It is a ground floor kitchen extension. The heating pipes are sitting in/on that silver insulation. There is a void underneath, and there are air bricks on the outside.
Hope the insulation is top spec. & it seals the pipes in completely from the under floor void or you will be loosing heat & spend a fortune keeping spiders, bugs & the odd mouse in a very desirable des res!
Its a good point you make, I was getting worried about how the heat is going to get through the chipboard, plus ply plus tile - do you think it will work?
With piped U/F systems now being installed on suspended floors, it’s common practice for the heating pipes to be installed below the floorboards (where else would you put them!) but, again, reflective insulation under the pipes is important for the system to be efficient. Obviously the thicker the floor – chipboard, ply overlay then tiles, the longer it will take for the heating system to get up to temperature.
I'll check what adhesive they are using. If they are using the correct type, do you think it will be okay to tile straight onto the chipboard?
For many reasons (& IMO), chipboard is the worst material you could possibly use for any floor; it’s obviously popular as it’s by far the cheapest, both in material & labour costs to lay it. If just fitting carpet or vinyl, the worse you will have to put up with over the years is creaks & movement but, as has already been said, tiling onto chip board is not good. It’s not as rigid as ply & any damp, water spills or even water from a frequently washed floor could find its way through into the chipboard. There are some water resistant boards but the water proof properties of general flooring chipboard are little better than toilet tissue & as soon as it gets wet it will swell & there goes your expensive tiled floor! Except for specialist (& very expensive) products, water proof tile adhesive & grout is only “water proof “ to the extent that won’t deteriorate if they get wet but they are not impervious to water. It can still absorb water & this can work its way through to the base, especially if there are any small flaws or cracks.
A 6mm WBP ply overlay screwed every 200mm would normally stiffen it up nicely & provide sufficient protection but, in your case, it creates a thicker barrier for your U/F heating. It maybe not a helpful comment but, personally, I would never have used chipboard as a tile base in the first place! If it’s at all possible & practicable I would cut my losses, pull it up & replace with minimum 18mm thick WBP ply; but you may need to go thicker, depending on the spacing of the floor supports. IMO, it’s the only way you’re going to guarantee a job that will be resilient & last; but a decent tiled floor is not cheap!
Backer board is insular & must be installed UNDER the heater element not over it; otherwise it will completely stuff the U/F heating system! I’m even reluctant to suggest over boarding with ply for that reason!
