tonyshouse Posted February 8, 2021 Share Posted February 8, 2021 More likely engineer would want steel beam, SJ, channel etc to protect their PI insurance 1 Link to comment Share on other sites More sharing options...
Moggaman Posted February 8, 2021 Author Share Posted February 8, 2021 3 hours ago, Iceverge said: As you can see we used steel lintels for the wide openings (2m) on the external leaf. All The narrower ones (1m) were standard 100x50 precast lintels. This really is a question for your structural engineer though. If I had my time again I'd avoid precast floors. You end up with a very thick floor ~450mm, the added expense of including a suspended metal ceiling. They're a PITA to core through for services. Installing them without guys making ribbons of any airtightness tray is nearly impossible. Despite requests and being on site they still crowbar the slabs back and forward over the plastic membrane. Thanks @Iceverge. Your build is similar to mine except for urs is a full 2 storey. I think i will go block on flat, even tho posters, who are probably right!, say it is over the top. It is an extra 900 to 1000 blocks. The 6 inch block is not popular to lay where i am from and the blocklayer said it would they would charge me alot more to lay a 27kg block that a 20kg block so i dont think the cost difference with be prohibitive. My engineer was on to me about widening the internal wall so i think i will. The benefits are very wide window reveals which we like ie window seats and peace of mind with the Hollow Core sitting on something a bit wider. 'As you can see we used steel lintels for the wide openings (2m) on the external leaf.' - Was this 2 steel beams ie one wide steel beam(215mm) on wide inner leaf and another beam approx 100mm on outer. 'All The narrower ones (1m) were standard 100x50 precast lintels' - Was this 2 No.100mm lintels side by side on the inner leaf and 1 No 100mm lintel on the outer leaf?. In relation to Hollowcore, i have 2 quotes.. Clare and Limerick.. I take what you are saying , the first floor at 450mm is deep and I havent started think about services yet!! For those wondering, even tho I am building in Ireland, I like the UK forums because I find the feedback frequent and inciteful and we are not all that different! Thanks 1 Link to comment Share on other sites More sharing options...
tonyshouse Posted February 9, 2021 Share Posted February 9, 2021 I think concrete lintels on the outside skin would be ok though I would prefer to see 140mm ones rather than 65mm ones, on the inner skin where concrete planks are bearing on them definitely steel beams or channels every time need to keep wind out of hollow cores especially cross draughts. Tony tray does it bit I foam filled the ends too. service holes should not be core drilled out but designed and performed in ! 1 Link to comment Share on other sites More sharing options...
Dave Jones Posted February 9, 2021 Share Posted February 9, 2021 7 hours ago, Moggaman said: Thanks @Iceverge. Your build is similar to mine except for urs is a full 2 storey. I think i will go block on flat, even tho posters, who are probably right!, say it is over the top. It is an extra 900 to 1000 blocks. The 6 inch block is not popular to lay where i am from and the blocklayer said it would they would charge me alot more to lay a 27kg block that a 20kg block so i dont think the cost difference with be prohibitive. My engineer was on to me about widening the internal wall so i think i will. The benefits are very wide window reveals which we like ie window seats and peace of mind with the Hollow Core sitting on something a bit wider. 'As you can see we used steel lintels for the wide openings (2m) on the external leaf.' - Was this 2 steel beams ie one wide steel beam(215mm) on wide inner leaf and another beam approx 100mm on outer. 'All The narrower ones (1m) were standard 100x50 precast lintels' - Was this 2 No.100mm lintels side by side on the inner leaf and 1 No 100mm lintel on the outer leaf?. In relation to Hollowcore, i have 2 quotes.. Clare and Limerick.. I take what you are saying , the first floor at 450mm is deep and I havent started think about services yet!! For those wondering, even tho I am building in Ireland, I like the UK forums because I find the feedback frequent and inciteful and we are not all that different! Thanks pointless. thermolite and if you want to lose more floor space for a large reveal and window seat more insulation and stud it. 1 Link to comment Share on other sites More sharing options...
Mr Punter Posted February 9, 2021 Share Posted February 9, 2021 With the blocks laid flat you gain nothing structurally or thermally. You have an extra £1,200 in materials and £2,000 in labour plus additional time. You also lose 9m2 of floor space, which at £3,000 per metre would be £27,000. Not the way I would chose to drop thirty grand! 1 Link to comment Share on other sites More sharing options...
Iceverge Posted February 9, 2021 Share Posted February 9, 2021 We needed 215 blocks on our inner leaf because we have quite long runs with no buttressing walls internally. I did ask our engineer about reducing block width but he wasn't keen. Also it left us free to have 2700mm ceilings internally. We would have been limited to 12 courses of 100mm block on edge otherwise. With the dropped ceilings we would have ended up at about 2500mm ceiling height which I thought was too low. The first floor is 100mm blocks on both inner and outer leaf. The Precast slab only bears on 100mm of the blockwork anyway. In hindsight we should have airtight painted the top of the bearing blocks, shuttered around the edge of the slabs and poured the slab and screed as one for airtightness. Forget about any membrane or tray like @tonyshouse did. 14 hours ago, tonyshouse said: need to keep wind out of hollow cores especially cross draughts. Tony tray does it bit I foam filled the ends too For a tony tray to work I think you have to personally install everything. The installers only want to drop their slabs, sledge and crowbar them into place, and leave. In their mind they're not getting paid to do anymore. The hollowcore factories are now offering to seal the ends AFAIK. Link to comment Share on other sites More sharing options...
Mr Punter Posted February 9, 2021 Share Posted February 9, 2021 14 minutes ago, Iceverge said: The hollowcore factories are now offering to seal the ends AFAIK That is good. We have fixed up into hollowcore planks and got about half a bucket of water from each core. I guess the ones we didn't drill still have this. Link to comment Share on other sites More sharing options...
tonyshouse Posted February 9, 2021 Share Posted February 9, 2021 What is the airtight paint doing? Link to comment Share on other sites More sharing options...
Iceverge Posted February 10, 2021 Share Posted February 10, 2021 (edited) 3 hours ago, tonyshouse said: What is the airtight paint doing? Preventing air leaks through the blocks below the slab. These won't be wet plastered as they are above the plasterboard in line with the suspended metal ceiling. Also painting the top of the blocks guarantees a continuous unbroken airtightness line to the poured concrete. Edited February 10, 2021 by Iceverge Clarity 1 Link to comment Share on other sites More sharing options...
tonyshouse Posted February 10, 2021 Share Posted February 10, 2021 Nice Link to comment Share on other sites More sharing options...
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