My 170cm bath tub is 169cm, how do I fill this gap?

[jacoscar]

I installed 20mm backerboard to the side wall to bring the space to 171cm (to allow 1cm margin for installation and tiling). Now I realised the bath is 1cm shorter. Can I glue another set of 1cm backerboards to the existing one to close the gap?

 

[CountryFan]

Yes, could do what you propose, or make a ledge with 2x1 batten and quadrant tiles.

 

[jacoscar]

Yes, could do what you propose, or make a ledge with 2x1 batten and quadrant tiles.

Is it sufficient to glue it or do I need mechanical fixings?
The 20mm boards are dotted and dabbed + mechanical fixings, which where a nightmare to fix to the hollow blocks behind

 

[quantumgroup]

Before adding another board, I'd measure the actual gap along the whole bath edge and check that the bath is properly supported. Any extra board needs to be fixed in a way approved by that board manufacturer, especially over hollow blocks, and the bath-to-wall junction still needs a proper waterproof detail; silicone alone isn't a structural filler. I work with Quantum Group, a wholesale supplier of tiles and tiling products. We supply tile backer boards and waterproofing through retailers and can provide product information or help locate your nearest stockist. www.quantumgroupni.com

 

[blup]

Use a large plastic strip that slopes down towards the bath and a decent quality sealant. Wood or similar will attract moisture and eventually rot