Gus Potter

It depends! But here is a rough outline of how we go about designing steel fire protection. The following is in the context of the self builder, not multi storey, multiple occupancy structures. Ok, the process / theory is.. roughly this. The starting point is to understand how steel behaves when it gets hot. Someone ask me / others a while back.. why does my oven not start to melt / distort when I cook a pizza hot? The above is what we call a fire curve (SCI, Steel Construction Institute data ). There are different fire curves. They vary depending on fire loading (how much and what types of stuff can contribute to a fire, how "intense and rapid" the heat delivery) but the above is one we would refer to in a typical domestic self build. You can see that up to about 350 Celsius the steel maintains much of its strength, which is why your oven does not "melt" and fall to bits. After that the steel strength starts to plummet. When we fire protect steels as @saveasteading says This is correct. All we are doing it to stop the steel from getting hot enough, then soften too much, and thus not carry the loads on it for the time required by the building regulations for example. Now we can either select a geometry of steel member and make it very heavy such that there is so much mass of steel that it does not get heated quickly enough to soften to the point of failure. In lay terms. If we had a solid round bar of steel say 150mm in diameter it has a large cross section area compared with the exposed surface. This is what we call the heated perimeter / cross section area ratio (Hp/A), the Euro codes have slightly different way of presenting but they mean the same. They are presented using the ratio Area / Volume, A/V. But if we have the same cross section area of steel and weight in an I shape (a universal beam) it has a much larger surface area and thus will heat up much more quickly and thus lose strength more quickly. Now we ain't going to be using solid 150mm diameter steels. What we could look to do is is insulate the steel. This could be by way of fire proof plasterboard or intumescent paint. But also we could build the steel into a masonry wall and maybe have only one side exposed to the fire on the inside of say a garage. Or we could have the steel built into a floor that in itself insulates some of the exposed faces of the steel. Below is a screen shot of a table that shows how we need to consider the exposed sides. They key here is that the lower the section factor the slower the steel will heat up. The section factor changes depending on how many sides of the steel are exposed. But to go back to what @Great_scot_selfbuild asked., which was how heavy does a steel need to be so it does not need fire protection? The info below is taken from Corus literature 2003 as an easy generic example. The bottom line (Hp 61m^-1) is of interest to us here in a domestic self build. Using a design temperature of 550 deg you can see that the bottom blue line hangs in there, all other things being equal for 30 min. So let go back now and find a steel section with a section factor of lower than 61 m^-1 to try and get a handle on how big a column needs to be for example. A 203 x 203 x 86kg/m is a candidate if it has three sides protection (section factor 60), but that is a heavy steel. You also need to handle this safely on site. Ok let's see how a box section compares. Ok we can get down to 60 for three sides exposed protection.. not much difference. But if we reduce the sides exposed the numbers get a lot better. I've not shown them here. That main remaining key bit is what we call the load ratio mentioned above as 0.6 ratio. When we design a beam / columns or pretty much any structural member in your house we design for the normal expected loads. The self weight, permanent loads and the imposed ( live loads, people, book shelves etc) but in a fire we recognise that the floors, roof etc are probably not going to be fully loaded with people for example during a fire, the permanent / self weight load is still there. So we can make a reduction in the load if a fire occurs. Its based on probability and the loads that could be reasonably expected in the case of a fire. We call this an accidental load case and the safety factors get reduced for example. If we designed everything for the worst case buildings would be too expensive to build! The load ratio is the load (stress generated) during a fire compared with the ultimate capacity of the member. Often we design beams to be restrained by say a timber floor.. but if this has burnt away we can't count that. To conclude: The above I hope, gives you all a bit of insight into what we need to do / think about to design steels for fire. The take away is that sometimes it works using a heavy steel to avoid the expense of fire protection. The design can become much more complex if bolted / welded connections need to be taken into account. This kind of design consideration is a bit complex if you've not done it before, it's not common bedtime reading! It can be a tricky subject once you get into detail, something that many Architect's, BC officers are also not too familiar with. But it's a fundamental part of producing a safe design. My objective in writing is to try and help BH folk gain a bit more knowledge so you can ask and phrase any questions you have to your designers from a lay person perspective. You make a good point. Yes steels expand in a fire and will change shape and distort the surrounding structure, to the point it often has to be later demolished. The objective is that the building hangs in there so it does not fall on the fire brigade, set light or fall onto a neighbouring building not least.

Unlikely there are any record drawings, photos, back then photos were expensive to take, gut feeling is that there will be no meaningful records. From time to time I work on old buildings, we add load, change the load pattern (the floors get loaded in a different way as the use changes). For me it is one of the most rewarding types of design to undertake. It starts with researching the history of the construction and what the site was used for before construction, anecdotal information, ground conditions and so on. It is hugely interesting.. the history, folk think SE's (the failure we see of the column) just do sums but we don't, there is much more to the job. Frankly the maths are massively boring once you have done it a hundred times or more. What I find exciting and rewarding is the "detective work", the history, working out what has caused the failure I see. Then you need to convert that into say a report that a layperson can understand. The fun part of being an SE is the art and craft of design and detective work , but knowing you can "prove what you are saying". Now in all that,we at times need to exercise Engineering judgement, some of the maths are based on probability, some empirically based, but again these maths need to be presented often in a way that a layperson ( a lay person also includes most BC officers) can also understand. Yes there is. We can often identify historic steel sections. I have documents in my library that helps me do this. Once we have dated and potentially sized a section we need to look at the strength. As we go back in time the manufacturing process was less controlled and a bit dodgy cf modern terms. Thus we need to use a different set of safety factors for example. So yes Alan we can do it more often than not. I've attached a historic copy of the Dorman Long Handbook from 1906 to let all see the kind of things I look at. This is just one of the fun parts of my job, you can do the maths, takes time and study to learn this.. but then you get to be a historian.. a detective, when something goes wrong the person that can actually design a solution and keep folk safe. If any of you have kids, being an SE is not the worst job in the world! If your kids are ok at maths then they stand in good stead. For me the being an SE is about the art and craft of design. The best SE's are actually really creative folk, you need some thinking logic, the maths almost comes secondary. Dorman Long 1906 handbook.pdf

Just ask the planner, drop them an email and get it in writing. Disagree as we have no other information.

I think you're right. Had got myself over excited with the SE stuff! Hope all is well at your end.

What a belter of a photo! Now funnily this serves as a good example, all be it on a smaller scaler, as what not to do if self building or extending your house. I make some points. It's debatable. Technically to me it looks like a Universal beam, if you look at the flange width cf the web depth.. it look looks a beam, a column is more squat in profile. I can see from the photo the beam has buckled perpendicular to what seems to be a heavily loaded transfer beam at ceiling level. My gut feeling is that either the designer has made a massive cock up in calculating the loads on the, now call it a column. More likely is that they have not understood the top and bottom connections. They may have designed them as pinned, but then inadvertently introduced a stiff connection or some off centre loading ( called an eccentricity) that introduces a bending force in the column and not spotted it. This extra bending force reduces the capacity of the column to carry load. But on the other hand the Contractor may have thought they know better and just gone off and done their own thing. My experience of Contractors / project manager is mixed, I used to be a Contractor myself. Some think they know it all, some are arrogant in the extreme (pride comes before the fall) some are sensible enough to just make a call to the SE, which I now am. Now the photo is of a big building, heavily loaded. But when I design houses, wall slappings for extension etc the loads are much less, but I design with much smaller steels, thus pro rata they are doing just as much work. The design is lean. But if you listen to your builder without checking you are taking a big risk, don't be swayed by bravado, a builder telling you they know better. At the end of the day if the builder changes the design in any way and something goes wrong their insurance won't cover it, and possibly your home insurance won't either. It also critically unsafe. My advice is, if you want to deviate from your design drawings then call the designer, just lift the phone! IT'S THAT SIMPLE

Ok a bit of food for thought. You have a steel column, likely supporting a structural load. Let's say as a minimum you need some fire protection? Say 30 minutes. Now you can achieve that in two common ways. 1/ Box it in with say Gyproc Fireline board. Which probably gives you a detailing problem, which is why you are probably wanting to use Aerogel as it saves space. 2/ Paint the steel with intumescent paint. But for intumescent paint to work it needs to have space to expand into... you see the dilemma? As a rough rule of thumb the intumescent paint thickness needs to expand some 50 times to work properly. It needs space to do this. So you can't stick Areogell to the steel per say and you need manufacturer approval to stick it to intumescent paint. Now often BC etc don't pick up on this. But if something goes wrong, there is a fire, the steel fails and the building falls on say the Fire Brigade.. then the buck has to stop somewhere.. as an SE I'll be on the radar, Architect's also, and you if you have taken it upon yourself to become a designer then you are facing a huge liability. Now the above is a worst case.. but if you get a smart BC officer that knows about this stuff then they might be minded to fail your design unless you can prove otherwise. There are cases where the steel is well protected by masonry and very heavy and thick and thus possibly as at Paulie I think in Paulie's case the steels are so heavy they don't need fire protection. The load we use when designing steels for fire protection get reduced as they are called an accidental case. In lay terms we don't design most steels for the building being fully loaded up and a fire starting at the same time. I would go back and look at what your steels are doing, the loads and so on. Also have a chat with your SE to check if what you are proposing might invalidate their design for example. I appreciate you may not like this news.. but it's up to you and your risk.

Good questions. A soak away draining too quickly can be more easily mitigated than one that drains too slow, the too slow causes problems. Often you just need to understand the ground composition, then adapt the design a bit.

Interesting question. The one metre depth may actually be to do with health and safety in terms of accessing an excavation without support. If your house is on a slope, on a hillock then we don't want the water just running out further down, especially if it is from a septic tank for example. Sometimes it works to sit a soakaway deeper, for example there is a gravel layer a bit deeper down that can accept a bit of extra water. There is a trade off in that the excavation is deeper thus more cost.. but in a good gravel layer the soak away can be less extensive. What you mention 1.8m depth seems more like an "Engineered" solution which can be elegant and offer best value for money while still performing.

Yes agree. Moving the drain outwith the building foot print is the safest option and would probably simplify the foundation design and thus possibly reduce cost.

Would this help? It looks like you might have space to move the public sewer outwith the zone of influence of the new foundation? I'm assuming the direction of flow runs left to right on the drawing. If not then just reverse the diagram. For reference a private drain is a drain that serves only one house, a public sewer serves more than one house and often this asset belongs to the water board. As others have said you should determine,if you need build over permission for this, you will need permission to move the sewer, build over or near to it. The notation R/E indicates a rodding point. Best to do it right to avoid later potentially horrendous complications.

Can you post a drawing of what you are going to build. The figures you present seem high at first glance. But I often do these types of design, they can be very time consuming, although small, and thus the fee cost is higher in proportion to the floor area. To put this into context. I have a potential Client that needs a modest new build and the design fees are similar to your over all fee. An interesting number is £120/hr for site visits. Now the 120 rate is fine if for time spent on site as there is travelling and then inevitably writing emails etc when back in the office. But if it is also booked at £ 120/ hr for travelling and then writing emails when you get back to the office then that is different. Do that and don't be afraid to ask questions.

Agree, you might open a can of worms.

Yes there are some parameters that you breach at your peril. Daylight and over shadowing of neighbours are one, traffic visibility splays another for example. Folk often bend the permissions a bit.. but it's a risky business! If you do deviate from the plans then you should ask yourself, how confident am I that if I get pulled up I can get an amendment to planning? If I come to sell and a surveyor spots this are they going to write your house value down? If the house goes on fire for example could the insurers use a non compliance to angle towards refusing a claim? It's best to check these things so you can make an informed judgement.

Lovely looking house and a great job, well done!

Good observations, none of which I disagree with generally. Your house is often the most valuable asset so take time to read the fine print when the detailed insurance terms and conditions come through. I had one Claim where there was a bit of initial push back, gathering of information and a bit of SE by me reporting on a house on the south coast of England. The gable end of the house was next to the public pavement, lots of prams being pushed and pedestrians walking by, major HSE risk that they clocked once pointed out to them. The thing was so badly built and so expensive and difficult to fix that the warranty provider settled, from memory in about four months after I got involved. The warranty provider bought the house back, paid all costs; professional fees, legal fees, a bit extra for finding another house, removers cost and some ancillary stuff. Some claims can be pretty straight forward and get dealt with relatively quickly. It's not always that bad in terms of reaching a resolution. Some providers are using Claims handling companies.. the clue is in the name.. just how do they make their money? Obviously by making the Claims process as easy as possible and being helpful by not indulging in; gate keeping for example, offer up suggestions to the house holder at what is a stressful time for them .. or some may suggest not?

Hamilton Leonard Insurance Brokers, just changed their name to Roxburgh. Ask for Allan Burns, always helpful. 53 Moss St, Paisley PA1 1DR Phone: 0141 226 5161 Website: https://roxburghinsurance.co.uk/

Absolutely none. In simplistic terms I design it as the SE, take that liability on, check with my insurer in case they want to add a bit of an uplift to be compatible with the warranty providers reasonable terms. The warranty provider runs my design by their Engineers. They analyse the risk, add in a bit of a hassle factor for them and make their premium offer. You can pretty much insure anything. It often called gambling, it's just on houses rather than the horses.

From memory the regs for an ensuite are less strict, the door is the obvious weak point. My normal minimum spec for an ensuite wall is plasterboard each side with a minimum density of 10kg/ sq m (see Gyproc Wall 10) on a minimum of a 70mm deep wall stud. Then 50mm of Rockwool RW45 acoustic insulation. If you can stretch to a deeper stud then all the better. Depends on you ceiling height as there is a bit of structural design creeping in here as you don't want the wall too slender so the whole wall vibrates as a unit. . You need an air gap between the Rockwool and the plaster board as the air gap filters some bands of the sound frequency. If you pack the wall tight with insulation it has a detrimental effect. If you want to keep your guests happy then fit a good solid door, a good lock that gives them confidence, a good fan and a nice handle on the door! The regs between rooms are often different.

Try a broker that is Scottish based, we have lots and lots of timber clad houses. It's worth a call just to get a bit of advice.

Very much agree here. Most self builds are unique, start with a basic design that has a fighting chance of working and then adapt for specific design.. that is the fun part. They are indeed. I've done some adjacent to mine shafts with highly contaminated land, one on really soft sand on an airfield up near Nairn in Scotland, one daft one next to a canal in the Norfolk Broads, they really are bespoke animals. Down Norfolk way I did one where we basically "floated" a single storey building on the peat. This leans towards folk doing straw bale or oak frames with wattle and daub as it really maintains the design and environmental ethos. This takes a leap of faith and careful design of the drainage and service connections to a building that can rise and fall quite a bit. The building itself needs to be pretty flexible. The movement can be huge! But these are worth a shot when the piling option may be expensive. Piles in deep peat also need to be designed for bending as the wind pushing on the side of the house needs to be transferred to the competent soil deep down. I don't think it's conservative per say, we know the mechanical properties of their insulation. Things can start to go wrong it there is a late design change, poor design coordination between the different work packages or unexpected ground conditions, or most common a setting out error. That is why I want to understand the Client's capability, how much hands on control they have. Using PIR insulation sheets and fitting them together on site allows for flexibility as you go, maybe you need to pay for a bit more labour but at times the risk / economics stack up. Some Clients want fast and quick and are happy to take the risk that something minor can throw a spanner in the works. They rely on the Contractor to sort it out.. but then a dispute can arise.

Thanks for your comment, much appreciated. Yes, we need to be cautious here. One thing I don't want to do is level false accusation, or identify any specific claim. As I've got a bit of experience with this stuff it's not always the case that the Client has covered themselves in glory. Sometimes they have inadvertently cut corners (just made a genuine mistake), not followed the design drawings, or just don't disclose to me the full facts. While I decidedly don't like the approach some of the warranty providers adopt (deny, delay defend) you need to get to the bottom of how the Claim comes about and the prior communication between the parties. Only then can you see what you have to work with, worts and all. This is a summary I generally agree with. Now faced with this often the home owner does not often know where to turn to. More potential expense. Some warranty providers sub contract out the site inspections and the inspector has to hold a certain amount PI insurance cover. The warranty providers shed as much liability as possible onto the inspectors and their (the inspector's) insurer's know this. This may be prompting the request for additional reporting.. driven by the inspector. You need to ask if the inspector is covered / employed directly by the warranty provider or if the are sub contracted for example. As a word of encouragement I have come upon this kind of thing before. It often takes few frank phone calls to sort it out and the actual reason given for asking for additional reporting.

Now you need the will to live these days. I don't do this regularly (primarily as an SE) but for one reason or another I end up representing Clients that are making a claim on their warranty. I've done this for the last 15 years or so. I spent some 20 years as a building Contractor before that, cutting my teeth and learning how devious folk can be at times. In some ways I'm a poacher come game keeper. It's not part of my core business, I do it as it's good for my soul and I don't like to see domestic Clients getting taken advantage of. That said, over the last 15 years I've recovered on behalf of Clients a few million quid. The amount of money is less important, for me it's about justice and holding folk to account. What I've noticed in the last few years is that some of the warranty providers are more and more sub contracting out to Claims handling services. 25 years ago lots of the warranty providers withdrew from the market. At one point there was the NHBC and Zurich pretty much. Now we have lots of new entrants.. and it seems to me that there is a bit of a race to the bottom. The terms and conditions are a bit of a minefield for the unwary. There is a common case where they initially come over all friendly but then tell the Client they need to employ an SE like me at their own expense to provide a report. This happens even if the Client has provided photographs that clearly show there is a problem. It has come to my attention that they (Claims handling services) are ramping up the; deny, defend and delay tactics.. always been the case but recently I've noticed that they are cherry picking part of my SE reports and trying to fob the Client off. Even to the extent that they will quote part of a paragraph of my report.. which totally changes the context. Often young folk just can't afford this so they throw in the towel. It's a disgrace. Now this may be a genuine lack of understanding .. or a deliberate intent to defraud the Client. I'm happy for them to dig themselves a hole as often when doing a warranty Claim I'll turn it into an HSE (safety) issue. This makes folk personally liable and risks the HSE getting involved.. a big black mark if you are a warranty provider. My question is. Are folk finding Claims handling services helpful or not when you think you have a case for making a Claim.

Now is the time to really look after the materials you are using to build. In this weather if you press ahead you may be making a rod for your own back later.

All good points. Burying any gas pipe in an inaccessible position is fraught with danger. You need to consult a Gas Engineer. Now with much more air tight houses and the potential for negative air pressure we need to be extra careful.

As you say it kind of looks like the house has been previously altered. Would need more info to comment further as an SE / try and put a ball park cost on this.