6 Laying methods and fixing of the roof waterproofing

The waterproofing membranes can be fixed against wind uplift by

  • ballast,
  • mechanical fastening or
  • bonding.

Ballast and mechanical fastening also fix build-up layers under the waterproofing membrane, which can thus be loose laid. Bonding of the waterproofing membrane is only possible if the build-up layers are stationary, and on substrates, which are suitable for the corresponding adhesive.

6.1 Wind loads at the flat roof

The required

  • mass (weight) of the ballast,
  • amount of mechanical fasteners or
  • amount of adhesive

for the expected wind loads must be calculated with regard to

  • the location (wind zone, height, building category),
  • the dimensions of the building,
  • the form / slope of the roof and
  • the substrate / wall openings

and should be differentiated according to

  • the centre area
  • the perimeter area
  • the corner area

of the roof.

The calculation has to be done as a project-related individual calculation, according to DIN EN 1991-1-4 or to the corresponding national regulations.

6.2 Waterproofing membrane loose laid with ballast

6.2.1 Types of ballast and ballast calculation

» Gravel

consisting of washed round pebbles (16/32 mm) with max. 15 % broken stones can be directly applied as ballast on EVALASTIC® V waterproofing membranes without a protection layer. For higher percentages of broken stones, a protection layer must be installed (e. g. for pneumatic gravel feeding).

The thickness of the gravel layer must be at least 5 cm.



The weight of gravel 16/32 is approx. 18 kg/m² (≈0.18 kN/m²) per 1 cm fill height.

In perimeter and corner areas as well as on sloped surfaces the gravel layer can be consolidated with a suitable adhesive to prevent whirling up.

» Concrete slabs / hollow grid tiles

A loose laid protection layer e. g. rot-proof fleece, building-protection mat 11 (The compatibility of materials needs to be considered.) or similar, must be placed between the roof sealing and the concrete slabs or hollow grid tiles!

Concrete slabs laid closely together, (e. g. 100 x 25 x 5 cm) have a weight of approx. 22 – 24 kg/m² (≈0.22 – 0.24 kN/m²) per 1 cm thickness and hollow grid tiles (60 x 40 x 8 / 10 cm), filled
with gravel (16/32 mm), a weight of approx. 20 kg/m² (≈0.2 kN/m²) per 1 cm thickness. The longer edge of rectangular slabs must be laid parallel to the roof edge.

» Inverted roof

The thermal insulation, made of extruded polystyrene boards with a rebated edge, is laid in a single layer directly onto the EVALASTIC® waterproofing membranes without a separation layer. Between the thermal insulation boards and the ballast, a filter layer made of synthetic fleece (min. 140 g/m²), or a draining fleece layer, must be placed. The required thickness of the ballast 12 with loose laid waterproofing membranes is calculated for wind loads according to the “Guidelines for flat roofs”, Appendix I, or in an individual calculation. If gravel is used as ballast, the gravel layer must have a thickness of at least 5 cm.

Concrete slabs & Inverted roof

» Paving flags

Paving flags can be installed on alwitra paving slab supports, in an underlayer of gravel or chalk free grit, or in a bed of mortar (on a draining layer). Between the paving slab supports or the gravel or grit underlayer and the EVALASTIC® waterproofing membranes, a protection layer of building-protection mat11 or similar should be installed. Screed or mortar layers are to be separated from the roof sealing with a double-ply PE membrane as “sliding layer”.

alwitra paving slab support with spacer PA 20 plus:

» Installation notes

Laying accessible paviours onto alwitra paving slab supports secured against reverse rotation and over-tightening is simple and largely unaffected by weather conditions. Once the waterproofing is completed, the following is applied one after the other:

  • protection layer
  • paving slab supports (if necessary, with support plates)
  • paving slab (min. 4 cm thick)
  • spacers

Stelzlager mit Platten

It is recommended that installation should commence from outlets towards perimeters, cutting slabs at the perimeters as required.

At the perimeters the paving must be permanently secured against lateral movement. An adjacent coarse gravel band is not sufficient.

The paving slab supports are located beneath the cross joint of four slabs. A slab is supported on each corner by one pad of the four supports. Along the perimeter of a paved area, paving slab supports are cut and no spacers installed.

Paving slabs

Skizze zum TextInfinitely and individually height-adjustable up to 20 mm pads allow for tolerances in the thickness of paving slabs and substrate, so that the top surface is smooth and evenly sloped.

Individual height adjustment, both upwards and downwards, can be made with a screwdriver even after the paving has been laid, without the need for lifting the slab.

On the base plate, at the adjusting wheel of every pad, serrations are provided behind the spacer. Insert a screwdriver through the open joint into the serration and turn the adjusting wheel: clockwise rotation of the adjusting wheel will lower the pad, anti-clockwise rotation will lift the pad.

If the paving is to be installed with a lower slope than the roof waterproofing, the paving slab supports must be placed on stackable 20 mm high alwitra support plates.

Note: The recommended minimum-tilt of the paviours amounts 1 %.

» Roof gardens

Between the roof garden build-up and the EVALASTIC® waterproofing membranes, a protection layer or a membrane combination (protection / drainage / filter layer) must be installed.

Skizze zum Text

The load from the garden layers 13 depends on the material, the thickness and the moisture content of the draining, filter and vegetation mat. For calculating wind uplift, the load of the dry roof is to be taken.

11 E. g. “KRAITEC protect” company Kraiburg, Salzwedel, Germany or “Regupol 9510”, BSW, Bad Berleburg, Germany. Disposal of other building-protection mats can possibly lead to slight staining and embossing at the surface of the waterproofing membranes.

12 Lower values indicated in admission reports for the insulation system “inverted roof” refer only to the wind uplift protection of the insulation boards.

13 Please ask your roof garden supplier.

6.2.2 Loose laying with ballast

Protection against wind uplift 14 with ballast is permissible only if the bearing capacity of the roof construction and, if necessary, the maximum deflexion for these loads have been proven.

» Installation scheme

Installation scheme

The ballast, including protective layer, must be applied immediately after laying the waterproofing membranes (seam testing), if necessary in sections.


14 Also for noise control.

6.3 Waterproofing membranes loose laid and mechanically fastened

6.3.1 Fastening methods and determination of the required quantity of fasteners

Loose laid EVALASTIC® V waterproofing membranes can be secured against wind uplift linear in the seam overlaps by mechanical fastening with any approved fastener:

Skizze zum Text

The fastening method, as well as the required quantity of fasteners has to be indicated in the specification. The required quantity of fasteners will be determined in a project-related individual calculation. 15

In case of refurbishment, an individual calculation should be done, if necessary based on pullout tests by the fastener manufacturer. On non-ventilated roofs, fastening of the waterproofing membrane at the same time as fastening the thermal insulation.

If the insulation boards are not sufficiently secured this way (min. 2 fasteners/m²), they must be additionally fixed prior to installing the waterproofing membrane.


15 On request, as a service of the fastener manufacturer.

6.3.2 Fastening plan

If required, project-related individual calculations 16 will be produced, including installation instructions, material requirements and fastening plan.

The fastening plan contains

  • the dimensions of the field, perimeter and corner areas, as well as
  • the required quantity of fastening elements per roof area.

With mechanical seam fastening, the membrane width(s), the chord width (top chord spacing) of the metal sheets and the position of movement joints and large roof penetrations (arcade and single rooflights, natural smoke vents) are taken into consideration. In order to draw up an individual calculation and a fastening plan, a Data Sheet confirmed by the roofing contractor will be necessary.


16 By the individual calculation of the respective manufacturer.

6.3.3 Fasteners

Prior to any application, fastening systems must be tested and certified. The selection of the fasteners (type, length) technologically depends on:

  • the thickness of the build-up structure
  • the material of the supporting substructure (profiled steel decking, timber deck, derived timber product, cement or lightweight concrete)
  • the strength of the substrate
  • the corrosion impact from the build-up structure (especially in the case of refurbishment)

The instructions of the fastener manufacturer are to be only tread resistant fastening systems must be used.

6.3.4 Mechanical fastening in the seam area

» Installation scheme

Installation scheme

Especially in corner areas, fasteners may be necessary outside the seam overlap, for example in the middle of the membrane. The fasteners outside the overlap area are covered by seal-welding

either in a row with unbacked tapes (16 cm wide)

Skizze zum Text

or individually with round unbacked details.

Skizze zum Text

» Position of the fasteners

Load distribution plates must be installed at least 1 cm from the edge of the backing, rectangular load distribution plates with the longer edge being parallel to the membrane edge.

Position of the Fasteners

The fasteners must be driven in only so far as to permanently prevent rotation of the load distribution plates and to ensure that the latter press the waterproofing membranes against the substrate without wrinkles.

» Use of setting tools

For an efficient and highly safe fastening in an ergonomical working position, setting tools may be used. Use only setting tools with a bit stop or a dynamometric clutch.

Use of setting tool

17 See also 4.1 “Tips for installation”.

6.4 EVALASTIC® waterproofing membranes bonded

Bonding of the roof waterproofing is only recommended if loose laying with ballast, or mechanical fastening is not possible. Bonding of the roof waterproofing is only possible provided that all underlying functional layers are permanently stationary (Testing before refurbishment!).

For bonding, use fleece backed waterproofing membranes EVALASTIC® V or EVALASTIC® VGSK with a self-adhesive coating.18 The laying of EVALASTIC® V waterproofing membranes is done either by rolling or folding, after applying the adhesive onto the substrate (generally, bituminous felt).

After removal of the separation foil, EVALASTIC® VGSK is laid as described in chapter 6.4.5. The limited mobility of the roof waterproofing resulting from the bonding makes it necessary to be especially careful when forming dilatation joints, flashings and cappings. Dilatation stresses deriving from the roof and the layer build-up must be absorbed without causing any damage.

Overlaps of membrane type backings at the joints of thermal insulation layers must not be bonded.


Prior to expansion the roof waterproofing, non specially designed movement joints with a width of up to 5 mm are to be covered with a tape (sliding strip) with a width of 25 cm, fastened at one side.

After bonding, subsequent changes in the colour of the membrane surface cannot be excluded.

6.4.1 Preparing the substrate for refurbishment

The scope of the work necessary to prepare surfaces for refurbishment 19 depends on the existing layers or plies.

Existing bitumen covering with compressed gravel ballast
Cut open or completely scrape off blisters. Remove compressed gravel ballast with appropriate tools and level the substrate. Apply a compensation layer, e. g. a bituminous felt.

Existing bitumen covering under loose gravel ballast
Remove gravel ballast and bonded, tightly adhered pebbles with appropriate tools, e. g. ‘scabbler’ or roofing plane. If necessary, even the substrateby additionally torching the surface. Level any depression (e. g. removal of blisters or folds) by applying welding tapes.

Existing bitumen covering with a sand / grit coating
Cut open or completely scrape off blisters. Level any depression (e. g. removal of blisters or folds) by applying welding tapes.

Existing synthetic membrane roof sealing
Prior to bonding to existing synthetic membrane roof waterproofing, consult with the alwitra Technical Department is obligatory.

6.4.2 Adhesives

Depending on the installation temperature (season), as well as on the type and characteristics of the substrate, the following adhesives are used:

» cold-bonding adhesives

  • solvent-containing synthetic adhesive alwitra L 40 rolled onto the complete surface
  • moisture-curing single-component PUR adhesive alwitra PUR D, poured in lines (beads)

» hot-melt bonding adhesives

  • bituminous hot-melt bonding agent 85/25, 100/25 or 115/15, brushed onto the complete surface or poured in lines (beads), elastomeric bitumen hot-melt bonding agent, brushed onto the complete surface

Bituminous hot-melt bonding agent can only be used for black EVALASTIC® V waterproofing membranes (also at lower temperatures). On bituminous felts with a sufficiently thick bitumen coating, without sand or grit application, (e. g. bituminous welding sheet, min. 4 mm thick) or on bitumen beds, EVALASTIC® V waterproofing membranes can be bonded with melt-on method.

Cold-bonding adhesives require an installation temperature of at least +5 °C.

Note the instructions, especially with regard to

  • the substrate conditions
  • the installation temperature
  • the quantities to be applied in the field, perimeter and corner areas.

If the adhesive is applied in lines, the roof waterproofing at the perimeter and at openings must be ensured in order to prevent wind uplift.

Prior to bonding to weathered substrates (refurbishment), a test bonding has to be carried out to determine the behaviour of the substrate and the required amounts of adhesive.

When applying adhesives, make sure that seam laps (welding area) and membrane joints in particular are kept clean from adhesive.

Fillers or other solvent-containing adhesive compositions are not suitable for bonding EVALASTIC® membranes. Bonding with alwitra adhesive L 40

Technical data:

Basebitumen- and solvent-free PSA adhesive
Installation temperaturefrom +5 °C to +40 °C
Storagedry, cool, protected against light
Shelf lifemin. 12 months

Substrate conditions:

stable, plain, dry, clean, free from dust, grease and oil, free from separating agents.
L 40 is suitable for bonding on many standard substrates such as concrete, light weight concrete or sanded, gritted or mineral-coated bituminous felt. Bonding on PUR / PIR rigid foam boards with L 40 is not permissible.


Thoroughly stir the adhesive in the container (25 kg or 9.5 kg).

The adhesive is applied

  • on one side, rolled onto the complete surface in a grid pattern (one-side bonding)
  • on two sides, rolled onto the complete surface in a grid pattern (contact bonding)

Minimum quantity of alwitra adhesive L 40 (Minimum quantity according to DIN EN 1991-1-4.)

  • for one-side bonding
with polyester fleece backing
with glass /
polyester fleece backing and
self-adhesive coating
effective thickness of
waterproofing layer [mm]
1.2 / 1.51.5
Membrane widths [m]

- with welding lap on one side

- with welding lap on both sides

1.05 / 1.55
1.09 / 1.59
Tape widths [cm]54 / 79
Standard length [m]25
Specified lenghtson request
Standard colourslight grey
Special colourson request
EVALASTIC® tape widths [cm],
16 / 20 / 25 / 33 / 50 / 66 / 75 / 105 / 155
EVALASTIC® preformed details

- internal / external corners

- flange 1

- lightning conductor and
cable penetrations

EVALASTIC® coated metal sheets
- sheets 1 m x 2 m
light grey

- alwitra L 40

- alwitra PUR D
alwitra membrane cleaner
self-adhesive [cm]

- with welding lap on one side

- with welding lap on both sides

33 / 43

66 / 86
alwitra primer SK

alwitra primer SK-L

2, 3

2, 3
1 For alwitra flat roof rainwater outlets and vents

2 Primer for EVALASTIC® VSKA tapes

3 Primer for various substrates, e. g. bituminous membranes
  • for contact bonding, e. g. at parapets and kerbs min. 450 g/m², at rough sheet piles min. 600 g/m².
  • alwitra adhesive L 40 is only suitable for bonding of fleece-backed EVALASTIC® V waterproofing membranes.

The above-mentioned quantities must be increased depending on the substrate conditions, especially for rough and absorbent substrates (e. g. gritted bituminous felt). Excessive application of adhesive (adhesive clusters) on polystyrene rigid foam boards coated with a bituminous felt may lead to funnel shaped destruction of the rigid foam.

Before the membranes are rolled or folded onto the adhesive, allow for sufficient airing of the solvent to reduce the amount of volatile solvent trapped under the waterproofing membrane to a minimum. High amounts of solvent under the waterproofing membrane may lead to temporary blisters in the membrane which will again disappear, with the volatile solvents diffusing out. The airing time depends in particular on the ambient temperature and humidity.

The so called finger test is the most practicable method for determining the right moment. If the finger test produces adhesive threads, bonding is still possible.

Finger test to determine the right moment

After rolling or folding the waterproofing membrane onto the adhesive, it must be immediately pressed on tightly with a broom.

The position of the waterproofing membrane can be adjusted immediately after it has been rolled or folded onto the adhesive alwitra L 40 without impairing the adhesion. Again press on tightly.

Always check the adhesiveness.

The equipment is cleaned with alwitra cleaner L 40, this must also be done before longer work breaks.

18 In flashing areas, EVALASTIC® VSKA waterproofing membranes can be bonded to suitable substrates.

19 Analysis of the roof build-up provided Bonding with alwitra adhesive PUR D

Technical data:

Basestyrene-butadiene rubber
Consistencyvicscous, rollable / brushable
Densityapprox. 1.02 g/cm³
Shelf lifemin. 24 months
Storagedry and cool, protected against direct sunlight
Substrate temperaturefrom +5 °C to +80 °C
Ambient temperaturefrom +5 °C to +40 °C
Adhesive temperaturemin. +10 °C
Open timeone-side bonding: approx. 10 to 15 min
contact bonding: approx. 15 to 20 min

Substrate conditions:

stable, plain, clean, free from dust, grease and oil, free from separating agents, slightly moist to dry. If the substrate is dry, air humidity is low and temperatures are high, moisten the substrate by spraying water fog (max. 15 g/m²)! 20 Sanded, gritted or mineral-coated bituminous felt.


one-side bonding, poured directly out of the container (5.5 kg / 2 kg) in lines (beads) 21, approx. 50 – 60 g/m per bead. Allow for airing of the adhesive for approx. 5 – 10 minutes, then before a film can form on the adhesive bead, roll or fold the membrane onto the PUR D adhesive beads and press on with a broom. The width of the line under the pressed-on waterproofing membrane must be ≥ 4 cm.

Minimum quantity of alwitra adhesive PUR D (Minimum quantity according to DIN EN 1991-1-4)

Building height 1centre area /
inner perimeter area
outer perimeter areacorner area
up to 8 m300350400
over 8 up to 25 m350450500
over 25 mon request
1 Buildings in wind zone WZ 1 + WZ 2 and terrain category II + III

For fast adhesive application (up to 8 beads simultaneously) with regular spacing, the use of PUR adhesive applicators (“application trolley”) is recommended.

The tools must be cleaned e. g. with acetone before the adhesive has cured.

After rolling or folding the waterproofing membrane onto the adhesive beads, it must be immediately pressed on with a broom.

You must not correct the position of waterproofing membranes after they are rolled or folded onto the PUR D adhesive beads, as this will significantly impair adhesion.

Adhesive beads may show through the waterproofing membrane.

PUR D is only suitable for bonding of EVALASTIC® V waterproofing membranes with a fleece backing on sanded, gritted or mineral-coated bituminous felts. Bonding on unbacked rigid polystyrene foam is not permissible.
PUR D is not suitable for bonding insulation materials.

20 E. g. with an orchard sprayer.
21 Warming in a water bath will increase flowability. Bonding with bituminous hot-melt bonding agent and by melt-on method

Technical data:

Base1-component polyurethane prepolymer, moisture curing
Consistencyliquid, pourable
Densityapprox. 1.10 g/cm³
Shelf lifemin. 12 months
Storagedry and cool, protected against direct sunlight
Substrate temperaturefrom +5 °C to +60 °C
Ambient temperaturefrom +5 °C to +40 °C
Adhesive temperaturemin. +10 °C
Open timeapprox. 20 min

Substrate conditions:

  • stable, plain, clean, free from dust, grease and oil, free from separating agents
  • if necessary, with a bituminous priming coat


one-side full or partial brushed (brushing method) or poured application (pouring method)

Minimum quantity of adhesive (Minimum quantity according to DIN EN 1991-1-4):

g/m² (number of lines/m²)
Building height1centre area /
inner perimeter area
outer perimeter areacorner area
up to 8 m200 (4)200 (4)300 (6)
over 8 up to 25 m200 (4)300 (6)
over 25 m400 (8)
1 Buildings in wind zone WZ 1 + WZ 2 and terrain category II + III

The bituminous hot-melt bonding agent, with an installation temperature according to the previous table, is poured or brushed onto the substrate. The EVALASTIC® V waterproofing membranes can be rolled or folded onto the hot-melt bonding agent directly, or later, when the bonding agent is remelted by torching.

In any case, keep the upper side of the membranes and the welding edges clean from bituminous hot-melt bonding agent; do not lay the membranes against the prevailing wind direction.

On bituminous felts with a sufficiently thick bitumen coating, without sand or grit application, or on bitumen beds, EVALASTIC® V waterproofing membranes can be bonded with melt-on method. The bitumen coating or bitumen bed is melted with a suitable tool over the whole width of the membrane and the EVALASTIC® V waterproofing membrane is rolled onto the melted bitumen and pressed on.

Correcting the position of a waterproofing membrane after it has been rolled or folded onto the bituminous hot-melt bonding agent is not possible. After partial bonding, the bituminous hot-melt bonding agent may show through the waterproofing membrane.

6.4.3 Suitability of cold-bonding adhesives

With cold-bonding adhesives, pay special attention to their suitability for contact with the substrate. On substrates which have a top separation layer, e. g. a PE foil or a talcum coating, you cannot use cold-bonding adhesives. Such separation layers may be applied to bituminous felt sand on membrane-shaped backings or bituminous adhesive layers of thermal insulation boards to avoid sticking of the material on the roll or transport piles 22.

Baseoxidized bitumen
Softening point85 °C 1100 °C 1115 °C 2
Penetration depth [0.1 mm]252515
Installation temperature180 °C200 °C210 °C
Consistency at installation
1 at roof slopes ≤ 3°

2 at roof slopes > 3°


22 Contact manufacturer for further information.

6.4.4 Installation scheme

» Rolling method

Image of the Installation scheme

» Folding method

Image of the folding method


23 See also 4.1 “Tips for installation”.

6.4.5 Bonding with self-adhesive membranes EVALASTIC® VGSK

EVALASTIC® VGSK waterproofing membranes have a glass/polyester fleece backing and a synthetic adhesive compound coating. They are 25 m long and are produced with an approx. 5 cm wide unbacked welding edge on one side. The self-adhesive layer is bitumen- and solvent-free and covered with a protective foil when delivered.

Until installation, the EVALASTIC® VGSK membranes must be stored in a dark place or covered with tarpaulin. Holes in the lower separation foil must be covered to preserve the high adhesiveness of the self-adhesive layer.

Technical data of the self-adhesive layer:

Building height1centre area /
inner perimeter area
outer perimeter areacorner area
up to 25 m200 - 400
(> 10 %)
400 - 600
(> 20 %)

1500 - 2000
(100 %) 2
400 - 600
(> 20 %)

1500 - 2000
(100 %) 2
over 25 mon request
1 Buildings in wind zone WZ 1 + WZ 2 and terrain category II + III

2 on mineral-fibre insulation boards with bituminous adhesive layer. Approval of insulation manufacturer required

The EVALASTIC® VGSK membranes are not suitable for the waterproofing of flashings or roof penetrations. Perimeter fastening (see chapter 7) is obligatory. Bonding on unbacked EPS rigid foam boards

EVALASTIC® VGSK membranes can be directly bonded to stable, unbacked polystyrene EPS rigid foam boards. The substrate must be clean, dry and free from dust. The membranes are bonded directly to the thermal insulation without any primer. The lap width should be at least 6 cm (the self-adhesive layer will adhere to the overlapped membrane at a width of approx. 1 cm in the rear area), to avoid damage to the insulation material by hot air ingress. EVALASTIC® VGSK membranes can be applied, as described above, without any additional precautions at rated wind loads up to 2.5 kN/m2 (Wres according to DIN 1991-1-4). Bonding on other substrates, e.g. bituminous sheets

The underside coating of the EVALASTIC® VGSK membranes adheres in connection with alwitra primer SK or SK-L (up to rated wind loads of 3.5 kN/m2) to various standard substrates e. g. bituminous felt, concrete, zinc and steel sheets, aluminium and synthetic materials. Application instructions for alwitra primer SK and SK-L

alwitra primer SK

Technical data

Suitability of alwitra
cold-bonding adhesives on
lightweight concrete+++
render, brick work++ 1
steel sheet, aluminium++ 1
timber-based boards+ 1
bituminous sheets ²++ 1++
bituminous sheets, PE-foil,
polyester fleece on the
upper side
EPS / XPS rigid foam board
EPS rigid foam board,
backed, glass fleece
EPS rigid foam board,
backed, bituminous sheets ²
++ 1++
PUR / PIR rigid foam board,
unbacked, aluminium-laminated
PUR / PIR rigid foam board,
mineral fleece
mineral fibre boards,
mineral fibre boards,
++ 1
mineral fibre boards,
with anorganic coating
+ 1
1 also vertical surfaces (contact bonding)
2 sanded, gritted or with mineral-coated bituminous felt on the upper side

Legend: ++ especially suitable, + suitable, - not suitable

alwitra primer SK-L

Technical data

BasePSA adhesive, bitumen-free, solvent-free
Installation temperaturefrom +5 °C bis +40 °C
StorageIn a dry, cool and dark place
Shelf lifemin. 12 months

Substrate conditions:

stable, plain, clean, free from dust, grease and oil, free from separating agents


Thoroughly stir the alwitra-primer SK / SK-L in the container (25 L / 10 L). Apply evenly to the complete surface with a brush or a paint roller.

Min. quantity of primer:

approx. 0.2 L/m² (wet, depending on the substrate). The applied quantities must be increased for rugged and absorbent substrates.
The primer must be completely dry before applying the EVALASTIC® VSKA membranes.


The alwitra primer SK-L dries faster in cool weather.

The condition of the bonding substrates and the necessity for precoating with alwitra primer SK / SK-L (acc. to the table) may alter depending on the weather and construction site conditions. If necessary, a test bonding has to be carried out.

Basesolvent-free emulsion, bitumen-free
Consistencyliquid, rollable / brushable
Installation temperaturemin. +5 °C
Airing timeapprox. 30 min 24 (after that, the roof area can be walked on)
Storagedry, cool, frost-protected
Shelf lifemin. 12 months

» Installation scheme

Installation scheme primer

Tear off the protective foil, pull it to one side and press on, removing any blisters

24 The airing time to a great extent depends on the quantity applied, the materials and the weather conditions.