True - and the semi-detached model is a compromise between terraced and detached.
In terraced houses, the ‘end terrace’ is often more desirable to buyers than mid-terrace - because there is more direct access to the back of the property, the strip of land it is built on may be wider, and there may be additional windows in the end wall.
Semi-detached houses are, I suppose, just terraces of two.
According to English Heritage’s listing of one of the houses, it has been suggested that ‘the south side of High Street may be substantially of one build in C14 or C15’.
But even if that was not the case, the plots would have been laid out by the landowners, the canonesses of Lacock Abbey. As was usual in most medieval English towns, those plots were narrow but long, running back from the street. This can still be seen in the Google Maps satellite view. That configuration would have been difficult to alter even if the canonesses then sold the freeholds of the individual plots. The width of the street fronts is often the most unchanging feature in historic English towns.
Once the narrowness of the plots had been fixed, building the house across the street end was the obvious option. The garden was as important as the house, as it provided space for animals and/or vegetables. But why put those in front of the house, when they would be (slightly) safer behind? The gardens weren’t decorative.
If you have a deattached house in the UK, you are wealthy.
The population density is quite high in the UK and land is expensive. So the various housing styles over the centuries tended to make for efficient use of land by packing them into terraces like this.
While it may have an advantage in terms of cost of building, living so close to your neighbours has downsides. I live in a late Victorian house in a terrace, it was built about 110 years ago, while nice to look at, with some nice internal features, these houses have annoyances. The short foundations mean they suffer the effects of ground subsidence so you get cracks and various repairs are needed to stopping them from collapsing. They are made of brick with woodfloors. Between the floors is an air cavity, then the plaster of lower floors ceiling. So there is little vertical sound and heat insulation. Given that these old houses are now turned into apartments, it means you can hear a lot of what is going in the apartment above or below you. This is a big issue if the people next door are crazy, have noisy kids or play their music loud. We also get water damage through leaks from washing machines and showers. This happens a lot. I had a builders boot come through my plaster ceiling a couple of months ago. It was a bad day.
The shared walls of the terrace had a big advantage when homes were heated by coal fires. Each room with a fireplace needed a chimney. If there are three floors, that is three chimney flues going up to the roof. If the wall is shared in a terrace house next door, the three flues of that house can be combined in the same structure. So you get six chimney pipes on the roof in chimney stack. Usually there is the same arrangement at the back of the house. This was common format for many terraces way up until the introduction of gas and central heating in the 1970s. The climate in the UK is quite cool, it might get over 80F for just a few weeks in the summer but it hovers around 50F for lot of the year, so heating is a priority over air conditioning. Retrofitting heat and sound insulation in these places is painfully expensive. Those old chimneys are redundant with gas central heating, but they leak heat.
In the UK it is more economic to convert old houses rather than build from new. It is a national obsession. The English dream of a dinky little cottage in a village in the countryside (deattached) with a nice garden front and back. Something very old, but with central heating and all modern conveniences. An Englishmans dream of simple life in a bucolic paradise that supposedly existed before the industrial revolution herded people into cities.
Consequently we are not overly fond of our neighbours and rather wish we had some more distance from them. American huge detattached houses with their big yards and huge garages sound quite luxurious. Until we hear about the coackroaches and other annoyances like earthquakes.
Also in the days before cars and autbusses and railways, the closer you lived to your work and job and market, the better. Plus, building materials were not cheap (the value of using pre-built walls.) Go back even farther, and the trick was to find an open area of land on which to build inside the city walls for protection. A lot of old British villages (old european villages) are very compact.
I’m sorry, “actual pictures”? Did I post sketches rendered from memory? 
As for the perpetual nightmare of fires spreading, it doesn’t keep me up an night any more than the fear of earthquakes or alien invasions does. I’m (much) more worried about living with inflation on a fixed income.
Oops, apparently a misapprehension due to my browser configuration or something. What I got when I clicked on your link was simply a page full of plain old Google search cites – perhaps because I run my browser with Javascript disabled. Turning JS on and trying again, I get an actual map of your neighborhood and a pic.
Anyway, those Painted Lady pics I posted are pretty, don’t you think? 
See London, Fire of, Great.
in the days before hydants and efficient pumpers, yes, a fire was a disaster.
And for that matter, see also San Francisco, Earthquake of, Great, which also included a Fire of, Great.
Terraces can be very desirable residences.
Here is a very fine Regency terrace built just about the time the US was getting going. They were orginally for ‘society’ people, many who had grown rich from the plantation wealth coming from the colonies.
That style of Georgian House with its high ceilings and big windows is very attractive, but the devil to heat in winter.
Old houses are a flawed passion, but they have great style.
Contributing to the SF fire, I think, was that the hydrant system was knocked out, many roads were impassable to firefighters, and the difference between common and separate walls was moot when the two walls were intermingled kindling.
For what little I’ve read, when a fire happened in medieval times, everyone pitched in to fight it as best they could and it was not uncommon for entire blocks to be damaged.
I live in an 18 century terrace. They were often constructed in a row by mine/factory owners to house their workers so they got some rent off their wages and to attract workers (skilled workers were often in short supply) Another local consideration was votes. At one time Members of Parliament were often voted in by very few votes as to qualify to vote you had to own a small amount of land etc, a terrace wouldn’t typically qualify. Some times it wasn’t unheard of for local worthies hoping to be an MP to build qualifying houses and import voters. (sometimes the voters also openly sold their votes at normal market stalls or as in the case of Tintagel in Cornwall their was only one vote, that of the vicar)…
18 century Terraces were often a joint enterprise with individual builders grouping to invest and fit out separate houses often differing ornaments can be noticed when builders would offer owners buying “off plan” a catalog of bits to be fitted. Sometimes though one builder failed to complete his part of the bargain either running off with the cash or going bankrupt so some terraces fell down or remained unfinished. The Semi-detached got round this by having only two houses at risk…
I’ve lived in a couple of semis (semi-detached houses) and the fireplaces were always on the joining, support wall. That wall was very thick and insulated most of the noise, but possibly not all of the heat - before the fireplaces had been either ripped out or replaced with gas fires - so there was an additional benefit of ‘sharing’ some warmth in Britain’s bleak, frosty, miserable winters.
That goes (almost) double for terraced housing and quadruple for apartments. Apartments I’ve lived in have been well-built and ‘cosy’ although not particularly small.
A detached house I lived in was next to a field and the exterior wall, and rooms, on that side were always noticeably cooler. We ended up having to upgrade the insulation and add a large conservatory.
Occasionally, when the next tenement falls down, or in the case of Glasgow and Clydebank, gets bombed, you are left with the inside wall of the neighbouring properties still visible. See the fireplaces on the end gable of this block. Many of the properties I remember from Glasgow and the surrounding area have been renovated, and as part of the build, the new end gable gets a skim of brick or harling.
Burnt-out Crieff flat 'draws tourists' - BBC News is a more recent example of fire damage showing the shared wall.
You are going to have to take my word for this one…
An associate of mine worked as a custodian in one of the high rise blocks in Glasgow, similar to the blocks that will come down to open the Commonwealth games. Early one morning, there was the sound of the jackboots charging up the stairs, as the Police drugs squad paid a courtesy call to a dealer that was in the block. The flat had been converted into a cannabis growing factory complete with growing lamps. The Police spent the rest of the day hauling away bags of evidence.
Later that week, the lady that lived above the dealers flat complained to the custodian that her flat was now freezing. Because of the heat from the growing lamps rising up from the flat below, she hadn’t needed to put her own heating on…
My semi’ built in the 50s, has a (redundant) chimney in the centre of the house, not on the shared wall. The original houses came with a solid fuel boiler in the kitchen to heat water. On the other side of the wall, in the sitting room, there was a fireplace. There was also a small one in the bedroom above. We assume that the other rooms must have relied on electric heating, since they have no chimney. Unlike many American houses, and most modern British houses, all the internal walls are built from solid blocks, and the common wall is a double cavity wall built from brick.
These houses don’t seem to have shared walls. They seem to be build side by the side, but each with its own walls. Am I mistaken?
They could have used electric fires in the fifties but when I was a boy in the early sixties we used paraffin heaters in each room without a fire - like thissE9swm(vcyBR(c,guT6Q~~60_35.JPG). And yes, they were dangerous. They got extremely hot, they could be easily knocked over (spilling paraffin), and they gave out fumes - only dispersed by the draughts under the doors and round the windows :smack:
I don’t know Lacock itself but if it like the same sort of street around here it will be a mix. Some will have been built together and share walls, others will have been added or replaced at different times and be separate. In our case the street has been there for a thousand years, the cellars of some of the houses date back to the 13th century and a couple of the actual houses to the 15th century. Inevitably over that period there are lots of different building techniques.
Many years ago I took a walking tour of Philadelphia. Originally you were taxed by the frontage of your property, why the row houses there evolved as deep but narrow.
The main advantage of semi detached is usable and more versatile floor space.
I’ve built several semi-detached (also called duplex) homes in Calgary inner city. These sold for close to 1 million a side and are in a sprawling prairie city. Usually these are 50 ft lots that have been subdivided. A semi detached allows you to build two 20 ft wide homes instead of two 17 ft wide homes. Although you can make the 17 ft wide homes with similar square footage by making them longer, that 3 ft of width makes a real difference in useful floor space. You also eliminate two sides of exterior finishing and soffit which is not an insignificant saving. Everything else, including services is separate for each side.
One thing that people probably do not realize is that semi detached houses do not actually share a wall; there are two walls separated by a 1 inch air gap. The only things connecting the two sides are foundation, tin fire guard on each floor and exterior finish.
