Sliding doors and underfloor heating panic mode

[Greenleaves20]

We’re almost at the end of our extension project and I’m having a panic about the warmth of the room. We have a 7.7 x 6m kitchen dining living area with corner sliding doors of 4m x2m and velux windows. Currently mix of concrete and wooden planks on the floor prior to the engineered wood being glued down next week. The radiators are in and on but my worry is the room currently feels uncomfortably cold, eak!! We’ve spent a fortune on this extension and hadn’t even thought about underfloor heating and now I’m panicking that the room will be horribly cold a lot of the time. Anyone been in a similar situation? Did it all feel much warmer once the floors and skirtings etc were in? I’m wondering if we need to get more radiators put in at this stage? We calculated the radiator BTU so if have expected the two radiators we have to be sufficient…

We are in the same place, similar sized room with sliders, windows and a lantern. Our floor is going down next week but it's still going to be cold. Two new tall radiators too. We were all set to have electric under floor heating but changed our minds following consultation on here and worries about the cost of running it. In the end we have gone for a smart controlled plinth heater to warm up the room quickly. Our electrician installed it today and now he tells us he hates electric UFH as it invariably goes wrong and is not easily mended. He thinks we made a good choice. The plinth heater blasted out for just 10 minutes today and the chill was gone even without the radiators being on. It has a timer and thermostat so I can just use it for a pre breakfast boost if I like. Best of all it cost me £250 instead of £3000.

Ahh great idea @sluj thanks. Where have you put it in? Is it visible when you walk into the room? Thanks!

Ours has gone under the oven housing unit so it's only visible in our toom if you turn around and look back at it. Having said that, the grille is white in a very pale grey plinth so it doesn't look horrible. You can get other colour grilles too. I had to really shop around for one that had a Bluetooth programmer and thermostat though.

I have room 4m x 9m with 3 ceiling lanterns and 3 sets of doors and stone floors. I have rads total 18,000 BTU. Only two are needed, that is output 12000BTu at D50.
A lot depends on what kind of insulation you have. And how long you are leaving the heating on for and if that is long enough to heat up the fabric of the building.