Thorfun

overthinking is what I do best! 🤣 I'm fixing in to concrete blocks that form a block and beam ceiling. I have an SDS drill but also a standard chuck hammer drill too so either is possible. I think 5.5 is too big. I have loads of spare blocks I can test on and can start with 5mm and see where that takes me. I know DeWalt might not know but I'm really confused as to why they say a 4.8mm bit when they don't offer one. it's not like DeWalt at all! normally a manufacturer will only recommend their own products so they can sell more stuff. and yes I am a cynical b*****d.

I'm planning on asking DeWalt technical support what drill bit they recommend. I can't believe they'd recommend something they don't make themselves!

Yeah I saw that. It’s not that I can’t find a 4.8mm bit I just think it’s weird that DeWalt make Tek screws that require a drill bit they don’t produce!

Nice. They don’t do a 4.8mm bit though. although what’s confusing the Tek screws I have are DeWalt and say they need a 4.8mm bit but DeWalt don’t make a 4.8mm masonry drill bit that I can find.

well, I have some concrete screws that do not say on the packaging what drill bit size to use. and research on the web seems to suggest that it depends on the material being screwed in to.

yes! but what size drill bit do you use for those 6.3 x 32mm blue Tek screws? the DeWalt ones I bought say 4.8mm drill bit on the box but other makes on the web say 5mm.

What size drill bit would you use for 6.3mm Tek screws in to concrete blocks? 😊

sadly the day job keeps getting in the way of the self-building and I've used all my holiday allocation up this year on the house so the only time I have left to work on the house is weekends and public holidays.

**** it. everything I can find online says for 6.3mm concrete screws to use a 5mm drill bit. I'm sure it'll be fine.

thanks all. was measuring it up and I'm kind of limited by the beams and not wanting to fix too close to the edge of a block! so after a long think I'm going to fix in to the first block from the wall (approx 300mm) and then every second block which equates to approx 1000mm centres along each primary. it's a similar story for the distance between each primary in that I don't want to fix too close to the edge of a block and so I'm going to see what distance works best. it'll probably be a bit all over the place but hopefully will be a mixture of either 600mm or 900mm centres if I can make that work and will be more effort having to cut the insulation to size rather than just slotting it in but, like @joe90 says, as long as I don't exceed the maximum centre distance then I can fix as often as I like, right? the more the better for strength it just costs more and takes more time. my issue now is I bought these https://www.toolstation.com/dewalt-tapper-pro-blue-hex-head-self-tapping-screws/p86871 as @nod said the blue tex screws are best for fixing the hangers but the box says to use a 4.8mm drill bit! ffs. I have a 5mm drill bit and it's now too late on Christmas Eve to get a 4.8mm bit. if I can't fit the ceiling I'm going to have to spend time with the family over Christmas instead.

i'm struggling to find definitive answer to how far from the walls the first hanger should be for the MF7s to connect to. most of the information on the web just says "install a 1200mm center grid". but some mention 450mm for the first hanger from the wall and others i hear mention 450mm from EVERY wall should be the first hanger and then 1200mm centers from there. so confusing. i've trawled videos and the whitebook but can't get a definitive answer and some even contradict themselves! e.g. one video says that the hangers should be 450mm from every wall but then the video shows only 450mm from one wall. in the whitebook i see these drawings for standard ceilings which simply show 120mm from each wall for the first hanger. and this video also shows just 1200mm from each wall but this video says the first fixing must be max 450mm from the wall and then at 1200mm centers. anyone help clear this up please?

Maybe something from a structural engineer would carry some weight?

probably not want you want to hear but as has been said above if you apply for demolish and rebuild you'll save VAT which on a 180m2 house at £2k/m2 is well over the £52k CIL. so for the worst case scenario if they do enforce the CIL then if you're looking for a silver lining it could actually save money in the long run as you'll save VAT.

wtaf!

congratulations! having recently received our I know what a great feeling it is.