Would be grateful for some advice on the building work we are doing at the moment. Victorian-semi, rear kitchen and dining room have been knocked into one with a 6m extension added to the rear. Leaves approx 10m x 6m room which has already had some concrete poured and is about to have UFH fitted. At the far end of the room is a bifold door that we are trying to get as flush as possible inside. This room needs to seamlessly connect to the hallway which is currently carpeted, under the carpet is floorboards resting on joists. We are fitting Todd Tedd Castlewellan 10mm engineered herringbone. Each plank is 75mm wide, 10mm deep, 490mm long. It is square cut rather than bevelled. We intend to have it glued down. Trying to figure out the best route for floor preparation as have had differing suggestions from builders / floor fitters and wider internet wisdom. Trying to account for the following: Decent, seamless as possible fit of the herringbone floor. Minimising time between screed pour and fitting (as the kitchen and a bunch of other stuff needs to go on top. Bifold door is already installed so threshold is set. The bifold threshold is the same height as the existing floorboards. Rough sketch attached. Thinking as it stands... Floor Prep for Joists Area (B): The existing floorboards aren't good enough to have 10mm herringbone glued to them directly. So either need to be removed or plywood boarded (or some other board?) across the top, but adding a board on top (even 6mm) would require a slope to match the bifold threshold. I will need to take the skirting boards off anyway, in doing so, should it then be easy to remove the floor boards and have plywood added? I don't think the current floor boards at 18mm thick, can I get away with plywood, other material thinner than that? Floor Prep for Concrete Area (A): This needs to be really, really flat and smooth. I'm having a bit of trouble getting specific information about the exact type of screed they intend to pour. In my mind, the eventual height should be exactly the same as the final, prepared area in (B), but if it is a mm lower, the wood will be easier to plane/sand away than the concrete. I have quite a few questions though: Main Screed: It is about 8-10cm from current concrete level to the threshold on the bifold door. From what I read online, regular screed is going to take a really long time to dry - maybe as long as 160 days. The UFH pipes etc will take out some of the volume, but it is still a lot. Having the UFH on low will help. But I'm wondering if there is anything specific I should request... My builder has offered a "Retanol Xtreme" additive that supposedly makes the concrete stronger earlier. I'm not sure if this will actually make it dry quicker and have the floor layed earlier? Advice on the main screed and any additives / special fast dry potions very much appreciated. Final screed: I suppose it rather depends on the above, but I'm wondering whether I need a very "self levelling" screed to give the super-flat finish that (I think) I need for the floor. I've seen latex screed being advised. I've also seen some "liquid pour" screed on youtube. Do I need two different screeds? Might it need 77mm regular screed+3mm latex? Timing: If I need two, do I need to let the main screed dry out before putting the latex down? Does the latex 'seal' the floor? Anything else I should be thinking about? Very appreciative for any advice!
I’d call a flooring contractor in as it’s a far to complex task for diy. Also I wouldn’t have a seamless finish in your doorway as need to allow for expansion
Also if you intend to glue it you will more than likely need to prevent construction moisture in your new concrete, even with ufh it will need a moisture test once the system is commissioned.
