Every surfboard is a foam core wrapped in fiberglass cloth and resin. The foam type and resin type are two of the most foundational decisions in a custom build, and they're paired โ some foam types work with only certain resins. This guide explains the options, how they pair, and what we default to.
Don't confuse foam *type* with foam *density* โ they're separate choices. Type is the chemistry (PU vs EPS); density is how much that foam weighs per cubic inch. [Read the foam densities guide](/build-guide/foam-densities) for the density side of the equation.
Why It Matters
Foam and resin choice affects every part of how your board feels and ages:
- Weight โ epoxy + EPS is the lightest combination; polyester + PU is the heaviest.
- Flex and feel โ PU foam has a warm, forgiving flex most surfers grew up riding. EPS is stiffer and can feel chattery in small waves but comes alive in bigger surf.
- Durability โ epoxy resin bonds stronger than polyester and holds up to dings better over time.
- Cost โ polyester is the cheapest resin, epoxy is about 15โ25% more; EPS foam costs more than PU.
The combinations aren't all interchangeable. PU foam works with either polyester or epoxy resin. EPS foam works only with epoxy resin (polyester will dissolve EPS). So in practice there are three realistic combinations.
Foam Types
Polyurethane (PU)
The traditional foam โ what most boards have been made of for decades. Warm feel, forgiving flex, good float-to-weight ratio, slightly softer than EPS. PU is what you've probably ridden on every stock surfboard you've ever rented or owned. It's the default for a reason.
Expanded Polystyrene (EPS)
Modern lightweight alternative. Significantly lighter and stiffer than PU. Excels in overhead surf where responsiveness matters more than forgiveness; can feel twitchy or chattery in waist-high mush. More expensive than PU. Requires epoxy resin โ polyester will chemically attack EPS and ruin the board.
Polyester Foam (PF)
A budget alternative to PU with similar properties, slightly cheaper. Rarely used by modern shapers. We don't stock it.
Resin Types
Polyester Resin
The traditional surfboard resin. Affordable, reliable, easy to work with, smells like every surf shop you've ever walked into. Pairs only with PU foam. Produces a classic board โ slightly heavier than epoxy, with a warm flex.
Epoxy Resin
Modern resin. Lighter, stronger bond, more durable against UV and dings, lower VOC (more environmentally friendly). Works with either PU or EPS foam. Costs about 15โ25% more than polyester. Creates a more durable board that ages better.
The Three Realistic Combinations
PU + Polyester (Traditional)
The classic surfboard construction. Used for decades, ridden by everyone. Affordable, warm feel, time-tested, easy to repair. Slightly heavier than any epoxy build.
Best for: budget builds, surfers who specifically want the traditional feel, and boards where the classic aesthetic matters.
PU + Epoxy (Our Default)
PU foam's forgiving flex paired with epoxy resin's durability and lighter weight. This is the build we default to on most custom orders because it delivers the best performance-to-durability ratio for everyday surfing. A PU + epoxy board rides like a PU + polyester board but lasts longer and weighs slightly less.
Best for: the vast majority of our customers. This is what we'll build unless you specifically request one of the alternatives.
EPS + Epoxy (Lightweight Performance)
EPS foam with epoxy resin. The lightest, stiffest combination available. Excellent in bigger surf where every pound matters and where the extra stiffness translates into speed through turns. Feels chattery in small, gutless waves where a softer board would actually ride better.
Best for: experienced surfers in overhead surf, guns, step-ups, and lightweight shortboards. Less forgiving for intermediate riders or small-wave boards.
What We Default To
PU + Epoxy on most boards. If you don't tell us otherwise, this is what we'll build. It's what we'd ride ourselves for everyday conditions.
EPS + Epoxy on request for riders who want maximum weight savings and are surfing bigger waves where that weight savings pays off. We'll pair it with our standard heavy glassing schedule โ the extra cloth layers compensate for EPS's stiffness and keep the board feeling alive.
PU + Polyester on request for budget-conscious customers or surfers who specifically want the classic traditional feel. It's a valid choice and what most classic Lundquist boards were built with in the early years.
Blake's Take
The foam and resin combination is one of the few decisions in a custom build that's genuinely hard to change once the board is built. Everything else โ tints, airsprays, finish, logos โ can be redone, touched up, or adjusted over the life of the board. The foam core and the resin holding it together are permanent.
If you're not sure which way to go, default to PU + epoxy. It's the safe bet, rides beautifully, and lasts a long time. Go EPS + epoxy only if you're specifically surfing bigger waves and want the weight savings; go PU + polyester only if budget is the deciding factor or you're specifically after the traditional feel.