Installing Bitumen Membrane Properly

A bitumen membrane on roof is used to create an extra layer of roofing that gives an additional protection, insulation as well as sound-proofing qualities to the roof. The use of membrane roofing virtually wipes off the necessity of making gravel roofs, which are very difficult to look after or repair. Roofing membranes are available in large rolls of 50 feet length, which enables to cover up a lot of roofs with a single roll and makes it easier to install the membrane. In addition, it requires minimum care for maintenance. These days, modified bitumen is used as roofing membrane. It comprises asphalt and rubber or plastic polymers. The polymer mix admits the asphalt to assume its most beneficial qualities. Similar to the gravel and tar roofing, you need a surfacing material for the modified bitumen membrane also. Modified bitumen membrane is normally installed employing a heat generating equipment. The heat melts the seams and creates a seal. In some cold applications an adhesive is also used. The modified bitumen is also referred as torch down roofing. This type of membrane is mostly used on flat roofing.

Tools and Materials Needed:

  • Roofing Membrane roll    
  • Roofing gloves
  • Safety glasses
  • Broom
  • Hammer
  • Knife
  • Spark igniter
  • Propane torch
  • Capped roof nails
  • Flashing material
  • Spray primer
  • Roofing felt
  • Tape measure

Step 1 - Cleaning the Roof

Remove debris and dirt from the roof with a broom.

Step 2 - Fixing Roofing Felt

Spread a roll of flame resistant felt on roof. Fix the roofing base felt using the capped roofing nails at about 6-inch spacing up to the sides and also to the center of felt sheet.

Step 3 - Installing Flashing

Place the flashing material alongside the roof edge. Secure the flashing with roofing nails at a spacing of 8 inches using hammer.

Step 4 - Primer Coating

Coat a layer of primer using the sprayer on the edge and flange of flashing.

Step 5 - Spreading the Sheet of Bitumen Membrane

Open out the roll of modified-bitumen membrane and spread it over the roof. The edge of the roof should be overlapped about 2 inches with the membrane. Cut the material with a knife.

Step 6 - Adjusting the Membrane Material

Place the membrane sheeting over the flashing. Make the sheet flat. It should overhang about 1/2 inch on the flashing. Roll back the modified membrane sheet halfway to make it stretched tight.

Step 7 - Igniting the Torch

Light up the propane torch using the igniter. Make adjustment so that the flame is blue.    

Step 8 - Joining the Membrane with Felt

Heat the bitumen membrane material to fuse it and join with the felt. Move the torch flame down to the intersection of sheathing and roofing membrane. Roll over the roofing membrane along the width till you see the heat bubbles rising on the membrane material. Press the edges with your foot to seal them with the flashing and proceed onwards.    

Step 9 - Fusing the Seams

Roll out modified-bitumen membrane sheet on the roof. Overlap all the edges of the sheets rolled earlier. Heat the sheets and roll them. Carefully heat the seams to fuse them together so that they make a proper bond. Press the seams with your feet and keep on moving forward.

Step 10 - Covering the Edge of Flashing

Stretch the strips of membrane on edges of flashing. Let it overhang by 1/2 inch. Heat the strips to fuse with flashing. Seal the strips by pressing them down.