Gus Potter

Technically.. on paper maybe.. but you have such a mix of materials that it would just be a guess and probably too conservative. The way to design it is to assume the fixing is acting like a short cantilever out from the wall.. like a dowel supporting say a flying shelf in you kitchen. You then add the wind load sucking the cladding off the wall which adds tension to the fixing.

Hiya. Hope this helps. Bit of theory first and a few general comments. Excuse the spelling and grammer please! A gabion wall is fundamentally the same as what we would call a gravity retaining wall. Its weight does most of the work to stop it moving. The difference is that gabion walls move about a lot more and often they are designed for a 20 -25 year life span rather than a 50 year life span which houses are designed for to meet mortgage requirements.. Now for all. If you truck about you'll see many more developments by big house builders where they have big high gaboin walls to retain gardens, the houses themselves are set back. Can you smell a rat? The thing to take away from this is that gabions have a time and a place and much is to do with how much they move and their seviceable life.. before serious maintenance. Ok how do we design a gabion wall.. 1/ We need to know what it is holding back. @Great_scot_selfbuild it's your driveway. Now if its gravel then I would say.. how much do you want to spend.. do you mind if the gabions moves a bit and you need to level out the drive every 5 years? If you say I'm ok with that then I know I don't need to worry to much about movement (serviceability). I also need to know how long you expect it to last! The building regs can be a moot point here in terms of movement.. the regs aim to make sure it will still be safe! To design a gabion wall we often apply the same principles as we would use for a concrete or brick gravity retaining wall. Rule 1.. we need to make sure it does not tip over. Often walls have drainage behind but behind the drainage layer we also have a bit of sideways soil pressure. The drainage can avoid hydrostastic water pressure and having a "funny" effect on the soil. Rule 2.. there needs to be enough of a key and friction load at the bottom of the gabions to stop them just sliding sideways. For all types of gravity retaining wall design we allow for a surchage load ( a load applied to the top of the ground) of roughly 1000kg per square meter on the drive way in this case.. thems the rules folks! Drianage or not this surchage load causes a sideways thrust on the wall. Rule 3 / This is a biggy.. we need to watch put for a global failure (often called a slip circle) where the whole wall, driveway and soil above up the slope just takes off and moves down the slope. This can be a catastorphic failure and very dangerous. Some times to mitigate we need to drain the soil much further up the slope.. even then we are taking a risk. If you have challenging topography then I would need to know what is happening further up the hill. You may need to extend the scope of any site investigation. Now most SE's should have a grasp of these basics. But its your vegitation, could be trees an local topography that needs nuancing. I see you are using a Fittleworth stone gabion fill and probably you SE will just design these gabions as having no intelocking effect.. so the design will be standard. Theoretically the design can be realtively easy.. but for economic design.. that requires you to to identify what you expect and balance that with how much you want to spend on ground investigation. To sum up.. I've given you a few tips. Have a chat with some SE's and say.. I've read this and that, here is what I would like to do and what do you suggest would be a good balance between soil investigation and practical common sense design? Once you can get a handle on what your expectations are in terms of long term perfomance of the gaboin wall then most SE's will be able to handle that kind of design. What they will do is make sure is does not fail dangerously and if it moves about a bit, then you now know that .. and everyone is happy.

Redo the pointing in the brickwork above so the water is shed out the ways and see if that helps.

Gabions can look great. You can creat a structural butress in them if you want to design an Arctitectural seating area for example.. The quality of construction matters. cheep infill and badly placed = less perfomance.. time taken to lay the stone.. like a dry stone wall can increase the service life. You can use decorative stone on the outside.. grow plants on them and so on. Great habitat for wildlife too once they age a bit. The structural design concept is a little different in that you expect them to move about quite a lot unlike say a concrete retaining wall which can't move quite as much.. well you hope not!. These things move which makes them flexible and forgiving and so long as you recognise that you are off to a good start. The presence of the trees makes the design more fun! I think some of the keys to this are: 1/ You need good ground information.. soil properties, water tables and hydraulic gradients etc. 2/ A good detailed topographical survey so you can see just how much you need to retain, the slope of the ground and the location and type of trees / vegitation. 3/ A good idea from you as the Client about how you want to finish the driveway and how often you anticipate maintaining it. The retained soil may move about so if you have a tarmac drive it may crack. 4/ Available drainage paths for draining the soil.. but then you need to watch what happens to the trees if you take their water source away or make them compete harder for water. You can do a lot to help yourself here (as you are doing) by trying to get your head around the things we need to know and importantly why.. to enable a design that meets your expectations economically and also in terms of later maintenance. If you can gather some of this info then it will help you find the right SE for you.

If I've drained a rad or messed about with the UFH I tend to top up with a splash of inhibitor. I have a mixed system.. part UF and part rads. Luckily I have a towel rail in a first floor bathroom that is a magnet for an air pocket. I unscrew the half inch cap on the top of the rad and just pour in some inhibitor before repressurising / opening up the flow and return valves.

It will be scary if it's not properly restrained against not least movement in the direction of the ridgeline... in fact likely dangerous. John you have a number of pivot points (like rocker bearings) and due to the nature of steel fabrication and behaviour it will tend to buckle sideways due to the vertical load. I can see where you are coming from ( gables taking out the wind load I assume) but it is very important that this arrangement of steel has solid restraint against moving in the direction of the ridge and also perpendicular to the ridge. Please check your SE drawings and make sure you follow them religiously.. don't let the builder / steel fabricator go off and do their own thing. Do this before you load up the roof further. If in doubt get some temporary bracing in.

Hiya and thanks for posting on BH. I've had a quick look at what you propose. With my SE hat on.. because it it so big you probably have loads of stiff structural floors / roof deck.. unless there is a massive atrium. This can be an economic form of construction. The size tends to lean towards standard commercial building construction.. nothing new and you should get competetive prices for a project of this scale.. it's basically office construction that is fitted out as a house with enhanced U values, heating / cooling systems etc. Looks great to me! Keep posting.

Good advice. Lets see some detail, a drawing or two. Look at it another way.. there are plenty BCO's that will be happy to help you with this, make suggestions. In my day job I often have open and frank discussions with BCO's.. we don't fall out.. we chew the fat and talk about how we can meet each others technical requirements and do a good job.

Less than 3.0k is achievable for say the steel work with one winder. The biggy is the finishes.. solid oak treads and glass. If you are a fan of LVL (basically thick ply wood) and want a contemporary look.. like Ikea say but bespoke then you can save loads on the treads and afford to make the odd mistake if doing DIY! . The glass ballustrade.. you can't compromise on that as it is for structural safety first and foremost. To finish though folks.. as I've said before build / design into your structure strong fixing points if you want a stair like this. Tell your SE early you want this!

Here are a few of my thoughts for you to mull over... I'll do my best to explain. In my day job I often take on these kinds of projects, an old house that needs a bit of an upgrade. I've got one on my books at the moment, circa 1915 house with solid wall, little insulation. Out the back is essentially an out house that I'm turning into a utilty area / shower room and internally knocking out some walls to make it open plan. Now that needs BC approval as I'm extending the floor area, carrying out structural alterations and increasing the insulation envelope. To make this work it's not possible to get enough insulation into the out house to meet the U values so to compensate I'm upgrading parts of the old house. But you are not doing this! The last bit of text was to hopefully let you see how we compensate elsewhere. I'm based in Scotland but the English regs are similar ( know the Scottish regs but don't do bedtime reading of the English regs / nuances.. but I do projects in England if they are of interest to me ) if they were not then we would be totally stuck when we refurbish / upgrade old buildings. It is often impossible to upgrade an old building to make each wall / floor / roof element for example comply with the latest regs. This excercise is about doing what we can (in so far as reasonably practicable) and all the UK regs allow for this in some form or another. For you it seems that you are not extending the insulation envelope or floor area. Thus my starting point would be to go back to the regs and see what needs BC approval. I think you'll find that a lot of the things you are doing (if any) don't require formal approval.. but in the regs there is a bit that says even if you don't need formal approval they still need to be compliant with the regs in terms of say workmanship, durability and safety ( the bit that worries you about the law? ). In terms of upgrading they don't say that anything you do must meet modern U value regs for example. Look for the phrase "in so far as reasonably practicable". This means that you can carry out upgrading work even if you don't meet the target U values. But in doing so you still need to comply with the regs.. for example.. you don't compromise the structural integrity of the house.. introduce a condensation risk, a fire hazzard and so on. If you want you can possibly regularise it by way of BC permission.. but they may turn round and say to you.. nothing to do with us so long as what you are doing is still compliant with the regs, British Standards and so on. I would go back and read the regs carefully and you may well find that you can upgrade your house the way you want if you apply common sense and do a bit of research. Hope this helps a bit.

Just be aware.. structural steel can be a bit " industrial" looking. What a lot of these photos don't show is the welds and what it looks like from underneath. Structural steel is not as straight as you think and fabricators will work to standard tolerances.. tread mounting plates distort for example which can lead disappointment if you want a high end look on the cheep. These things can look great but they do need an understanding about fabrication costs.. for the different levels of quality and how the treads marry up and fit to the steel. For me my job is to explain the different nuances to Clients. Yes get a local fabricator cheep but make sure your tread / glass / tension wire / balluster design can cope with what the fabricator can reasonably be expected to deliver. For all.. SE wise these things are too hard in principle to design. Box sections are favoured as they can resist the twisting effects better than say an I beam. But if you want something like this it's best to let your SE know at an early stage of the design so they can build in strong points of support at the top and bottom of the stairs. There are lots of folk on BH that have asked questions too late in the day about connections at the top of the bottom of the stair that have to resist twisting (torsion) effects.. which can be quite onerous in terms the top and bottom connection design. Also you need to think about newal posts.. stiff points for mounting glass and tension wires for example. It's not diificult or horribly costly if you plan early.

Detective Columbo time for you tomorrow then! report back what you find. It's good to get to the bottom of this so you don't reduce the concentration of the inhibitor in the system or over stress other parts of the system due to one part not working properly. But you know that anyway!

Again... keep you head up and stick with it... more often than not things suddenly get resolved. BC have a "process" and "holidays". Post when you feel able and all the best. Offer of PM ing me still stands.

Your design team should be able to sort this out. Cut them a bit of slack as dealing with BC can be like chasing cats. Some BC's don't work to the same professional standards that can be expected in normal professional life.

What has happened to romance! Too many folk thinking about cost and practicalities of stuff on BH and maybe not seeing the whole picture. You can't beat a real fire / stove. A home is not a home without compromise between needs and wants. Now I bet a lot of folk have an expensive car outside that is depreciating fast.. cf with making a home with a bit of comfort and luxury. We are not building a sanitised office! We have a wood burning stove in a room and sometimes I shut the door, settle my self down in front of it with a large kebab.. that stinks, watch telly and.. be selfish. Yes I know the flue cause probelms with air tightness but in the morning the air is purged.. I'm forgiven. Self building is about compromise.

No wonder, that is a big but not unexpected list of comments. However at times a game is played at your expense. BC folk get holidays and are adept at kicking the can down the road. It can be fearful for the public! I do this as a day job..make submission to BC.. lets leave it at that. Don't throw in the towel at the moment. From experience a lot of these things can often be resolvedvery easily. Your Architect should know how to navigate this common problem. If you feel you want a second and broad opinion then post all of the info and drawings you have on BH but sanitise it so you can't be identified. By all I MEAN all as there are folk that will dedicate time to helping you, some of us do this as a day job so you'll get probono professional advice. Now once you resubmit there is a way of wording your response where you can back BC into a corner where they need to talk to you face to face or on the phone. You turn the tables on them.. again this is part of the game. Keep you head up and forget about giving in. If you get stuck PM me, I can spend 15 min on the phone with you if you need a bit of probono advice and hopefully lift you spirits.

Pay particular attention to this, also the drainage flows and loads (surface water.. hard standings matter) if you are increasing occupancy. This can open a can of worms so beware. Probably does not apply to you but if a new build then you need to watch out for land contamination on the site as this can have an impact on the type and cot of water pipe you need. If in doubt ask now rather than get caught out later.

@GEO-PAR I do like what you're trying to achieve, very elegant Architecturally. Deflection is a key.. will come to that in a bit. I think you will have trouble with that at the clear span of some 1800mm. The way it is detailed is potentially risky in terms of failure of the stone lintel and bits falling on folk. Here are a few comments (with my SE hat on) on the structural design of something like this at this span. Firstly though for all stone lintels can work well if the span is short (image by @scottishjohn) and you have masonry above that is bonded to the top of the stone (no dpc / cavity tray as this acts as a slip plane) the composite action (stone lintel and masonry working together) form an arch thus the actual load on the stone lintel is small. For a piece of stone spanning ~1.8m say with a shallow depth of 150mm the primary design force is going to be a bending force, unless you have a huge uninterrupted wall above which forms a bigger arch. @GEO-PAR the detail seems to show the bottom of the Catnic in contact with the top of the stone. The Catnic is more "bendy" than the stone thus the stone could carry a lot more load than you expect not just its self weight. It takes a lot of finesse to design something like this that is not common bedtime reading. I would revisit your detail before progressing. The quality of the stone, type, mechanical properties and knowledge of that is vital. If you have ordered and paid for the Catnic then you need to work around that. This is something that interests me as I love a bit of stone.. but to make more detailed comment I would need to know all the loads from above and how the floors etc are supported on the inner leaf for example. In summary.. I would recommend that you check with your SE that your detail is ok... as it look a bit off to me based on what you have posted so far.

Asking for a friend? Why do you need to break up and remove the slab?

It does. You have experience so play to your strengths. There is nothing like fitting the insulation yourself as you will get it right, builders are working against the clock. DIY insulation.. often delivers better quality of workmanship / air tightness which is a key requirement. You've obviously got a grasp of the basics on keeping a house warm while avoiding / mitigating condensation risks. In terms of using software... unless you really know your onions and understand the limitations of any software then trust your common sense... which it seems you have. As an SE / Designer I use a lot of different software design tools but always carry out a "sense check" as ultimately I'm responsible for what I design. Jeremy produced a great spread sheet which I've interrogated. It's a great tool to get folk enthused.. he did a great job here and a service to all. The spread sheet has it's has limitations but you can't knock Jeremy for that. At the end of the day I think it will boil down to buildability and what suits your skill set rather than the cost difference in the various types of insulation delivered to site? Remember that one day of a good trades person that you don't have to stand over can cost £200 -250 a day say.

Was this the cost of the material or did you take into account labour installation cost, buildability, wastage and how complex it would be to make air tight. Often when I design the insulation I look at these things and think.. yes the higher spec insulation may give a better U value but getting it properly installed on site properly is going to cost much more overall. For self builders there is often no point in trying to be smart. If you get too technical a lot of local builders will either not do what you want them to do.. then you have a barny or they charge a premium.. and then still not deliver the quality of workmanship required for some of the high spec insualtion. Service voids are handy, the spark will love you for that as they don't like cables buried in insulation. Start with your structural TF stud depth. Then think about who / what kind of contractors are avialable / how much you are going to do yourself. Look at the structure of your TF.. does it have loads of dense clusters of cripple studs, noggings and so on.. then think about the spacing and wastage of the insulation, air taping etc. Keep it simple and buildable then use Ubakus say to add weight to your common sense assumptions and understanding.

This is true.. but to completey change the installation method, pile construction (cased, end and friction bearing assumptions, flight auger etc) and drastically the driven depth when close to a boundary raises questions.

Good to hear from folk outside the UK. I spent some of my SE training with a cold formed steel outfit that were big in AU. We did cold formed steel sheds, some of these were for the big mining companies with huge floor loadings and height requirements. I loved designing some of the stuff and the R & D. Australia has such a varied climate. There is a big band in the North that is in the cyclonic region... very windy. Then they have the bit on the east.. high altitude and snow.. then all types of soil and termites! Then there are the hot bits that we in the UK normally associate AU with. @Aus_Doug where are you going to be building location wise?

What a good post and example of approaching things pragmatically. For all. Retaining walls like this often don't have an indefinite life span. A bit of tecky stuff. From time to time the wall gets frosted and this causes the soil behind the wall to swell up a bit right at the top where it can apply a good overturning force, mind you it needs to be a hard prolonged frost. This pushes the wall sideways as the ice crystals grow for example. Then you have settlement of the retained soil and surcharge loading, can be just the wieght of a big tree locally, trees can be heavy! Now you may have heavy rain and this excess water causes the soil to weaken behind the wall so it shoves the wall sideways and then you can add a bit of water pressure. Any trees or big shrubs can push the wall sideways as the roots grow. If you have a timber fence attached to the top or down the side of the wall then the wind loading can push the wall. Now in goetechnical terms (we have many) it's easier for the soil to move than to shove it back into place. We call this active (the soil moving) and passive soil pressure.. shoving the soil back into place. It can often take roughly 2 -3 times the effort to shove the soil back to where it was. Now once the wall moves a bit then cracks tend to develop in the retained soil. These can get filled with muck.. in other words the wall often never can recover it's position... it a slow progessive failure. Odd that there is no mention in the deeds. Anyway. If I was you I would try and figure out what has caused the cracks in the wall. Do what you can to mitigate this if it is on your side. Then have a chat with the neighbours and say.. I've done everything I can on my side to stop it geting worse. Let's see how it goes. Any good will on your side will stand you in good stead later.

I love these... I think they are elegant. SE wise pretty straight forward to design. The rub is the connections at the top and bottom of the steel rectangular section.. often the builder leaves a mess with inadequate vertical and torsional (twisting) support. I know a bit but I think.. it's Marc.. that knows more.. can't remember his online name off the top of my head. For me it's the detailing and marrying it all up with the glass. SE wise the rectangular steel section is made to a tolerance.. not always straight and true. To that you weld stubs, tolerances here and on top of that, plates to take the treads. You can get distortion in the plates from the heat of the weld. All that adds up. Ok so now you have some steelwork that is a bit off here and there. Usually you can't see that. What is important is how you mount the treads level as that draws the eye if they are off level.. There are a few ways of doing this, shims, resin and so on. As a DIY project this is all perfectly achievable at reasonable cost... provided you put a bit of time and effort into it.