Bostik Bituminous Mastic for Waterproofing Roofs - 2.5L

• Bostik Bituminous Mastic For Roofs is a multi-purpose trowel grade bituminous material for waterproofing, stopping, bedding, pointing and sealing.
• It can be applied to mastic asphalt, roofing felt, currugated iron, cast iron, fibre cement, slates, lead, copper, zinc, concrete and timber.
• It dries to a flexible black material which remains soft and pliable for a long time after application.
• Size: 2.5L   (Available in sizes 1.2L and 2.5L)

Preparation:

• Bostik Bituminous Mastic For Roofs must only be applied to surfaces that are completely dry.
• Ensure that when applied to bitumen felt no moisture is contained within the felt.
• Ensure the roof surface is structurally sound, clean, dry and free from surface contaminents such as grease, oil, dirt and loose materials.
• Remove any organic growth i.e. moss or lichen with Fungicidal Wash.
• If the surface is either dusty after cleaning, or covered with weathered bitumen, prime with Bostik Penetration Primer for Roofs and allow to dry.
• To assist application in cold weather , store the amterial in a warm room overnight prior to use.

Application:

Apply with a steel trowel or putty knife.

Crack / holes:

• Force Bostik Bituminous Mastic into the cracks, covering over the area to be treated by 25mm either side, at a thickness of 3mm.
• For large cracks and holes apply over areas to be treated and embed a closely woven glass fibre membrane into the compound to overlap the crack or hole by approx 50mm.
• Allow to dry and then apply a second coat, fully covering the reinforcing membrane.

Corrugated iron / fibre cement sheeting:

• Tighten loose hook bolts and trowel around with Bostik Bituminous Mastic.
• Remove loose screws then rebed screws and washers in Bostik Bituminous Mastic and tighten; top seal and trowel to a smooth finish.
• If a sheet is cracked: clean, prime and apply a bandage with a strip of woven glass membrane embedded in Bostik Bituminous Mastic.
• Allow to dry, then overcoat.
• Where it is required to seal side and end laps in corrugated sheeting use the same technique.

Tiles:

• Point up butt ends of ridge tiles, fillets and slates with Bostik Bituminous Mastic.

Lead and Zinc:

• Trowel over cracks and pinholes, where necessary reinforcing with a fully embedded and covered woven glass membrane.

Felt:

• Re-adhere loose felt especially flashings and details, then seal joints with Bostik Bituminous Mastic.