Gus Potter

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.

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.

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

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

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.

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.

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..

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

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"

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.

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

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

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.

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..

Interesting job this. A few initial thoughts, you have maybe covered this already though. The differential settlement could well be an issue. Worth looking to see (you may already have) if you can decouple / simplify the problem to avoid underpinning, creating a stiff point in the old house and so on. If you can you could allow the new extension to move independantly from the older structure and detail for this - tricky though! The 7.0 kN point load is not too onerous a reaction from the beam framing into the beam over the slapping. It may be that this is just carrying some floor load rather than floor and roof load etc. You may be able to under sling this beam from the roof above and transfer this load somewhere else where it is more easily dealt with. This now leaves you with just the slapping. What might be able to do here is to create a steel box frame. Beam over the top, two columns each side and a heavier beam at the bottom. The bottom beam goes just below ground floor level. The load comes down the columns and the bottom beam spreads the load more evenly over the whole length of the existing found which you don’t touch. Simplfying - the existing found still experiences roughly the same loading regime. You’ll lose a bit on the width of the opening but this is less disruptive. I saw a chimney breast in there. Worth thinking about but if you are using an old chimney to support say a pad stone / beam. Consider the integrity of the masonry. It may have some form of sulphate attack from soot so it looks ok on the outside but less so on the in. The box frame column can resolve any potential issues here. You can also use the columns of the steel box to provide lateral restraint to the walls where you cut an opening. Can come in handy. With a box frame you can then get really keen if you have to with the analysis by changing the stiffness of the connections, you can shift the load about this way a little to fine tune. There seems to be a wall at the back of the stair to come down. This will unload the found so maybe opportunity to add a bit of load back in here. Temp makes a good point about the existing single storey found in that the extra storey may overload them. Sugar plum – post some plan view drawings if you want, floor and roof joist layout. Need to nip off now. The trees, foundation depths are probably worth a later look.

We all make mistakes from time to time. It is difficult when you have a good relationship with your builder. Much worse though if you don't. Try your best to keep things friendly and the lines of communication open. Once the relationship starts to break down the cost and stress can rapidly mount. If you are not finished the work then the "extras may start to pile up" and the whole thing can start to turn into a total mess. If this happens unfortunately there are often no winners. Check it is indeed the builder's mistake, although they think it is at the moment. You mention it is a large extension. Suppose for example one of the walls is next to the boundary. It may be that the ground worker on the day applied some common sense and put the founds up to the boundary so that your structure was not on someone else's land. The ground worker may have saved everyone's skin! If you start some financial negotiation then try and put your self in the builder's shoes. Hopefully they too will take the same approach. This often helps both sides reach an equitable solution. If they claim on their insurance then their premiums go up for the foreseable future. If they have to just write you a cheque this is a total loss for them. It may be that you can negotiate whereby they do some extra work / provide materials at cost or less. You get a bit more and the builder takes less of a hit. Hope it all works out ok.

Hi Jilly and everyone. Jilly seems to have a common problem in that some builders are not interested, some are chancing their arm and one lacks confidence. To really simplify things. To me self builders often fall between two stones. We know that we can build something, save money, "realise the dream" and have that satisfaction of just doing it yourself. We often have confidence in our ability. This gets you started and a bit down the road. The posts so far are bang on but I have gone back a step to the beginning. I have cobbled this together so it's a bit rough / not polished. I'll get my excuses in for early for the simplistic analysis, but it may be of some use to someone. If you don't know what to do (say cost in Jilly's case) then you can start by ruling things out. This leaves you knowing definitely what you don't want and it can make it easier to decide what you do want. You'll get good advice on this site regarding how you drive down prices, negotiate a contract, specify what you require and how you approach any dispute that may unfortunately arise. But how do you actually get to this point in the first place? A builder may lack the skills needed for the sale but it doesn't mean they are a bad tradesperson! We are not looking for salespersons, we need good competant builders at a fair price. To the experienced members of this site.. remember starting out! How confident / experienced were we then? I try not to not to dwell on that too much, too embarrassing. To get you started with builder the first thing that is worth a try is to get their interest, you often need to appeal to their pocket. Their is a saying that the number at the bottom of a builders invoice is not their registered charity number, it is the vat number. To generate interest you can indicate that you are willing to pay a fair rate and make regular payments. For a small builder this can mean that they will get a bit of bread and butter work which leaves them able to expand or say chance thier arm with someone else in the knowledge that their mortgage is paid, cynical yes. Not all builders are like this and I would urge you to keep an open mind. Some for example just want to make a reasonable living as they may have family commitments that take precedence... they will still do you a great job though. To expand a bit further. A lot of self builders won't / can't afford to pay for a site investigation. In Jilly's case the builder has no idea what they will have to do once they get into the nitty gritty and so will cover their risk. They may worry that should they need to do extra work you won't have the money to pay or become difficult. The variation in price that Jilly mentions is in part to do with how the builder percieves the risk to themselves. In all negotiations it it worth trying to see things as others do. What Jilly could do is to say to the builder.. well if you need to go down and extra two feet what is the rate for every square metre of masonry, how much for the muck away, dealing with any ground water etc and how much profit / uplift will you add to this. You as a customer don't need to be an expert to ask this you just need to get the conversation started. This way you will encourage builders to engage with you. If they don't then maybe give them a miss. Once they do they will often open up and point out other things that could add to or in some cases reduce the cost. Once you have their interest they will often help you, and give good advice as they want to win the job. They will often view you as serious customer and more importantly a fair customer. The firm/ knowledgable /decisive / negotiating type of customer comes later. You will have put in the work and can expect to reap the rewards. If you can garner (fairly) interest from a say two or three builders then you will learn lots from them. You'll start to get some transparency on the price breakdown and then you are in a position to make an informed decision. You may start to see some convergance of the prices and be able to compare apples with apples. You'll get the odd outlier, too high a price and just as importantly the one that is too low, often best to avoid unless you are happy to deal with the spurious claims for extras. What I have outlined above won't suit everyone. However, the construction industry is just as much a people thing as every other field. If this approach suits you then it's worth a try, you've not much to loose other than say a bit of time. You will however learn a bit more and gain confidence by doing so. It does seem that at times the construction industry is more than blessed with it's fair share of chancers and so on. If you take take it one step at a time, learn as much as you can then you'll usually be ok. If you cut corners you run the risk that you may be a bit less lucky. It's all food for though. The quote from Ruskin below is worth a read. With hindsight I suppose I should have just posted this and left it at that! It’s unwise to pay too much, but it’s worse to pay too little. When you pay too much, you lose a little money – that’s all. When you pay too little, you sometimes lose everything, because the thing you bought was incapable of doing the thing it was bought to do. The common law of business balance prohibits paying a little and getting a lot – it can’t be done. If you deal with the lowest bidder, it is well to add something for the risk you run, and if you do that you will have enough to pay for something better.” John Ruskin 1819 – 1900

Hello Tammie. Good post. My view is that to get the best out of this site you maybe want to provide a bit more basic information. For example is it a new build? Is it a timber framed house or a more traditional type of construction.. your survey /home report / sales brochure may help here in that it may tell you what kind of house you have. If you wish you can give a bit more detail, where you are located in the country and just some back ground information. Try if you can to describe the symptoms in more detail. I think if you do this there are a lot of folk on this site that will chip in and help. I learn something new all the time here.

Hope this helps when choosing your joists, maybe thinking about deflection / strength of floors / cost and engineered type joists or solid timber. Roughly, if you weigh 100kg the joists will bend by X amount when you stand on them. If you put on a 50kg rucksack they will bend by about 1.5 times X roughly 50 % more. Remember that they will have bent a bit during construction due to their own weight and the floor / ceiling / services you install hence my approximation. But very roughly if you have joists at 600mm spacing and you reduce the spacing to say 300mm you will reduce the extra deflection due to walking about and so on by about half. The cost will increase as you need more of them and possibly more strutting / bracing etc. To get the best out of things.. Imagine you are working in the pricing depatment of a timber frame outfit. You may do tens and more quotes a day, many of them small and with not much financial motivation. You could get a bit bored after quoting the tenth domestic floor job? However, if someone gets in touch that has clearly put a bit of effort into understanding what they think they might need, phones up and says they need help but have tried their best to get to this point, then often the flood gates will open and you will get a lot of help, maybe a better price too! We are all human after all. For the very keen.. Maybe think about the benefits of having a slightly thicker floor in terms of cost and practical space to get all your services in. As an alternative you can increase the depth of the engineered joists / or thickness of the flanges and this too reduces deflection. All other things being equal you can do a qualatative analysis just to give you a feel for things. You don't need to know / calculate the loads etc you just need to know what is called the second moment of area of the joist. You can often find this in the manufacture's property tables for engineered joists. The second moment of area (units often mm^4 / cm^4 or m^4, does not matter so long as you compare like with like) is partly a function of the depth of the joist.You will be able to see how it rapidly it increases with a small increase in joist depth or introducing a thicker flange on an engineered joist. The higher the second moment of area roughly the less the deflection. There is another kind of deflection called shear deflection but we are just trying to get a rough feel for things at the start. If you are looking at the tables just make sure you have the axes correct. Under the British Standard notation the value you want is the Ixx direction. Under the Eurocodes which most data is now presented in the vertical direction is called the Iyy direction. Again and roughly if you increase the second moment of area by say 20% you will reduce the deflection proportionally . There a few other things to consider but at the early concept stage this can be a very useful tool to give you a feel for things.

Hi all. For the self builder here are a few practical observtions. Can anyone else chip in? If you are self building your frame will often be out in the rain a lot longer. Engineered joists require a lot of other stuff to make them work and you need to know how you supervise that to ensure you have all the other bits that make a long span Engineered Joist work. One reason they are cheep in terms of spanning is that they they are working a lot harder / efficiently, they rely much on bracing, stiffeners and so on. In summary, they are very much less forgiving than a solid bit of timber. There is a big difference between the self build and the major house market. If you are self building it maybe takes you longer. Also, you could be employing a general local builder rather than an experienced specialist kit erector with all the site / quality controls in place... yes there are many large house builders that don't deliver on this. Say you have an Engineered joist where the web is glued to the flange... then although the manufacture's say they use water proof glue they caveat this a lot in terms of what you need to do to look after them during construction. Perhaps take a 1.0m length off cut of a glued Engineered Joist, soak it in a barrel a few times to reflect a self build application, take it out and hit it with a hammer... then decide if that is the right thing for your application. You may find that the flanges separate from the web pretty easily. The ones with the metal webs are essentially mechanically fixed and seem to be a bit more forgiving in terms of the self build where things might be out in the rain longer. Russell makes a good point on the deflection /vibration so consider his advice. A 10.0m span is not small so be very careful! In summary, sometimes for the self builder perhaps look at your own circumstances in terms of budget, programme and then match the materials to give you the best outcome and reduce your financial risk?

Worth a thought..great stuff from "self build on Skye" They are nearly finished and already enjoying life. I built the garage first with a shower, bog etc and old second/ third hand kitchen that someone was chucking out. Slept in a 14 foot caravan next to it so planners didn't boot us out.. going back a bit now . Installed the bath well before the first fix, a cylinder with an electric heater, just a wind and water tight shell. Still remember having the first proper bath in the dark in my own home...and I needed it! It's these wee things that keep you motivated and your head up!

I need to go to spec savers. Can't see the generator.

Yes you are not far off the mark that is is a steep learning curve. We all make mistakes, even the "pro's". When you do, prepare to pick your self up and march on. It will be hard at times and every project is differant. If you put in the work things will go better at times than you expect, so look forward to that also. We talk about luck? Seems to me that the folk that put in the work into the research and consider advice seem to be a bit more lucky in general..just and observation. There is however a another bonus in this. You tend to get a home or say an extension that belongs to you, no one else has the same! Maybe adapt what you read here and make it your own. There are a lot of folk on this site that have extensive knowledge and experience so they can really help you form a balanced view. When you get stuck they will make time to help you. Remember, it's your project and your decision so you maybe want to take as many views as you can, and make what is called an "informed client decision" This is still one of the few sites that are not commecially driven (at least I think this for now). The "structural side" of this is my thing and I try, if I can, to chip in. Make the best you can of this site. Digest the information you get here and make your own informed decision. Take that approach and it will serve you well. All the best. Gus.

Well done. Try and find some time out to be proud of and reflect on your achievement. That will be hard to find as by now you'll have realised that island living is very rewarding, socialble and a great place to bring up kids. All the best.

For the DIY er that wants to build say a small wrap around extension, dodging away at the weekend and wants to keep hire costs and trips back and forward to the hire shop down. Thanks Tonyshouse. To quote Tony. "A piece of orange string, set out front of building first then the critical side square to it then c/l of trenches then the rest of it I mostly used ancient Egyptians 345 and double checked by measuring the diagonals os any rectangle" Levelling. What about a water level. Get a garden hose & some clear plastic tubing say 2.0m long from the DIY store. Couple 1.0m of the plastic tube to each end of the hose. Get some food dye. Choose your own colour – just make sure it is a darkish one so you can see the water in the clear tube. Get ALL the air out the hose. Calibrate it by putting the two tubes together – the water in each should be at the same height. Jiggle / shoogle / do something to it and check again. Pin one end of the clear tube to something and take the other end to where you want, just make sure the water does not spill out. Mark the levels of the water to the bottom of the meniscus. Now you have a datum and you can measure up or down from that. Change the tube ends round and check again to give you confidence it works. Lastly, when you are finished plug the ends of the tube to preserve the coloured water. The great thing about this is that it goes round corners and as many as you like. A laser beam goes in a straight line unless you can apply some physics I think. You can take it into the house to check the floor levels to tie say an extension in... probably plug the ends first in case you get dye on the carpets. No points for that! Setting out dimensions For smallish stuff invest in a good steel tape, fabric ones stretch very easily without you knowing. If measuring over a distance use blocks, wood or something to support the tape frequently so it does not sag and try and keep the same tension on the tape each time you take a measurement. Set out and double, triple check. If you take your time you’ll get will within the tolerance a bricklayer can build to. You can use Pythagoras (3,4, 5 triangles to get a right angle) there lots of school maths formulae you can use to calculate the sizes say if you know the length say two sides of a triangle and the angle between them. Hope someone has fun with this and saves a few quid.