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Roll-on waterproofing is simpler to install and cheaper - you just unroll it, glue it down or heat-weld it. If your foundation is flat and doesn't have complicated features, it'll do the job fine. The downside is you get a lot of seams, and if you don't seal one properly, you'll have problems later. Plus over time the joints can separate due to temperature and humidity swings.
Spray-applied insulation goes on as a continuous layer with no seams - that's its main advantage. It seals better, especially where the foundation has cracks, uneven spots, or lots of protruding elements. But it costs more, requires equipment and application expertise, and if the technique isn't done right, quality suffers.
In the end it comes down to budget and foundation condition. If you're pinching pennies and the base is relatively flat, roll-on works. If you want a more reliable result and can afford to spend more, spray-applied is better. A lot of people do both: lay down roll-on as the base layer, then treat critical spots with liquid sealant or mastic on top.
What type of foundation do you have - strip or pile? If the surface is actually even and accessible, roll-on will be easier to lay down, but spray is better at protecting the joints and corners specifically, where a roll can start leaking over time - it's more insurance against headaches.
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Strip foundation, the surface is even. Thanks, I'll try the spray-on version then for reliability.
I'd go with roll-on if you're doing it yourself - way less hassle and fewer mistakes! Spray-on requires special equipment and experience, otherwise you'll get missed spots and uneven coverage, and redoing it later is a pain! Here's a tip: before you apply the roll-on, brush the foundation surface and prime it with primer - you'll get way better adhesion, and you won't have peeling in the worst possible places down the road.
Spray-applied is more convenient if the foundation has protrusions, corners, and complex geometry - the coating lies evenly without gaps or tears. I had experience with roll-on at my dacha: it seemed simple, but the seams where the foundation goes up and down started leaking after a couple of years, and I had to redo it. True, spray-applied is more expensive and requires professionals, while roll-on you can do yourself if the foundation is perfectly level and simple in shape.
What's your budget and who's doing the work - you or hiring professionals?
I ran into this question when I was helping some friends with their basement renovation. They had a strip foundation that was pretty even overall, but with tons of tiny cracks. At first they wanted the roll-on kind - seemed cheaper and straightforward. But then we started thinking about the seams and corners, where problems usually start. In the end we went with spray-on, brought in a decent crew - and honestly, the result is completely different. The coating goes on as a monolithic layer, no gaps at the seams, everything's airtight. We overpaid by like 30-40%, but you feel way better about the waterproofing holding up.
Roll-on works fine if the surface is perfectly smooth, you're confident in the seam quality, and you're willing to keep an eye on them. But if we're talking about an actual house rather than a shed, and the foundation's seen better days - the spray-on is worth the money. I wouldn't recommend doing it yourself, it's easy to miss spots or apply it unevenly. Now the roll-on, if you really pay attention to the seams, you can handle that yourself, especially if you've got some experience.
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