FAQ
TL;DR: Slim frames as thin as 8 cm exist; "If you have a decent frame, you can replace the entire contents." Use proper anchoring and face finishing with plasterboard for a flush bowl in aerated concrete. [Elektroda, Parowy, post #17378255]
Why it matters: It helps DIYers and installers mount a flush, reliable concealed WC in aerated-concrete walls without a bulky shelf.
Quick Facts
- Slim 8 cm frames are available (e.g., TECE); they’re wider but thinner for tight niches. [Elektroda, Parowy, post #17378255]
- Set the frame face approx. 2.5 cm behind the wall; screw two boards to the frame for a flush tile base. [Elektroda, ewoo, post #17390165]
- Chemical anchors: threaded rod + two‑component resin; mesh sleeves for voids; cone‑shaped holes; clean dust for bond. [Elektroda, paul0, post #17393315]
- Longevity: Geberit Duofix recessed in 24 cm aerated concrete ran ~10 years failure‑free; mineral wool cut noise. [Elektroda, Felini, post #17393787]
- Alternate layout: With rear access, mount the bowl on pins and put the cistern in the garage/boiler room. [Elektroda, William Bonawentura, #17398964]
Can I mount an 8 cm slim WC frame flush in a 24 cm aerated-concrete wall?
Yes. Users report successful in-wall installs in aerated concrete. Frame anchoring and face finishing are key. One pro noted, “No problem with building in the wall.” Set levels, tie the frame, and finish flush. [Elektroda, ewoo, post #17390165]
Which frame type works best for a recessed install—heavy-duty masonry or light-construction?
Slim heavy-duty frames at 8 cm exist and fit niches. A regular frame also works when anchored and faced properly. TECE offers 8 cm units, wider but thinner. Choose trusted brands and plan face build-up. [Elektroda, Parowy, post #17378255]
How deep should I set the frame and how many boards go on top?
If the wall stays plastered, recess the frame about 2.5 cm. Then screw two plasterboards to the frame. If the whole wall will be boarded, recess similarly and use one in the niche. Ensure no voids between boards. [Elektroda, ewoo, post #17390165]
Will maintenance access be adequate with a concealed cistern?
With reputable frames, you service through the button opening. “You can replace the entire contents” via that access. Ensure the service opening aligns and remains unobstructed. This keeps repairs feasible without opening walls. [Elektroda, Parowy, post #17378255]
What’s the main failure risk with concealed WC frames?
Hidden cisterns work well until internal parts fail. One user warned that “access is illusory” when something collapses inside. Plan for support and parts availability. If access worries you, avoid full concealment. [Elektroda, gimak, post #17378063]
How do I fix the frame securely in aerated concrete?
Use threaded rod with a two-component anchoring resin. Add a mesh sleeve if the wall has voids. Shape the hole like a cone for stronger pull-out. Clean the hole thoroughly before injecting resin. [Elektroda, paul0, post #17393315]
Do I need to blow out drilled holes before anchoring?
Yes. Blow out dust, brush the hole, and blow again. A small compressor with a 24 l tank works. Use a long-nozzle blow gun for reach. [Elektroda, paul0, post #17393342]
How do I mount an 8 cm slim frame flush? (3-step How-To)
- Forge the niche and set the frame face about 2.5 cm behind the wall plane.
- Anchor the frame using upper brackets into the opposite side, or a 50×30 profile fixed with CX5.
- Cut boards to niche size and screw to the frame; keep surfaces flush. [Elektroda, ewoo, post #17390165]
How can I reduce flushing noise from a concealed cistern?
Fill the cavity around the cistern with mineral wool. It damps operating noise without blocking service access. One setup ran about 10 years failure-free using this approach. Gypsum fiber board like Fermacell provides a rigid skin. [Elektroda, Felini, post #17393787]
Are there slim frames under 10 cm?
Yes. TECE slim frames are about 8 cm thick. They are wider but thinner overall, suiting tight niches. Confirm bowl compatibility and mounting height before cutting. [Elektroda, Parowy, post #17378255]
Can I put the cistern on the garage/utility side and keep the bowl flush?
Yes, when the other side is accessible. Mount the bowl on wall pins and place the cistern in the garage. The bathroom wall remains flush, and service becomes easier. Plan water and flush piping routes. [Elektroda, William Bonawentura, #17398964]
Is quick-setting cement like Ceresit CX5 useful for fixing brackets or profiles?
CX5 sets in 3–5 minutes and cures strong. It locks profiles or posts in drilled holes. One installation has held for over eight years. Mix to a pourable mass and work quickly. [Elektroda, ewoo, post #17398926]
Does installation quality really matter?
Yes. One user enjoyed five years trouble-free with a quality installer. A friend’s identical set failed due to choosing only the cheapest service. Assembly quality determines results more than price. Prioritize alignment, anchoring, and sealing. [Elektroda, mawi2, post #17377870]
Will an 8 cm frame leave enough room for the drain?
Slim frames are wider to preserve drain clearance. Verify your outlet path before cutting the niche. Check trap and bend clearances against the frame specification. Ask installers to confirm the drain alignment. [Elektroda, Parowy, post #17378255]
Can a light-construction frame work inside a wall recess?
Yes, with smart layout. One setup used a light-construction frame in an 8 cm wall. The frame protruded into a boiler room and was boxed there. The bathroom side stayed perfectly flush. [Elektroda, ewoo, post #17399008]
Any slim heavy-duty frames people installed successfully?
Yes. One user installed an 8 cm heavy-duty Cersanit Slim&Silent frame. They aimed for a fully flush bowl on a 24 cm wall. Slim masonry-rated frames are available and workable. [Elektroda, Kons18, post #17390330]
