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Kerdi vs RedGard Waterproofing: Which One Fits Your Project
Both are listed tile waterproofing membranes. One arrives at a set thickness; the other is built up on site.
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Written by HyreRemodel Research Desk Primary-source research and fact checking
The short answer
Kerdi vs RedGard waterproofing is sheet versus liquid. Schluter KERDI is an 8-mil polyethylene sheet with fleece on both sides, set in thinset mortar, and ICC-ES report ESR-2467 lists it as meeting ANSI A118.10 and for use as a shower lining under IRC P2709.2.
RedGard is a liquid membrane rolled or brushed on; Custom Building Products lists it for crack prevention under ANSI A118.12 and as an IAPMO pan liner meeting ANSI A118.10.
Kerdi gives a fixed thickness with seams to overlap; RedGard gives a seamless coat whose thickness depends on the installer.
What decides between Kerdi and RedGard?
A sheet is the same thickness everywhere. A liquid is only as thick as it is applied.
Kerdi needs overlapped seams and preformed corners. RedGard has no seams; corners and pipe penetrations are treated as its instructions require.
Kerdi pairs with Schluter drains and bands. RedGard goes over many substrates and drains; check each maker’s list.
How do Kerdi and RedGard compare?
From the ICC-ES report and the maker’s product page. Read the current technical data sheet for coats, cure and flood-test timing.
| Compared on | Schluter KERDI (sheet) | RedGard (liquid) |
|---|---|---|
| Form | 8-mil polyethylene with fleece both sides | Liquid, applied on site in coats |
| Waterproofing standard | ANSI A118.10 (ICC-ES ESR-2467) | ANSI A118.10 as an IAPMO-listed pan liner |
| Crack isolation | Not claimed for KERDI in ESR-2467 | ANSI A118.12, per the maker |
| Bonding | Set in thinset mortar | Bonds as it cures; tile set over it |
| Thickness check | Fixed by the sheet | Depends on coats and coverage rate |
| Seams | Overlaps and bands at joints | No seams; corners detailed per instructions |
When Kerdi fits
The sheet does not depend on how hard it was rolled.
Drains, bands and preformed corners from one maker.
Schluter makes a thicker, vapor-retarding KERDI-DS; ESR-2467 lists it as 20 mil.
Schluter sells a board and membrane system; check that every part is on one maker’s list.
When RedGard fits
Niches, benches and curves are coated without cutting sheet pieces.
RedGard is listed under ANSI A118.12.
Coats and rate written down, per the maker’s data sheet.
A single liquid product listed for both uses can cover the bathroom floor and the shower in one approach.
Ask for a flood test either way.
Whichever membrane is used, the shower floor should be flood tested before tile goes down, as your inspector or the maker requires. Ask to see it.
What to ask the tile installer
Ask them to follow the data sheet.
Makers specify compatible mortars. See thinset mortar.
What to have ready before the tile bid
Niches, benches and curbs add corners to detail.
A linear or point drain, and which membrane it is listed with.
Cement board, foam board or drywall, each per the membrane maker’s list.
Ask for photos before tile goes on.
Where this goes wrong
Thickness is the waterproofing. Follow the coverage rate.
Drain and membrane makers list what they warrant together.
A leak found after tile is set means tearing it out.
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Questions
Do I still need a shower pan liner with these membranes?
Is Kerdi or RedGard more waterproof?
What is ANSI A118.10?
Can RedGard be used as a shower pan liner?
Can I mix Kerdi and RedGard?
Does HyreRemodel recommend one?
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