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Description Tech info.
איטום גג

A proffesional roof sealing system

Cat no. 313

Product description

Multigum is a professional combined polymers based sealing and coating material, that when dried becomes a very resistant, long lasting sealing membrane. The high flexibility, combined with its resistance to tear, endow the material with a high bridging capability over structural cracks. Multigum is a paste material, easy to use for spray, roller or brush spreading. Multigum is a water-based, user friendly and non-inflammable material.


Multigum is used for sealing new concrete roofs, old bitumen sheets coated with aggregates, old acrylic coatings, old polyurethane coatings and metal roofs. Multigum is also used for coating and sealing external walls (Multigum matt version).

Technical spesifications


Blue / White paste material

Specific gravity:

1.35 gr/ml


40,000 cps.



Cold Flexibility:



Accelerated weathering in U.V. (2000 hours):

Very good resistance.

Crack bridging capability according to I.S.I. standard no. 4518: 500 cycles of 1mm amplitude plus 6,000 cycles of 3mm amplitude. Thickness of MULTIGUM – 2mm. (Dry)

No cracks.

Instructions for use:

Surface preparation:

Check that gutters are in good working order, that walls and floor meeting corners are rounded, and verify minimum slopes of 2%.

For a new concrete roof:

Application should be performed on a stable, clean and dry concrete (not foamed concrete) that was casted minimum 30 days before application. Remove intensively all loose particles. Apply 250 gm/m² of Aquapoxy. Drying time:1-2 hours. In case of a porous concrete, apply additional layer of Aquapoxy in quantity of 150-200 gm/m² .Allow to dry 1-2 hours.


For a roof coated with old acrylic sealing product:

Remove intensively loose membrane parts. Rinse intensively the roof to remove the mud and wait until completely dry. Fill depressions deeper than 6mm with cement mortar, modified with acrylic polymer. Apply 200 gm/m² of Aquapoxy. Drying time: 1-2 hours.


For a roof coated with bitumen membranes covered by aggregate:

Remove loose aggregate particles off the roof. Rinse intensively the roof to remove the mud and wait until completely dry. Apply Aquapoxy at a quantity of 300 gm/m².Allow to dry for 1-2 hours.


For a metal roof (galvanized or paint coated):

Remove intensively all sediments and loose particles. Apply polyurethane mastic type BPU-2 at all overlap lines between two adjacent metal plates, over the joint between them and over all the screws. In case the open joints are long/wide, apply butyl tape coated with fleece, 15 cm width, along the joint. Apply Primer MS-1 at a quantity of 200 gm/m² over the metal surface. Wait 1-2 hours for drying prior to application of Multigum. In case of paint coated metal roof, it is highly recommended to apply first the waterproofing system on a small spot in order to verify the proper adhesion to the specific paint.    

For an old asbestos roofs:

Remove intensively all sediment and loose particles. Rinse intensively the roof to remove the mud and duckweed and wait until completely dry. Apply polyurethane mastic type BPU-2 at open overlap lines between two adjacent plates and over all the screws. Then, apply Primer MS-3 in a quantity of 300 gm/m². Allow to dry for 1-2 hours and then apply additional layer of Primer MS-3, 150-200 gm/m². Allow to dry 1-2 hours.


Performing of sealing layer:

  1. Apply Multigum Blue in quantity of 1.0 kg/m² along the walls and floor meeting corners, gutters, pipe penetration and along cracks (in 15 cm strips). Let it dry for 2 - 4 hours.
  2. Apply a first layer of Multigum Blue over the surfaces by spray or brush, in a quantity of 1 – 1.25 kg/m². Letting to dry for 3 -5 hours.
  3. Apply 1 – 3 layers of Multigum White in a quantity of 1 – 1.25 kg/m².

Drying time between layers: 3 – 5 hours.

Total quantity: 2.5 – 4.5 kg/m², depends on slopes, type of substrate and dimensions of the roof.

For achieving a reliable and long lasting waterproofing system, It is recommended to reinforce the fresh Multigum Blue with polyester fabric type POLYFABRIC (a glass net is acceptable as a less qualified reinforcement). A minimum quantity of 4 kg/m² Multigum is recommended in this case.

 Apply Multigum White also over the parapets in quantity of 1.6 kg/m² - 0.8 kg/m² for each layer.

When using a brush for coating, the layers should be performed in cross brushing directions.

Drying time:

Contact dry time: 3-5 hours (in 25 ºC and 50% R.H).

Final drying: 14 days.


In the shadow, protected from extreme cold (over 5ºC) and high temperature conditions.


22 kg.

Warning and safety measures:

  • Do not swallow, wash hands with water and soap immediately after use.
  • Drying time may change due to variation in temperature and relative humidity conditions, as well as layer thickness.
  • Do not apply 3 days before rain or about 6 hours before dew.
  • Do not apply in temperature below 5ºC, and not more than 35ºC.
  • Multigum should not be diluted, do not add water or any other material.
  • Flood test can be applied at least 14 days after application.
  • Multigum should not be applied in a rate of more than 1 kg/m² for each layer.
  • During the winter time(in temperature under 13 ºC), let the first layer of Multigum dry for 18 – 24 hours prior to application of the second layer. The quantity for each layer will be 800 gr/m².
  • In case the drying time between the first and the second layer of the Multigum is more than 24 hours, you should apply a layer of Primer MS-3 in quantity 150 gr/m² on the first layer and wait 1-2 hours for drying, prior to the application of the second layer.


The instructions that appear on the product are based on knowledge and experience amassed over the years.  We reserve the right to change these instructions without prior notification.  The operator is responsible for keeping informed of the latest updates.  These instructions are solely recommendations and do not constitute liability for the product.  Prior to use, the user must check the product’s suitability, and the application and environmental conditions that meet his specifications.  If in doubt, please contact us and we will be happy to instruct you.

Talk to us

Bitum Ltd - Haifa
Central Branch
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