Joe87 Posted May 24, 2023 Share Posted May 24, 2023 Hi, At the moment in my garage/ workshop I have the roof joists on show. I am planning to maybe nail up some thin ply board. How thin is to thin? I was hoping to not have it to thick if possible. Although there will be downlights in the ceiling that will need to be held up. Will 3mm ply for example start to sag?? Thanks Joe Link to comment Share on other sites More sharing options...
SteamyTea Posted May 24, 2023 Share Posted May 24, 2023 How far apart are the joist. If 600mm, then yes it will sag. Can you put in some lightweight 'noggins' every 300mm? 1 Link to comment Share on other sites More sharing options...
TonyT Posted May 24, 2023 Share Posted May 24, 2023 6mm for me 1 Link to comment Share on other sites More sharing options...
Joe87 Posted May 25, 2023 Author Share Posted May 25, 2023 11 hours ago, SteamyTea said: How far apart are the joist. If 600mm, then yes it will sag. Can you put in some lightweight 'noggins' every 300mm? 400mm centres. So fairly close together. 9 hours ago, TonyT said: 6mm for me Is this what you used? If so did you have downlights? 6mm is fairly good. I may have a load of that already. Link to comment Share on other sites More sharing options...
SteamyTea Posted May 25, 2023 Share Posted May 25, 2023 1 hour ago, Joe87 said: 400mm centres. So fairly close together With 6mm that may be ok. Still out some cross bracing though. There was a calculator link posted up about ply sagging, think it was in one of the shelves posts, @Adsibob one I think. 1 Link to comment Share on other sites More sharing options...
Adsibob Posted May 25, 2023 Share Posted May 25, 2023 (edited) 7 hours ago, SteamyTea said: With 6mm that may be ok. Still out some cross bracing though. There was a calculator link posted up about ply sagging, think it was in one of the shelves posts, @Adsibob one I think. The calculator cited was this one I think, but it is designed for shelves: https://woodbin.com/calcs/sagulator/ but I guess if you have support from above every 400mm, it’s perhaps similar in principle to a 400mm depth shelf. Either way, I think 6mm would just about be okay, as long as you added additional bracing for any pendants. But why are you using plywood as your ceiling? You can’t plaster plywood. Edited May 25, 2023 by Adsibob 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted May 25, 2023 Share Posted May 25, 2023 2 hours ago, Adsibob said: why are you using plywood as your ceiling? You can’t plaster plywood It is a garage, so damp. And there is ply already on site. 1 1 Link to comment Share on other sites More sharing options...
Adsibob Posted May 25, 2023 Share Posted May 25, 2023 24 minutes ago, SteamyTea said: It is a garage, so damp. And there is ply already on site. Ah yes, sorry i didn’t read the OP properly. I would just go with the 6mm ply then. 1 Link to comment Share on other sites More sharing options...
joe90 Posted May 25, 2023 Share Posted May 25, 2023 If using only 6mm I would make sure ply edges between joists were supported (I.e. scrap wood screwed to both edges). 1 1 Link to comment Share on other sites More sharing options...
markocosic Posted May 25, 2023 Share Posted May 25, 2023 Floorboards above the joists. Spray the bottoms white. LED strip lights (the equivalent of florescent tubes) in the "bays" between the joists. Sockets on the sides on the joists. That'll give useful spread out diffused light (unlike downlights that bounce off what you're working on and blind you) and sockets in places such that you don't need to run extensions everywhere. Plus you can put lightweight bulky crap on top of the floorboards. 1 Link to comment Share on other sites More sharing options...
MarkyG82 Posted April 3 Share Posted April 3 Apologies for resurrecting this thread. Keeps related info in the same place and reduces the number of things to look through. I am in the same boat and was planning to put a small amount of insulation between the floorboards and the ceiling skin. The aim is to improve comfort, noise insulation (in and out) and finally to help reduce heat loss from the house due to it being a joined garage. Am I being excessive by wanting insulation or is this a worthy endeavour? I will put effort into the front garage doors, floor and last remaining single skin wall. Will that be enough to help control sound and heat with a basic boarded space above? I guess I could insulate and skin at a later date if needed. Link to comment Share on other sites More sharing options...
BotusBuild Posted April 3 Share Posted April 3 1 hour ago, MarkyG82 said: Am I being excessive by wanting insulation or is this a worthy endeavour? Worthy endeavour IMO 1 hour ago, MarkyG82 said: Will that be enough to help control sound and heat with a basic boarded space above? What is they say, Every Little bit helps. 1 Link to comment Share on other sites More sharing options...
MarkyG82 Posted April 3 Share Posted April 3 @BotusBuild thanks. I think I will put effort into the insulation and ceiling. Pretty sure I've figured out that I can do the work around the edges and doors first. That way I have a more organised space to be able to get to the ceiling. Link to comment Share on other sites More sharing options...
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