February 12, 20251 yr Hi guys Any glazing fitters who can give me some advice on this? I'm getting conflicting advice at the moment from my fitter/builder. We are fitting Sliding Doors in the kitchen/diner (cortizo cor vision). The horizontal width of the door threshold is approximately 120mm and the doors are fitted flush with outer skin. This means 20mm "overhangs" into the wall cavity (we 100mm inner outer blockwork with 100mm cavity). We have beam and block floor with tiles/screed finish/wet UFH. Can this extra 20mm be fitted to the floor screed? My husband says probably not because the screed won't be strong enough but the glazing fitters say it "should" be fine. We were thinking of just carrying on the concrete mix at the bottom of the cavity up till the door threshold as in the picture below to support the "20mm overhang" of the doors into the cavity to support it. Does this seem sensible? I believe the weight of the door unit is approx 50kg/sqm and door is 4m wide and 2.6m height making the total weight of doors approx 520kg. Thanks Ali
February 12, 20251 yr Author Hi, I could do yes - would the 150mm PIR be a good enough base for the doors?
February 12, 20251 yr The doors will sit on and be supported by the outer leaf, just overhanging by 20mm.
February 12, 20251 yr Not much of an overhang into the cavity. My understanding of building regs is a minimum of 30mm of frame into the insulation. (could be wrong). However, the more you can get into the layer of insulation the less of a cold bridge you will have. Consider having frame extenders to each side of the doors, and fitting insulated plasterboard to the inside reveals, and the head if you have room.
February 12, 20251 yr 33 minutes ago, Big Jimbo said: Not much of an overhang into the cavity. My understanding of building regs is a minimum of 30mm of frame into the insulation. (could be wrong). However, the more you can get into the layer of insulation the less of a cold bridge you will have. Consider having frame extenders to each side of the doors, and fitting insulated plasterboard to the inside reveals, and the head if you have room. My get out of jail card there, these days, is to line the door and window reveals with Marmox boards instead of plasterboard. Insulated plasterboard is quite a pig to work with when you have to cut around the metal fixings plates, especially when it's long thin lengths! Marmox is impervious to water / moisture ingress, insulates, and the grey coating will take a coat of plaster directly so no need to plasterboard over it. Downside is it will take less of a 'hit' from a point impact, vs plasterboard + skim, but if you have a good spread who has put 2 sets on then you should be fine with Marmox + skim + paint. You can easily router out the rear of the Marmox, nowhere near as messy as plasterboard, and it can be bonded on vs screws very successfully.
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