Crumpetman Posted March 17, 2023 Posted March 17, 2023 Hi I have been totally renovating my property and had a single story wrap around extension built with block and beam. All floors have concrete slabs but the block and beam is below the house slab level and so is the entrance area and side extension. My builder said I would just have to level them all out by using different thickness of PIR Insulation, but i'm worried this might cause issues in the future. Anyone have any thoughts please?.
Iceverge Posted March 17, 2023 Posted March 17, 2023 No issues. Just use the Maxim amount of insulation you can. How much depth do you have to make up?
Crumpetman Posted March 17, 2023 Author Posted March 17, 2023 It varies from room 1 x 25mm 1 x 35mm 1 x 60mm Im a bit worried if I dont get a totally level surface then I might end up with cracks in the 60mm screed?.
Iceverge Posted March 17, 2023 Posted March 17, 2023 (edited) You have a total of 25mm for insulation or 25mm difference? Edited March 17, 2023 by Iceverge
Crumpetman Posted March 17, 2023 Author Posted March 17, 2023 sorry no there are 3 different levels throughout the house to make up to the existing slab 25, 35 and 60mm. I then intend to put 100mm PIR Board across all floors.
Iceverge Posted March 17, 2023 Posted March 17, 2023 Ah yes. Can you get to 150mm as a minimal. The. 175mm, 185mm and 210mm on the other areas to make it level. I expect you'll have joints anyway at the doorways so this should take care of any differential movement. If you are worried about cracking in the middle of the room you could use 70mm concrete with 10mm chip and plasticiser with some steel mesh powerfloated to finish.
Crumpetman Posted March 17, 2023 Author Posted March 17, 2023 Cant get 150mm as minimum as would not get a decent ceiling height. I could look into the 70mm concrete option which will probably cost a bit but seems to be a running theme with the cowboys I used. Every days a learning day. Thanks for your help
Iceverge Posted March 17, 2023 Posted March 17, 2023 Concrete is normally cheaper than screed but needs care to get a good finish. You could omit the screed altogether and just put two layers of OSB glued and screwed together floating on top of the insulation. This could give you up to another 50mm to play with and certainly wouldn't crack.
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