Wheat malt is barley malt's closest sibling on a homebrew shop shelf, but the kernel underneath is a genuinely different grain, and that difference shows up directly in the glass. Wheat has no husk in the way barley does — the outer layers that protect and filter a barley mash simply aren't there in the same form — which is both the source of wheat beer's famously persistent, fluffy head and a real practical headache at lauter time.
No husk, no natural filter bed
A mash running heavily on wheat malt lacks the loose husk material that normally forms a barley mash's natural filter bed during lautering, and a grain bill pushed toward wheat malt's practical ceiling can run slow or stick entirely without help. Rice hulls, which contribute no flavour or fermentables of their own, are the standard fix — stirred into a high-wheat mash purely to rebuild the physical filter bed the wheat itself doesn't provide.
Where the 70% ceiling comes from
Wheat malt's high protein content is exactly what gives wheat beer its two signature traits — long-lived, dense foam and a characteristic haze — but too much of it relative to barley malt in the grist makes those same proteins a lautering liability, which is the real reason 70% functions as the conventional practical ceiling rather than a fermentation limit. At 2-4 °Lovibond and roughly 100 °Lintner diastatic power, wheat malt self-converts comfortably and carries plenty of enzyme margin on its own; the ceiling is a mash-mechanics constraint, not an enzyme one.
The protein-rest question
Older brewing references recommend a low-temperature protein rest (roughly 122-131°F/50-55°C) before the main saccharification step on a high-wheat mash, aimed at breaking down some of the protein load before it can cause a stuck sparge or excess chill haze. Modern, well-modified wheat malt from most maltsters needs this less than the under-modified malt those recommendations were originally written for, and plenty of brewers skip the rest entirely at 50-60% wheat with good results — it's a technique worth knowing about and reaching for specifically if a wheat-heavy mash is running slow, not a mandatory step for every batch.
A style built around a legal minimum, not a maximum
German Hefeweizen inverts the usual base-malt logic: Bavarian brewing law has long required a minimum wheat malt content — traditionally at least 50% of the grist — rather than treating wheat as a specialty addition layered onto a barley base. That requirement traces back centuries to restrictions on wheat brewing under the various purity laws that eventually became the Reinheitsgebot, when wheat was considered too valuable a bread grain to spare for beer except by specific royal privilege. Modern Weissbier brewers work well within the 70% mechanical ceiling regardless, typically landing 50-65% wheat malt alongside Pilsner or Pale malt for the balance.
Flavour and the yeast's role in cloudiness
Wheat malt itself contributes a bready, slightly tart, grainy character rather than the sweeter maltiness of barley base malts — subtle enough that a Hefeweizen's dominant banana-and-clove impression comes mostly from its specific yeast strain, not the malt bill. The haze most drinkers associate with wheat beer is a genuine mix of wheat protein haze and suspended yeast, which is why Hefeweizen is traditionally served unfiltered and gently roused rather than poured clear.
Unmalted alternatives
Flaked or torrified wheat can stand in for a portion of malted wheat where a brewer wants the body and haze without the malt's own flavour contribution, though neither carries wheat malt's diastatic power — malted wheat (or a high-enzyme barley base alongside it) still needs to do the converting.