Can I render Thermalite blocks?

Yes you can, I have much experience with this. I have found that a coat of sbr is sufficient enough preparation, perhaps even an overkill. The Key is in the material. Avoid sand and cement, in fact avoid any cement based material and opt for pre mixed Bags of base coat firstly. This is essential as standard with render and will eliminate suction having the scratch coat. Then depending on weather I only Ever use a water brush to splash the scratch coat before applying top coat. And that would only ever be if it had been a couple of days In between applications of scratch and too coat. Or the sun was shining hard on panel on a hot day. Which almost never happens here in Scotland! Hope this helps

Should never use thermalite block externally... and render. Prone to frost and cracking issues!

Not the best blocks to render over render has a high risk of cracking best to give them a wash over with pva just before scratch coat with plenty of water proof in the mixes top coat should be ok with the water proof in the mixes only use plastering sand &cement

Yes, although cement based render has a tendency to crack over time when applied to thermalite. Try K-Rend.

Yes, you can but be very aware that the thermal blocks suck the water out of the mix. To prevent cracking wet wall down before and mist over after the render is layed on. Repeat misting with water every few hours.

yes but use sbr pva use it strong to stop suckshone put water proof through sand and cement best water proofer is freflo

Yeah you can but i wouldnt recommend cuz by the time the cracks will be there