Ouse floodplain decks in York

The Ouse runs through York and out across the vale. Some gardens back towards it. Many do not, even in a postcode that feels riverside. This guide is about gardens where water is a neighbour, not a claim that a named road floods.

What the flood map is for

The flood map for planning is a public map. You enter an address and read that plot. We do the same before we design a deck close to the river. We do not publish zone numbers here, because a figure taken from one house and laid on the next is how bad advice starts. A bank or a slight rise can change what the map says about the house next door.

Tell us what the map showed when you ask for a quote. If it shows a constraint, the deck is still only a deck. It is not a barrier and it will not keep water out of a house. If the ground floor itself is the worry, that belongs with the council and with work to the building, not with a platform packed against the wall.

The Planning Portal's ordinary limits still apply. A deck more than 30 cm above the existing ground is outside the usual house rules and needs an application. Near a river it is tempting to lift the boards just in case. That lift can be the thing that needs permission. Height is taken from the ground that is there.

Air under the frame

On a low plot the void is the detail that matters. Posts, joists clear of the soil, and sides that are not closed into a box let air move. After rain, or after water has stood and gone, the timber can dry. A frame sat on the ground and skirted all round stays wet. We leave the underside open.

Boards have a small gap so water passes through instead of sheeting at the house. At the wall the deck stops short, leaving a slot where rain can fall clear of the brick. We do not pack that slot. The wall needs to breathe, and the slot is also how air enters the void.

Posts stand in a proper concreted hole where the ground is soft, so the frame does not rack. We do not rest a bearer on a loose block in mud. The BGS Geology Viewer is the regional picture. The hole is the local one. Strensall, north of the city, is mostly sand and is not an Ouse garden. An open void is still right there, because of rain rather than the river.

Boards that can dry

A board near the river spends more time damp than one in a sheltered yard, especially in shade or under trees kept for the view. Composite does not take water into itself the way bare timber does, so it is often the calmer surface where a garden stays humid. Hardwood can still be right if the underside can dry, and if you accept oil or the silver colour of timber left alone. The frame is what saves either board.

Mud brushes off. A gentle wash on a drying day is enough. Forcing water up into the joists does harm. Leaves should not sit as a mat in the gaps. Once a year, look underneath. If the void has filled with soil or a stored crate, the airflow has been undone. A cover left on through a wet month holds moisture on the spot you use most.

Not every York garden

York is not one flood place. Terraces away from the river have other problems, mostly access and short yards, covered in our notes on terrace access and low decks. Northern villages sit on sand. This page is for gardens towards the Ouse. If you are unsure, the flood map answers the water question.

Conservation areas and listed houses sit on top of that question. Planning Data shows the boundaries. A listed building's grounds are outside the Portal's ordinary deck rules. Being near the river does not cancel those checks. City of York Council decides the borderline cases. We flag them rather than guessing from a dry afternoon.

If water has stood in the garden, tell us where and how long it took to go. We will keep the frame open, set the posts properly, and keep the height honest against the 30 cm idea. Where a person could fall more than about 600 mm, a guard is the usual Building Regulations idea. The guard is about the fall, not a wall against the river.

Common questions about decks near the Ouse