Filling gaps in sub floor

[vrytir]

Hi, i have wooden floor on which i want use tilemate boards and ufh on these then self leveling compound then tile on this. Question is should I fill gaps between wooden boards with something or just spread the adhesive and dont bother about gaps? Should I also use primer g before spreading adhesive?
I know I use adhesive to fill gaps between tilemate boards.

 

[White Room]

What size gaps are we talking about.....

 

[vrytir]

About 3mm

 

[brian c]

never used the said boards but cant you screw them down?

 

[White Room]

Are they a cement board like hardie.....

 

[Ajax123]

3mm gaps won't need per filing and to be honest filling them might be counterproductive as it would restrain expansion and contraction. I would make sure they are securely screwed and would deffo consider screwing the insulation boards down using screws with washers....