In a renovation you survey first and design second
On a new build the brief is the client and the plot. In a renovation the brief is the house. From that follows the rule which governs the order of everything else: first establish what is actually there, then design what will be there. A project that reverses this order gets redrawn sooner or later, and redrawing on a half-opened building site is the most expensive kind of work I know.
The typical story runs the other way. The owner has a layout in mind, it gets drawn from old plans out of the archive, and on site it turns out that the partition on the drawing is load bearing, that the floor is seven centimetres out of level and that there is damp masonry under the plaster. None of this surprised the house. It surprised us, because we did not look. This article assumes the decision to renovate rather than demolish has already been made, and asks about the order of the building work itself.
The surveys that set both scope and budget
A measured survey of what exists
The measured survey is the only document you can trust. Original drawings are a historical record, not a survey: they say how the house was meant to be built, not how it was built or what three owners did to it since. A good survey captures wall thicknesses, clear heights, floor levels, the position of chimneys and the height relationships between storeys. Skip it and the project is either redrawn piecemeal on site or built with deviations that surface when the kitchen and the staircase are installed, which is when change costs the most.
Structure wherever anything load bearing is in question
If anything load bearing is to be cut, if a floor build-up changes, if a loft becomes habitable or if new mass arrives in the house, the preparation must include a structural assessment. A structural engineer does not merely say "it can be done". They say which members, what propping and in what order, and that last part sets the programme for the whole structural phase.
Damp before any finish
Damp is the one defect that reliably comes back. Fresh plaster and a new floor hide it for two winters. The diagnosis has to separate rising damp from a leaking roof, from condensation on thermal bridges and from a burst pipe, because each has a different cure. It also covers the risk of mould growth wherever the work changes the temperature profile of a construction.
The condition of the services
For electrics this means cable sizes, conductor material, protection, earthing and the capacity of the incoming supply, which in old houses often will not carry today's appliances. For water and drainage it means pipe material, falls and where the waste actually goes. For heating it means whether the pipework is worth keeping or will change anyway with the new floor build-up.
| Survey | What it establishes | Who does it | What a bad answer changes |
|---|---|---|---|
| Measured survey | Dimensions, heights, levels, construction thicknesses | Surveyor or the designer | The layout and the whole schedule of quantities |
| Structural assessment | Structural system, floor capacity, possible openings | Chartered structural engineer | Demolition scope, cost of lintels, the programme |
| Damp diagnosis | Source of moisture, salts, state of the damp course | Damp remediation specialist | The order of works, sometimes the whole brief |
| Condition of services | Electrics, water, drainage, heating, incoming supply | Test engineer and services designers | Extent of chasing and the need for a new supply |
| Material survey | Asbestos, lead paint, wood-boring insects in the roof | Laboratory, timber specialist | Method of strip-out, waste disposal, the date |
Decisions and the consent route
Only once you know what the house can carry and what it hides does it make sense to decide the layout. The order runs one way: surveys, concept, drawings, then consent. It cannot be reversed, because the building authority assesses a project, not an intention in the owner's head.
Consent is governed by Act 25/2025 Coll. The difference between the routes is qualitative, not a percentage. Work that changes neither the load-bearing structure, nor the external appearance, nor the use of the building generally falls into the lighter route, a notification of structural alterations. As soon as you touch the structural system, alter the appearance, the footprint, the number of dwellings or the use, it becomes a building permit. The specific classification is confirmed by the relevant building authority before you file: one phone call saves months. If the house sits in a heritage zone or a protection zone, another consulted authority joins, and with it more time.
Money, and the number that decides the mood of the job
The budget is assembled after the surveys, otherwise it is a price list of wishes. A construction budget should tie its items to quantities taken from the survey, not to a flat rate per square metre.
The most important line, though, is not a trade. It is the contingency. A renovation budget without a reserve is not a budget, it is a wish, because the walls of an old house always contain at least one thing nobody could see: a rotted joist end over a damp corner, a flue that does not run where the drawing says, or a floor of three layers, two of them cinder. The reserve should not hide inside item prices; it should stand on its own so you can watch how much of it is gone. The difference between a calm renovation and a miserable one is not whether something unforeseen appears. It always appears. The difference is whether the money for it was ready in advance, or whether halfway through the job you are deciding what to cut.
The order of works on site and why it is that order
The sequence is not custom. It follows from four rules: do nothing that will be demolished; work top down and coarse to fine; wet trades before dry ones; and put nothing expensive into a wet house.
Strip-out and opening up is not just demolition, it is the last and most accurate stage of the survey. Only here do you see the true state of floors and walls, and the design must be checked against what appears. Demolition and structural work follow immediately, before any new layer, because they bring vibration, dust and changes in geometry. Roof, windows and envelope have a single aim: a closed, dry house. While rain still gets in, every following trade is working into a wet building. If deep energy renovation is part of the brief, the order of the energy measures themselves has its own logic and is covered in a separate piece on the order of deep renovation measures.
First fix services go into open construction, before plaster and screed. Between the trades the order follows freedom of routing: first what needs a fall, the drainage, then what cannot be bent, the ventilation ductwork, and last the electrics, which go almost anywhere. Wet trades then make good the chases, form the bathroom tanking and pour what has to be poured. Screeds come next, and with them the one programme item no decision can speed up: drying. An anhydrite screed and a cement one both give off moisture long after they are walkable. Plaster and skim are the last wet layer. Only once the house has dried do the dry trades and finishes arrive, and last of all joinery and floors, timber that will warp irreversibly in a wet building.
| Step | What must be finished first | Commonest mistake |
|---|---|---|
| Strip-out and opening up | Surveys, drawings, consent | What is found never gets back into the design |
| Demolition and structural work | Structural assessment and propping design | Demolishing without propping or an engineer's method |
| Roof and envelope | Structural demolition, new openings | Windows fitted only after the plastering |
| First fix services | Dry house, openings and partitions done | Chasing into walls that are already plastered |
| Wet trades and tanking | Signed-off services and a pressure test | Bathroom tanking rushed in under the tiles |
| Screeds and drying | Floor services, thermal insulation | Booking the floor layer by the calendar |
| Plaster, skim, paint | Dried screeds, services complete | Painting onto walls that are still damp |
| Joinery and floors | Dry house, a survey of what was actually built | Ordering the kitchen off the drawing, not the site |
All at once or in phases?
Phasing is a legitimate decision, but it helps to know its arithmetic: done in phases a renovation costs more in total, and is far kinder to cash flow. It costs more because the site set-up repeats, every trade mobilises again, the scaffold goes up twice, finished areas have to be protected from the next phase and bulk prices are lost. It is easier on the wallet because you do not have to borrow it all at once.
If you do phase, draw the line along construction packages, not along rooms. Structure, roof, envelope and first fix belong in phase one even if phase two is three years away. What can wait is the kitchen, the floors, the upstairs bathroom, the render. Postponing the removal of a load-bearing wall means paying twice: once for the finishes, and again for the same finishes when that demolition destroys them.
Living in the house during the work
It is usually the cheapest line in the budget and the most expensive line in your relationships. It works only on three conditions: the work is phased, the occupied zone is separated from the site by a real partition rather than a sheet of plastic, and you keep a working bathroom, kitchen and heating throughout. During strip-out and during the wet stages it never works: demolition dust reaches everywhere, and a house drying out its screeds is an unhealthy place to sleep in winter.
Reckon also with the fact that living on site slows the site down. Trades work shorter days, cannot shut the water off for a whole day and tidy up after themselves every evening. Somebody pays for that time. If the rent you save is less than the cost of the delay, moving out is the cheaper option.
What to take from this
A renovation is an order of operations, and that order is a decision, not improvisation. Survey and diagnose while the house is still a question. Decide and obtain consent before anything is demolished. Budget with a visible reserve. And on site respect the physics: a dry house before first fix, wet before dry, timber absolutely last. If you cannot police that yourself, appoint a construction supervisor. It is the cheapest insurance against twenty good tradesmen ruining each other's work.