchors has to be determined for each building individually. According to new European and national wind load standards several factors have to be incorporated. Amongst the most essential influences are the building construction (height, ground plan, profile) as well as the surroundings of the building. Exposed conditions in coastal areas, on mountains or outside closed housing areas normally lead to significantly higher wind loads. Details and actual maps with zones of different wind loads are part of national standards.

From the system point of view the anchor usage is increased by the bearing load of the used insulation board as well as the characteristic load and the plate stiffness of the employed anchors. Therefore the working guidelines of the ETICS provider have to be observed.

Generally speaking: the higher the building and the more exposed its surrounding area, the higher the necessary number of anchors. On the other hand highquality anchors often mean a lower usage of anchors per square metre – and thus save material cost and working hours.

Ways to perfect anchoring

Correct processing is decisive for the function of the anchor

The position of the anchor results from the anchor scheme of the ETIC system owner. Common anchorage alignments are for example:

• alignment of anchors for insulation boards with formats 1000 x 500 mm, e.g. rigid foam plates of polystyrene and 800 x 625 mm, e.g. mineral wool plates (table 1)

• alignment of anchors for insulation boards with formats 1000 x 200 mm, e.g. lamella plates of mineral wool (table 2)

Anchors should always be installed in the area of the adhesive, so that they can support the adhesive joint by means of contact pressure in the best way possible.

Ways to perfect anchoring

Drilling methods

Depending on the drilling machine and the hammer drill respectively, the following drilling methods are possible:

• rotary drilling - without percussion
• percussion drilling - many percussions with low energy
• hammer drilling - few percussions with high energy

Das Verfahren zur Bohrlocherstellung ist abhängig vom jeweiligen Verankerungsgrund und kann der folgenden Tabelle entnommen werden. Use categorie A    B C      D     E Drilling method percussion/hammer drilling rotary drilling without percussion

When drilling in rotary mode (without percussion), use our special drills to achieve a clean hole in a short time. Drills are wearing parts. Their durability depends on the solidness of the substructure: The harder it is, the higher the abrasion. To achieve an efficient work progress, drills should be exchanged in time. When drilling, please exactly follow the specified installation values of the individual anchor type (especially the minimum drilling hole depth). The exact geometry of the drill hole is important for the bearing capacity of the anchor. Therefore always drill orthogonally and never change direction while drilling. This is especially important with regards to soft substrates. Before inserting the anchor clean the hole from drill dust by pulling out the drill several times. With regards to plate anchors the anchor plates are either installed countersunk into the insulation board following the EJOT STR principle or plain with the surface on the insulation exterior (always in combination with additional plates). When installing plain with the surface it should be regarded that the upper side of the anchor plate forms one level with the upper side of the insulation. When the plate moves in too deeply, the cavity needs to be levelled out before installing the mesh. This leads to heightened plaster in the area of the plate and bears the risk of cracking plaster. When the plate does not enter deep enough, a thicker mesh layer has to be installed over the whole facade in order to achieve the minimum render thickness over the anchor plates. This results in higher costs. EJOT advises: When using the EJOT STR principle, the anchor plate is quickly and cleanly countersunk into the insulation and covered with an STR cap. This way a smooth and homogenous insulation surface as basis for an even rendering is established. No additional work for levelling out the anchor plates is needed. Moreover, the anchor plates are detached from the rendering.