This sounds like when I take my van to 4 different garages and every one diagnoses something different,,,,
Well if it helps my advice (without knowing the specifics of the exact product you have) would be to read the instructions that come with the floor, sorry if this sounds patronising but these do vary quite a bit with each individual product so is important to adhere to this to keep your warranty valid! If you lay your product using an alternative to the recommendations you can kiss that warranty goodbye!!
I have laid glue system engineered floors and I have laid with the secret nail technique, both very similar floors aesthetically but totally different in their installation requirements, both sytems when used correctly were fine and both floors have been down for years without issue!
Floating glued engineered floors can be layed onto the chipboard, lay underlay first obviously 😀 I recommend using a foil back underlay which has built in damp proofing and sound barrier in one,, expensive stuff and as you have a moisture resistant chipboard base you could prob scrimp a bit on this if you wanted, I personally think if you pay all that money for a floor why scrimp on the underlay but each to their own on that one!!
With reference to the glue system I have had to remove glued down engineered flooring twice in my time doing insurance contracts... this was a nightmare and ripped the subfloor to pieces, I have never in my time had to glue a floor to a sub floor, I’m not saying these systems don’t exist but I have never come across one, (only started out 2 weeks ago tho..lol im lying about that, ive been doing insurance contracts for the last 15years and layed more floors than I can remember) as I see it this product needs to expand and retract and gluing it down to a subfloor contradicts this surely??
all the engineered floors I have laid with a “glue system” are layed floating, you put 3 or 4 rows together, gluing the tounges or grooves, (personally I apply the glue liberally to the tongue and wipe of excess glue with a clean damp cloth as I go) once you have these rows glued they should be clamped with flooring clamps and left to cure,, once this has cured you have a nice solid section packed off and the rest of the floor can be layed, glueing all joints, if the area is one big area you may want to clamp and leave again, always allow required expansion to perimeters and then skirts/beading on to cover,, this product can expand and contract as one with the correct amount of expansion to the perimeters!!
I appreciate you said you have 175m2 but most floors over a certain run will ask for thresholds to be installed for expansion purposes,I much prefer to see a continuous floor rather than thresholds but if it says that you gotta have it then to keep your warranty valid, you gotta have it... £1000 for glue??? Are you serious?? That is madness...again about that warranty lol...even I would ding that off at that price and go and buy evostick all weather glue from b&q, dries clear and does a very good job!! As I said you may be dealing with a floor system I have never layed and if the instructons are tosh get on the phone to the manufacturer rather than the retailer, cant void a warranty if they give you the advice 👍
