PeterW Posted May 10, 2021 Share Posted May 10, 2021 18mm OSB is support all 4 sides even with T&G so can’t see the benefit tbh as any cost reduction will be lost on labour and frame out etc. Link to comment Share on other sites More sharing options...
SimonD Posted May 10, 2021 Share Posted May 10, 2021 51 minutes ago, PeterW said: 18mm OSB is support all 4 sides even with T&G 18mm OSB only needs support at short ends on joist, no extra framing required. Link to comment Share on other sites More sharing options...
PeterW Posted May 10, 2021 Share Posted May 10, 2021 But if the short edges are not supported or land between then you need to nog it out. Link to comment Share on other sites More sharing options...
SimonD Posted May 10, 2021 Share Posted May 10, 2021 2 minutes ago, PeterW said: But if the short edges are not supported or land between then you need to nog it out. Yes, of course, but isn't that the case with any floor board? And surely you'd frame your floor to avoid that problem. Link to comment Share on other sites More sharing options...
MortarThePoint Posted May 10, 2021 Author Share Posted May 10, 2021 OSB3 prices are close to T&G plywood now. What do people think of using plywood instead? Link to comment Share on other sites More sharing options...
SimonD Posted May 10, 2021 Share Posted May 10, 2021 9 minutes ago, MortarThePoint said: OSB3 prices are close to T&G plywood now. What do people think of using plywood instead? Wow, plywood used to be about 2.5 times the price which is why I went with osb. I'd go for plywood without any worry. Link to comment Share on other sites More sharing options...
PeterW Posted May 10, 2021 Share Posted May 10, 2021 18 minutes ago, SimonD said: Yes, of course, but isn't that the case with any floor board? And surely you'd frame your floor to avoid that problem. No - 22mm Egger can land anywhere and is self supporting. And you can’t frame posi or JJI joists easily with noggins so it’s more of an issue with modern floor systems. Link to comment Share on other sites More sharing options...
MortarThePoint Posted May 10, 2021 Author Share Posted May 10, 2021 (edited) 3 minutes ago, SimonD said: Wow, plywood used to be about 2.5 times the price which is why I went with osb. I'd go for plywood without any worry. I'm seeing prices around £14-15 for 18mm OSB3 T&G 8x2 I've been paying £18 per 8x4 for SE sheathing plywood and can see £16 for 18mm T&G 8x2 What do you think of this: https://sheetmaterialswholesale.co.uk/tg-exterior-softwood-plywood-18-x-600-x-2400mm/ Edited May 10, 2021 by MortarThePoint Link to comment Share on other sites More sharing options...
PeterW Posted May 10, 2021 Share Posted May 10, 2021 2 minutes ago, MortarThePoint said: I'm seeing prices around £14-15 for 18mm OSB3 T&G 8x2 I've been paying £18 per 8x4 for SE sheathing plywood and can see £16 for 18mm T&G 8x2 What do you think of this: https://sheetmaterialswholesale.co.uk/tg-exterior-softwood-plywood-18-x-600-x-2400mm/ Whats wrong with 22mm P5..??? Link to comment Share on other sites More sharing options...
MortarThePoint Posted May 10, 2021 Author Share Posted May 10, 2021 Just now, PeterW said: Whats wrong with 22mm P5..??? I have a downer on added formaldehyde so am planning to use 18mm OSB in the house. In the garage I have trusses rated to 2.5kN/m2 and so want to put a surface down that meets that. 22mm T&G OSB3 is a rare beast in the UK, 21mm T&G plywood is available though, or I could go SE e.g £25/sh for 25mm sheathing plywood. I've found the thickness of that SE plywood to be very variable though. Link to comment Share on other sites More sharing options...
SimonD Posted May 10, 2021 Share Posted May 10, 2021 47 minutes ago, PeterW said: And you can’t frame posi or JJI joists easily with noggins so it’s more of an issue with modern floor systems. I disagree. It's just as suitable for modern floor systems. You'll typically still frame posi and JJI joists at either 400 c/c or 600 c/c (or 16" and 24" c/c), so there's no problem there, other than with a little measurement and lining up the board properly at the start of a run. No big deal. If you really need noggins with posi and JJI, I think in many cases it's easier as you're clipping and nailing these to the top flange, just as you would to support a partition wall with these systems. Alternatively you can use full depth LVL or timber with packers and full depth blocking. James Jones have a great technical library illustrating all these details https://www.jamesjones.co.uk/assets/uploads/assets/downloads/brochures/site-guide-floors-3rd-sept-20.pdf Link to comment Share on other sites More sharing options...
PeterW Posted May 10, 2021 Share Posted May 10, 2021 Ok so this is all additional cost ..? And wastage ..? If I have a run of joists at 600 centres with the final one at 275, and a total span of say 3875mm, then a board won’t work. With 22mm Egger, you can land the offcuts (so the ~1m length) onto the next run as it’s over 2 joists and then carry on as normal. No noggins or intermediates required and glued up it meets all the MIs. 18mm OSB doesn’t allow that, so you now need to slow the process down and nog where the boards fall or bin anything that’s not a multiple of 1200. Doesn’t make sense and is more costly, increased labour and also needs additional components. Add in the 42 day weather guarantee with Egger protect (which you don’t get unless you go OSB4) then why would you do it ..?? It’s not even a cost saving these days with board pricing. Link to comment Share on other sites More sharing options...
SimonD Posted May 10, 2021 Share Posted May 10, 2021 Yes, context is important, I agree. That said, it won't always end up with additional cost and wastage. E.g. at 400 c/c the equation changes. I don't know what board pricing is right now but last I received comparative quotes for Egger v osb, the osb was significantly cheaper. My approach would be to use the materials most suitable to the situation and design. A developer or contractor will no doubt approach it all differently to a one man self-builder. I lay out the board arrangement in CAD first to know how the boards will work. The last time I calculated and boarded a floor @ about 100sqm I ended up with less than 3 boards in total wastage as off cuts and zero noggings. The last time I left it to builder & supplier, I ended up with 4 boards extra from an approx 12sqm room including noggings.. Link to comment Share on other sites More sharing options...
SimonD Posted May 10, 2021 Share Posted May 10, 2021 5 hours ago, MortarThePoint said: I'm seeing prices around £14-15 for 18mm OSB3 T&G 8x2 I've been paying £18 per 8x4 for SE sheathing plywood and can see £16 for 18mm T&G 8x2 What do you think of this: https://sheetmaterialswholesale.co.uk/tg-exterior-softwood-plywood-18-x-600-x-2400mm/ Those seem like good prices at the moment and they have availability. My local timber merchant said they can't get osb until maybe June sometime. Having just looked it up, it's interesting that price difference is now only a few quid between chipboard, osb and ply (I know, I'm slow on the uptake ? ). I've not used Radiata pine plywood yet but by all accounts its quality is up there with the usual European stuff - however, I'm off to a specialist plywood supplier later this week to look at samples of some other Chilean plywood for furniture making. If you like, I can report back on that visit if there's anything helpful in what I find. Link to comment Share on other sites More sharing options...
MortarThePoint Posted May 10, 2021 Author Share Posted May 10, 2021 5 hours ago, SimonD said: Those seem like good prices at the moment and they have availability. My local timber merchant said they can't get osb until maybe June sometime. Having just looked it up, it's interesting that price difference is now only a few quid between chipboard, osb and ply (I know, I'm slow on the uptake ? ). I've not used Radiata pine plywood yet but by all accounts its quality is up there with the usual European stuff - however, I'm off to a specialist plywood supplier later this week to look at samples of some other Chilean plywood for furniture making. If you like, I can report back on that visit if there's anything helpful in what I find. I'd love to hear what you learn, thanks Link to comment Share on other sites More sharing options...
MortarThePoint Posted May 11, 2021 Author Share Posted May 11, 2021 Squareness tolerances are generally quite poor: 3mm/m I'm a bit confused by the tables below as they suggest P5 has much higher UDL capacity than OSB3. The P5 DOP has a Bending Stiffness of 3500N/mm2 and a Characteristic Bending Strength of 11.7N/mm2. The OSB3 DOP has Bending Stiffnesses of 4930N/mm2 along one axis and 1980N/mm2 on the other axis and Characteristic Bending Strengths of 14.8 and 7.4 N/mm2. OSB3 (2008 I think): link CaberFloor P5: link Link to comment Share on other sites More sharing options...
MortarThePoint Posted May 11, 2021 Author Share Posted May 11, 2021 On 10/05/2021 at 10:49, PeterW said: But if the short edges are not supported or land between then you need to nog it out. I believe you need to do this with all P5 including Egger Protect: https://www.egger.com/get_download/17e6c5ab-960a-4e7d-99ee-c46608c62f3a/Flyer_Advanced_Structural_Flooring_System_Fitting_Guide_UK.pdf On 10/05/2021 at 11:20, PeterW said: No - 22mm Egger can land anywhere and is self supporting. Do you have a reference? Link to comment Share on other sites More sharing options...
MortarThePoint Posted May 12, 2021 Author Share Posted May 12, 2021 I've started a separate thread about stiffening the subfloor: Link to comment Share on other sites More sharing options...
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