Torch-on is a thick bitumen membrane heated onto the surface, and it suits flat roofs and anywhere water tends to sit. Acrylic is a liquid coating rolled or sprayed on, and it suits sloped surfaces, fiddly detail, and places where an open flame is not safe. The right choice comes down to the surface and how much water it has to hold.
Torch-on is a roll of modified bitumen that is melted onto the surface with a gas torch so it bonds and the joins fuse together. The result is a thick, tough membrane. It handles standing water well, which is why it is the usual choice for flat concrete roofs. It is a job for someone who knows what they are doing, both for the quality of the seams and for fire safety, so it is not a DIY product.
Acrylic is a liquid that is rolled or sprayed on in coats, usually with a reinforcing membrane bedded in between. Once it cures it forms a flexible, continuous skin that follows the shape of the surface. Because there is no flame, it is safer to use near timber, over existing membranes, and in tight spots. It copes well with sun and movement, but it is a thinner layer than torch-on, so it generally needs recoating sooner.
On a like-for-like flat roof, a properly laid torch-on membrane usually lasts longer than an acrylic coating, which is part of why it often costs more up front. Acrylic makes up ground when the surface is awkward, when fire is a concern, or when you want a lighter, quicker job. We look at the surface and tell you which one fits, rather than fitting the surface to one product. For a sense of timelines, see how long waterproofing lasts, or look at our waterproofing work.
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