With any Self Build (or Renovation project), YOU are putting a lot of your time, effort, skill, and labour into creating the finished product. – So it would be nice to think, that at the end of the project, your input will be repaid to you by you achieving an increase in your “equity” (i.e. your “net worth”).

After all, what’s the point of of going through all the research, planning and the building process, if you could just as well have gone out and bought the same sized developer’s property and been just as well off?

So, when we think about taking on a Self Build project, most of us are normally thinking about the profit it will hopefully generate for us, as much as, if not more than, the affect it will have on the “quality” of our lives.

What we need to do before we start, is to decide how our time and effort can be put to best use in order to maximise the benefits, both “financially” and in our “quality of life”.

This section will concentrate on the “financial” aspects (other parts of the guide will cover the “quality of life” point of view).

One area you can think about, well before you even start to do any definite planning, would be to assess which areas of the project you would be best investing your own time into, that will give you the best chances of making a decent profit.

You may have a “trade” (joiner / plumber etc) which could be useful for the project. You may be physically fit and able to “fetch and carry” all day. You may be good with figures, or at designing. You may just have a lot of “free time” that you can dedicate to the project.

What you need to do at a very early stage is to decide which of your strengths are going to help you to maximize your profits.

If your “strengths” are in the “office environment”, - but you decide to spend a good proportion of your time “hand digging” a trench (because you want to be physically involved in the project), then no matter how hard you work down in the trench (you are not super human), you will only ever be taking the place of one labourer. - You may decide that you can dig ALL the trenches yourself and take the place of an “excavating machine” (which could the work that you do in a day, in about 5 – 10 minutes!). However, if you have good skills with paperwork, numbers and in negotiations, you could well be better off staying completely away from the physical work, and concentrating on the planning and the organisation. Why?

Say a site labourer costs around £10 / hr, and works 40 hours a week. – He costs £400 / week.

Excavator cost: Approx £25 / hr.  - But it will do the work that you do in a week in a couple of hours!

 

So, after approximately 2 hours (costing £50 ), the excavator is going to be doing work that you would be starting to do in your second week! - This could substantially shorten the project duration.

 

So, now if, instead of labouring, you spend 40 hours in the office measuring the quantities and making phone calls, you could make very substantial savings in other areas:

By measuring the quantities of all the drainage materials yourself, you may save £150 (rather than having to pay an Estimator to do it). You then have time to make a few phone calls to local suppliers to ask for their “best prices” on the materials you need. One supplier may give you a quote for everything you need, of £2,500. Another may quote you £1,900 (this is entirely possible – prices vary widely depending on where you go). – You save £600

You can then get on with doing the same for other parts of the project, like the concrete, brickwork, lintels, insulation, roofing materials etc, and possibly save yourself another £300+ in Estimating fees, and possibly a few thousand pounds in materials costs.

This work may take you most of the 40 hours we are talking about in this comparison, but if you have any time left you could spend it finding and contacting a number of Drainage Contractors to arrange to meet them on site

If, for example their prices were to range from £3,000 - £5,000 (which would not be an unusual “spread” of figures from 6 tenders), and the lowest quote of the six of from someone you would not have contacted had you been working down the trench, you could possibly be saving £2,000 on that ONE ITEM alone.

So, adding up the savings you could have possibly made by working in the office rather than down the trench, you could have saved a possible £3,050 in a week! – Compared to £400 if you had been “toiling” down the trench!

Now multiply that out by doing the same thing with windows / doors / roof / kitchens / bathrooms / tiling / flooring / carpets etc, and you should see the potential you have, by thinking about how you spend your time, to maximize your profit potential.

Ok, point made! - Next!

“Location, Location, Location” is covered on a separate page, but the geographical position of your project can be of great importance to its completed value. A good plot in “the right” area can produce profit margins generally higher than in less sought after areas, especially if the design and the quality of the finished property is right “for the area”. You may pay more for the plot, but, as a general rule, usually, the extra money you pay at the outset is more than recouped when it comes time to sell (But: Don’t jeopardize the size or quality of the “building” by spending too much of your budget on the land and not leaving sufficient for you to be able to develop it properly).

is of great importance when it comes to the “development cost” and therefore the “profit”.

Is the plot sloping?

Could there be problems underground (mines / caves / water / rock / existing drains etc )?

Will you need retaining walls?

Will you have to upgrade an access as part of the development?

Are there any “Ransom strips” associated with the land?

Are all the services close by?

Will you just need a simple strip footing, or a major “raft foundation” or even piles?

Are there problems with the vegetation? – Knotweed for example, which can cost a fortune to get rid of, or treat.

Are there existing building which have to be removed before you can start on the new development?

The ideal plot for Self builders, for maximising profits would usually be a simple, flat, rectangular plot, which is wide enough for the house of your chosen design, with enough room for ample parking at the front, access to the rear and a decent sized garden. Not overlooked, in a quite location, but close to everything you need. With all the services passing on your side of the road, right across your driveway location, and drainage running next to them.

It stands to reason that if those are the things that most Self Builders look for when buying a plot, then, as well as making the project cheaper, quicker and easier, the chances are that it would also be the most sought after when you come to sell it.

Unfortunately, not many plots offer that full list of “wishes”. But, if you at least have “ a wish list” to help guide you as you are evaluating each plot you look at, you will find that some plots come closer to being “just right” than others.

Try to make sure you get your external design right for the area where the new building is going to be situated.

If your development “blends in” with what is around it, or stands out in a “good way”, it will be a more marketable and valuable prospect. However, if you build YOUR idea of a “dream home” in a place where it just doesn’t suit its surroundings, the chances are that it will not appeal to “as wide a market”, and it therefore may not achieve your maximum potential “end value”.

The house itself might give you exactly what you always wanted in terms of living in it. – Plenty of room, the ideal internal layout, just the right specification, your dream garden etc, but if it “sticks out like a sore thumb” from what is around it, its value will probably be lower than it could be.

Try not to over complicate the external appearance. You can get a lovely looking property that is simple in design and cheap to build. You can also get a finished product which some people might think is “beautiful” but others will think is “over designed” and “over complicated”, “doesn’t suit the area” where it is situated, “uses lots of many expensive, but WRONG materials (for where it is being built), and has cost a fortune! – this “Unique and expensive “extravaganza” probably won’t sell for anything like its potential, or possibly even its COST, because no one will want to be associated with it! – Imagine the building in the image built near to where you live. – Would you buy it? – It’s a well known building and probably worth a fortune in its right location, but PLEASE don’t build one like it next to me!

 

One of my “Mantras” is:

I’ll look at the implications of that properly in a later SECTION, but basically, all things being equal, a square is the cheapest shape to build.

A square building of 10m on each side encloses 40sq metres, which is the maximum possible floor area for the length of its external walls. – That means that it is also, like for like the cheapest way to give you “a square foot of space”.

If you keep to a simple square layout, then (again, like for like) you will use less brick / blocks / wall ties / insulation / mortar / roof tiles / floor boards / plasterboard etc. The timber frame should also be cheaper, and so should the roof trusses.

As soon as you start to change the basic shape of building from a basic square, you start to enclose less floor area as a percentage of the total length of the external walls. - This automatically increases the build costs / sq metre.

As you change the shape from a basic square, you also start to increase the costs of the project in other ways. For example, if you add extra corners (i.e. if you design the building as an “L” shape, or a “U” shape) you start to increase the “unit cost” considerably.

A complicated roof with various slopes and angles can cost a two, three or even four times as much as a simple trussed roof.

Many Self Builders will add a small one storey annexe to the corner of the building, as maybe a “utility room”. Those little extra “shapes” stuck onto the side of the main structure involve a lot more work, and cost a lot more per square ft than the main structure itself.

Although all these “points” I have made regarding the shape and layout of the building are “things to bear in mind” when you design, I am not advocating for a minute that all buildings should be “square”. The world would be a very boring place if they were. BUT, if you want to increase your profit potential you just need to know that the further you “wander away” from that basic shape, the higher your costs / sq ft will be, and this will obviously increase your overall cost without necessarily increasing the value of the finished property. – Thus reducing your potential profit.

Large open spaces have smaller “unit costs” than small enclosed spaces.

So, an “open plan” design will generally cost less than the equivalent area which has been divided into small rooms. – Think about it. Rooms have walls. Walls cost money to build and decorate. They need plastering / skimming ( or plaster boarding and taping), decorating / skirting boards / possibly covings. Some of them need doors, which need hinges / latches / handles / decorating. - If you decide to use something like “solid oak” doors and skirtings, this can add substantially to the cost of each wall. They may have foundations underneath them which can also more than double their basic cost.

Again, I am not saying “make everything open plan”, but just bear the cost implications of lots of small rooms in mind when you come to the design stage.

There is the scope to “spend” or “save” thousands of pounds by your choices of internal doors. You can pay from £15 to £300+ for an internal door. On top of that there is the cost of ironmongery (from £5 a set to £50+ a set). Then add the cost of the joiner hanging the door and decoration.

If you are thinking of using “feature doors” and high quality ironmongery, this one item can take a huge chunk out of your budget, but is also a area where you can look to make considerable savings, whilst keeping the level of quality that you are hoping for.

As mentioned in the last paragraph, the “open plan” principle helps to keep the “door” cost down, because if you have less walls, you will obviously need less doors. - But if you don’t use the open plan design, just shopping around for a good deal can make a big difference to your budget.

Some “feature” doors can cost upwards of £250 each. In a 4 bed detached house you may need up to 17 of these doors. Add the cost of good quality ironmongery at, say £35 a set, then possibly “3 coat” staining them to finish them off. THEN, add the labour cost to hang them and fit the ironmongery and you could have a total cost of getting on for £6,500. - However, if you “shop around” and manage to find a really nice “pre finished” door which you like, at £190, and you get a good deal on ironmongery at £20 / set, your total cost comes straight down to £4250. You have just saved enough to pay for a couple of nice bathroom suites, - just by doing a bit of shopping round and being prepared to be a bit flexible.

You can save even more by thinking about each door in the design and deciding whether or not you actually need it:

Do you need that “double set” of doors from the living room to the dining room or would just one door do the job? Do you need 2 doors going out of one particular room, or would one suffice? If you are opting for high quality doors, then using the figures I have given in the example above, for every door you can “omit” from the design, you can save around £385.

There are no particular “best” room heights for residential housing. The standard room height tends to be around 8’ or 2.4m. Some developer’s rooms tend to be a bit lower than that.

If you stick to the 2.4m height you can actually save money compared to having a lower ceiling (which you may think should be cheaper because it uses less materials). - Large plasterboards tend to measure 2.4m in height. If your wall is also 2.4m in height, you will save on “labour” by the fact that you don’t need to cut every single board, and you will also save on waste by the fact that you won’t be throwing away a part of each board you use. These cost savings won’t be highly significant, but ever little helps! However if you go the other way, and add height above the 2.4m level, you COULD increase your costs by a more substantial amount:

If you opt for a taller room, and have to fit a full 2.4m plasterboard PLUS a “cut piece”, of say 200mm to give you a 2.6m ceiling height, it has the following effect:

More waste: - You will waste part of each board as you cut the offcuts from it. Not only that, you will now need to order longer lengths of timber for “stud (timber) walls” (Standard lengths of timber are usually 2.4m long). With a “head piece and a “sole plate” this usually gives a maximum height for a wall of about 2.5m. If you specify a taller room, then you will need to order 3.0m lengths of timber for the studs, instead of the 2.4m. Most of the extra length will actually often be wasted.

More labour input: - Each section of each wall will take possibly twice as long to be fitted with plasterboard due to the extra measuring, cutting and fixing of the small extra piece. – Plasterers will usually want to be covered for their extra time too!

More materials: Using those 3.0m lengths of timber instead of 2.4m can add about 20% to your total order for this item when you take waste into consideration.

Also worth bearing in mind is the fact that as your increase the room heights inside, you increase the amount of height of the external walls. If you increase your room height on each of 2 floors of a house by just 6” (150mm), you add a total of 300mm to the height of the property. If the external walls have a perimeter of, say 40m, this adds 12 sq metres of extra external wall area “per skin”. So at say £350 / 1000 for bricks £300 / 100 to lay them (plus mortar etc), and £8 / sq m for blocks and the same to lay them, you could add in the region of £1000 to the build cost. JUST for the external walls by adding that small extra height internally.

The increase in value in the finished building by increasing your room height will be either “negligible” of “non- existent”. (It can actually make the room look smaller! Why? - Because our eyes tend to be used to seeing rooms with the standard ceiling heights and we base our impression of room size on that “baseline”. - If your room has a higher ceiling, then, to make our brains think it is the same size as a “normal height” room, it would actually need to be larger! (this is not easy to prove to you here! - Just bear it in mind!!)

Just as with many other parts of the project, every individual item, small or large, included in this section can have a significant “knock on” effect on the overall costs. Many items which can affect costs will hardly be noticeable and may easily “go under the radar” at the design stage.

We tend to “gloss over” a lot of details during the early stages of the project, and sometimes don’t realise that the sentence we just uttered will cost us an extra £1,000!!

For example: 5” pencil round” costs very little, perhaps £1.50 / m. Solid oak, 9” skirtings can cost £20 / m+. – Within that range will be something that suits you. – If you like the look of solid oak, and feel that it will “sell the house” better (which it will), you could opt for an MDF skirting with an “Oak Veneer”. It looks just about exactly the same but costs a lot less.

In a 4 bed house you could easily need a couple of hundred metres of skirting. If you choose MDF, veneered over solid wood skirting you could save over £2000 whilst not really having any negative effect on the value of the house compared to using the solid oak.

Doors are another example. They can cost between £15 and £300 for each internal door. Choose wisely and you could save possibly another couple of thousand pounds without affecting the end value of the property.

One thing to bear in mind, which you need to weigh when you are doing things to save money is that the “Fitting Out” is “WHAT WE SEE”, and, just as importantly “WHAT OTHER PEOPLE SEE”. – One day those other people could be potential buyers. – Going too cheap may reduce the overall attractiveness of the house, and therefore reduce its value by far more than the money you saved by using the cheaper materials.

So, as a guide: If you are hoping to maximise your potential profits, and / or you intending selling on the house within a couple of years or so, you need to think about “what features other people are likely to be attracted to” when you choose all of your finishing items, and then try to balance that with “sensible and cost effective choices” when it comes to buying everything you need.

Also remember: If you simply concentrate on getting the house looking how you want it, that’s great if you are planning on staying there for a few years, but if that’s not the case, then you need to bear in mind that your taste will not always be the same as other peoples tastes, and choose you finishing items to appeal to as wide a section of the potential buying market as possible, whilst also being acceptable to you.

This subject gets “a paragraph” in this section, and more than one dedicated section later in the guide, because of its importance within the whole project.

Your kitchen can easily account for 10% - 25% of your total “build” budget. – BUT, a £20,000 kitchen may not, in fact add any more value to the finished property than a £5,000 kitchen. It is therefore an area worth giving a lot of thought to if you want to maximize your potential equity in the property once it is finished.

Following simple guidelines can save £1,000’s, whilst adding value to the property, and not even be noticeable in the finished product. I won’t go into depth on this here, but if you take a look at the sections of this guide which deal Kitchen Design, you’ll see how you need to think about every decision, and how making decisions which you may not otherwise think twice about, can have significant cost implications.

If you could design and install a “high quality kitchen in your new home that you are “completely happy with”, at a cost of £6,000, - or you could pay £20,000 for a “higher quality kitchen that you are “completely happy with”, then which would make the most sense economically?

That £14,000 difference, on a £60,000 budget house actually equated to nearly 25% of your total development budget!

Or, look at it another way:

If you pay £14,000 less for pretty much the same kitchen which will retain the same potential market value for the finished property, would you rather have the money in the kitchen units or in your pocket?

Also bear in mind, that the £20,000 kitchen has to be paid for. If you could cut your mortgage by borrowing £14,000 less, it would give you more money in your pockets EVERY MONTH after you have finally moved in, without affecting the market value of your property.

The same rules that apply to kitchens, apply to bathrooms. They can eat up many thousands of pounds, and a good percentage of your total budget, and, if you pay more than you need to, they may not add anything worth mentioning to the value of the property.

Again, there are pages dedicated to bathrooms later in the guide, but briefly on this subject I would recommend spending plenty of time shopping around for the best deals. Every Bathroom shop you visit will have wide ranges of available equipment and their prices will vary very substantially. Just spending a couple of days calling at as many shops as you can find could save you thousands of pounds.

Careful use of tiles, mirrors and lighting can have a huge impact on a bathroom. - Far more than spending an extra £2,000 on a slightly bigger bath, or hundreds of pounds on some fancy accessory. LED lighting is relatively cheap, especially if you install it as you build the house, but it can create some stunning effects. If you buy one or two nice feature mirrors at, say £150 each, which then reflect and enhance the lighting, then add nice, but not necessarily expensive tiles, you can create the effect of a “5 Star hotel” at for surprisingly little money! – The “Wow” factor does not necessarily come with the big round bath, or the top of the range spa bath. It can just as easily be achieved with a bit of thought at a fraction of the cost.

A colour scheme that you may think is a “beautiful combination of bright and airy colours giving a wonderful natural feel to a room”, may in many other people opinions be “brash and in bad taste”!! – That’s the reason developers stick with magnolia and white colour schemes. They need to present their properties: “To attract the maximum number of people and “offend” as few people as possible”. Magnolia and white are the colours that you see “piled high” in DIY shops, Decorating Suppliers and Builders Merchants. Why? - Because they sell very well - because lots of people like them and they “offend” very few people!

I am not advocating that you only use those two colours. Far from it, if you are being “individualistic” enough to want to create your own home from scratch, the chances are that you want the interior to be something different and better than what most other people are “dished up” by the developers. JUST BEAR IN MIND that you may want to sell the property on in a couple of years and that if you want lots of people to be interested in buying it, it needs to appeal to a wide section of the “buying public”. – The more people that like it, the higher your likelihood of getting your asking price, and therefore the more profit you will make.

A straight flight of standard softwood stairs can be bought for couple of hundred pounds. You can also easily pay up to around £10,000, or possibly more for hand crafted hardwood feature stairs. In a “Grand” house with a large budget the extra cost could be justified, and be seen as an investment, but in a standard 4 bed detached it is probably not a good idea if you are hoping to make money.

You can create the effect of a higher quality set of stairs by simply making them slightly wider than normal. A standard width set of stairs will be around 850mm. But, if you increase the width to, for example 1100, with an extra wide “rounded” feature bottom step, and buy some nice spindles and handrail. You can give the “appearance” of an expensive staircase without the cost. In fact the staircase I have just described could probably all be bought for less than £500. – But, what it would do, especially if it is fully visible from the front door, is to give anyone walking into the house the feeling that they have entered “something different and better” from the norm. – This is exactly the effect you would be looking for if you came to sell the property in the future and wish to maximise its selling potential and therefore it’s selling price.

An extra £200 - £300 should allow you to specify a “higher quality” softwood for the stairs, which would be of a good enough quality to “stain” rather than paint. This can further increase the appearance of quality.

By making a small investment in increasing the quality and appearance of your staircase, you could increase the market value of the property by up to £5,000. By spending £10,000 on you staircase you may find that you only increase its value by a small amount more than £5,000.

The increasing popularity of LED lighting is changing the way Self Builders are able to create “special effects” at relatively little cost. See the sections later in the guide on lighting to see more detailed examples of how different types of lighting can be incorporated into your new home, but here, I’ll just give you some of the basic considerations which can affect the cost of your installations and how they can affect the end value, therefore your profits.

Plastic electrical fittings cost a couple of pounds each. Chrome or brass can cost around £20 each. Feature lighting can cost £hundreds per fitting. (Note: These are only the cost of the actual fittings themselves and the prices quoted do not include for the cost of the cable or the labour cost of installing the lighting system. – This will remain roughly constant, whichever type of fittings you decide to use)

If you plan on installing an average of 3 sockets, 1 light switch, 1 TV outlet, 1 BT outlet and 1 ceiling light fitting in each room, if they are all in the standard white plastic they could cost less than £20. - However, if you opt for the more expensive brass fittings at £20 each, and a reasonably high quality light fitting at, say £150 you could easily spend £290 per room.

If you are building a 4 bed house you may have 14 or so “areas” (including all the rooms, plus hall and landing). At a cost difference of £270 per “area” for the cheaper option versus the more expensive option, you could spend around £3500 extra for the high quality fittings than you would for the basic fittings. On an average 4 bed house project, this could equate to around 4% - 5% of the total budget.

As to the potential of the higher quality products to increase the value of your property? – Well, I would say that in general, because these fittings tend to be high visibility, as long as you keep “a grip on the reigns”, and don’t go too over the top, this extra cost could be a worthwhile investment. A nice chandelier in the entrance hall, complimenting the feature staircase (that didn’t cost you much!), with a nice carpet or good quality laminate flooring can really set the “tone” for the whole house, and create the “Wow” factor, not only for you and your visitors, but also for anyone who may walk through the door in a couple of years who could potentially be buying it from you. That £3500 cost to upgrade the whole house could probably add up to double that amount to the market value.

A reasonably nice and good quality tile can be found for around £12 / sq. m. Or even less if you shop around. - You can easily then spend up easily to £50 / sq. m. for the more specialist “feature tiles”.

If, for example you decide to tile the walls to full height and the floors in 2 bathrooms , 1 kitchen, 1 utility room and 1 hallway. You could easily use up around 100 sq. m of tiles.

You that need to add to that, the standard “fitting cost” of around £12 - £15 / sq m, and all the accessories you will need (tile edge trims, adhesive, grout etc), which together could add around £3 - £8 / sq m.

However, if your “expensive tiles” are also difficult, labour intensive, need a lot of cutting, or are fiddly, to fix, you might have to pay an extra £10 / sq. m just for the fitting. – Taking the fitting price up to around £25 / sq m.

 The difference between using the £10 tile on a standard “easy” project, and the £50 expensive tile which needs a lot of labour input, could have cost implications as follows:

£10 / sq m tile. + £12 / Sq m fitting. + Plus £3 / sq m for plastic accessories, adhesive etc.

£50 / sq m tile. + £25 / sq m fitting. + plus £8 / sq m for brass accessories, adhesive etc

As to whether the extra cost would be a good investment to increase the market value of the finished property? – I would say that tiling is very important, as one of the things that create the “Wow” factor, but don’t go daft.

If your budget is up to £100,000 I would try to keep your basic tile costs to less than £20 sq m. You should be able to get some very nice tiles for that sort of money. If you manage to do that then you should find that the money you spend will increase the value of the property by “more than cost.

The other option you have is to reduce the area you tile. For example, the figures I have used above were for tiling the full bathrooms, floor to ceiling. If you just tiled to “half height”, or even just around the bath and shower, plus a splashback behind the sink, you could reduce the amount of tiling substantially. This would allow you to increase the cost of the tiles and accessories without risking spending too much.

Carpets / laminate flooring can be bought from less than £5 / sq. m.

Reasonable quality carpets and laminates can be found from around £10 / sq. m.

High quality flooring will cost from £15 / sq m and upwards to over 50 / sq m.

In a 2000 sq ft house you will need to cover around 100 sq m of floor area.

The £5 flooring, together with £3 / sq m underlay and fitting at around £2.50, would cost you around £1050

The £10 flooring, with £5 / sq m underlay and £2.50 fitting would cost around £1,750.

The £50 / sq m flooring, with £8 / sq m underlay and £2.50 fitting would cost around £6000

Using the £10 sq m flooring would not necessarily detract from the value of the house when compared to the products that cost £50, as long as the carpets you choose would be acceptable to a wide range of tastes.

However, the value and selling potential of the property could be reduced in time if you opt for “cheaper” carpets which start to look “worn” quickly, or if they are of a colour which shows the dirt very easily. Making areas of the house look “grubby”.

In areas of high “footfall” and areas at entrances to the house (front and back doors), you may be better opting for a  reasonable quality floor tile or laminate flooring, which will generally take the “wear and tear” better.

The extra cost involved in fitting the £50 / sq m carpets throughout the property would most likely not result in an increase in the value of the property which would cover its cost, although it may have some minor positive effect on the value.

Clever use of cheaper flooring in less important and less used areas, and high quality flooring in high visibility and high use areas can help to create that feeling of a “high quality” home without having the “high quality” price tag attached!

I am convinced that if you follow the guidelines written here and throughout this guide, before you start to design your project, you will be far better equipped to save a very considerable percentage of you development costs in ALL areas, from design, planning and preparation, through the whole of the building and finishing process. I am also convinced that you should be able to increase your potential profit margins significantly.

Over 20+ years, I have completed many projects, both for myself and for clients at FAR lower cost / sq ft figures than you will see quoted anywhere in written publications or case studies. - The only reason I have been able to do that is because I have followed all the guidelines that I am setting out for all of you, in this guide.

 

For example: When average figures being quoted for new build a few years ago, “per square ft” were around £60 - £70 / sq ft, I was successfully developing high quality properties in the region of £25 - £35 / square ft. – If you take an average Self Build 4 bed detached house of 2000 sq ft, you get comparative figures of £120,000 - £140,000 for the average development costs, and £50,000 - £70,000 for my ACTUAL development costs. – A saving (or an extra profit) of around £70,000. – ON ONE PROJECT.