Flat Roof to Terrace Conversion Questions Checklist

Write down when the roof was last covered or repaired, who did the work, and whether that was arranged by you or by a previous owner of the property.

A covering with a known date and a known installer is a very different starting point from one whose history nobody can describe, and it changes what the first conversation is about.

Find any paperwork that came with the roof covering, including installer documents, product literature and guarantee terms, and note what those terms say about later alterations.

Terms attached to a covering frequently have something to say about work carried out on it afterwards, and reading them now is easier than explaining a decision later.

Whether a particular guarantee remains available after alteration is a question for the party who issued it, and not something to settle by reading the document alone.

Record whether anyone has ever told you the roof was built to be walked on, and note who said it, when they said it and whether they had looked at the roof.

Most flat roofs were built to be reached occasionally for maintenance rather than occupied, and the difference between those two is the whole subject of the project.

List everything currently sitting on the roof — an aerial, a satellite dish, a flue terminal, an outdoor unit, a soil vent pipe — and photograph each in position.

Every one of these is fixed through something, and each has to be either kept, moved or removed, which is a set of separate decisions rather than one.

Note where rainwater leaves the roof at present — an outlet in the surface, a gutter at one edge, a spout through a parapet — and photograph each point.

Once a surface is laid over a roof, the points where water leaves are no longer visible, so recording them while they can still be seen is worth doing.

Photograph the whole perimeter from ground level and from an upstairs window, including where the roof meets the house wall and any parapet or edge trim.

Perimeter and abutment photographs taken before anything changes are the record nobody thinks to make and the one that is most often wanted later.

Take photographs from windows or from ground level rather than climbing onto a roof whose condition and loading nobody has assessed.

Write down what the room directly below is used for, who uses it and at what times of day, so that the effect of footfall overhead can be discussed concretely.

A kitchen below a terrace and a bedroom below a terrace produce completely different conversations, and the room's use is easy to forget to mention.

Note what would be happening on the terrace while that room is in use — chairs moving, people standing, a table being dragged — and write it down as something to raise.

Sound reaching the room below from a trafficked surface is a design subject in its own right, and owners usually discover it only after the first summer.

Ask whether anything about this change would involve the ceiling below being opened, and record the answer, including whether the room would have to be emptied.

Work reaching down into the room below is the part of the programme owners are least prepared for, and knowing early lets the household plan around it.

Decide and write down whether the room below can be out of use, for how long, and what the household would do instead during that period.

A written answer to this is something a designer and a builder can plan around, whereas a vague willingness to cope tends to collapse when the date arrives.

List anything fixed to or running through that ceiling — lights, a loft hatch, an extract duct, pipework — and note which items you would want kept where they are.

Ceiling-mounted items are the first casualty of work above, and saying which matter to you before the drawings are done avoids an argument afterwards.

Photograph and date any existing stain, crack or mark on the ceiling below before anything begins, and keep those photographs somewhere separate from the project file.

A dated record of what the ceiling looked like beforehand is the only way to tell an existing mark from a new one once work has finished.

Write down how you imagine reaching the terrace — through an existing window opening, a new door, an external stair — and note which of those you would accept.

Access is usually the constraint that decides whether the idea works at all, and stating a preference early lets a designer respond to something concrete.

Note whether a flush threshold between inside and outside matters to you, or whether a step down onto the terrace would be acceptable, and record which it is.

A level threshold and a roof upstand pull in opposite directions at the same point, so the designer needs to know which way your priorities run.

A level threshold is not achieved simply by lowering an upstand; how the two are reconciled is a design matter for the roof designer.

Write down who would use the terrace, including children, older relatives and visitors, and note anything about how they move that the access has to suit.

Guarding, thresholds and surface choices all follow from who is expected to be up there, and the answer is rarely just the two people who asked for it.

Ask what the arrangements would be for leaving the terrace if the usual route were not available, and record the answer rather than forming a view yourself.

This is one of the questions most likely to be settled by the designer and the relevant authority together, and it is better raised at the start.

Whether a roof may be occupied, and what escape and guarding provision that brings, is determined by the designer and the relevant authority.

Stand at an upstairs window and note what a person on the terrace would see, and which neighbouring windows or gardens would see them in return.

Overlooking in both directions is the part of a terrace scheme most likely to be raised by others, and it is easiest to picture before anything is drawn.

Note the largest thing you would want on the terrace and how it would be carried up there, including whether it would fit through the intended access.

A terrace reached through a narrow opening quietly limits what can ever be put on it, and that limit is easier to accept if it was a decision.

Ask which approach is being proposed — a surfacing carried on supports above the waterproofing, or a surface applied directly as the wearing layer — and write the answer down.

These are genuinely different arrangements with different consequences for access and maintenance, and owners are often unaware a choice was made.

Ask where water passing through the joints in the surface goes, and where the outlets receiving it sit once the finished surface is in place above them.

Drainage at a terrace happens at a level nobody can see, and a clear answer here is one of the better indicators that the junction has been thought about.

Ask what protects the waterproofing while the surfacing above it is being built, and record the answer as part of your notes on the programme.

The layer doing the work is finished before the terrace is built on top of it, so the sequence itself is one of the hazards to it.

Ask whether the structure beneath has been assessed for the surfacing, its supports and the use intended, and record who is carrying out that assessment.

Making a roof occupied changes what it carries, and the answer belongs to a qualified structural engineer rather than to the person laying the paving.

Nothing you observe establishes whether an existing roof can carry a terrace; that is a determination for a qualified structural engineer.

Note that outlets, upstands and the waterproofing will all sit beneath the finished surface, and ask how each of them is reached once the terrace is complete.

A terrace laid as a continuous field over its own outlets can only be opened destructively, and that is decided by the surfacing layout at design stage.

Keep every answer you receive about the build-up in writing, with the date and the name of whoever gave it, in the same file as the roof paperwork.

Later owners, and you in several years, will see only paving, so the written account of what is beneath it becomes the only description that exists.

Ask what any guarding would be anchored into, and whether that anchorage passes through the layer resisting water, recording the answer without forming a view on it.

Guarding anchorages sit at the roof edge, which is the position with the least tolerance for a penetration, and the answer is a designer's to give.

Write down what you would like the guarding to look like and how much you would accept it obstructing the view, separately from how it is fixed.

Keeping appearance and anchorage as two separate conversations stops a preference about glass or metal quietly dictating where a hole through the roof goes.

List anything you would eventually want on the terrace — planters, a screen, lighting, a shade structure — and raise all of them now rather than after completion.

Every one of these is a load and often a fixing, and the moment to discuss them is while the build-up is still being designed.

Fixing anything into a completed terrace may penetrate a concealed water-resisting layer, and should go back to the roof designer before it happens.

Ask how the surfacing is held in place at the edges and corners of the roof, and record the answer alongside your notes on the surfacing choice.

The perimeter behaves differently from the middle of a roof, and a loose-laid surface that is fine in the field may not be at the edge.

Photograph where the roof meets the house wall, and ask how that junction changes once a finished surface sits well above the present roof level.

Raising the finished level at an abutment changes what the existing weathering is doing, and that junction is the one most often discovered late.

Note what the edge of the terrace would look like from the garden and from neighbouring windows, and write down anything about that appearance you care about.

Perimeter trims, upstands and guarding fixings are all visible from below, and they tend to be resolved technically without anyone asking how they look.

Ask which areas of the surface are intended to be lifted for access, where those areas are, and how the surfacing is put back afterwards.

Access provision is a design decision made in the paving layout rather than something discovered later, and the answer should be a place, not a principle.

Ask what collects in the space beneath the surface, how it is removed, how often that is expected and who is expected to do it.

Leaves and grit wash through the joints into a space that is invisible from above, which is how a terrace quietly stops draining.

Ask for a written description of what sits beneath the surface, including outlet positions, and keep it with the property paperwork rather than only in email.

A later owner sees paving and nothing else, so this description is what allows the terrace to be maintained instead of taken apart to find out.

Write down who you would contact if a stain appeared on the ceiling below, and keep that name with the paperwork rather than relying on memory.

Water appearing internally is rarely directly beneath where it entered, so having the original designer or installer identified saves a great deal of guessing.

Ask what the surface itself needs in normal use, including cleaning, and whether anything about that would affect the layers beneath it.

Pressure washing, chemical cleaning and moving heavy furniture are all ordinary owner activities that interact with the assembly below.

Having written all of that down, decide and record whether you accept those ongoing duties, because that decision belongs with you rather than the designer.

This is the honest end of the conversation: a terrace is a maintained assembly, and the owner is the party who ends up maintaining it.

Write down a question for your local authority about what applies to making this roof occupied, rather than deciding the answer from what a neighbour did.

Requirements vary by place and by building, and this is one of the areas where a similar-looking project nearby tells you very little.

Requirements and consents for occupied roofs vary by location and tenure; confirm what applies to your property with the relevant local authority.

If the property is leasehold or part of a converted building, find the lease, note what it says about the roof and about alterations, and mark those clauses.

A roof is very often not within the demise, and finding that out after a designer has been engaged forces the whole scheme to start again.

Note whether the roof adjoins another property, touches a shared wall or drains towards land you do not own, and record what you find.

Shared structure and shared drainage widen the conversation beyond your household, and the earlier that is known the less disruptive it is.

Write down a question for your buildings insurer and your lender about whether they expect to be told about a change of this kind.

Each sets its own expectations, and a short question now is easier than an explanation after the terrace exists.

This checklist states nothing about what an insurer or lender will decide; those are questions to put to them directly.

Decide whether you want to speak to neighbours before anything is submitted, and write down what you would tell them and what you would ask.

A terrace is visible and audible from other properties, and a conversation held early is a different one from a conversation held in response.