The moment you notice a deck is the step out of the door. Around Northallerton that step has to work in a wet wind and after a frost, not only on a dry visit. Our team sets the level from the sill, then checks it against the garden and the rules on height.
The sill sets the height
The sill is the bar at the bottom of the back door. The deck should sit a little below it, so water cannot run back in. A surface proud of the sill sends rain at the threshold. If a flush exit would be too high for the wall or the ground, we explain the step instead.
Measure from the sill to the garden as it is. The Portal's usual starting point for a house is 30 cm above the existing ground, and a flush exit can break it. North Yorkshire Council decides the edge. A flat or a listed building's grounds sit outside the ordinary house rules. Planning Data shows conservation areas. The sill does not skip those checks.
An outward-opening door needs its swing. The deck, a mat and a step must leave that arc clear. We check the door on the visit, open and closed. A door that only just clears the old step will not clear a thicker new board unless we have planned the drop.
Water away from the threshold
Rain in the vale is often blown at the door. The deck needs a fall away from the sill, small enough that a chair does not rock, strong enough that water moves. Boards have a gap so the surface does not hold a sheet. At the wall we leave a slot, not a tight fillet. Water that reaches the house should drop through that slot, not sit on the sill or soak the bottom of the frame.
Do not pack that slot. The wall needs to breathe, and the slot feeds air under the joists so a frost can dry out. A boxed edge holds meltwater against the door. The frost note is the wider version.
Mats are part of the detail. A mat that never dries becomes a dam on the sill side of the deck. It should be something you can lift. A tray under a planter has the same habit if it sits in the fall and stops the water. We will point at that on the visit if the only place for pots is the place the fall needs.
A step, not a climb
If the indoor floor is higher than the garden, the change of level happens outside, in even steps. A single generous step beats two cramped ones. A tall last step is how people miss their footing in the wet.
Where a person could fall more than about 600 mm, a guard or a handrail is the usual Building Regulations idea. An ordinary sill-to-lawn step is well under that. A door that opens onto a deck over a falling garden may not be. We measure. We do not add a rail at the door for show, and we do not leave a real drop because the sill itself felt safe.
The step should be obvious: a clear nosing, a board that is not slippery when it is wet, and a landing you can stand on while the door opens. On a windy plot, which the exposed decks page describes, that landing is also where you pause. It does not need to be large. It needs to be there.
Air at the wall
The frame must not press on the brick or stone. A bearer tight to the wall traps damp and gives frost a wet timber to work on. We hold the structure off the wall, ventilate the void, and keep joists out of the soil. Posts are concreted properly so a freeze does not lift the deck into the sill six months later. A deck that has risen against the door is a failed level, not bad luck.
A sheltered DL6 yard stays damp, so the gap matters. An open DL7 garden throws rain at the door, so the fall matters. The geology viewer and the flood map are for the ground. We do not publish a zone, and a sill is not a flood defence.
When you ask for a quote, say if you hope to walk out level, and if the door opens out. We will measure the sill, the ground and the swing.
Questions people ask about door sills
Can the deck be flush with the kitchen floor?
Only if that does not put the outdoor surface too high against the wall, or more than about 30 cm above the existing ground. Often a small step down is the sound answer. Water must not run in.
Why is there a gap at the wall?
So rain can fall clear of the sill and air can move under the frame. Packing that gap traps damp against the door, which is the opposite of what the level is for.
Will frost lift the deck into the door?
Not if the posts are properly concreted and the frame can dry. A shallow fixing in wet ground can heave. We do not use one depth for every garden. We dig what the ground needs.
Does an outward-opening door change the deck?
Yes. The swing has to stay clear of the board, the mat and the step. We check the door open. A deck that blocks it is the wrong height, however neat it looks shut.
