Extensions in Lexden

Extending in Lexden

Colchester’s most established suburb, and the one where the trees decide your foundations.

Lexden sits immediately west of Colchester city centre, running out along Lexden Road towards Stanway at the city’s western edge. Prettygate fills the ground between Lexden and Shrub End. It is the address people move to and stay in, which is exactly why so much of the work here is extending rather than moving.

It is also, technically, one of the more demanding parts of Colchester to build in. Three things combine: a conservation area covering part of it, housing stock built between the wars with foundations to match, and a very large number of mature trees on shrinkable clay. None of those is a problem on its own. Together they mean a Lexden extension is rarely the cheapest per square metre in the city, and a quote that treats it as though it were has not looked properly.

The housing stock

Mostly interwar, mostly hipped, mostly with side access. That combination sets the options.

The bulk of Lexden is 1920s and 1930s semi detached and detached housing, with pockets of Victorian and Edwardian villas along Lexden Road itself and post-war infill on the side roads. There is also genuinely old property around Lexden village.

The interwar houses share a set of characteristics that shape what is worth doing. They generally have a decent garden depth, so a single storey rear extension has room to work without swallowing the whole plot. Most have side access, which matters enormously for cost, because materials and spoil can come round the side rather than through the hallway. Most have hipped roofs, which is why hip to gable loft conversions are so common here: squaring off the hip is what turns an unusable loft into a floor.

The Victorian villas along the main road are a different proposition. Deeper plans, higher ceilings, often with a rear outrigger, and frequently within the conservation area. Extensions there are design conversations rather than form filling.

Foundations on the interwar stock are typically shallow strip footings, often under a metre and sometimes considerably less. That matters when a new extension founded to modern depths is tied alongside them, because the two will not move together.

The conservation area

Lexden has one. It does not cover everything, and knowing which side of the line you are on changes the job.

A conservation area does not stop you extending. What extending in a conservation area does instead is remove some permitted development rights and add a materials conversation.

Inside it, side extensions generally lose permitted development status, cladding usually needs consent, and the council will take a view on materials and detailing rather than only on massing. A rear dormer loses permitted development status here, though a rooflight sitting within the plane of the slope does not, which is a distinction worth knowing before anyone redraws the roof. Colchester City Council also has additional control over some tree work in a conservation area, which is worth knowing before anyone touches the oak at the end of the garden.

The practical effect is that a Lexden extension inside the conservation area needs to be designed with the existing house rather than bolted onto it. Matching brick, matching or deliberately contrasting glazing, and a roof form that makes sense. That is not a hardship. It usually produces a better building than the alternative.

The boundary is specific and it is not intuitive from the street. We check the designation on your address rather than assuming from the postcode.

Trees, clay and what it does to the price

This is the single biggest variable in Lexden, and it is the one most quotes ignore.

Lexden is a heavily treed suburb. Mature oaks, limes, horse chestnuts and the occasional poplar, in gardens and along the roads. The ground beneath them is shrinkable clay that moves with the seasons.

A mature tree draws a very large volume of water out of the ground across a growing season, and its zone of influence reaches well beyond the spread of its canopy. Where an extension foundation falls inside that zone, it has to be taken below the depth at which seasonal moisture change occurs, and that depth is a function of the species, its mature height and its distance from the building.

On a clear Lexden plot with nothing significant nearby, a foundation around 900mm to 1.2m is usually sufficient. Within influencing distance of a mature oak, two metres is common and two and a half is not unusual. At that point the sensible engineering answer often changes shape entirely: a piled foundation with a suspended reinforced slab and a compressible void former beneath it, which costs more up front and is far cheaper than underpinning a cracked extension later.

Trees with a Tree Preservation Order on them, and any tree of size within the conservation area, bring a further constraint: you may not simply remove the problem. Nor should you want to. Ground dried by a tree for fifty years will slowly take that water back if the tree goes, and swell. Heave acts upwards, and it does more damage than settlement.

Access, neighbours and the party wall

Side access is the quiet cost saving. Semi detached is the quiet complication.

Most Lexden houses have a side gate, and that genuinely reduces the cost of building compared with a terrace where everything is barrowed through the hall. It also means a skip can usually go on the driveway rather than on the road with a permit.

The semi detached majority means the Party Wall etc. Act 1996 applies to a large share of the work here. Cutting into a shared wall, building up to the boundary line, or excavating within three metres of the neighbour’s structure to a depth below their foundations all require formal notice, and on Lexden’s shallow interwar footings that last one is triggered more often than people expect, because the new foundation is deep and theirs is not.

Notice periods are set in law at one or two months depending on the section, and the period runs from service rather than from when everyone becomes agreeable. It can be shortened only one way: an adjoining owner who consents in writing allows the work to start sooner. What you cannot do is proceed unilaterally because nobody has objected. This is routine and not a dispute, but it has to be started early, because a party wall notice served the week before you wanted to break ground simply delays you.

What people build here

Three briefs account for most of the work.

The single storey rear extension to open the back of the house into a kitchen and living space is the most common. The gardens take it comfortably and the rooms it produces suit how these houses are used.

The hip to gable loft conversion, often with a rear dormer, is the second. It is the natural move on a hipped interwar semi and produces a genuine double bedroom with an en suite rather than a compromised attic room. Part B is what makes it complicated: a loft conversion turns the stairwell into an escape route, which means fire doors and a protected route down to the front door.

The two storey side or rear extension is the third, generally on the detached stock where there is room. This is where planning is most likely to be a full application rather than permitted development, and where the design conversation about matching the existing roof form actually matters.

Drainage and the ground beneath

Older suburbs have older drainage, and it is rarely where the plan says.

Lexden’s drainage was laid down over a long period, and on the interwar stock it frequently runs in places that do not match any drawing anybody still holds. Shared drains between semi detached pairs are common, and a run that serves both houses is a public sewer for these purposes even where it sits entirely within one garden.

That matters because building over or within three metres of a public sewer requires a build over agreement from Anglian Water. It is a separate application on its own timescale, and it can require a CCTV survey, a foundation designed to bridge the run rather than load it, or a diversion. Discovering it when the digger is already on site is the expensive version.

We look for it at survey stage. Lifting the manhole covers and following the falls takes twenty minutes and it is the cheapest twenty minutes on the job.

Surface water is the second half. Lexden’s clay drains poorly, so a soakaway that would work on gravel does very little here. A new roof plus a new patio produces run off that has to be taken somewhere sensible and designed rather than assumed, and on some plots that means a connection rather than a soakaway.

Timescales in this part of Colchester

Add time for the conservation area and for tree work, not for the building itself.

The building programme in Lexden is no different from anywhere else in Colchester: a straightforward single storey extension is commonly eight to fourteen weeks on site, longer where foundations are deep or piled.

The front end is where Lexden differs. If your property is inside the conservation area and needs a full planning application, that is an eight week statutory determination period from validation, and it is worth allowing for a pre-application conversation before that. Where trees are protected, any consent needed for work near them runs on its own timescale. Party wall notices run one or two months.

Those periods overlap and we run them in parallel where we can, but a realistic Lexden front end is two to three months rather than the six weeks people hope for.

Questions we get asked in Lexden

Is my house in the conservation area?

Part of Lexden is and part is not, and the boundary does not follow the obvious roads. We check the designation on your specific address as the first thing we do, because it changes the planning route.

There is a big oak two gardens away. Does it affect me?

Possibly. Influence depends on species, mature height and distance, and for a large oak that distance is considerably further than most people assume. It is assessed properly rather than guessed at.

Can I take the tree down to save money on foundations?

Usually not, and often you should not want to. It may be protected, and removing a mature tree from clay that it has been drying for decades introduces heave, which is a worse problem than the one you were solving.

Do I need to tell my neighbour?

If the Party Wall Act applies, and on a semi it usually does, you serve formal notice as the building owner. We tell you when it is required and can arrange it. It is a legal process rather than a courtesy, and the timescales are fixed.

Getting a price for a Lexden extension

We are based in West Bergholt about four miles from Lexden, so this is home ground rather than a postcode on a coverage list.

Our team comes out and surveys the property properly: the ground, the trees, the access, the existing footings where we can see them, the drain runs and the conservation position. Most people who call us already have drawings and permission and want a builder to price the work and build it. That is the ordinary job here, and we are glad to work to somebody else’s plans. Where the drawings do not exist yet, we bring in the technician who draws it and the structural engineer who calculates it, we manage the planning route with Colchester City Council, we notify Building Control, and we run the job as main contractor.

We carry £2m public liability cover and everything is built to current Building Regulations. We notify Building Control, arrange the inspections and see the job through to the point where they issue your completion certificate. The survey and the quotation cost nothing.