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My foundation plan looks like this: The two piers that are right in the middle (I’ve drawn a purple ellipse over one of them) are there so the entrance hall (in the middle at the bottom of the picture) will be open plan onto the kitchen, which is in the middle at the top of the picture. I envisaged 100mm wide concrete block piers being built up off the top of the poured concrete foundation (where the piers are) all the way up to the RSJ that will support the side of the landing that overlooks the galleried entrance hall. The top of the stairs may also be supported on this RSJ.

How does this look to you? I’m assuming the unevenness in the centre of the floor will be taken out by sand or screed before the membrane then insulation go on, but what about the edge? I’m concerned about building my block wall (inner skin) up off the edge of the of this BB floor because it looks so far off level. The beam at label A is standing much higher than the blocks either side. The block from B to C doesn’t look flat. The top of the left edge of the block at D looks a lot higher than the top of the right edge at E. The beams went onto DPC. I don’t see that the DPC is doing anything because there’s a dollop of mortar connecting the concrete block in the BB floor to the trench block beneath. I already had a conversation about this picture with somebody & I realised our conversation wasn’t making sense because they were looking at the picture on a phone & they couldn’t see the picture properly, so answers from desktop computer users will be more highly valued, please. I didn’t notice this unevenness until I got the picture off my camera & onto the PC. So there’s a chance that the imperfection is exaggerated by the stupid modern camera, with its wide angle lens. I will have a good look at this when I’m on site tomorrow.

I’d just like to check that it’s normal to fit blocks with bits missing from the edges into B&B floor. Will the builder just stick some mortar into these? If so, will it matter if the mortar slops down to form a bridge to the wet ground, about 250mm below the beams? Once the B&B floor is done, it will likely be many months before we start building the walls. Should I tell the builder to just leave the holes, in case his weak mix (relative to concrete blocks) deteriorates through the winter, & we can fill the holes when we’re ready to build up the floor? How will the small rectangular holes by the sleeper wall be filled?

Does this look OK? I don't understand how it's going to work.

I'm looking for some advice on floating floor construction build up. As part of a renovation project for our ~1990's built home, I want to insulate the ~70 m2 ground floor which is currently of uninsulated beam and block construction with a vented cavity. We are constrained on height of materials that can be added on top of the beam and block, mostly to match existing finished floor level at the bottom of the hallway staircase, but also to avoid shrinking the ceiling height (currently ~2.4 m above finished floor level). So far, it seems like a ply (or other floorboard) sub floor floated on phenolic foam insulation panels will give best combination of thermal resistance, stack height, and cost. We would then add floor coverings, likely all vinyl tile with one room carpeted. I've added a sketch of the proposed build up. I'm looking at using Kingspan K103 which has a compressive strength of 120 kPa at 10% compression. The main questions I have are: Is 18 mm ply going to be rigid enough to avoid deflections / point loads being transferred to the insulation panels? Do we need battens anywhere? So far thinking adding these in doorways, under kitchen units, and for bathroom fittings. IS it necessary to factor in a 6mm ply layer on top as a "sacrificial" covering in case we go with glue down vinyl? Should this be fixed with screws? Interested in thoughts on these points, and anything else I might be missing. If there are any general guides to floating floor construction would appreciate the share.

Hi folks. Anyone understand how you install a radon barrier, when you have block and beam ground floor - the builders QS says we need to "fill" up the underside on the floor. Is this correct - I would have thought it can be installed lower down. Approx, the void w/o fill would be 900mm. TIA

well, finally we have progress! after architect, (bar steward) and building control messing up warrant and having to get another which arrived friday, we are now out of the ground. the drains and tank went in at the beginning of the week and today the beam and block went down. water pipes tomorrow and soon the caravan can be connected. sooo glad to have progress.