Floor Insulation Questions Checklist

Note whether the floor sounds hollow underfoot or dull and solid, and whether it gives slightly as you walk across the middle of a room.

This is the crudest test there is, but it is often the first indication of whether there is a void beneath at all.

Walk round the outside and record any vents set low in the wall near ground level, marking their positions on a sketch of the building.

Low level vents usually accompany a floor that spans a void, and their presence, number and condition all matter to a surveyor.

Write down what the visible surface is in each room, whether boards, blocks, tiles, sheet material or a covering laid over something else.

The finish often hides an earlier floor, and the layers already present change what is realistic underneath.

Record whether any hatch, lifted board, meter cupboard or cellar opening lets you see beneath the floor, and photograph anything visible.

Any existing opening saves opening up a floor purely to look, which is disruptive and rarely necessary at this stage.

Note where the floor changes from one room to the next, since a rear room or a later addition frequently sits on a different arrangement entirely.

Owners often describe the floor as one thing when the house actually contains two or three quite different constructions.

Gather anything you hold about earlier floor work, such as a room that was relaid, a leak that was repaired or a level that was changed.

Past interventions explain most of the surprises found later, and the paperwork is easier to find now than mid job.

Write down which rooms are coldest at floor level, in what conditions, and whether it is felt underfoot or as moving air around the ankles.

Cold surfaces and moving air feel similar but come from different causes, and separating them early saves wasted work.

Note where air can be felt entering: at the skirting, between boards, around a pipe coming through the floor or beneath a door.

The locations tend to cluster, and the pattern tells a professional far more than a general complaint about cold floors.

Record any earthy or musty smell that rises from the floor, and note the rooms and conditions in which you notice it.

A persistent smell from beneath a floor is a matter for a suitably qualified professional to look into rather than something to seal over.

Note what the household already does about it, such as rugs, draught excluders, closed doors or simply avoiding a room in cold conditions.

These habits show the severity and the location better than any description written after the fact.

Write down whether the cold or the draught appeared or worsened after earlier work such as new heating, a new covering or an added room.

A change in behaviour that follows a change in the building is one of the most useful things you can hand over.

Record whether a cellar, crawl space or open undercroft gives access from below, and photograph the underside of the floor where you can see it.

Access from below can change the job entirely, because the rooms above may not need clearing at all.

Note whether the floor would have to be lifted from above, and which rooms would therefore need emptying of furniture and floor coverings.

Lifting from above brings the whole household into the job, and that reality belongs in the discussion from the start.

Write down whether the void beneath looks shallow or generous where you can see it, without measuring or crawling into it yourself.

Do not enter an underfloor void; confined spaces beneath floors are for a suitably qualified professional with the right equipment.

Note anything visible under the floor that would obstruct working there, such as sleeper walls, ducts, debris or old spoil.

Obstructions are the usual reason an approach that sounded straightforward becomes a room by room job instead.

List what stands on the floor and cannot easily move: fitted units, a heavy appliance, a stove, a staircase, a fitted wardrobe or a fireplace hearth.

These are the points where a scheme stops, and each of them needs a stated answer rather than an assumption.

Note any low level vent that is blocked, painted over, covered by a shelf of soil or hidden behind planting, and photograph each one.

Vents are lost gradually and nobody registers it, which makes a photographic record genuinely useful.

Record whether paving, decking, a driveway or a raised bed has brought the outside ground up close to or above those vents.

Ground raised against a wall is one of the commonest reasons an underfloor void stops behaving as it was meant to.

Write down whether an extension, porch or conservatory has been built across a face that previously carried vents, and gather anything you hold about that work.

A later addition can close off the path air used to take, and the effect shows up in the room on the far side.

Put the question of how the space under the floor is meant to be served to a qualified professional, and ask what the vents you found mean for it.

Only a suitably qualified professional standing on site can say whether the air reaching the space under this floor is sufficient.

Note any sign of standing water, wet ground or watermarks visible beneath the floor, and record the conditions in which you saw them.

Water beneath a floor needs to be investigated by a suitably qualified professional before any covering or insulation is considered.

Record any room that sits above a garage, store or workshop, and note whether that space below is heated, unheated or open to outside air.

A floor over an unheated space behaves like an outside surface, and it is often the coldest room in the house.

Note any part of the building that oversails a passage, alley or entrance, since the underside there is fully exposed to the weather.

These oversailing areas are easy to miss on a plan and obvious to whoever sleeps above them.

Write down whether any bay, projection or overhanging section carries a floor beyond the wall below it, and photograph its underside.

Projections have a floor exposed on more sides than a plan suggests, which is why they run cold at the edges.

Record what the exposed underside is finished with, whether boarded, rendered, plastered or open, and note any staining or loose areas.

Work to an exposed soffit above a garage or passage raises questions for a suitably qualified professional, including fire separation to confirm locally.

Note any pipework, meter or cabling running in or across a floor over an unheated space, since it is exposed to cold along with the floor.

Pipes above an unheated garage are a familiar source of trouble in cold conditions and belong in the conversation early.

List the doors in each room concerned, and note which already sit close to the floor or catch on a covering.

Every door in the affected area has to be taken into account, and the list is longer than owners expect.

Note where the floor meets an external door and what the level does there, since a raised floor changes the step both inside and out.

Level differences at an external threshold raise access and water questions that should be put to a suitably qualified professional.

Record where a staircase lands on the floor concerned, because a raised floor alters the bottom step and the rise it forms.

Any change at the foot of a staircase affects the going and rise, which is a matter for a suitably qualified professional and for confirming locally.

Write down whether skirtings, architraves and any original mouldings are to be kept, reused or replaced where the level changes.

Original joinery rarely survives being taken off and put back, and the decision belongs to you rather than to whoever happens to be lifting it.

Note where fitted units, an appliance or a fixed bench sit on the floor, and ask what a level change would mean for each of them.

A raised floor in a fitted room can trap appliances in place, which is discovered at the worst possible moment.

Consider what happens where a treated room meets an untreated one, and decide whether a level change between them is acceptable to the household.

Partial schemes create steps in unexpected places, and agreeing to them in advance is far better than meeting them at the end.

Record whether heating pipes run beneath the floor or through the void, and note where radiators or emitters connect down into it.

Pipework in a void constrains where insulation can go and sometimes needs a trade attending while the floor is open.

Note where waste and drainage leave the building at low level, and whether any gully, trap or access cover sits inside or immediately outside.

Anything affecting drainage below a floor should be put to a suitably qualified professional before work is planned around it.

Write down where the stopcock, isolation valves, meters and any access covers are, and whether they would still be reachable afterwards.

Burying an isolation point under a new floor is a small mistake that becomes a large one during a leak.

Record whether underfloor heating already exists, in which rooms, and gather any paperwork showing where its pipes or cables run.

Fixing into or working above existing underfloor heating is a matter for the installer or a suitably qualified professional to advise on.

Note any cabling visible in the void or entering the floor, and ask an electrician what needs to be established before anything is covered.

Cabling in or under a floor raises questions that only a qualified electrician should answer for your particular installation.

Decide and record whether existing boards, tiles or a particular finish are to be retained, and accept that lifting and relaying can change how they look.

Boards rarely return exactly as they were, and being explicit about the risk avoids a difficult conversation later.

Write down whether the work would proceed room by room or across the whole floor at once, and which arrangement the household can actually live with.

Sequencing decides whether you stay in the property, and it is worth stating your preference before a programme is set.

Note where furniture, appliances and contents would be stored while rooms are cleared, and who is responsible for moving them.

Storage for a cleared room is a real requirement that gets assumed away by both sides.

Agree in writing how dust is contained, which routes are protected and what happens to rooms that are not part of the work.

Lifting floors generates a surprising amount of dust, and containment is easier to agree before than to argue about after.

Ask for photographs of the void, the pipe runs and the timber before the floor closes again, and keep them with your property papers.

That record is the only view anybody will have of the void until the next time the floor comes up.