How deep can a mortar bed be on top of a concrete hot tub base when laying porcelain?

80mm is too much. A typical mortar bed should be around 25mm. The fall away from the property should ideally be at 1:80 ratio

20 to 30mm and slope probably 1.5 - 2cm every metre fall is what we do 80mm is ridiculous

I would use a 35mm to 45mm bed

When it comes to laying porcelain slabs on top of a concrete base, there are certain guidelines to follow to ensure a proper installation. Here are some considerations regarding your specific situation: Mortar Bed Thickness: While it's important to have a sufficient mortar bed to support the slabs and provide a level surface, having excessive mortar thickness can lead to issues. The typical recommended mortar bed thickness for porcelain slabs is around 10-15 mm. However, going beyond that thickness can increase the risk of unevenness, cracking, and instability. Falls and Levelness: The falls you mentioned indicate the slope or incline of the slabs. It's common to create a slight slope to ensure water drains properly and doesn't accumulate on the surface. However, if the falls are excessive or inconsistent, it can lead to water pooling or uneven weight distribution, which may cause problems over time. Hot Tub Base: Placing a hot tub on top of the patio introduces additional considerations. The hot tub requires a solid and level foundation to ensure stability and avoid structural issues. Excessive mortar thickness between the hot tub base and the slabs can create an uneven load distribution and potentially cause problems. Potential Problems: With the current situation you described, there are a few potential concerns: a. Unevenness: The inconsistent falls you mentioned could result in a patio surface that is not level. This can lead to water pooling, instability, and potential trip hazards. b. Excessive Mortar Thickness: If the mortar bed continues to deepen as the remaining slabs are laid, it may result in an overly thick layer that can impact stability and load distribution, especially for the hot tub. c. Load Distribution: The combination of excessive mortar thickness and uneven falls may create an uneven load distribution on the hot tub base. This can potentially cause stress and damage to the hot tub structure. Recommendations: It would be best to address these concerns before proceeding further. It may be necessary to consult with a professional contractor or a specialist in patio installations to assess the current situation and provide appropriate guidance. They can determine if adjustments need to be made, such as correcting falls, leveling the surface, or potentially removing and relaying the slabs to ensure a stable and functional patio, especially for the hot tub placement. Remember that these recommendations are general guidelines, and it's crucial to consult with a professional who can assess your specific situation and provide the most accurate advice based on the site conditions and the intended use of the patio and hot tub.

I ADVISE TO GO 30/40mm. I USE 5 PARTS OF SHARP TO ONE PART CEMENT OR STRONGER. I ALSO USE SBR MIXED WITH CEMENT TO FORM A SLURRY MIX. A GOOD LUCK SLIGHT BRUSH ON THE BACK OF TILE HELPS TO CREATE A REALLY FIRM BOND. THE FALL WHEN LAYING PORCELAIN SHOULD BE AROUND 15mm FALL FOR EVERY 1000mm FALLING AWAY FROM PROPERTY.