Wakebath · B2B project decision guide
Survey the slab before choosing the tray support.
Locate slab highs and lows, calculate the depth at the required bearing zones and check the space for the trap and threshold.
Short answer. Measure the concrete across the tray footprint. Compare the readings with the bearing zones and support method for the exact model. If the approved installation cannot accommodate the slab, correct the substrate or assess a compatible raised configuration. Dry fit the waste and threshold before setting the tray.
A slab can be flat and sloping, or generally level with a short ridge through the middle. Record flatness and elevation separately. Use the tray's stated installation reference points to preserve the moulded drainage fall.
Measure the Full Footprint from One Datum
Mark the tray outline, waste centre and bearing zones from the current underside drawing. Establish a level datum with a laser or equivalent site instrument. Take readings at the perimeter, centre, waste opening and each bearing zone. Sweep a straightedge along the length, width and diagonals to find ridges and hollows between survey points.
| Record | Decision it supports |
|---|---|
| Datum, numbered points and their elevations | Find the maximum and minimum available bedding depths or support adjustments. |
| Straightedge span, gap and position | Locate a ridge that could carry the tray at the wrong point or a hollow beneath a required bearing area. |
| Slab condition and existing layers | Refer cracks, movement, weak toppings and incompatible finishes for assessment before setting the tray. |
| Waste opening and pipe route | Check the fit of the body and pipe without losing required support. |
| Adjacent finished floor level | Calculate entry height after tile, adhesive and threshold components are included. |
Attach the marked plan to the readings. A single “7 mm out” measurement gives the next trade neither the position nor the span.
Match the Bearing Method to the Model
A finished tray can require a continuous bed, defined support feet or a proprietary mounting system. Obtain the fitting instructions and drawing for the exact model. Check the substrate preparation, permitted materials, adjustment range and cure conditions. Where a riser is allowed, identify its part number and every required support position.
| Assembly | Check before releasing it |
|---|---|
| Finished tray with continuous bedding | The approved bedding material can achieve the required contact throughout the bearing zone at the measured depths. |
| Finished receptor on specified feet | All required supports bear as detailed. Any adjustable components and centre supports are set and secured as instructed. |
| Tile-ready former | The named former, substrate preparation and drain support form one system. The tile assembly supplies the finished walking surface. |
Sterling's guide 1017263-2-B requires every foot of the listed receptor to contact the floor. Mira offers an optional riser for its Flight Low model 1.1697.495.WH. Schluter calls for floor levelling before placing the relevant KERDI-SHOWER prefabricated substrates. Match the example to its product. Unapproved packers, isolated pads beneath a full-bed tray and force applied through the waste connection need review before work proceeds.
Work Through the Thickest and Thinnest Points
For a flat bearing plane, subtract each measured slab elevation from the planned bearing elevation. For ribs or recesses, calculate against the actual local underside geometry.
| Point | Slab elevation relative to the high point | Required depth with an example bearing plane at +12 mm |
|---|---|---|
| A, high point | 0 mm | 12 mm |
| B, long edge | −3 mm | 15 mm |
| C, central hollow | −7 mm | 19 mm |
| D, far corner | −5 mm | 17 mm |
Suppose the approved assembly on a hypothetical job permits 10 to 16 mm at those bearing points. C and D exceed the assumed range. Review compatible substrate correction and resurvey, or revise the assembly and recalculate the threshold and waste route. The range illustrates the calculation. Obtain actual limits from the product and installation documents.
Dry Fit the Waste and Entry Together
Show the trap body, outlet connection and pipe in section. Include room for the prescribed jointing tools and any future access. Check whether the waste opening intersects a required support zone or the body would contact the tray underside. Refer proposals to cut or grind near structural concrete, a buried service, heating or waterproofing to the responsible designer.
Measure the entry step from the adjacent finished floor at the door line. A riser may solve the trap clearance and raise the profile fixings or change the clearance beneath the glass. Recheck the complete entry and enclosure geometry before approving it.
Release the Work in Stages
| Hold point | Record before release |
|---|---|
| Before setting | Exact model, manual revision, numbered slab survey, approved support method and waste section. |
| During setting | Photos of the prepared slab and supports, specified reference readings and material identity. |
| Before covering | Cure record, stability check using the approved method, accessible waste check and service route photo. |
Rocking after cure calls for investigation of the support and waste alignment before finishing. Record where it occurs. Verify the agreed checks after any correction.
Common Site Questions
Can I tilt the tray towards its waste?
Use the specified installed orientation and reference points. If drainage looks poor, check the moulded fall, installed levels, waste and pipework against the product detail.
Can extra bedding fill any hollow?
Check the approved material and thickness at every bearing point. If the proposed depth falls outside the specified working range, correct the substrate or review another permitted assembly.
Prepare the concrete floor survey
Share the tray model, underside drawing, slab readings, waste section and finished floor level. Mark the proposed support points and any area that needs correction.
Send your project input packReferences and Further Reading
- Sterling installation guide 1017263-2-B, section 3 on supporting the identified receptor.
- Mira Flight Low 1.1697.495.WH, model information and optional riser.
- Schluter Shower System Installation Handbook, substrate preparation for the named prefabricated tile-ready components.