Thorfun

sounds like he's after you to project manage yourself if he's asking you to find people to supply and fit rather than being a main contractor and offering a turnkey solution. obviously, there's a lot of savings to be had by project managing but it is time consuming! normally, afaik, a main contractor will get his plumber/sparky/chippy to fit the stuff that you can source if you want. but I guess everyone is different and there's no one solution to this building malarky.

I'm seeing him tomorrow so I'll speak to him then and get back to you if that's ok.

?? is this a refurb? i didn't think anyone used felt any more when there are such good breathable membranes out there that will allow the airgap to be above the rafters! As @Iceverge's lovely U-value calculations show to get the same U-value as the PIR between the rafters you'll need 100mm PIR underneath. ultimately these decisions are all about compromise. we used https://www.insulationshop.co/140mm_isover_timber_frame_batt_32.html between our rafters (190mm of it) and 100mm PIR below. if you used mineral wool insulation with a thermal conductivity of 0.032W/mK you might get closer to the U-value with only 75mm PIR. i spent many hours going through different permutations on a U-value calculator to get what i wanted.

i bought another driver with no minimum load and the light works perfectly. thinking 3W might be too bright for the usage we want but will compare with the 1W lights i've also got coming.

they're going in the ground so need to be walk-on-able (like your glazing) also i have a posi-joist in the wrong place so can only fit very narrow cutout spots. all of that means the availability in the UK is poor. found some Astro ones at £30 exc. (https://www.lighting-direct.co.uk/astro-terra-round-28-led-ground-light-brushed-stainless-steel.html) but only 1W, lower lumens and requires constant current drivers. also still 3x the price of buying direct! once i've found a brand i like the look of i'll take it apart and show it to my sparky and see what he says. after all that testing it will still be much cheaper. plus it's low voltage so risk 'should' be lower i guess.

firstly....there are other suppliers so you're not stuck with what the one supplier has! also, what is the make-up of the roof above the rafters? we fully filled our rafters, made possible by what's above it.

100%!! although, when i need around 20 of these things and the Collingwood ones are £60 each it really starts to add up. i could buy 50 from China and keep 30 as spares and still be quids in.

i know a rather good builder based in West Sussex. i didn't use him as i went timber frame (although his comical response was "I have a hammer" 🤣) but i've seen his work and it's very good and he's a really nice guy to boot. if you don't get on with your chosen builders and want another to try let me know. fyi, i haven't asked him if he'd be interested in something in Surrey but happy to make an introduction if you want/need one.

way too late for me! there's no way i'm taking mine all down and replacing them. 😂

+1 for mineral/glass wool between the rafters. it wasn't a nice job but a lot better than it would've been compared to fitting PIR between the rafters!

if you're going the battens route then 100mm through the PIR will be fine as it's just to hold it until the battens go up and they'll REALLY hold the PIR to the rafters. i made sure i had at least 50mm of screw in to the rafters. so for our 100mm PIR i held them in place with 120mm screws and washers and then used 180mm screws through the 25mm battens which gave us a 55mm hold in the rafters. if you're not using battens then i don't think 25mm hold is enough for 75mm PIR personally. i'd be looking at 120mm screws at a minimum but would probably get 150mm screws. can be had online for good prices.

exactly what i was planning! but was probably going to end up with the Loxone PSU rather than a 3rd party one.

i'd rather send it back to Amazon and get a refund and buy something that works! but i'll exhaust all other avenues before i do that (e.g. add more load, try with other led strips if i can find them in some box somewhere etc)

most likely a WhiteWing driver in our Loxone cabinet controlled by DMX with Loxone. so centralised driver. found some mini-ground mounted spots from Collingwood. £65+VAT! this one from China cost me £10 and is smaller.

yeah. I also bought a 1W model from different seller to compare the wattage/lumens etc. these are so cheap compared to UK bought ones that I figured I'd lose so little doing this testing it was worth it. at the end I should have a good idea as to what lumens give me what in real life so can make an informed decision about what to buy for the final lights.

not overloading for sure. I only have one led light on it at the moment. I am just researching and testing at the moment to see if it's worth buying these lights direct from China as they're stupidly expensive over here! thought I'd buy a couple to test (others are en-route). the one I currently have is the 3W model, they do offer a 1W model I just wanted to see if 3W is too much for what we're illuminating as part of the research. photo of sticker below: I can only presume that I've not hit the minimum load. I'll see what I have. problem is most of my stuff is in boxes in the loft of the existing bungalow or basement of the new build so hard to get to and find stuff!

ahh...yes. it did have a minimum load. sorry. so confused like I said. I'll just purchase another 12-24VDC driver that doesn't have a minimum load and see how I get on! might just purchase this instead though: https://www.amazon.co.uk/110-240V-Massager-Essential-Diffusers-5-5x2-1mm/dp/B09YQYJ4B8/ref=sr_1_6?keywords=24v+power+supply+led&qid=1681386910&sprefix=24v+p%2Caps%2C90&sr=8-6 I presume that'll do the job to test single lights?

I'm so confused. I thought I HAD bought a 12-24VDC driver! 🫠

ok. so is this the constant current/constant voltage question I'm also trying to figure out?

found a driver on Amazon that says: The led driver is a constant voltage power supply and is Incompatible for lighting products with adjustable luminosity and chromaticity, otherwise it is prone to burning. For example, dimmable LED lights and color-changing light bars. so does this mean that as my light fitting is dimmable I shouldn't be using a constant voltage driver?

are you saying that if I leave it for a while it'll stop pulsing?

anyone know how I find out if a light is constant current or constant voltage? I don't see anything on the AliExpress website. I ask as I see drivers state 'not suitable for constant current fittings' so how do I know!

Thanks. It’s what I thought it might be. I’ll try and add extra load and see what happens. thanks for the offer of the other driver but I just wanted something to test Chinese lights with before I purchase a load. They will all eventually be driven by a driver in my Loxone cabinet.

in doing some research I bought one of these from AliExpress https://www.aliexpress.com/item/1005002156645871.html?spm=a2g0o.order_list.order_list_main.10.21ef18028Q8IPM (3W version) and one of these from Amazon to drive it https://www.amazon.co.uk/dp/B08QZ366KG?ref=ppx_yo2ov_dt_b_product_details&th=1 (12W version). when I put it together the light is pulsing in a slightly irregular pattern. I've checked with a voltmeter and it's rock steady 240V at the input to the driver but the output is pulsing from 0V DC to 24VDC (ish). the driver manual says 'Min. Load recommended) 7.2W. if I disconnect the light from the driver the voltage is still pulsing. have I simply bought the wrong driver? am I not loading the driver enough? or is the driver or the light faulty?

we had strip foundations dug to 2m on the 'arms' of our build (the bits without a basement underneath) and then put an insulated raft on top like these photos show. it was designed by TSD so maybe give them a chance to come up with a design?