LSB Posted February 21, 2023 Share Posted February 21, 2023 (edited) Morning Next question, we have a wall of 18.4m with rooms split into 5m, 4.5m and the rest one room at 8.9m The internal walls are solid rather than stud walls The 8.9m has 2 sets of opening doors of 2m. This is block / block obviously tied together. Does this need any additional strengthening to be stable. I do have SE drawings, which includes a steel frame to support the flat roof, but it's not obvious if there should be a pillar along this wall. It may be that I don't understand the drawings and the marks in the wall are steels, they just seem very small. We are also not having bi-folds now, but sliders, not sure if that makes any difference. Just spotted this on one of the other drawings I guess this is a steel, as in the thing called Wind Post. Thanks Edited February 21, 2023 by LSB Link to comment Share on other sites More sharing options...
markc Posted February 21, 2023 Share Posted February 21, 2023 If you are just opening up 2x2m holes for doors then it’s unlikely any additional pillars or wind bracing will be required. Really only a problem when full width open plan extensions are added 1 Link to comment Share on other sites More sharing options...
Canski Posted February 21, 2023 Share Posted February 21, 2023 Yes a wind post is made of steel and is usually fixed to the foundation. I’ve seen a few cases where they are only shown on the ground floor plans or even worse only as a dotted line on the elevations. Not much help when you have only been given a foundation plan. Link to comment Share on other sites More sharing options...
LSB Posted February 21, 2023 Author Share Posted February 21, 2023 25 minutes ago, Canski said: Yes a wind post is made of steel and is usually fixed to the foundation. I’ve seen a few cases where they are only shown on the ground floor plans or even worse only as a dotted line on the elevations. Not much help when you have only been given a foundation plan. we are only a ground floor 🙂 single storey barn conversion, but the wall shown is our not-wall, i.e. it's the open side where no wall exists All the rest must be kept. We do have steels specified for the roof, but of course they do need something to rest on. The steel experts have not been consulted yet, they are in the factory next door to my hubbies factory and are on-site today, just not our site. Link to comment Share on other sites More sharing options...
Nickfromwales Posted February 21, 2023 Share Posted February 21, 2023 Ask BCO about this, and if there is any need for buttresses etc. The steel may be able to have tongues on it to allow fixing the wall and the steel together mechanically, which may help retain max GIA. 1 Link to comment Share on other sites More sharing options...
Temp Posted February 21, 2023 Share Posted February 21, 2023 9 hours ago, LSB said: Next question, we have a wall of 18.4m with rooms split into 5m, 4.5m and the rest one room at 8.9m There is something in Approved Doc Part A about long walls but got a feeling you are OK if those dividing walls are brick/block. What you might also need is an expansion gap. We did on a shorter wall. Link to comment Share on other sites More sharing options...
Temp Posted February 21, 2023 Share Posted February 21, 2023 Couldn't find it in Part A but google found several reference to 9m. Example.. https://www.housebuild.co.uk/construction/building-guidelines/building-regulations-and-other-guidance/part-a-structure/structure-loading-and-ground-movement Quote The maximum length of wall between vertical supports should not exceed 9 m. Longer walls should be provided with intermediate support, dividing the wall into distinct lengths, by buttressing walls, piers or chimneys, which provide support throughout the full height of the wall. https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.nhbc.co.uk/binaries/content/assets/nhbc/tech-zone/nhbc-standards/tech-guidance/6.1/movement-joints-in-masonry-walls-.pdf&ved=2ahUKEwjVtbXgqqf9AhVQY8AKHaMJCF8QFnoECBUQAQ&usg=AOvVaw0iIrfduR9YBQe2mpnAS2Xm Quote As a general rule movement joints in the outer leaf of external walls should be provided at not more than the following centres: Claybrickwork 10m - 12m Light weight concrete block/brick (aircrete or using light weight aggregates gross density not exceeding 1,500kg/m3) 6m Dense concrete block and brick (using dense aggregate gross density exceeding 1,500kg/m3) 7.5-9m Calcium silicate brick 7.5-9m Any masonry in a parapet wall (lengthtoheightratio>3:1) half the above spacings and 1.5m from corners. Movement joint widths for clay bricks should be not less than 1.3mm/m i.e. 12m = 16mm and for other masonry not less than 10mm 1 Link to comment Share on other sites More sharing options...
George Posted February 22, 2023 Share Posted February 22, 2023 12m - but that's just the scope of application for Part A rules. The outer leaf brickwork may need a movement joint to prevent cracking. I discussed a similar issue here: Link to comment Share on other sites More sharing options...
Gus Potter Posted February 22, 2023 Share Posted February 22, 2023 On 21/02/2023 at 09:01, LSB said: It may be that I don't understand the drawings and the marks in the wall are steels, they just seem very small. Good spot asking that they (wind posts) seem small.. you have a feeling something is a bit off? You have just demonstrated one of the first steps in competancy.. if it looks wrong it probably is! So for all on BH.. if it smells like.. "off" to you then start asking questions! Hope you can glean something from the following general explanation and adapt it to your particular design. I simplify things a bit but the intention is to convey the basic principles, still a long story though! also forgive my spelling and grammer. Ok to start let's say you have a masonry external wall that has a typical window and a door in it. The window is in one room and the door in the other. Between the window and door you have a masonry wall (internal wall) that ties into to the external wall. You may want to take away the internal wall to form say an open plan space. As the internal wall is bonded to the external wall you lose the benefit of the internal wall stopping the external wall moving out / into the garden. The internal wall is acting as what we call a lateral restraint... to stop the external wall from moving in and out. Or you may just have a big long room with a window and a door on the external wall. But the window only extends so far down from the ceiling so you only have a relatively short bit of slender masonry between the window and top half of the door frame.. but change the window to a full height door and now you have a much longer column of masonry between the now two doors. Generally masonry columns can in theory take a lot of vertical load provided the load goes straight down the centre of what we call the neutral axis. For ease of explanation imagine you have a square post or rectangular column. The neutral axis is in the same place as the centre of gravity.. lets just say it's the centre of gravity. If this was the only thing that happens we could be knocking holes in walls with glee and leaving slender masonry columns and all would be ok. If you think about it you may jack up your car, put a concrete block under it and dive underneath or sit a heavy greenhouse on a concrete block? The block does not crush.. but jack the car up 1.0m and pile the blocks up you can see they may wobble/ coggle and buckle sideways... called a lateral failure.. the blocks don't crush they buckle sideways and will be able to carry a lot less load than their compressive strnght load. But in real life the roof loads and loads from say first floor joists / roof truss don't act directly over the centre of gravity of your newly created column and thus they also cause a bending effect in the masonry.. the column wants to bow inwards or outwards as the off centre load causes what is called a bending moment in the column. If you take a ruler and support the ends and push down in the middle with your finger then when you bend the ruler the bending "force" is called the bending moment. The bottom of the ruler stretches (tension) and the top is in compression. If you were able to compress the ruler at the edges end on you would see that it also wants to bend a bit in the middle.. and this genrerates what is called often an eccentric bending moment. Now masonry is good in compression but we avoid creating any tension in the mortar beds as mortar is broady speaking only meant to take compression. In summary when you create a masonry column you need to know where the roof and floor loads sit in relation to the "centre of gravity" of your new masonry column. Next the wind loading: When the wind blows it can create suction or pressure load on the doors / glass. The load on the glass goes to the frames and this gets transferred to the surrounding masonry.. often the new column, unless the window manufacturer can show that their glazing system truly spans from top to bottom and does not load the column. Ask the question. If you get an answer then please report back. Most windows and doors have brackets up the sides.. they must be transferring some horizontal load to the column? This wind can make a huge difference as it can really introduce a significant horizontal loading to the column. All of a sudden when you check this new column for the wind loading it fails by miles and I mean by miles! .. as it's now taking suction pressure loads from the glass. OK what do we do now? One simple way is to calculate the vertical load from say the roof / floor joists and check the masonry column for that only. If there are lots of off centre loads from above we work out how much bending effect they are causing in the new masonry column. Next we work out how much wind pressure suction is acting on the glass and what bending effect this causes in the new column. We look at how the window / door frames work. We introduce a vertical "wind post" that carries the wind horizontal loads and the bending effect from say the roof and floor joists not being over the centre of gravity of the column. We then design the "wind post" to carry the sideways horizontal wind and eccentric bending loads from above and make sure the post is connected to something solid at the bottom and top. We decouple the problem into downwards loads and sideways (lateral) loads. Lastly we recouple the wind post and masonry. We can design the wind post so that it may carry the sideways loads but if in doing so it bends by 10.0mm in the middle then the masonry will also have to move by 10.00mm.. as the wind post is connected to the masonry.. not good! In practice what we do is to look at each bit of the design and say.. how much can we let the wind post bend by (which usually determines it's size) without cracking the masonry and finishes. If you look up the data that the wind post manufacture's give on their wind posts.. they are a bit.. vauge! A lot work on horizontal deflection of height / 300 /360.. some less some more.. but they then introduce a big caveat.. which is it's.. up to you to check the rest.. and your glass etc! Say you have a 2400mm ceiling height... 2400 / 300 = 8.0mm horizontally. Now if we were to bend a masonry column by that amount horizontally.. you doors also .. may complain. If you want to be realistic then design on height say of H/750 to 1000.. also remember that there will be some stretch and play in the fixings so you'll get some extra movement here.. 2400 / 750 = 3.2mm or less. Now you can calculate how much the masonry joint will open up on the outside / inside and if it will recover and not let the water in (crack the render).. Remember though that wind post don't always have to be steel.. I do plenty that are made of timber wind posts as this lets you tailor the job to joiners that you may already have on site. @LSBTo finish. Hope this helps you on your way. It's a bit long but if still stuck then post some elvation drawings and a bit more info. 1 Link to comment Share on other sites More sharing options...
LSB Posted February 24, 2023 Author Share Posted February 24, 2023 On 22/02/2023 at 23:39, Gus Potter said: Good spot asking that they (wind posts) seem small.. you have a feeling something is a bit off? You have just demonstrated one of the first steps in competancy.. if it looks wrong it probably is! So for all on BH.. if it smells like.. "off" to you then start asking questions! Hope you can glean something from the following general explanation and adapt it to your particular design. I simplify things a bit but the intention is to convey the basic principles, still a long story though! also forgive my spelling and grammer. Ok to start let's say you have a masonry external wall that has a typical window and a door in it. The window is in one room and the door in the other. Between the window and door you have a masonry wall (internal wall) that ties into to the external wall. You may want to take away the internal wall to form say an open plan space. As the internal wall is bonded to the external wall you lose the benefit of the internal wall stopping the external wall moving out / into the garden. The internal wall is acting as what we call a lateral restraint... to stop the external wall from moving in and out. Or you may just have a big long room with a window and a door on the external wall. But the window only extends so far down from the ceiling so you only have a relatively short bit of slender masonry between the window and top half of the door frame.. but change the window to a full height door and now you have a much longer column of masonry between the now two doors. Generally masonry columns can in theory take a lot of vertical load provided the load goes straight down the centre of what we call the neutral axis. For ease of explanation imagine you have a square post or rectangular column. The neutral axis is in the same place as the centre of gravity.. lets just say it's the centre of gravity. If this was the only thing that happens we could be knocking holes in walls with glee and leaving slender masonry columns and all would be ok. If you think about it you may jack up your car, put a concrete block under it and dive underneath or sit a heavy greenhouse on a concrete block? The block does not crush.. but jack the car up 1.0m and pile the blocks up you can see they may wobble/ coggle and buckle sideways... called a lateral failure.. the blocks don't crush they buckle sideways and will be able to carry a lot less load than their compressive strnght load. But in real life the roof loads and loads from say first floor joists / roof truss don't act directly over the centre of gravity of your newly created column and thus they also cause a bending effect in the masonry.. the column wants to bow inwards or outwards as the off centre load causes what is called a bending moment in the column. If you take a ruler and support the ends and push down in the middle with your finger then when you bend the ruler the bending "force" is called the bending moment. The bottom of the ruler stretches (tension) and the top is in compression. If you were able to compress the ruler at the edges end on you would see that it also wants to bend a bit in the middle.. and this genrerates what is called often an eccentric bending moment. Now masonry is good in compression but we avoid creating any tension in the mortar beds as mortar is broady speaking only meant to take compression. In summary when you create a masonry column you need to know where the roof and floor loads sit in relation to the "centre of gravity" of your new masonry column. Next the wind loading: When the wind blows it can create suction or pressure load on the doors / glass. The load on the glass goes to the frames and this gets transferred to the surrounding masonry.. often the new column, unless the window manufacturer can show that their glazing system truly spans from top to bottom and does not load the column. Ask the question. If you get an answer then please report back. Most windows and doors have brackets up the sides.. they must be transferring some horizontal load to the column? This wind can make a huge difference as it can really introduce a significant horizontal loading to the column. All of a sudden when you check this new column for the wind loading it fails by miles and I mean by miles! .. as it's now taking suction pressure loads from the glass. OK what do we do now? One simple way is to calculate the vertical load from say the roof / floor joists and check the masonry column for that only. If there are lots of off centre loads from above we work out how much bending effect they are causing in the new masonry column. Next we work out how much wind pressure suction is acting on the glass and what bending effect this causes in the new column. We look at how the window / door frames work. We introduce a vertical "wind post" that carries the wind horizontal loads and the bending effect from say the roof and floor joists not being over the centre of gravity of the column. We then design the "wind post" to carry the sideways horizontal wind and eccentric bending loads from above and make sure the post is connected to something solid at the bottom and top. We decouple the problem into downwards loads and sideways (lateral) loads. Lastly we recouple the wind post and masonry. We can design the wind post so that it may carry the sideways loads but if in doing so it bends by 10.0mm in the middle then the masonry will also have to move by 10.00mm.. as the wind post is connected to the masonry.. not good! In practice what we do is to look at each bit of the design and say.. how much can we let the wind post bend by (which usually determines it's size) without cracking the masonry and finishes. If you look up the data that the wind post manufacture's give on their wind posts.. they are a bit.. vauge! A lot work on horizontal deflection of height / 300 /360.. some less some more.. but they then introduce a big caveat.. which is it's.. up to you to check the rest.. and your glass etc! Say you have a 2400mm ceiling height... 2400 / 300 = 8.0mm horizontally. Now if we were to bend a masonry column by that amount horizontally.. you doors also .. may complain. If you want to be realistic then design on height say of H/750 to 1000.. also remember that there will be some stretch and play in the fixings so you'll get some extra movement here.. 2400 / 750 = 3.2mm or less. Now you can calculate how much the masonry joint will open up on the outside / inside and if it will recover and not let the water in (crack the render).. Remember though that wind post don't always have to be steel.. I do plenty that are made of timber wind posts as this lets you tailor the job to joiners that you may already have on site. @LSBTo finish. Hope this helps you on your way. It's a bit long but if still stuck then post some elvation drawings and a bit more info. thanks very much, that was really interesting, I need to read a few times to digest and attempt to understand. Then I will explain to HID which will test if I have really understood. The height of the roof at that point is 3.013 (existing roof height of barn) so even more to consider than you example. And I thought the foundations were complicated. Link to comment Share on other sites More sharing options...
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