Question 1

1. Do I need adhesive for roof felt?

Accepted Answer

It depends on the system. For cold-bonded felt systems on flat decks the adhesive may be needed for full bonding of the felt to the deck and for sealing laps. On pitched or shed roofs the first layer is often fixed with galvanised clout nails or pins, and then adhesive is used at the overlaps or for subsequent layers. Always follow the felt manufacturer’s specification and check the substrate and exposure conditions.

Question 2

2. How do you apply roofing felt adhesive?

Accepted Answer

The following steps reflect typical practice for using roof felt glue. However, remember that product specification takes priority: always refer to the felt and adhesive manufacturer’s guidelines.

Make sure the roof deck is clean, dry, sound, and free from grease, rust or loose materials.
If the surface is dusty or porous (for example concrete), prime with a bitumen primer and allow to dry.
Apply the adhesive using a squeegee, brush or mop. Follow the coverage rate set out by the manufacturer’s guidelines.
Allow the adhesive to become tacky, typically this can take from 15 minutes to 1 hour, but may be longer in cold or damp conditions.
Lay the roofing felt: overlap side laps a minimum of 75 mm and end laps a minimum of 150 mm.
Press out air and roll the felt (for example with a 15 kg roller) to secure full contact between felt and adhesive.

Question 3

3. Is roofing felt adhesive waterproof?

Accepted Answer

When correctly applied and cured, the adhesive forms a flexible, strong bond that contributes to the water-resistance of the roofing system. It’s part of the waterproofing build-up rather than a fully exposed waterproof membrane on its own.

Question 4

4. How long does felt adhesive take to dry?

Accepted Answer

Drying varies with coat thickness, substrate and weather. A typical period is 24 to 48 hours, though in cold or damp conditions it may take longer.

Question 5

5. How much felt adhesive do I need?

Accepted Answer

The coverage rate varies from product to product, and you can normally find it in their instructions. For example, Bostik lists the coverage for their Bituminous Roof Felt Adhesive as 0.6–0.8 litres per m² for full-area bonding.

You can use this information when planning to work out how much you need:

Measure the total roof deck area in m² (length × width).
Check the adhesive’s coverage rate.
Divide the roof area by the coverage rate to get an estimate of how many litres of adhesive are required.
Add a buffer for overlaps, waste, down-turns and more porous substrates.
Note: Remember to check the product’s Technical Data Sheet for exact coverage and adjust for substrate type and weather conditions.

Example calculation:

Roof area = 10 m × 4 m = 40 m²
Example coverage rate = 0.7 l/m²
Calculate total adhesive = 40 ÷ 0.7 = 57l
Add buffer of 10 % = 63l to order

Roofing felt adhesive

Bostik Bituminous Felt Adhesive For Roofs 5.0L Black

Black Jack 5ltr 904 Roof Felt Adhesive

Everbuild Felt Adhesive 2.5L

Ikopro Roofing Felt Adhesive 5L

Bostik Bitumen Roofing Felt Adhesive 2.5L

Black Jack 2.5ltr 904 Roof Felt Adhesive

Cromar Bituminous Roofing Felt Adhesive 5L

IKOpro High Performance Felt Lap Adhesive - 310ml