Gus Potter

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About Gus Potter

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  • Birthday 20/09/1964

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  • About Me
    Signed up after having reviewed the questions, comments and responses. Very refreshing and positive. The enthusiasm and knowledge of the contributors to this site is infectious!
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    Near Glasgow

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  1. Hello all. Bri44, I feel for you, it's torture when stuff like this happens. Unfortunately, I see this type of problem more often than I wish. I hope the following will help crystalise your thought process. For all, when faced with a problem it can help to rule things out if you don't know what to do next. This leaves you with a short list of your options and this can make the decision making process easier. A lot of folk buy a property in good faith, if there is no trust then life is pretty poor for all of us. I'll leave out quality of workmanship / competency of design, detailing and so on here as others with more specific knowledge and experience have touched on this already. Suffice to say some of the briefs realting to build problems (which relate to warranties) I have seen are frankly unbelievable, a bit like Harry Potter... That is fun this is not. It does not reflect well on the building industry. I'll run through the previous posts and chip in my thoughts. Bri44.. will a developer buy back a house? .. yes they will. I have seen this offer tabled.. Mr Punter.. good point.. in fairness it's not always true that small builders won't step up to the plate when they get it wrong. In terms of quality of work and so on the big builders can be just as bad as small ones. Don't forget that often a big builder will perhaps get a better offer from say a timber frame manufacturer half way through a development. Someone will make a commercial decision but often no one will make sure the cheaper frame is still compatible with say the founds and the original design.. It’s often a case of "well I'm only paid from the neck down"... not my problem. Russell... I would council not to appoint a Solicitor at this stage. That is actually what I often think they want you to do. I may be that they just want to shift something onto next year’s financial balance sheet! If you get a solicitor it will cost you. For the warranty provider/ big builder it essentially becomes some sort of accountancy problem until they actually need to cough up? At the top end, remember that the warranty providers are an insurance company. The NHBC started out in the public interest when the government set out to improve the housing stock after the war.. Whether they are still doing so and by how much is for them to answer. My experience with the NHBC differs from their original statutory brief and I'm happy to stand by the statement I have just made. In summary I often form the view that this enables them to wage a war of attrition, use their financial clout etc and this can head off having to settle for large amounts... they ( NHBC and Developers etc) know that a lot of people will give up or can't afford to seek professional advice. This is a way of mitigating the number of claims that need to be paid in full if at all. Mike makes some good points. As I roughed out earlier, small cracks are hard to diagnose. If you can be sure that the movement does not pose a structural / safety risk then you maybe want to just look at ways of managing the small cracks that will appear from time to time as the building moves about, over the seasons say. The are a good few expert folk on this site that know about rendering systems and so on so hopefully they will chip in with some advice on how you can apply render systems that can cope with a bit of movement. Declan also make good practical points.. all very well on paper and sitting in an office but practical experience counts for a lot and is intrinsic to any build. Experience counts! Mike Graham.. Mike makes good salient points, material behavoir and the importance of looking after the materials before installation. Onoff.. good forensic question as expected! No mucking about here! Bassanclan touches on the NHBC...I've said enough for now and await developments. Turning back to BRI44. Bri. Advice I often give is once you get to this stage where you have battled away, got a bit of a result but no conclusion is to seek out someone who can take the time to undestand your particular circumstances. As a word of encouragement the email chain in this type of case can extend to more than a thousand so you're not alone. If you can find and SE for eaxmple who has some experience with warranty providers, knows how they operate and can get under the bonnet then your are off to a good start. I have found that once you drill down, cut through all the periferal sales and quality guff and really poke them on the technical and structural safety side of things they start to engage. They may be great on damp proof membranes but generally they are not so strong and also less resourced else where.. this can help bring them to the table. It's not a technical thing per say. You use the technical side to appeal to their bottom line and it is this that get results. It make them nervous as some.. don't have a well resourced solid structural / technical side. The argument I make is that this is going to cost you a lot more than you think! So get serious and start negotiating as adults. I'll caveat that by saying that there are some that don't take this commercial and cynical view. I don't want to prod too many bears at the one time. If you want to do a bit of research look at where most of the warranty providers funds come from and draw your conclusions from that. Lastly Bri, although I laid in a bit much of this is to do with people skills. There are say SE's, Surveyors, Contractors and so on that have seen it all... or most of it They are old salts at dealing with this. Often what you may need is just half a day to sit down with them. They will charge you for their advice and for listening to you but for a relatively small fee they could unlock the door. I find that sometimes when dealing with builders, developers and warranty providers that rather than confronting a problem head on and playing against their strengths it's easier to just back door them.. cynical yes.. but hey it was them that let you down so what do they expect.. no friends in the desert I think is the expression.
  2. Cracking crops up on a petty regular basis and it can cause concern to say the least when it's your home. It is a pretty complex subject but here is an attempt at a lightheated over view of some of the in's and outs. I have caveated some stuff here and there. Looking at the photo (in insolation) that Bri44 posted the crack is relatively small in nature. If you can stick your finger in a crack then you should take action and seek advice. If you notice the crack is getting slowly wider or translating (moving sideways say) over perhaps a few months then think about getting some advice but don't leave it, if days or less then act quickly and take professional advice. You need to be a bit like Columbo here. Strangely, small cracks are often harder to diagnose than big ones. There may be only one or two cracks or there may be lots of small hairline cracks. Often when you have say one big crack the causes are more easily indentified. The stating point is to recognise that houses move all the time. The materials they are constructed from tend to be different - timber - steel - concrete - brick etc and all these materials age and behave in different ways. They expand and contract differently when the temperature goes up or down for example. The house sits on the ground and this too moves about. Bri44 has a clay soil. Clay behaves in a different way from say sandy / gravel type soils. One key difference is that they can shrink and swell depending on how much water they have in them (moisture content). With that in mind some of the things you look at are: Is the site level? Are the founds at the same or different depths - If you have a dry summer then the upper layers of clay tend to be drier than the ones below so they shink by different amounts. Thus the foundations go up and down by different amounts and this leads to differential movement.. which can cause cracking. Do you have any trees or hedges near the house. When in leaf the vegitation sucks the water out the clay soil and causes it to shrink. If you have cut down a tree then it can take a number of years for the soil to read adjust and it will move a bit (usually swell) when it does so. If you have a leaking drain then it can cause the clay to swell locally and this can lift the foundation up while the rest is staying still or shrinking or moving down under perhaps dry summer conditions. Again, if you have installed a new drain that is deep with say pea gravel round it you can sometimes drain the clay and this can cause it to shrink. There are a multitude of factors to consider so it's not always easy. If you have a house with very deep foundations at one end and shallow ones at the other and with a lot of infilled ground round the house at the deep end then as the fill settles over time it can drag down the walls a bit, add load to the founds via the dragging on the walls and they settle a bit more. Often if you are designing piles with made ground you'll examine this effect closely. Moving up to the superstructure. The type and shape of the cracks can tell you a bit. You have a look at where any movement joints are placed in the walls and if they are in the right location. Has the building been altered? If you have knocked out a load bearing wall and put in a beam you often change the way the founds are loaded and this too can result in a bit of cracking. Importantly you want to look at the rest of the house. Are the roof tiles out of alignment. Go inside the attic and look here. Small movements at ground level can be amplified up at roof level so are sometimes easier to spot. Are the doors and windows working ok.. have you notice they are starting to jamb in places? Has the house been left unheated or over heated... are the floors level. Is there other development going on, under or near your house.. The above is just a flavour of what you want to look at. Once you gather all this information you hope that you'll have some idea as to the causes. Then you work out if you need to do anything or just monitor the situation and see if things settle down. More often than not for small cracks it a case of keep an eye on it. You can use "tell tales" or precise levelling techniques to montor movement before you resort to drastic measures. For the curious there is a good document published by the BRE (BRE251) which gives some good guidance and goes some way towards categorising the size and type of cracks. Lastly, Columbo always solves even the most complex of cases. But with small cracks you may just end up with a short list of suspects but no arrest and subsequent conviction.
  3. Gus Potter

    Joists

    Absolutely agree Nick. Flitch beams seemed to be falling out of fashion for a bit... like flares (the trousers) but they are back in fashion now! This is a great friendly site for passing on / picking up tacit knowledge and so on.
  4. Gus Potter

    Joists

    Bang on Nick about the trim out for the roof lights. As you say, it makes the detailing / buildability of the roof lights easier. Gus
  5. Gus Potter

    Joists

    For all. Here is an old rule of thumb which I have applied to Ian's case. This can be used just to get you a feel for how deep a flat roof joist needs to be. Appolgies for mixing units. Ian.. what about this? if you have enough support and it's a warm roof (insulation on top roughly and thus no ventilation required to the joist void) then run a beam within the roof depth to bridge the bit of the kitchen that juts out. Now you have 26 joists @ 4.4m and 7 @ 1.6m. The beam needs to span roughly 7 x 400 mm = 2.8m so you should manage to get something within the roof joist depth that does not result in the beam downstanding from the ceiling. Based on an actual joist metric thickness of 47mm and a spacing of 600mm (2 feet ) then.. Ian has a 4.4m span domestic roof ~ 14.4 feet. Take the span in feet and divide by two.. 14.4 / 2 = 7.2 inches. Add one inch = 7.2 + 1 = 8.2 inches. Now convert to metric 8.2 x 25.4 = 208mm. Take the next metric size up for a C graded timber = 220mm This is the ball park depth you need for the joists. A common length for a bit of structural timber is 4.8m so it's off the shelf = cheeper than say a longer offered length of 6.1m as they generally need to be cut from bigger trees and so on. You may be able to form the transfer beam from say three 220 x 47 timbers, if that is not enough then you can introduce what is called a flitch beam (two bits of timber with a steel plate between & all bolted together) or if that is still not enough! then a small steel beam. The attraction of this is that all the 4.4m joists will bend and sag over time by roughly the same amount. You are working with solid timbers which a lot of local builders / diy folk are more comfortable with. If you cut a joist too short, nip to the mechants and buy another off the shelf. The connections between the timbers and transfer beam can be done with off the shelf timber hangers too. If a steel beam.. you bolt timbers to the steel I beam web and fix your hangers to these, this avoids trying to fix the joists to the steel directly. Now you have a rough joist size and the concept you can start fine tuning. Watch out for other "non standard" types of load such as snow drifting off a higher roof and so on. You can fine tune stuff by changing the timber grade, closing up the spacing of the joists and so on. Lastly the same old rule of thumb applies to solid joist floors with normal domestic loading at concept design stage but generally you add 2 inches to the depth instead of one. This is an old rule so now we also check explicitly for floor vibration and so on. Once you weigh all this up, the skills of the bulder, practicality, material procurement and so on you may find that solid timbers are the most economic / least risk option? All the best Gus
  6. Hobbiniho makes some good points. I’ll weave some other TF stuff in as I go which I hope helps all. In reverse order. Yes, when you look at the configuration of the roof it appears to be fairly standard. Generally, truss designers start out with 600mm spacing as this fits with the spanning capability of standard tile battens and so on. You can then close the spacing / double up if need be when you start to get stuck, say where you have extra localised loads – dormers etc. What you try and avoid is to start changing the depth of the members as this starts for example to cause problems with the alignment of the roof bracing. If you have a good height and want to convert the attic later and the ceiling joists / rafters are different depths then how do you floor / line it out easily? A lot of TF houses throughout the UK don’t have sarking or boarding on the roof. This sarking/ boarding stiffens the roof and often stops people from falling though during construction and maintenance. An SE will often take advantage of this stiffening (called diaphragm action) to shift horizontal loads (loads cause by the wind for example) to where they are more easily dealt with. When you go in the loft you may just see a vapour / moisture control layer and you can feel the tile battens and so on through this. If so, you should see more diagonal type timbers bracing the roof. In old money you’ll often see roofs in Scotland say with rafter spacing of 18” (~458mm).. this keeps the roof member sizes down a bit and lets you use a thinner sarking board. If you are slating onto sarking you don’t want “bouncy” sarking as it’s really difficult to drive the slate nail to just the right depth to keep the slates tight. The closer truss spacing can help here. In other words you need to look at things holistically and not just the trusses in isolation. As a general point. If you are building a single storey extension on a house that has big roof you need to think about snow drift loading. The snow can blow off the main roof and overload the extension roof below. It can drive against any wall above the extension roof and fall back. Snow drifts can be heavy. Another great example is where you have an large span, high eaves height agricultural shed..lots of snow available to pile up on a lower lean to roof. Glenboy posted a couple of drawings. There may well be others that show more detail. While some features of Glenboys drawings may look a bit odd under scrutiny they look to me like concept / early stage provisional drawings. Often a designer will just add rough stuff or notes when a Client is just trying to get a budget price for the works. What I think these drawings are doing is to say to the builder... We need some kind of beam in here, we need some trusses and so on and this is the size of the thing... so give us a rough price for that. The detailed design comes later in the process. In terms of the timbers stacked vertically. I would like to see the rest of the end detail and the TF panel drawings before exploring further. For all. Every house is different and has it’s nuances. Sometimes, where you are tight for height for example you need to go back to first principles of design and this can throw up some less commonly seen details.
  7. Justin. What a project! Roughly where is it? How far north, west or east? What are you doing with it? For all. If you are introducing insulation and start to seal things up then you start to loose the drafts.. roof / floor ventilation and so on. Again for all.. generally dry / wet rot etc does not thrive in cold, dark drafty environments. The more drafts the drier things tend to be.. but that does not fit with the way we want to live now.
  8. Hi Sean. Great link to Tulse Hill, just shows you what can be done! Hopefully you'll find a builder, if not then..go your self. May take you a bit longer but you'll save some money and have that quite satisfaction of having done it yourself. The difficulty many face is finding the time. Apparently a day on Pluto is 6.4 Earth days..
  9. Love this stuff! Don't bother with a slate cutter. To get you started, buy a slating axe. I have a left handed one..as I'm cack handed. I use an off cut of a steel I beam over which I dress the slates. Some basic points which I hope may be of use to someone. You need to grade the slates. The thicker and wider ones go at the bottom near the eaves. I grade second hand slates ( you need to do this with new slate too to make a proper job) into three piles. You can do four but you may lose the will to live. Grading the slates basically helps you keep the roof tight and flat. Have a look at an old slated roof and you will see thicker wider slates at the bottom, thinner narrower ones at the top. When you get to the verge or a valley you need to turn the slate and trim it the other way. What you are doing here is to encourage the water to move back into the roof in the case of a verge.. so it does not drip down the gable walls. In the case of a valley you are trying to stop constant dripping on to the lead valley and making a hole over the years. You try and channel the water down to the gutter so it drips here and this is where you often have a thicker lead piece. You call this "tailing" of the slate. This can't really be done with a machine..it's a craft. In Scotland it rains a lot, much is light rain.. so it drips a lot. In England say you tend to have much more intense rain.. thus the flash flooding but more dry spells and less of that constant dripping. I want to have a rant now! The new home warranty providers and a lot of the slate providers require that all slates are double nailed at the head. Great if your poviding a 10 year warranty, eg if a slate cracks you often don't see it as it does not fall out like a single nailed slate. But a good well maintained roof should last for at least 80 years? For the roof pro's.. repairing a double nailed / every slate roof is hard going? You can fix the slate but the slate ripper causes more damage that is hidden? Yes there are repair type clips and so on but.. A common traditional method of slating in Scotland is to single nail each slate in the main part of the roof. Every third course you cheek nail a row of the slates, these slates now have three nails and stop the ones below from lifting off in the wind. This way when you want to maintain the roof you can get into turn the slates and easily extract the broken one without damaging the felt / membrane underneath. It's worth I think trying to master this skill, it can be very rewarding. I have left this out but make sure you choose the slate nails carefully depending on whether you are near the sea or not. You'll have a bit of wastage until you get the hang of it. Use the trimmings / wastage as decorative material for paths etc? What is worth while doing is investing in a slate holing machine. You turn the slate upside down. The punch makes a concave hole in the top side of the slate and the nail head sits nicely inside so it does not tip up the slate on top..helps get the " tight roof". You can hole the slates by hand but I would suggest getting a feel for cutting / shaping / tailing them first. All the best. Gus
  10. Hello Glen. Hope this helps. Coming off the main house you have a gabled portion (call this gable 1) then you have another bit on the end of gable 1.. call that gable 2. When you are forming timber lintels in a TF kit you can generally nail them together. Common spec would be " nail timbers together with pairs of nails at max 250mm horizontal centres, for deeper lintels you use three nails vertically. You need to keep an edge distance between the nail and the edge/ end of the timbers. In other words you if put the nails too close to the edge / end of the timber it is no good. Also, if you put the nails too close together this is less helpful as you start to encourage the timber to split and so on. To support the ends of the lintels you commonly use what is called a cripple stud arrangement. The window you have on gable 2 looks fairly wide so you may have two shorter timbers under the lintel to hold it up, these are the cripple studs. Smaller openings tend to have just one cripple stud each end of the lintel.. the reasons for this are a bit lengthy to go into detail here. Then you have another stud which is the same height as all the other studs and this is nailed to the cripple studs. You nail through this full height stud into the ends of the lintel. Over the top of the whole thing (unless you are tight for height) goes what is called your top rail and on top of this you have a head binder.. this is the bit of timber that ties all the panels together. Once you nail all this up the lintel is held in place. If you search internet for timber frame cripple studs you''ll see drawings and so on as to how this all fits together. Some of points I make above are conservative in nature, you can fine tune stuff later. Turning to the tying. It's good to get this out the way early on as it's just as important to stop things moving sideways as it is to stop things falling down vertically. Well done picking up on this commonly missed feature. As a further word of encouragement! There are a few ways you can approach tying gable 2 into gable 1 and gable 1 into the main house. The starting point is to determine the ceiling height.. are the ceilings flat or is there some vaulting going on? There are trusses called raised tie trusses - see internet. Here you would line through the ceilings and tie them all together at this level with wind bracing, usually 100 x 22 timbers. Lastly I see the are some UB's (universal steel I shaped beams) on your drawing. It could well be that unless you have a very big main house roof that you can swap these out for timber beams, solid timber or laminated type. I'm a big fan of trying to mimimise the trades, simplify the material procurement process and so on. Here, if you can use timber instead of steel then it's easier for the joiner. You need them for the kit anyway. It's often a lot easier to connect old/ new timber to other timber than connect it to steel. Also, if you get / measure the steel wrong it's often harder to fix. If you cut a bit of wood wrongly.. nip to the mechants, buy another bit and try again. You can use the " reclaimed" timber on the wood stove if you are lucky enough to have one..or cut it into dwangs (Scotland) noggings (England and mostly else where?) That's what I do "occasionally"
  11. Just roughly. The drawing looks like you have a roof load. The 3no 150 x 50 vertically is fine and this is what I would expect to see. Using three timbers in this orientation gives you more capacity; strength, deflection and so on. You''ll often see this when you have a 6 inch TF kit (old money) metric sizes - 145mm deep studs or similar. If you have a 4 inch kit (89 mm deep studs or say 95mm) then you'll often see just the two lintel timbers vertically aligned, but they need to be deeper to carry the same load as 3no 145 mm timbers forming the lintel on your drawing. Using three timbers means you get a shallower over all lintel depth, all other loads and so on being equal. The thickness of each timber is often 45 mm (actual timber size as opposed to nominal size) so you need to pack out by 10mm on the inside ( 3 x 45 = 135mm but the studs are 145mm hence the 10mm) , you carry your inner insulation envelope round the lintel on the inside and this is a recognised way of mitigating the cold bridging. The horizontal lapping and the orientation of the timbers you may be thinking about is to do with how you connect each timber frame panel together at the top, bottom and where you have a corner. This is essentially to do with tying the panels together rather than supporting a roof load say. There is other stuff to do with TF shrinkage. Wood shrinks by differents amount in each direction relative to the grain. In summary you are best to put the timbers the way your drawing shows rather than on the flat, although they still may be strong enough.
  12. Thank you all for your great analysis, discussion, explanation and references. You have all been a great help. I had this thing at the back of my mind that the fuse board could be a max of 3m even with 25mm^2 tails. Thanks again for the time you have taken to write your posts, it's much appreciated. You all have just solved what I thought was a problem for me! It would have taken me days to figure this out on my own.. and I would have needed a good bit of luck to boot. Gus
  13. Hi Hughes. This is a post in two halves. This is for Hughes. and.. As this is a self build type hub the following is partly a general thing for folk that are at the beginning of a journey. Hughes, sounds to me that you are nearly there.. maybe you just need a bit of encouragement. If you take care, measure twice and so on.. it's all doable. For all.. If you're thinking about a self build or DIY project then if you can find something smallish to practice with you are off to a good start. It may just be using your hands, get a feel for basic tools, (a spirit level, tape and so on) the names for other common tools, materials (bricks, blocks) and the language that is used on sites like this. You may want to be less "hands on" but the same rules apply. Hughes, your post struck me. I remember someone from Motorola sales explaining to me about the FUD factor ..fear, uncertainty and doubt. I think it's still relevant to a lot of people; how we fear stepping into the unknown, you know there are uncertainties, then you doubt you own ability. What if you put in the work you need to do, take professional advice if need be at the right time, trust in your own judgement, march on and reap the rewards. All the best
  14. No but.. If you get no joy then think about doing the base yourself? I have seen some fantastic bases / column pads done by first timers who have taken a bit of time to understand what is required, set it all out carefully, made a good finish and cured the slab properly, also seen some horrific ones done by the "professionals" in a rush.
  15. I have chucked in some other general stuff here but for SugarPlum it’s worth a closer look at the decoupling. The timber frame will also shrink a bit so you have that movement to account for too. Keep it simple – hence the attraction of separating (decoupling) the old and the new. Interesting point about the NHBC guidance. It is guidance though. Once you get a handle on the particular features and behaviour/ nuances of the existing structure you can apply first principles of design and adapt the guidance to fit the particular scheme. You need to put a bit more detailed design work in and think laterally, but it should save you money in the long run. We know every building is different in its own way so one solution fits all. That’s why we love them. Plum, you may well still be able to have the slapping so don’t throw in towel just yet. You could save a lot of money not underpinning so the additional cost of a box frame may not be significant. Had a look a Sugarplums floor plan. Point worth clarifying with the timber frames designer is how the lateral stability works, this is the bit that stops the building moving sideways when say the wind blows. There is a fair bit of glass in plums ground floor so less wall panels to resist the sideways movement. This can start to crop up later especially if you live in a windy spot so best to get this out the way and clarified early as it can transfer down / impact on the foundation design. Aside, if you have a drawing showing loads, if possible find out if they are “unfactored” or “factored loads”. An “unfactored load” has no safety factors applied. The difference between the two is significant. Plums’ ridge beam is worth a look at in general terms. Plum – if you are unlucky and things start to go pear shaped with this then you have a few options so perhaps don’t worry too much. For the curious - If you have a basic roof then roughly the two rafters are tied together at the bottom. This tie forms the ceiling and the whole lot often sits on the outside walls. The rafters want to push the walls out, the ceiling ties hold the two walls together. When you vault the ceiling the tie is often cut out unless you leave them in and make a feature of them. You can solve wall spread often by putting in a beam up at ridge height (as Plum mentions) that say spans gable to gable. But you have now transferred roof weight to the gable. You may have a chimney flue or maybe or small opening, right under where you want to put the end of the ridge beam. Old gable walls can be a bit less stable at times. One way of getting round this is to put in an A frame on the inside of the gable. This supports the end of the ridge beam. The bottom of the A frame extends down to the attic floor level / main wall head level and you transfer the load back into the wall here. What you have done is take the load away - down and sideways from say the flue. Here there is a bit more compression in the wall and this can help too, the gable wall is perhaps less weathered etc so the wall can be more sound at this point. This method introduces some horizontal forces (due to what is called an eccentricity) which you need to deal with but it’s all doable. I'll leave the discussion on building regs, the NHBC etc for another time..