Basement Project Discussion Preparation Checklist

Write down whether the house has a cellar, a shallow void, a solid floor or a mixture of these, and say how you know rather than what you assume.

Professionals treat an existing below ground space very differently from a house with no void at all, and the distinction changes the first conversation entirely.

Walk each ground floor room and note where the floor sounds hollow underfoot and where it feels solid, marking both on a rough plan.

This is one of the few things an owner can observe without any tools, and it gives a designer a useful first picture of how the ground floor is built.

Photograph any existing below ground space with enough light to show the walls, the floor, the ceiling and any staining or previous repair.

Photographs of a dark space are more useful than a description, and they capture details you will forget between meetings.

Note where a stair down could plausibly land without cutting the ground floor in half, and mark the rooms it would pass through.

The stair is usually the single biggest change to the existing house, and owners often picture the new room without picturing the route to it.

Write down the age and construction of the house as far as you know it, and note where that information came from, such as deeds or a previous survey.

Age and construction shape almost every technical answer you will be given, and being clear about the source stops guesswork being treated as fact.

List any previous work that touched the ground floor, the foundations or the drains, and find the paperwork for it if any exists.

Earlier work often explains why a floor is unusual, and the paperwork saves a professional from having to establish it again.

What earlier work means for any new proposal is for a qualified structural professional to establish on site rather than something to infer from old paperwork.

Note whether the house sits level with the road, above it or below it, and which way the ground falls away across the garden.

Level differences decide a surprising amount about what is possible below ground and about where water naturally wants to travel.

Write down where water stands in the garden after heavy rain, whether it lingers, and which parts of the ground stay soft in wet weather.

These observations are made over ordinary weather rather than in a single visit, so an owner can supply something a visiting professional cannot.

Record any stream, pond, ditch, culvert or spring you know of near the property, and note roughly how far away and in which direction it lies.

Nearby water is one of the first things a specialist will ask about, and local knowledge is often better than what appears on a map.

Note anything neighbours have said about water beneath their own houses, keeping the remarks factual and attributed rather than turning them into conclusions.

Neighbouring experience on the same ground is genuinely useful background, provided it is presented as hearsay rather than evidence.

Ask a qualified professional what ground investigation would be needed before anyone could say whether the idea is feasible here.

Knowing what investigation is involved early prevents the whole enquiry stalling later when it turns out nothing can be answered without it.

Ground conditions cannot be judged from the surface or from what happened next door. Only qualified investigation can establish what is beneath your property.

Record any substantial trees standing near the house, noting roughly where they are and whether any have preservation arrangements you are aware of.

Trees near a building raise both ground questions and consent questions, and both are much easier to handle when raised at the outset.

What a nearby tree means for the ground and for any consents is for a qualified professional and your local authority to confirm, not something to judge yourself.

Sketch the outline of the house and mark which walls are shared with a neighbour, which sit on a boundary and which stand clear of both.

This single sketch answers a question every professional will ask, and it prevents a conversation being held on the wrong assumption.

Note whether neighbouring houses sit at the same level as yours, higher up a slope or lower down, since that relationship matters below ground.

Level differences between adjoining properties change how the ground and any water behave along the shared line.

Ask a qualified professional what notices or agreements with adjoining owners may apply to work of this kind, and confirm the process locally.

This is a legal area with its own procedure, and starting it in the right order avoids delay and ill feeling later.

Obligations towards adjoining owners are legal matters that vary by location. Confirm what applies with a qualified adviser rather than assuming.

Record whether nearby properties have had comparable work carried out, and write down what those owners have told you about how it went.

Neighbouring experience is useful context for your questions, even though it says nothing definitive about your own ground or structure.

Note where neighbours park, where their bins are collected from and how they reach their own doors, since works of this kind disturb all of it.

Most disputes during works are about access and disturbance rather than about the design, and they are easier to manage when anticipated.

Write down the names and contact details you hold for adjoining owners, and keep a tidy record of conversations from the very beginning.

A calm, dated record of what was discussed with whom is worth a great deal if the relationship is tested later in the project.

Walk the route from the street to the area under discussion and note every gate, step, tight corner and level change along the way.

The route is usually the constraint nobody mentions until late, and an owner can describe it better than anyone visiting for the first time.

Note whether the rear of the property can be reached without passing through the house, and who owns any land that route crosses.

A rear route that crosses someone else's land is a permission question rather than a practical one, and it needs raising early.

Rights over land belonging to others are legal matters. Ask a qualified adviser what applies before relying on any access route.

Record whether the road outside is narrow, one way, or subject to controlled parking, and note which body administers the restrictions.

Street conditions determine what can realistically stand outside the house, and the administering body is often the same one you will deal with later.

Ask what would happen to material taken from the ground, where it would be held on site and how it would be removed.

The answer affects the garden, the street and the neighbours, and it is a fair question to put before any commitment is made.

How excavated material is handled and removed is regulated and specialist work. Put this question to qualified professionals rather than planning it yourself.

Write down whether you intend to keep living in the house while the work is under way, and be honest with yourself about that answer.

Living through the work changes sequencing, access and the amount of protection needed, and it is a decision professionals need early.

Note any overhead cables, low branches, archways or narrow gateposts on the approach that could restrict what is able to reach the property.

Height restrictions on the approach decide what plant can be brought in at all, and they never appear on a drawing of the house or the garden.

Write down the activities the lower level is meant to support, in plain words and in order of importance to the household.

An ordered list forces the trade-offs into the open and gives a designer something to test options against.

Note whether the space is intended to be lived in or used for storage, plant and utility, because the two lead in very different directions.

Rooms people occupy raise questions about light, air and escape that a store simply does not, and mixing the two blurs the brief.

What is required for a space people occupy below ground is a technical and regulated matter for qualified professionals to explain.

Record whether you expect the lower level to open to the garden, and note what would have to change outside for that to be possible.

A connection to the garden usually means altering ground levels, which brings drainage and boundary questions with it.

Consider whether the new level should feel like part of the house or like a separate world of its own, and write down which you want.

This single preference influences the stair, the finishes and how much daylight the scheme has to chase.

Note what would have to leave the existing rooms for the plan to work, and where each of those things would go instead.

Schemes often assume that clutter, plant and storage simply disappear, and naming their new home keeps the plan honest.

Write down what would make the finished space a disappointment to you, since that often defines the brief faster than listing what you want.

Stating the failure conditions gives a professional something concrete to design against and surfaces expectations you have not voiced.

Note where drainage covers appear in the garden, the paving and any side passage, and photograph each one with something nearby for scale.

Covers are the visible evidence of a system nobody has drawn, and they give a professional a starting point for tracing it.

Ask a qualified professional how waste from a level below the existing drains would be dealt with, and what that means for the design.

The answer often introduces equipment, maintenance and power requirements that owners have not considered at all.

Drainage arrangements below existing drain level are specialist design matters. Nothing should be assumed about what would work at your property.

Write down whether the property has ever taken water from any source, what you were told at the time and who told you.

History of water is material information, and it is far better volunteered by you than discovered later by someone else.

Record whether the area is known locally for surface water problems, and note where that reputation came from rather than treating it as established.

Local reputation is a prompt for a proper enquiry, not a substitute for one, but it tells a professional where to look.

Ask whether any water management arrangement under discussion depends on electrical power, and what is expected to happen during a power failure.

Dependence on power is the question owners most often forget to ask about equipment that is expected to work quietly in the background and never be thought about.

Ask what ongoing attention any water management arrangement needs, who would carry it out, and what happens if it is neglected.

Maintenance obligations that arrive with a new system belong in the decision, not in a handover folder discovered afterwards.

Maintenance regimes for below ground water systems must be set out by the qualified professionals who design and install them.

Write down where daylight could plausibly reach the lower level from, such as a lightwell, an opening at the stair or a change in external ground level.

Naming the possible routes early keeps the scheme honest about how much of the space can realistically be lit.

Note whether a lightwell would sit in a part of the garden or forecourt you currently use, and write down what would be given up for it.

Lightwells take outdoor space that owners rarely account for when picturing the room below.

Ask a qualified professional how the lower level would be ventilated, and record the answer rather than assuming an opening window will do it.

Below ground air movement rarely works the way it does upstairs, and the strategy affects the layout.

Ventilation strategy below ground is technical design work. No approach is suggested here and none should be assumed suitable for your property.

Record where the meters, incoming supplies and the main stopcock are now, and note whether any of them sit in the area under discussion.

Incoming services are often in exactly the space owners want to convert, and moving them involves the supply undertakers rather than the builder.

Moving meters or incoming supplies involves the relevant utility undertakers. Confirm the process with them and with a qualified installer.

Note where the boiler, cylinder or heating plant sits, and whether the emerging plan quietly assumes that it moves.

Plant relocation is a common hidden assumption in early sketches and carries its own set of requirements.

Write down whether you expect plumbing, a kitchen or reliable connectivity at the lower level, since each adds routes that need planning early.

Adding these later means chasing routes through a finished structure, which is exactly the work everyone hopes to avoid.

Collect the deeds, title plan and any documents referring to the land, and mark anything you do not understand so it can be asked about.

Rights, covenants and boundaries recorded in these documents can affect what is possible, and they are easy to overlook in the excitement of planning.

Write a single page describing the house, the ground, the access and the aspiration, so every professional starts from the same account.

One shared description prevents each adviser receiving a slightly different version of the story and reaching different conclusions.

List the questions you cannot answer yourself and mark which belong to a designer, which to a structural professional and which to the local authority.

Sorting questions by who owns them stops the same query being asked of the wrong person and coming back unhelpfully vague.

Note what you have already been told informally and by whom, keeping opinions clearly separate from things you have seen documented.

Informal advice hardens into assumed fact remarkably quickly once it has been repeated in a few meetings.

Record what you would do if the answer came back that the scheme is not feasible in the form you imagined, and what your fallback would be.

Deciding this in advance keeps a difficult conversation productive rather than turning it into a search for a professional who agrees with you.