R1plusR2

75mm is the minimum requirment. we upped to 100mm due tomaking up some height id made sense to use insulation. On the extension side the dpm can and will be taped into the dpm, but we will have an issue on the old side as ETC pointed out due to inner dpc on the old side of the house being lower and slate. We was advised to just bring it up thr wall on this side. I dont know much about sap cslcs other than we didnt need them due to the glazing being kept to a standard, or at least thats how it was explained to me. I only know this because i innitially wanted a bigger skylight

Thanks for the reply ETC. I did ask to be fair. Its mostly because i have found other things in the plans were incorrect previously, they were minor things and got corrected. But naturally i tend to look everything up and sometimes thats not a good thing but ey ho, i have ocd and cant help it! Thanks all

Hi ETC. Are you saying a radon barrier should of been specced? Perimiter insulation is on the detail and wont be missed.

Right so its an accepted method. He did advise the secondary membrane to seperate the screed from the insulation. Thats put my mind to rest then. What about slapping the concrete onto the mot1, should i stick some dpm down just to stop the mix drying out too quick?

Hi peter, Sorry thats a typo in my first post, il edit that. My main question is, is it normal to have a dpm on top of concrete rather than under it? Theres no dpm under the concrete on the drawing

Hi all I have a floor buildup plan that my afchitect has specced out for us. I have attached a screenshot of the floor buildup. I have been prepping the floor for concrete the last two days and i just cant let it go that it seems off. To me it seems an odd design but maybe its just "different". The buildup is Screed 75mm pir but we have decided on 100. 1200g dpm 100mm **concrete base* Mot1 Sand/hardcore sub base If you noticed the buildup wording is different to the detail drawing, it clearly shows dpm on top of concrete. I have flowed screed planned for the finish rather than sand/cement. He also advised a dpm to protect the celotex but wasnt 'required' My concerns, Firstly is the dpm in the right place as most seem to be under the concrete? Second, if we dump concrete straight over the hardcore wont it dry out too fast due to the ground wicking the water out the mix too fast usually the dpm would retain the water I do have some other questions but id like to clear this up first to put my mind to rest

Brill. Thats great. Thanks for the help!!

Hi Decal52 Thank you for the response. Right so i am on the right track there. After leveling off is there any need for compaction? Im thinking this would be a bad idea as its solid under it so it cant really go anywhere, i could hand tamp it. Normal practice obviously it would if it were on top of mot1 or subgrade. I have got 25mm pir kingspan for the perimiter edges/upstands. I was told these dont need to be level as its best to trim excess off later after screed? So think i will do that.

Hi peeps So heres my first topic, sorry its a bit of a basic one. We had the 100mm base poured in our kitchen extension at the start of our project. I am now at the point of putting in the insulation and underfloor heating. We made some bad choices on a builder so i have a few knock on effects to deal with. The concrete pad was pumped and tampered with a rake and runs out 25-60mm in places according to my laser level. Plus you can see it by eye. So basically its not smooth or level. In my eyes theres a massive risk the dpm will pierce. The floor buildup on spec 50-60mm liquid screed Underfloor heating (wet) stapled 1200G DPM 100mm insulation 1200g DPM turned up and joined at dpc walls 100mm concrete pad Usually if its hardcore it would be sand blinded, but as its a dpm on top of a pad, should i just blind and compact/level it that way anyway? Id like to get it nice and level for an even screed thickness.

Hi all. I am currently doing a kitchen extension under permitted development with plans submitted. Structure has been built but we are onto the details such as groundwork/screeding etc now. After having bad builders in and ended up putting things right it brings me here to try and gain some extra knoledge from you self builders. So yea, hello!