Patio Drainage Questions Checklist

Mark every puddle on a simple drawing of the paving, describing each position by the slabs or joints around it rather than by measurement.

The paving itself gives you a reference grid, so an owner can describe positions precisely without a tape in hand.

Note whether the same puddles return in the same places after different rainfall, or whether they move about from one spell to the next.

Puddles that return to the same spot point at the surface itself, while wandering ones more often point at where the water arrives from.

Record how long each puddle takes to go in your own terms, such as gone before the rain stopped or still there the following morning.

Relative persistence across the terrace is the useful comparison, and it is worthless without the date recorded beside it.

Show how deep a puddle is by which slab edge, planter base or step riser it comes up to in the photograph, without putting a number to it.

A familiar reference in shot lets anybody read the picture later, which is exactly what an unmarked photograph prevents.

Note whether the standing water falls where the table, chairs, door or route across the terrace actually are, or somewhere nobody goes.

Where the water sits in relation to how the space is used decides how much this matters, and only you can supply that.

Mark the areas of paving that shed water at once and never hold any, so the terrace is described by its contrasts and not only by its worst corner.

A professional reads the contrast across one surface far more usefully than a general statement that the terrace floods.

Watch which way water moves along the strip beside the wall during rain, and note whether it runs along the wall or away from it.

Water tracking along a wall base is easy to miss because it never forms an obvious pool anywhere.

What the relationship between paving and the building should be is a matter for a qualified professional to assess on site.

Photograph any band of staining, discolouration or salt-like deposit on the wall above the paving, and note how far along it runs.

The extent of a stain along a wall often matters more than its height, and it is easily recorded in one picture.

Note whether the paving reads as high or low against the wall compared with other parts of the building, without putting a figure to it.

A relative note made before anything is disturbed is genuinely useful and cannot be wrong the way a measurement can.

Paving levels against a building affect the fabric of the property and must be assessed by a qualified professional before anything is altered.

Watch what happens at any door sill during heavy rain, and note whether water reaches it, sits against it or passes it entirely.

Sills are a fixed reference everybody understands, so an observation there travels well to whoever you speak to.

Look for splash marks on the lower wall where rain bounces off hard paving, and note how high and how far they extend.

Spatter looks like rising damp to an untrained eye, which is one reason this belongs in the record rather than in a conclusion.

Note any vent, grille or opening low in the wall and where the paving sits in relation to it, recording it plainly and going no further.

Their position relative to the paving is a fact worth capturing; what it means is not something to work out at home.

Anything involving vents, openings or the base of a wall must be put to a qualified professional rather than judged from outside.

Note where joints are open, washed out or noticeably different from the rest, and mark those areas on your drawing of the terrace.

Joint loss tends to follow the route water takes, which makes it a free map of movement across the surface.

Record where fine material appears at the surface between slabs after rain, and photograph it before it is brushed or washed away.

Material arriving from below is a significant observation, and it disappears the moment anybody tidies the terrace.

Note where a slab rocks underfoot or sounds hollow when walked on, and mark the position without lifting or disturbing anything.

Movement and hollowness together suggest something has changed beneath, which is precisely what a professional will want pointed out.

Do not lift slabs or open joints to look beneath; what lies under paving is for a qualified professional to establish.

Photograph any white or powdery deposit on the paving and note where it appears, keeping the note descriptive rather than diagnostic.

Deposits of this kind have several possible causes, and describing where they appear is more useful than guessing why.

Map where algae and green film establish first each cold spell, since growth follows the areas that stay wet longest.

Growth is a slow record of persistent damp and it maps standing water without you needing to be present in the rain.

Note any line, dip or sunken run across the paving, particularly one that continues in the same direction beyond the paved area.

A line that carries on past the terrace often follows something buried, which changes the questions that need asking.

Follow the water off each edge of the paving during rain and note what it runs onto, whether that is lawn, border, gravel or another surface.

Terrace water is frequently just moved on a short distance to become a problem in the next part of the garden.

Note whether beds and borders beside the paving are visibly taking runoff, showing washed soil, exposed roots or a scoured edge.

Scoured soil at a bed edge shows repeated flow, and it appears long before anybody describes the terrace as a problem.

Record clearly whether any of the water leaving the paving heads back towards the building or towards an outbuilding.

This single observation shapes the urgency of everything else in the record and is easy to state without any expertise.

Water running towards any building should be described to a qualified professional rather than dealt with on your own judgement.

Note any channel, grating or gully at the edge of the paving, mark its position, and record whether water actually reaches it.

An opening that water never reaches is a common finding and it is only visible while rain is falling.

Where an existing opening leads, and whether anything may be connected to it, is for a qualified professional and the relevant authority.

Note whether water from the paving reaches a boundary, and record what you see without attributing responsibility to anybody.

A neutral factual record is what any later conversation about a boundary will need, and it is easily spoiled by early conclusions.

Walk to where the water ends up and note the condition of the ground there, including whether it is soft, scoured or permanently wet.

The receiving ground tells you whether the water is being absorbed or simply moved on to become a problem elsewhere.

Note how soon the terrace is usable again after rain in your own terms, and whether some parts come back into use well before others.

Usability after rain is the outcome an owner actually cares about, and it is rarely written down before a design conversation.

Note where furniture legs, planters and heaters habitually stand, and whether any of them sit in an area that regularly holds water.

Marks under permanent furniture record standing water even when nobody has looked at the terrace during rain.

Record the strips that stay dry under eaves, canopies or overhangs, since they behave nothing like the exposed paving beside them.

Sheltered strips confuse the picture badly if they are treated as though they receive the same rain as everywhere else.

Note whether doors open outwards over paving that holds water, and what happens to that water when the door is used.

A door sweeping through standing water is an observation that immediately gives a professional something concrete to consider.

Mark the areas that feel slippery in wet weather and record the positions, leaving any judgement about the surface to somebody qualified.

Where a surface becomes slippery usually matches where it stays wet, so the note belongs in the drainage record.

Whether a surface is suitable underfoot in wet or icy conditions is for a qualified professional to advise on.

Note where frost and ice sit longest on the paving, and add those positions to the same drawing as your puddles.

Ice returns to the areas that hold water, so cold weather quietly maps the surface for you without any rain.

Watch what water does where steps meet the paving, and note whether it runs down them, gathers at the top or sits at the bottom.

Steps concentrate water and the effect is obvious during rain, yet it is almost never recorded before a terrace is redesigned.

Note where the edge of the paving has moved, lifted, dropped away or lost its restraint, and mark each position on the drawing.

Edge movement often follows water that has been escaping in the same place for a long while.

Note whether the lawn or border sits above or below the paving at each edge, described relative to the paving rather than measured.

Ground that has crept above the paving edge can hold water on the terrace, and it changes very gradually without anybody noticing.

Record where raised beds, planters and built edges sit tight against the paving, and whether water gathers along them.

Built edges act as barriers, and a puddle along a raised bed is often about the bed rather than about the paving.

Note where water travels along the base of a wall or edge rather than pooling, and follow it to see where it eventually goes.

Travelling water leaves less obvious evidence than a puddle and is regularly left out of an otherwise thorough record.

Note any change in level that appears to be holding water on the terrace rather than letting it move away.

Identifying where water is held, rather than proposing what to do about it, is exactly the part an owner can contribute.

Bring one drawing of the terrace carrying puddles, joints, edges, openings and routes together, rather than a stack of separate notes.

Seeing all of it on one sheet reveals relationships that separate observations hide completely.

Take each photograph twice, once with water present and once after it has gone, from the identical spot, and keep the dates alongside.

Pairs are self-explaining, which means nobody has to take your description on trust.

Write down whatever you know about when and how the paving was laid, including anything a previous owner or neighbour told you.

Even a vague account, clearly labelled as recollection, points a professional at what is worth investigating.

Ask what has to be understood about the bedding and the ground under the paving before relaying or extending is even on the table.

This question usually reorders the conversation, because it puts investigation ahead of appearance.

Ask who should look at the junction between the paving and the building, since it may not be the same person who looks at the paving.

The wall and the surface are often different specialisms, and assuming one professional covers both wastes a visit.

Keep your own explanation of the cause on a separate sheet, clearly marked as your view rather than as part of the observations.

A clean set of observations is worth far more than a persuasive theory that quietly shapes how everything else is read.