Tips on building an extension: Building Control
It goes without saying that one set of red tape to pass through is never going to be enough for any local authority. So if you want to do something to your own home they have two sets for you. Planning permission is the one you are more likely to get stuck on but building control is technically more difficult. You can apply for them together but planning and control will be dealt with by different departments. Having got my planning permission and not knowing what else to do, I submitted the same plans to building control. A week later a letter came back with which said, "Your application for building control is not complete, please supply the following items: full construction details." In other words I was so far short that they were not even prepared to give a specific list of what else I needed. Building control is about making sure the way you build your extension meets suitable standards. It covers electrical work, heating and insulation as well as the fabric of the building. So does it require a lot of technical knowledge to get through? In face of my first rejection I decided to get in a professional structural engineer. I had quotes from two of them. One for £450 and one for £1000. Neither of them gave the impression that they were particlularly smart. I realised that of they could do it for so little money it was not going to take them long. They would not much in much effort and in fact, it must not be such a difficult thing to do. Fruthermore, they did not appear to be in any hurry to get it done. They tried to scare me by warning that the building control officer would want structural calculations done, but how difficlut could that be? The councils provide a lot less infomation about how to do it than they do for planning, so I just bought a load more books to find out what to do. FoundationsThe first thing I had to worry about was the foundations under the garage. If they had been built just strong enough for the one existing floor, then I was in trouble. Underpinning them would cost £10,000. Terry, a man I found in the yellow pages under "not very skilled builders" came round to dig a hole exposing the foundations. He had to remove some slabs and break through three inches of old concrete before he could start digging out the heavy wet clay and rubble down to about 4 feet. He left it nice and clean so that the building controller would have a good view. I did not begrudge him the £150 he asked for doing it. I was also able to find the original 1963 plans of the house at the planning office. They showed where the foundations run under the house. In combination with what I saw in Terry's test pit, I had a good idea of what the foundations should be like. The measurements and a foundaion plan formed the first part of the "construction details document" that the building controller was asking for. More DetailsThe rest was just a description of what I would do to get round each of the regulation I could find out about. I just wrong down that I would install a new heating system meeting the efficiency standards required and stuff like that. I realised I would have to give details for floor joist sizes and spacing. It sounds difficult but in fact there are tables in the books that tell you what you need depending only on the width of the area the joists need to span. I added that I would inlcude smoke alarms, double glazing and all the obvious things. I sent it all to the control department with fingers crossed. A few days later I got a call from Graham, the control officer. He politly suggested that I did not have much idea of what I was doing and that I should come in for a chat. When building an extension the building control officer is your best ally. He is not after your money. He is just responsible for making sure you build safely and securely. Graham patiently took me through some of the points I has missed and gave me excellent advise. My initial application was rejected because he had a time limit within which to give a response, but I could submit again any time and did not even need to pay an extra fee for that. My next version of the construction details covered a lot more. I also drew some new
plans at a better larger scale showing where things like smoke alarms would be. Here are
some of the things he wanted me to add: Top Tip:The building control officer will help you get the details right provided you take the trouble to read a bit about it. Next Graham aranged a visit to see the site and especially the foundations. I was concerned that the foundations were only about a meter deep in places. Standards had become tougher in the area after a spate of subsidence problems nearby. They wer now asking for foundations to be 130 centimeters deep. It was a huge relief when Graham told me that the foundations were OK. Although they were not as deep as the guidelines wanted, they were a lot thicker and that compensated. He demanded a few more things. I would need to add an extractor to the utility room. The drain pipes were going into the sewer which was not allowed. In case you havn't noticed, many of these were existing porblems that were not in line with standards that had toughened since the house was built. Lastly, I was going to have to do some structural calculations. In particular, I had to say something about the strength of the beam that would go over the double garage door. I figured that this would just be a case of working out the weight of the bricks and roof directly above the door space. I did that and found a website called www.keystone-lintels.co.uk that supplies heavy duty lintels just right for the job. They had tables of supportable weight for any given span. My crude calculations seemed to show that it was going to be hard to find a lintel strong enough. Then I checked my handbook of structural calculations and learnt that the supported weight only comes from a right-angled triangle above the beam. Now I knew I had a good margin of safety. My document of construction details now came to 12 pages. I don't know if a structural engineer would have gone into so much detail but I was satidfied that I now knew myself how the thing would stand up. If you want to see all the details I put down ...
Before the final submission to building control I called round some builders to give quotes based on the detailed plans I now had. I was able to ask each one a little about how they would construct various parts and what materials they would use. Some information such as what insulation to use was needed for the construction details Top Tip: Get some information out of the builders when they are round to do a quite, but don't get them round before you have most of the details worked out. My fourth submission to the building control department was accepted.
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