Here's a couple of links for anyone not familiar with the product:
http://www.geocell-schaumglas.eu/en/
https://www.limecrete.net/glasscrete/

I used a similar product (technopor) in some parts of my build and I too found I couldn't get it to lock into a level surface - fortunately it didn't matter in my case.

I see that in the limecrete photos in the link I posted, they use sheets of something - thin ply? - to give a surface they can walk on during installation.

It sounds like you will need some weight to anchor the geogrid in place. Steel mesh should definitely do the job, but perhaps you could succeed by tying bricks or even lumps of concrete to the grid at points where it tries to lift up. In fact perhaps just putting something heavy on top of the grid at places where it lifts would be enough?

just wondering what depth and size of foamglass you used and whether you had to compact it in layers? I would also like to avoid similar problems when I do something similar

my experience is you dont get the 25% reduction and the gear moves around a lot , a ply sheet over the top as suggested is good.
it wont work like type 1 mod or similar hoggings
lay the fabric and whack again, a tamp is useful , try and flatted the roll under pressure prior to work , perhaps cut to length and press between 2 ply sheets with weight on.

Hi Pigglet,
I've recently done this and don't worry, you are not alone. It really is a difficult and worrying undertaking.

I persevered with a heavier thwacking plate which also had went into reverse. This was very difficult and frustrating as, like you I have many corners and alcoves. As the plate tends to dig in l found that it was best to avoid the corners as far as possible and then get a heavy lump hammer and a 4 foot plank, lay the plank along the edges of corners etc and hammer it down. Split plenty of planks, but it seems to work.
I found it very difficult to get the plastic mesh flat, but in some ways the pipework helps. I put bricks on the areas where the pipes/ mesh lifted and then used dollops of limecrete to hold the stuff down as we layed the limecrete. We also put in screeds on limecrete ridges to get things level and this also helps hold things in place until the limecrete covers the pipework.

Once the limecrete is down the horrors of the process recede and it all seems ok.

Interestingly, one of the limecrete floors adjoins a modern concrete slab with 150mm celotex slab of insulation. It's in the same airspace and should therefore be at the same temperature. Several of us have noticed that there is a noticeable difference in the temperature of the floors if walked on without your shoes on. The limecrete feels warm and the concrete feels cold. Neither has its final floor covering on and neither is currently heated.

In our kitchen (around 40 sq meters) we have a limecrete floor with ufh under slate. Our cooker is a woodburning ESSE ( think AGA but made in Barnoldswick). The room sits a 20degrees C 24/7 and the floor feels warm. We let the ESSE go out 2 days ago and turned in the UFH. The room stays at 20 degrees, the floor feels exactly the same but the air is less "comfortable".

With all these floors the depth of foamed glass is different, partly by design but mostly because the difficultty of getting it level. The pipework, may not be exactly at the depth it should be but it all seems to work OK and seems to take more punishment than expected with no ill effects. So, persevere and don't worry do the best you can, It'll be fine! The rants and depression with installation will all be forgotten once the floors down and the heats stays in whilst the moisture stays out.
(Our RH has fallen from over 80% last winter to 50% this winter)

Good luck
Ian

Hi Piglet

How has the project gone? I am about to do something very similar to you!

Thanks
Paul