Most of the Victorian terraces in East and North London were built between 1870 and 1910. They went up fast, by today's standards: a street of twenty houses might have been started and sold within three years. The materials and methods were consistent because the builders were consistent. The same yards, the same trades, the same way of doing things.
That consistency is useful. When we open up a Victorian terrace in Walthamstow or Hackney, we already have a picture of what's there. Not because we can see through walls, but because we've opened a lot of them.
The walls themselves
Victorian terraces are solid brick. There is no cavity. The external walls are typically nine inches thick: two skins of London stock brick with a mortar joint between, built in English bond or Flemish bond depending on the period and the builder's preference. They are heavy, they breathe, and they have managed moisture for 130 years through a process of absorption and evaporation.
That last point matters enormously when people start talking about insulation. A cavity wall insulation product, injected foam, or an impermeable internal lining will change the way the wall manages moisture. In some cases it manages it badly. The right approach to insulating a Victorian terrace wall is a longer conversation than most salespeople suggest, and it starts with understanding how the wall already works.
The internal faces of those walls are finished in lime plaster, applied in two or three coats over lath. Which brings us to lath and plaster.
Lath and plaster
Lath and plaster is the Victorian equivalent of plasterboard. Thin strips of riven timber, fixed horizontally across the studs or brick with small gaps between them, then plastered over in coats: a rough base coat pressed into the gaps to create a key, a floating coat to level, and a finish coat to skim. When it was new, it was excellent. When it is 130 years old and has had decades of vibration, settling, and previous owners banging picture hooks into it, it can be in any state from perfect to impending collapse.
We assess it by tapping. A solid return means the key is intact. A hollow sound means the plaster has come away from the lath behind it. Both can exist in the same wall, sometimes in the same square metre. Where it is sound, we leave it. Where it is failing, we take it off properly and either re-skim onto the original lath or replace with modern board, depending on what we find underneath and what the client wants to achieve.
Lath and plaster cannot simply be skimmed over if it is failing. The movement will crack the new skim. This is one of the ways that a cheap coat of plaster unravels within eighteen months.
The floors
Ground floors in Victorian terraces are one of two things: suspended timber over a void, or solid ground-bearing construction added later. The original is almost always suspended timber. Floorboards over joists, the joists sat on brick sleeper walls with a void beneath for ventilation. The void is vented through air bricks in the external walls, which is why blocking those air bricks with rendered insulation boards is such a reliable way of causing rot.
Upper floors are suspended timber throughout. The joists span between party walls or are carried on timber beams, with boards nailed across them. They were not designed for the loads of a modern bathroom, a cast-iron bath full of water, or a kitchen island built from concrete worktop. We check the structure before specifying anything heavy.
Joist rot is common. It concentrates around the wall ends, where the timber is built into the masonry and has historically been damp. We check every end we can reach during the strip-out phase. Most of the time, the main run of the joist is fine and only the end needs attention. Occasionally we find something worse. When we do, we say so before we continue.
Chimney breasts
A standard Victorian terrace has a chimney breast in every room, front and back, on every floor. That is a lot of masonry, and a lot of structural implication. The chimney stack at the top carries the weight of all the breasts below it. If any of those breasts have been removed by previous owners, the question is whether the structure above was properly supported when they did it.
The honest answer is: often not. We have opened more than a few Victorian terraces to find a chimney breast removed in the 1970s or 1980s, with the stack above supported on nothing more than the lath and plaster ceiling it was supposed to be sitting above. Sometimes a length of timber. Sometimes a brick corbelled out sideways. It holds, until it doesn't.
If you are planning to remove a chimney breast, this requires a structural engineer, a steel beam of the right specification, and a builder who knows how to install it properly. We do not remove chimney breasts without engineer's sign-off. The same applies to any wall removal where we cannot confirm the load path above.
The services
Electrical wiring in a Victorian terrace that has not been rewired since the 1960s will be rubber-sheathed or cloth-braided. It is not safe to leave it. In a house rewired in the 1980s, you may find single-earth wire and older consumer units that do not meet current regulations. If you are opening walls and ceilings for a renovation, it is the right time to rewire. Doing it room by room after the walls are closed is significantly more expensive and disruptive.
Lead pipework is still present in some of the older unrenovated houses we work in, particularly on the supply side. It comes out. So does any galvanised iron pipework, which corrodes from the inside and eventually blocks or fails. Modern renovation is an opportunity to replumb correctly; it is not an opportunity to plaster over old pipes and hope.
Asbestos can be present in artex coatings and textured finishes added in the 1970s and 1980s, in some older insulation products, and in certain floor tiles. Where we suspect it, we test before we disturb. This is not optional.
Why none of this is a surprise
A builder who works regularly in Victorian terraces knows what is there before the first board comes up. Not the specifics, but the pattern. The same construction, the same materials, the same failure modes in the same places. The surprises are the exceptions: the previous owner who rerouted the drainage through the party wall, the structural steel that was put in correctly but never signed off, the room that turns out to have been an addition rather than original.
What we are doing in the assessment phase is confirming the pattern and finding the exceptions. A proper pre-contract survey and strip-out inspection, with time allowed for looking before committing to cost and programme, is how you avoid the thing that catches people: a quote based on assumptions that turn out to be wrong.
We build in contingency. We flag what we find as we find it. We do not carry on regardless and present the bill at the end.
The price you sign is the price you pay. That only holds if the scope is written with enough honesty to account for what the house is likely to contain.