Red2000

Here's an interesting Sir Humphreyism... According to their website, "The Consumer Code for Home Builders (“the Code”), which came into effect in April 2010, applies to all Home Builders registered with the UK’s main new Home Warranty Bodies: NHBC; Premier Guarantee; LABC Warranty and Checkmate and consists of 19 Requirements and principles that Home Builders must meet in their marketing and selling of Homes and their after-sales customer service." Interesting to see that their 'Consumer Code for Home Builders' (here) doesn't apply to consumers building their own home, even when they are registered with the LABC or similar organisation. Only a truly committed bureaucrat could come up with a title for a publication which is so perfectly self-contradictory. As Sir Humphrey said, "...dispose of the difficult bit in the title; it does less harm there than in the text."

But I did like the SLR ?

We were very lucky with our builders and I think that overall they were pretty good, dedicated people who were genuinely proud of their work. My only complaint about them is that they didn't want to learn anything new. They didn't even want to introduce standard processes which would save them countless time and money in the long run. They were not stupid - I just think it's a building-industry-culture thing...if it isn't something they have done before then they aren't interested in learning about it. The building industry is living in the past and that's why simple improvements to the way that buildings are constructed take absolutely ages to be adopted - if at all. Contrast this with the IT industry. The entire approach is different. If an IT developer is doing the same thing the same way they were it doing 5 years ago they'd be regarded as a dinosaur.

Have you noticed that some people's reaction to someone doing something new or creative or different is "wotchawannadothatfor?" Completely off topic but here's a little anecdote... I went up to the counter of a sports supplier a couple of years ago and asked the assistant for a particular piece of equipment. "What's it for?" was the reply. I secretly wanted to say "None of your effing business, mate" but I was polite and told him. Then another character who was leaning against the counter put his oar in and gave me the benefit of his knowledge, telling me that what I was trying to do would never work. I said thank you but I still would like those particular goods...please. However, they insisted on trying to tell me that I didn't know what I was talking about, it would never work, etc. Eventually I had had enough and had secret delight in informing them that if they would like to look inside a magazine that happened to be on the counter, they would find an article by me describing how my team had just set a world record in that particular sport and thanks for the advice but could I please have what I came in for. Needless to say, that shut them up good and proper. Innovators of the world - rise up, and tell these naysayers to get lost!

Apart from the cost, my issue with architects is this idea of splitting of responsibility. We wanted our builder to be responsible for absolutely everything. An anecdote supporting this idea is that some close friends of ours used an architect who specified a kind of tile which had to be stuck high up onto the outside walls of the house with some kind of adhesive. Soon after the building was finished these tiles started to fall off (which was extremely dangerous because they could have hit someone). It also made the house look awful with some of the tiles missing and some presumably still perilously clinging on. When the builders were asked to fix it they said that they had done exactly what the architects had specified and refused to help. When the architect was contacted he said that the builders must have used the wrong adhesive. My friends had to play 'piggy in the middle' and the legal battle went on for several years (with the house not getting fixed in the meantime) and causing my friends considerable stress. Eventually the court decided against the architect who, with perfect timing, promptly died! My friends were then forced to sue his estate - adding to the protracted proceedings and legal costs. I'm obviously not saying that all architects are like this and clearly they have something to offer some people. But it does show that when two parties are involved in the delivery of a single project there is always scope for responsibilities to become unclear. I have an engineering background and didn't find the design of our house very difficult. Also we employed (via our builder) an architectural technician to do the technical drawings. We found this worked very well indeed and I'm not sure I can really think of anything that I feel an architect would have added. But I agree that in some cases it would be a good idea to use them.

Hi Mike, Thanks for your interest...this is what we did: 1. My wife and I discussed our requirements for the house. There were easy things to decide such as how many bedrooms we wanted, the orientation of the house on the plot and that kind of thing. Then there were more difficult things such as how we wanted to use the house. This developed into what (in the IT world) is called a 'use case', i.e. when you enter the house, where will you put your coat? How will you greet/entertain/house guests? How can we make the house suitable for us when we get old and can't manage with stairs? Where will delivery vehicles park and drop off things like groceries? This list was pretty long but it was a very worthwhile exercise. My advice would be to try to think of all everyday situations and how you would like them to work in an ideal world. 2. One of the things that came out of this was a sort of 'bubble diagram' which showed which rooms had to be connected to which. For example, we decided that the guest accommodation should have shared access to the utility room (so that guests could do their own washing if they wanted to). 3. We then went on the hunt for ideas for houses which had layouts which matched our 'bubble diagram'. None matched it completely but locally there was a new house being built which gave us an idea of a basic layout which could work. 4. I then obtained the plans for this house from the owners (who also allowed us to look around it when it was finished) and created our own layout using the copied plans as a sort of template. I should emphasise that the two houses are substantially different - it was just that it gave us something to get started on. Some readers may be horrified to learn that I used Photoshop to create the drawings. Yes, I know this isn't a vector drawing package but it worked fine to create drawings that we could show the council. I took care to ensure that what I was drawing was going to be mechanically possible, even if RSJs were necessary in a few places. 5. These plans were submitted to the council, edited, re-submitted and finally approved. 6. They were then given to our builder's excellent draftsman (I think known as an 'architectural technician' - thanks ProDave) who turned them into proper plans (and he gave us some very useful additional ideas too) and these were passed on to the engineering company who drew up the underlying structure ready for approval. There were no problems with this approach other than to say that in hindsight I think I would have paid more attention to where drains were going to run. A limitation on the available gradient for drains is the space between floors and, when you are trying to prevent the height of the building getting excessive, this may not leave much room for the pipes to drop from the plug to the soil pipe. I hope this helps.

Ultramods, this is the type of wood-effect tiles we used... http://www.ceramicadelturano.it/prodotto/vogue-ceramiche-castelvetro/ (Before selecting them I attacked a sample with a drill bit and it made no marks at all !)

Thank you all for your comments - I will try to answer questions if I can. Yes, I suspect many people could write a book about their experiences on building a house! It's such an enormous project and is almost always carried out by people who have little or no experience. You won't be surprised to learn that we used to watch Grand Designs a lot prior to the project. One comment that Kevin McCloud made several times which I completely agree with is how much a well-designed house can change your life for the better. It really can make you more contented and relaxed - at least that was our experience (not during the build obviously!).

We have just finished a self-build and as we went along I made notes of the things I had learnt during the process. What follows are those notes and I hope they will be of some use to people who are just starting out on their projects. I must of course add the caveat that all that follows is only my personal opinion. Although I now have some experience I am no expert and it is of course up to everyone building their own home to seek professional advice about their project. RED'S ADVICE FOR SELF-BUILDERS 9th September 2018 GENERAL 1. Try to work with everyone on your project via email as much as possible so that you have an audit trail of what has been said to people. If you must have a meeting, confirm everything in writing, right from the start. 2. You are about to be on the receiving end of a lot of documents, mostly in electronic form. I kept all ours and it amounted to 1,132 files (in 169 folders) consuming 2.8 Gb of data. Decide early on how and where you are going to store your documentation (electronic and paper) and stick to whatever system you are using. DESIGN 3. Make sure the house is of a specification that is appropriate to the size/type of home you are building. A big expensive house must have a high specification or else you may find its value is disproportionately affected when you come to sell it. 4. Check the local vernacular for design ideas – it can be nice to reflect local building techniques or features and you will get fewer objections from the local community and council. Imposing your personal taste on an area is unlikely to make your life easier. 5. Keep basement walls as simple as possible – they don’t have to exactly reflect the above-ground level walls. Angles and corners increase cost, sometimes unnecessarily. 6. From the design phase onwards, ask that ALL drawings of plans and elevations include a metre scale so that when measuring things you can see how big they are. Sounds obvious but they were not included on ours. 7. Drainage issues can present huge problems in the future if you’re not careful. Look at your plans and see how close your sinks, baths, showers and toilets are going to be away from the soil and vent pipes (probably in the perimeter walls). The longer the distance the more difficult things get and the more likely you are to be plagued by blocked drains in the future. Additionally, be aware that the higher the volume of water, the steeper the gradient of the pipe and the larger its diameter should be. Otherwise you can end up with gurgling sounds, low water exit flow and blockages. This is all in BS5572 and is not that difficult to understand. In short, if you possibly can, keep plugs close to soil and vent pipes and make sure you can access/rod the pipework when it gets blocked! 8. Think twice before selecting fancy plug fittings for sinks. Ask yourself “How is anyone going to be able to fix this when it’s installed and covered in limescale/dirt/etc?" 9. With all fittings/equipment that may need servicing at some point in the future, will you know who the manufacturer was and will you be able to get spares? 10. Decide early on what type of cupboards you are going to have – don’t leave it until later on in the build. Ikea do a great range of cupboard carcases. If you want to go for these cheaper, pre-made type then the rooms can be sized to accommodate the standard sizes these units come in. 11. Be prepared for the fact that contractors involved in the building process rarely have any visibility of or interest in innovation. You may hear them say that that have been in the business for x years and have a wealth of experience but the problem is that what they actually have is a lot of experience doing the same thing over and over again – they tend not to be interested in new products, techniques or materials. Although it’s boring, the more standard your design is the easier your build will be. 12. In your design pay attention to the direction doors open and the positioning of light switches. 13. Ask how your architect/designer/builder wants you to provide information on the locations for items in rooms, e.g. sockets, switches, lights, etc. What symbol scheme should you use? 14. Check that the sanitary ware works together properly. Our toilet flush buttons are (annoyingly) hidden by the seat when it’s up. 15. A good rule for exterior tile and brick colours is ‘dark at the top, lighter at the bottom’. 16. Don’t use small stones on the driveway – it gets picked up on shoes and taken into the house. 17. Wood-effect porcelain floor tiles are very good – very hard-wearing and they look realistic. 18. If you're running water supply pipes some distance from the road, pay a bit extra and have the largest diameter fitted (63mm outside diameter?). Whilst static pressure may not be affected by narrow pipes when the water is not flowing, the pressure may drop substantially once flow starts. Trying to fix poor water pressure is expensive - fitting a large diameter pipe is cheap. Note that the connection to the main at the road will be a 'standard' size and will certainly be smaller than 63mm! PLANNING PERMISSION 19. The planning process is not nearly as hard as it sounds. Consider doing it yourself – don’t pay someone to do it if you feel you can. 20. If there are any trees that need to be cut down for your development, do it before you apply for planning permission but of course ensure that there are no Tree Preservation Orders (TPOs) or other restrictions in place. 21. Check that there are no restrictive covenants covering your property. You can check this to some degree of certainty by ordering the electronics deeds to your property (you can download them from the web for a few pounds). You can get restrictive covenant protection insurance just in case someone surprises you! It is reasonably cheap. All covenants are for the benefit of someone – and it is these people who can make a claim against you if you break the terms of the covenant. 22. Try to work with your local planning department rather than against them. Their aim is to build as many houses as possible (to meet government targets). Believe it or not they are on your side but they have the local residents at their throats trying to stop any building in their area. Give them reasons to allow your development. 23. Make your design a little bigger than you want and negotiate down. 24. During the planning process, all the documents that you submit to the council are likely to be published on their website. This in turn will be indexed by Google and other search engines. If you have submitted electronic copies this will mean that details such as your name and address will be instantly retrievable by anyone in the world. Therefore, if you want to retain some degree of privacy, always try to submit paper, hand-written copies of all documentation. 25. Keep records of everything that appears on the Council website – particularly the letters written by local residents. They will probably get deleted after a few months but having them in your possession can be extremely useful. 26. Planning departments express opinions on planning decisions to be made by councillors based on local and national policy. Highways departments do not have opinions – they have rules which allow them to provide planners with information about the way that a scheme will or will not meet Highways requirements. However, note that planners are allowed to ignore this guidance if they wish. 27. Back up everything you agree in person or on the phone with the planners with an email. PROJECT PRICE 28. Your project is going to cost you a lot more than you thought. There are several reasons for this: - Your contractors will not be motivated to watch your costs as closely as their own and so will find that things are more expensive than they thought they would be; - Contractors are not necessarily perfect at planning – they may be genuinely unaware of costs that emerge during the build and this ends up costing you money; - Prices tend to rise rather than fall; - You can’t remember everything and there will be things that you decide you want that you hadn’t budgeted for. 29. We found that ‘PC Sums’ (see Explanatory Note below), i.e. the non-fixed sums that amount to whatever the builder has to pay, were nearly always over the estimate, between 20-60% (and that’s without any extravagance!). If you decide that you want a more expensive option than a ‘normal’ item which would represent ‘par’ for the project then it is fair that you should pay more. However, on a fixed-price job, make sure you agree that PC sums are not allowed to escalate when you only want the ‘standard’ level of item. My recommendation here is: - Try to get rid of as many PC sums as possible. - Obtain some sort of agreement that the PC sums will remain within control. It is very important that they have some focus on giving you a REALISTIC idea of what your costs are likely to be rather than just minimum figures. Note that it not in their interests: -- to price up to a reasonable amount for PC sums (because it reduces the chance of getting the contract) -- to expend work to reduce over-spends on PC sums. - Set default prices for items of the most basic specification which could be installed for the PC sum if you have run out of money. For example, ask for a price for a specific fireplace that you would be happy with if you were running out of money. - Make a rule with your builder that whenever an item is quoted for against a ‘Prime Cost’ (or PC) sum item, that the PC sum is also given, otherwise you end up being asked “Is x thousand pounds ok to pay for item y?” when you don’t know how much the PC cost was for that item. 30. For an expensive product which is relatively easy to specify, get lots of quotes. This is more difficult with a custom-designed object like a staircase – you are really buying into the company that will design and make it for you and this may be a long process. 31. Ask your builder if they intend to charge an additional sum for some amount they have to pay to the builders’ association or something similar. This can occur if you ask them for a more expensive item, e.g. a better roof, and the cost of installing it is higher than you expect because the builder has to pay a premium to an association based on costs. 32. A significant cost will be the various charges and levies that the council will make against your project. Planning permission will be granted subject to the council receiving this money. 33. Check to make sure that ALL the costs are included in the price. We had to pay thousands of pounds extra for things like fitting a new gas connection, air circulation system and digging up the road for the water main. Make sure there are no (predictable) hidden costs. 34. Ask what the contractors will add on for anything that they buy (often 10%). You might be able to save money by ordering some things yourself. ARCHITECTS 35. Undoubtedly architects can assist a self-builder but we didn’t use one. There were several reasons for this: - We knew pretty much exactly what design of house we wanted - Architects are generally VERY expensive - They often have their own vision of the house which they try to impose on the client. A frequent complaint from clients is that they feel that they have had to persuade their architect to give them what they want! - By having a contractor and a separate architect you run the risk of being caught in the middle of disputes between the two. If there is only one contractor then everything is down to them. In hindsight I am very pleased we didn’t use an architect (we created our own drawings and an architectural technician drew them up for us ready for the structural engineers). SELECTING CONTRACTORS 36. When selecting a builder, ask them to bring all the process documents and templates that you would be expected to be involved in or provided with to a meeting. If they bluster and make excuses about ‘working on an individual basis with each customer’ you know that they don’t have any processes. This is NOT good and it means they will probably repeat all the mistakes they made on the last job on yours. 37. Have your house built on the basis of a contract with your builders for which they are responsible for EVERYTHING. If you allow a situation to arise where a builder can blame someone you hired then you are heading for problems. 38. If you are planning to specify a particular company to perform a special task in the build, make sure right from the outset that they are prepared to meet any associated contractors on site and go through the plan, stating who will do what and when. Make sure that the overall project manager will take responsibility for co-ordinating the various parties. 39. Make sure that concrete form-worker contractors are chosen with care and ensure you know exactly what they are promising in terms of quality before you start. 40. Avoid situations where two or more contractors are responsible to you for the delivery of an item. 41. Above all, when you build a house, the selection of the main contractor will create a relationship where you have to place a lot of trust in them so you must convince yourself that they are worth that trust. I think we were very lucky to have our builders. BEFORE THE BUILD 42. Satisfy yourselves that you understand who is liable if something goes wrong with your house. For example, if an architect specifies some material to cover a wall, what happens if it falls off? The architect may blame the builder for not using the correct adhesive, the builder may then claim that he did or that he wasn’t told. In cases like this, who pays to have it fixed? What happens if a foundation shifts due to ground movement? Whose responsibility is it to fix it and pay for it? 43. Before the build starts state explicitly what trees, etc. that you don’t want damaged. Digger drivers must be briefed on what to avoid. Sensitive areas MUST be taped off at least. If it can possibly be damaged it will be – watch Grand Designs! 44. Agree a length of time that you must be given to make a decision from first hearing about it. You don’t want to walk on site one day and be asked how big the window sills have got to be with an answer to be given within hours. 45. Agree a process for dealing with serious issues. Note that an issue which is serious to you may not seem serious to your builder and vice versa. This could lead to accusations of either over- or under-reacting to a perceived problem. If you agree a process before you start the build this should not be a problem. 46. There are guides for good practice in the building industry. For example, the LABC have an excellent manual and there are British Standards such as BS5572 (Code of Practice for Sanitary Pipework). The problem is that the British Standards documents can be expensive to buy (e.g. over £200) but they are often available for free on the Internet as PDFs. Ask to see the standards to which the tradesmen are working. Seek assurance that a) the tradesmen have a copy of the relevant standards and b) will stick to them. If you have a copy of the standards it isn’t difficult to go around and check simple things. 47. Make sure that your contractors agree that any concrete surfaces or steps will have a slight slope on them so that water will run off them and that they will fix any which don’t, no matter how difficult. 48. Ask your builders (in writing) if they have any interests in/relationships with any suppliers. This is not necessarily a bad thing – it may work to your advantage. Anyway, it’s worth knowing what the relationships are. 49. Agree what happens to materials that leave the site, e.g. waste wood. Will it be sold? 50. Ask yourself where you are going to store the things you buy for your house along the way, e.g. taps, electrical equipment, etc. Consider buying a small, secure container and putting it on site for the duration of the build (you can easily sell it again on eBay) or ask your builder if they can provide you with storage. 51. If your builder hires a contractor such as a painter or architect to work on your build then (unless they provide a transferable guarantee of some kind) they are not answerable to you at all – they are only responsible to the builder. Keep this in mind in terms of your agreement with your builder and any guarantees or indemnity that you may in future rely on. 52. Regarding stage payments, it would be good to agree that if faults are found in a stage that has already been paid for, then an amount from the next stage payment is withheld until the problem is fixed. If you don’t do this, there is no real incentive to fix problems when they arise. 53. Agree in writing with your builder that they will tell you if an item that you are deciding upon has any criticalities – e.g. will the flooring have to be less than a certain thickness, does a fireplace have to be of a certain type, etc.? Also agree that they will not allow you to drift into a situation where you get the blame for something like this. 54. Plan for the fact that concrete screed can take months to dry to the point where wooden flooring can safely be laid on top. 55. Make sure the builders are signed up to pay for any heating and electricity that they use prior to you moving in. Our bills for electricity and gas came to nearly £1,000! If they won’t agree to this, make them agree to cap the spend at a fixed amount. 56. Tell your contractor that you want all of the documentation for every item that is installed into your house. It is best to get it as you go along – when the house is finished all the people working on it will evaporate and the last thing on their priority list will be finding the paperwork that came with your shower mixers. DURING THE BUILD 57. Builders are not always right. Keep checking what they are doing! 58. Watch for quality issues involving techniques that your builders aren’t experts in. This will be anything that is slightly out of the ordinary. With us it was (surprisingly) the concrete basement. They didn’t know what to look for in good concrete or what standard to demand from the concrete suppliers. I was surprised to see unmixed concrete coming out of the lorry so I videoed it. Our supplier denied that there was a problem until they saw the evidence. In the end, several areas of bad concrete had to be hammered out of the walls and redone. Keep an eye out for this sort of thing if you can. Incidentally, the reason the concrete wasn’t mixed very well was probably because the concrete plant was only a couple of miles from our site and the materials hadn’t had enough 'spinning' on the journey to properly mix them. 59. If you have valuable items of your own on site, make sure there is adequate security and that rules for the site are established and adhered to, e.g. keeping gates locked. In my experience builders are not very good at shutting gates. 60. Be prepared to make decisions. I know this sounds obvious but there will be thousands. Ask for a decision schedule and stay ahead of it. Work hardest on the big decisions – floors, bricks, windows, tiles. Don’t get overwhelmed – just start working your way through it and you’ll get there in the end. 61. One often hears builders complain that the client doesn’t know what they want or that they won’t make a decision. However, this isn’t always the whole story and knowing what you want isn’t always enough. If the contractors shrug their shoulders and say that they’ve no experience of some product or technique that you want they may not show much interest in finding out. This can make choosing features/fixtures difficult. 62. Keep looking – or have someone you trust with an engineering background to look – at the important parts of the structure and be satisfied that they ‘look right’. Amongst several serious faults that we noticed we averted an extremely dangerous, possibly fatal structural error when we discovered that a load-bearing element had been mounted on a non-load-bearing support. This was a genuine mistake but it showed that another set of eyes can reveal all sorts of things that the builders may have missed. I was also amazed (and very thankful) for what others spotted that we missed. 63. It is possible (for reasons that are not foreseeable) that a change may be necessary to the design/spec of the building and that new prices will have to be obtained. For example, if electric garage doors were specified but these cannot be fitted for some reason and ordinary garage doors have to be fitted instead. A quote will have to be obtained for the ordinary garage doors and the difference between that cost and the cost of the (more expensive) electric ones should be removed from the amount you will be paying for. You should agree with your builder that prior to obtaining the quote for the new doors, that the actual cost for the original ones is disclosed so that you are sure to get a proper rebate. 64. Be prepared for the fact that the suppliers of building materials have not moved with the times when it comes to quality control. In fact in some cases, technologies that have been with us since before Roman times seem to have advanced little! Take for example bricks – you cannot pick brick colours from a board of brick ‘slip’ samples and then expect to get the same colours delivered. Ask any bricklayer. The only way to guarantee colours is to go down to the brick yard, select the ones you want and take them away with you. The same applies to exterior tiles. The quality control is nowhere near the standard applied to other areas of modern production (e.g. farm produce at supermarkets). The quality of concrete is incredibly variable in both consistency and mix. If you are looking for ‘fair-faced’ concrete surfaces, i.e. ones that are good enough to be visible, it may be a good idea to have a back-up plan in case it goes wrong. Note that the choice of concrete is often limited to those plants that are nearby – your builders may have little choice on which one they can use. 65. If you are working from samples then keep the samples of the things that you used to make choices and make it clear that the colours shown are the ones you expect to see delivered. If the supplier can’t guarantee that then pick another supplier. 66. Take lots of photographs of everything, no matter how boring. When the structure is finished and you need to know what’s behind a wall you’ll be grateful. Particularly useful is where pipes and other services are running behind walls and under floors. 67. Make sure that you decide and say where you need wood behind the plasterboard to support pictures, curtain rails and televisions, cupboards, etc. and then take photographs of where it is before the plasterboard is put on. 68. Keep a VERY close eye on what you are paying out. It’s a very good idea to create a spreadsheet which documents all the costs and then when they have been paid. AND FINALLY SOME OTHER NOTES… 69. In my experience professional bodies such as the Chartered Institute of Engineers are only there to protect their members, not the public. In my experience they will always maintain that their members are right and you are wrong – the member is the one paying them – not you. Always have in the back of your mind that you cannot rely on any professional body to protect you from their members. 70. Don’t expect the Local Government Ombudsman to uphold any complaint you make against the local authority. In my experience they rarely take any complaint seriously. Take a look at their website and try to find a dispute that has ended up in the resident’s favour. Even those labelled as ‘upheld’ often don’t force the local authority to do anything to rectify the matter. 71. If you are using a home automation system which controls the lights, make sure you put an ordinary light switch in the cupboard/room where system is. If it goes wrong you’ll need some light to fix it! Also, think carefully before using mechanical retractive light switches. For a simple on/off they should be fine but for special uses (e.g. double tapping for switching a light scene off) they are not very easy to use. Consider the touch-sensitive (capacitative) type - they are far easier to use. 72. Don't allow things which will need replacement or servicing to be boxed in with decorative panels, etc. Make sure it is easily accessible. 73. If you're building a basement in impermeable ground (e.g. clay) remember that basements can easily 'float out', i.e. rainwater can flow down the sides of the concrete, collect under it and then cause the basement to float. Yes, it sounds incredible and yes, basements are very heavy but so are battleships and the Archimedes' principle holds true for both of them. Make certain that a) that your builders have spoken to the engineer about this and fully understand and will mitigate the risks, b) that there is adequate drainage from the bottom of the basement during the build to prevent water collecting around the concrete 'ship' and c) obtain written confirmation from your engineer, backed up by his professional insurance, to confirm that the weight of the house's structure above will be sufficient to keep the house firmly in the ground when the project is finished. 74. I started with this but I’ll say it again – get all decisions in writing. If you make a decision verbally with anyone, back it up with an email. Explanatory Note: A PC Sum (Prime Cost Sum) is an allowance made by an architect or a builder in the price for a specialist contractor or specialist supplier. In most cases a PC Sum is allowed for electrics, plumbing, heating, kitchens, windows, etc. It is allowed on a lump sum provisional basis and the client is responsible for the actual end cost of the item plus a small percentage for the main contractor. It is in the contractor’s interest in the tender process to keep this figure as low as possible as it makes his overall figure lower even if it is well known that the provisional cost is insufficient.