My garage roof is approx. 8 x 3 metres. I have replaced the boards and now need to waterproof it. I was thinking of a base layer followed by a cap sheet, secured with two layers of felt adhesive. Can you advise the best type of felt to use and roughly how mush felt adhesive to buy?

If looking for a cold bitumen adhesive type system for an external outbuilding/ garage there are three options to consider:

– IKO Trade Underlay with IKO Trade Top Sheet                                                                       –              Up to 10 years life expectancy

– IKO Challenger 180 Sand Underlay and IKO Challenger 180 Green APP Cap Sheet            –              10 years material guarantee

– IKO Challenger 180 Sand Underlay and IKO Challenger 250 Green SBS Cap Sheet            –              15 years material guarantee

Each system product above can be bonded using IKOpro HP Roofing Felt Adhesive.
As a membrane adhesive, the coverage for IKOpro HP Roofing Felt Adhesive is 1-1.5m² per litre (1- 0.67L/m²) dependant on porosity of substrate…
So, for an 8x3m roof… enough adhesive would be needed to cover 48m² (24m² underlay + 24m² cap sheet)…
This would equate to 32-48L of adhesive.