MortarThePoint Posted May 19, 2023 Share Posted May 19, 2023 1 hour ago, Thorfun said: not sure yet! but it's moot as there's a 50mm gap between vertical battens at 450mm above FFL (you can see that in the photos) so even if the bottom batten does rest on the screen to higher of the two vertical battens still aren't resting on anything. i can screw the GL8 through the battens and all the way to the TF. if i use 180mm screws that's a 75mm bearing in the TF plus it's going through 25mm battens. pretty sure that should hold it all! I follow you, I hadn't spotted the gap circled in red: You could bridge over that gap with a GL2 or flat metal strip which would add some vertical strength. Actually, thinking about it, when you have plasterboard screwed to the battens the gap will be bridged. If there is a gap at the very bottom then it's academic as you say. I expect the screws you suggest would be OK, but they are cantilevering out quite far. Can you share some information about any required deflection head? Link to comment Share on other sites More sharing options...
Thorfun Posted May 19, 2023 Author Share Posted May 19, 2023 3 minutes ago, MortarThePoint said: Can you share some information about any required deflection head? If I knew what you were talking about I might be able to! 😂 4 minutes ago, MortarThePoint said: I expect the screws you suggest would be OK, but they are cantilevering out quite far. Yeah. It’s a bit of a worry but I can reduce the GL12 spacing drastically to assist with the load. Link to comment Share on other sites More sharing options...
MortarThePoint Posted May 19, 2023 Share Posted May 19, 2023 You have a deflection head above a non load bearing partition. It's basically a gap (typically 10-15mm) that allows the joists to move vertically without contacting the wall and accidentally loading the wall. Not really relevant at exterior walls as joists are anchored there so don't deflect. Link to comment Share on other sites More sharing options...
Thorfun Posted May 19, 2023 Author Share Posted May 19, 2023 18 minutes ago, MortarThePoint said: You have a deflection head above a non load bearing partition. It's basically a gap (typically 10-15mm) that allows the joists to move vertically without contacting the wall and accidentally loading the wall. Not really relevant at exterior walls as joists are anchored there so don't deflect. Ahh….right. In that case the battened walls are external so not relevant. So I can GL12 close to the external wall and use 600mm centres for them and should be rock solid? 1 Link to comment Share on other sites More sharing options...
JonBATConsult Posted May 23, 2023 Share Posted May 23, 2023 On 19/05/2023 at 06:30, MortarThePoint said: I'd recommend the Gyplyner system. It would be very easy to install. You could use the GL6 brackets to create up to 120mm void link. Longer brackets are available too. PB screws to GL1 track, lengthened using GL3 connectors. GL8 around the perimeter. GL12 is another option for the brackets. Also worth Googling "Gyplyner ceiling" for more info and videos. I compared suppliers and BG are more expensive but their dimpled finish makes it much easier. I'm using this system with AH185 (GL2) brackets. Travis Perkins carry all the BG bits but brackets were expensive so I got those ones from Minster. I'm screwing to concrete soffit (HCF). Plasterer wasn't familiar with this system so was a little nervous of whether it would be level. I've screwed (TechFast) each bracket in place on a 3mm packer to allow adjustment, but only a couple of brackets need tweaking thanks to using a laser level during installation. I've gone a bit OTT with GL1 @ 400mm centres and brackets around 900mm centres. I think the limit is 600mm X 1200mm, so I've made a lot of extra work for myself. What he said. A decent gang could install, tape and joint it all in a day it the lights a terminated in advance. Resilient hangers, bit of 25mm insulation in the void will improve sound insulation by a significant amount. Link to comment Share on other sites More sharing options...
Thorfun Posted May 23, 2023 Author Share Posted May 23, 2023 3 minutes ago, JonBATConsult said: What he said. A decent gang could install, tape and joint it all in a day it the lights a terminated in advance. Resilient hangers, bit of 25mm insulation in the void will improve sound insulation by a significant amount. I don’t have a gang, just me with the occasional help from the mrs. Link to comment Share on other sites More sharing options...
Thorfun Posted May 23, 2023 Author Share Posted May 23, 2023 On 19/05/2023 at 06:30, MortarThePoint said: I compared suppliers and BG are more expensive but their dimpled finish makes it much easier. Out of interest was ESP one of those other manufacturers? Had a quote from my BM for both Gyproc and ESP. I said I’d probably go for Gyproc as I figured in this instance you probably get what you pay for but he said he’d never had any complaints about the ESP stuff. Link to comment Share on other sites More sharing options...
JonBATConsult Posted May 23, 2023 Share Posted May 23, 2023 2 minutes ago, Thorfun said: I don’t have a gang, just me with the occasional help from the mrs. Thats a decent gang 1 Link to comment Share on other sites More sharing options...
JonBATConsult Posted May 23, 2023 Share Posted May 23, 2023 https://www.walls-and-ceilings.co.uk/metal/britishgypsum1.html?_=1684877947009&p=2 Great prices for the metalwork on here. Link to comment Share on other sites More sharing options...
JonBATConsult Posted May 23, 2023 Share Posted May 23, 2023 On 19/05/2023 at 12:20, Thorfun said: this post is an absolute gem. thank you @MortarThePoint. i've read quite a bit about MF ceiling systems in the past and your post seems to make the most sense to me. i was previously getting very lost with all the GL numbers but your simple 'use this, this and this' description was brilliant. so thanks again. i've looked in to the Gypliner system and watched a few videos and it seems really easy. so, once i've confirmed my posi-joists will take the load i'm going to be looking at using GL1 tracks, GL8 wall channels and GL12s for the brackets with the GL3 connectors. using the GL12s gives us up to 175mm drop potential and after discussions with SWMBO we're thinking to drop the ceiling down to allow us a full sheet of plasterboard on the walls. so that'll be approx 160mm drop and will give us 2.4m ceiling heights. does anyone know if screwing the GL8 wall channels in to 25mm battens will be strong enough btw? or should i be looking at going through the 105mm make-up of the external walls and in to the TF? i have 180mm screws left over from attaching the PIR. and any comments/concerns about this solution? and sorry @pocster to not use your suggested grid system. 😉 The weight of the frame is negligable in this scenario. Make sure you plasterboard and system achieves your fire requirements. Make sure speakers have a fire rating so they dont compromise the ceiling. 1 Link to comment Share on other sites More sharing options...
Thorfun Posted May 23, 2023 Author Share Posted May 23, 2023 7 minutes ago, JonBATConsult said: https://www.walls-and-ceilings.co.uk/metal/britishgypsum1.html?_=1684877947009&p=2 Great prices for the metalwork on here. Thanks for this as it just proves that my local Jewson continues to give me better prices than I can find online. Plus I can buy on credit. Link to comment Share on other sites More sharing options...
JonBATConsult Posted May 23, 2023 Share Posted May 23, 2023 Yeah i often find if you go and talk to your local you can get a price that is good. Maybe not with travis perkins though Link to comment Share on other sites More sharing options...
Thorfun Posted May 24, 2023 Author Share Posted May 24, 2023 10 hours ago, JonBATConsult said: bit of 25mm insulation in the void will improve sound insulation by a significant amount. we're putting 100mm RWA45 between the joists. there will be an extra 100mm above the MF ceiling as well and it'll be double boarded and sealed with acoustic sealant around the perimeter etc. as it's the TV room i want to reduce the noise transfer to the bedroom above. 9 hours ago, JonBATConsult said: Yeah i often find if you go and talk to your local you can get a price that is good. Maybe not with travis perkins though i have a very good relationship with my Jewsons which has been built up over the last couple of years much to many on here's confusion as they all find Jewson stupidly expensive! i did start with an account at TP but have never used them as their prices are really high in comparison. Link to comment Share on other sites More sharing options...
Pocster Posted May 24, 2023 Share Posted May 24, 2023 1 hour ago, Thorfun said: as it's the TV room i want to reduce the noise transfer to the bedroom above. And noise in the other direction 😉 Link to comment Share on other sites More sharing options...
Thorfun Posted May 24, 2023 Author Share Posted May 24, 2023 31 minutes ago, pocster said: And noise in the other direction 😉 i hope not as that's my kids bedroom! 😱 2 Link to comment Share on other sites More sharing options...
Pocster Posted May 24, 2023 Share Posted May 24, 2023 56 minutes ago, Thorfun said: i hope not as that's my kids bedroom! 😱 Oops ! 1 Link to comment Share on other sites More sharing options...
Thorfun Posted May 24, 2023 Author Share Posted May 24, 2023 ok, i've had some bad-ish news from the posi-joist company and i'm looking for some smart people to assist with the physics and maths and i know there are plenty on here, obviously that includes @pocster 😉. they have said that the bottom chords were designed to take a load of 200N/m2 (see @SteamyTea i got the units correct unlike some around here) and they said that a single layer of 12.5mm plasterboard is all i can put on the bottom chord of our posi-joists. they did say that as they don't have the job file which is probably now lost amongst the inaccessible files of the now defunct Flight Timber and so they cannot comment more. they are going on the details on the joist layout document that Flight sent me. so, from a quick google is seems that 200N/m2 is equal to 20.394kg/m2 and according to Gyproc their standard 12.5 wallboard is 9.7kg/m2. so, a double board of this stuff should only give a force of 19.4kg/m2, right? therefore i believe that the bottom chord should take a double board of standard 12.5mm plasterboard, right? anyone know if the above calculations are correct? and does anyone know what sort of load the MF dropped ceiling would add? 1 Link to comment Share on other sites More sharing options...
Dave Jones Posted May 24, 2023 Share Posted May 24, 2023 can you use hangers and 6x 2 ? if its a shed build could use 4x2 studs to support the nogs taking the hangers. Link to comment Share on other sites More sharing options...
Thorfun Posted May 24, 2023 Author Share Posted May 24, 2023 11 minutes ago, Dave Jones said: can you use hangers and 6x 2 ? if its a shed build could use 4x2 studs to support the nogs taking the hangers. so, for the dropped ceiling i guess i could look at completely decoupling the false ceiling but then that would add extra load on the TF and might cause those calculations to fail? but i'm also asking for the rest of the downstairs as all the posi-joists are designed with the 200N/m2 load on the bottom chord. so, from the way the guy was talking (although i think there might've been a bit of understandable arse covering going on) i wouldn't be able to double board anywhere. Link to comment Share on other sites More sharing options...
Pocster Posted May 24, 2023 Share Posted May 24, 2023 @Thorfun . You know what to do . Avoid all this fuss and extra cost and go with the obvious and easy solution . Link to comment Share on other sites More sharing options...
Pocster Posted May 24, 2023 Share Posted May 24, 2023 Yawn ….. Link to comment Share on other sites More sharing options...
Thorfun Posted May 24, 2023 Author Share Posted May 24, 2023 2 minutes ago, pocster said: Yawn ….. does that grid system attach to the beams above? 1 Link to comment Share on other sites More sharing options...
Pocster Posted May 24, 2023 Share Posted May 24, 2023 Just now, Thorfun said: does that grid system attach to the beams above? Yes ! But with nice simple hammer in bolts and wire … Link to comment Share on other sites More sharing options...
Pocster Posted May 24, 2023 Share Posted May 24, 2023 What’s the cost estimate for your ceiling ? Timber , pb , skim , paint ? Your area slightly larger than mine I believe Link to comment Share on other sites More sharing options...
Onoff Posted May 24, 2023 Share Posted May 24, 2023 I can always print covers up if you make a hash of the joints. 1 Link to comment Share on other sites More sharing options...
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