How High Should Ground Level Be Below the DPC? New-Build Air Bricks, Paths and Part M Explained
Walk around the outside of a new-build home and you may notice a thin damp-proof course near the bottom of the brickwork, air bricks close to the ground and paths that rise towards the front door.
That raises some obvious questions:
How far below the DPC should the ground be? Can paving be higher near a front door? And should an air brick ever be close to ground level?
For a typical external wall, ground and paving should generally be around 150mm below the damp-proof course (DPC) — roughly two brick courses.
But that isn't the whole story.
Modern new-builds also need to accommodate accessible entrances. A path may therefore rise towards the front door to provide a level or ramped approach under Part M of the Building Regulations.
That does not mean the normal moisture-protection principles can simply be ignored. The access route, DPC, wall and drainage should have been designed to work together.
Here is what homeowners should understand — and what is worth checking around your own home.
Quick answer: Around most of a new-build home, look for approximately 150mm between the DPC and the finished ground or paving. Around a designed accessible entrance, the path may legitimately rise higher, but there should be appropriate detailing to prevent the raised path from creating a moisture or drainage problem.
What is a damp-proof course?
A damp-proof course, usually shortened to DPC, is a moisture-resistant layer built into the wall near the base of the property.
Its job is to help prevent moisture from the ground travelling upwards through the wall.
On many brick-built homes you can see it as a thin dark layer running horizontally through a mortar joint. On other properties it may be less obvious because of the construction, render or detailing.
If you're not sure where your DPC is, don't rely solely on counting brick courses. Ask the developer or builder to identify it.
NHBC's homeowner guidance specifically recommends doing this if you are unsure where the damp-proof course is. (NHBC)
How far below the DPC should the ground be?
The figure homeowners will most commonly hear is 150mm.
Approved Document C in England states that, for an external wall, the DPC should generally be at least 150mm above adjoining ground level, unless the design provides another way of protecting the wall. (GOV.UK)
NHBC's homeowner guidance gives essentially the same practical advice: soil and paths around a home should generally remain approximately 150mm, or two brick courses, below the DPC, except where an area has been designed to provide level access into the property. (NHBC)
So if you walk around the side or rear of a typical new-build, approximately two clear brick courses between the finished surface and the DPC is a useful visual reference.
Why does that 150mm matter?
Keeping the DPC clear of the surrounding ground helps reduce the risk of:
soil or paving bridging the DPC;
rain splashing onto masonry above it;
water collecting directly against the wall;
moisture reaching parts of the construction intended to remain protected;
and air bricks or other ventilation openings becoming obstructed.
It is therefore reasonable to query newly installed soil, paving or a driveway that appears to have been brought directly up to or above the DPC.
However, less than 150mm does not automatically prove there is a defect. The design and location matter — particularly around an accessible entrance.
Why is the path at my front door sometimes higher?
This is where the simple 150mm rule needs some context.
New homes in England are also subject to Part M — Access to and use of buildings.
For the basic Category 1 standard, Approved Document M says the approach to a dwelling should use the shallowest gradient reasonably achievable and be step-free where possible. It can be level, gently sloping or, where necessary, ramped. The principal entrance should also have an accessible threshold. (GOV.UK)
This can mean the front path starts relatively low and gradually rises towards the entrance.
Consequently, you might see a perfectly normal 150mm clearance along most of the front wall but find the path much closer to the DPC as it reaches the door.
Doesn't that breach the 150mm rule?
Not necessarily.
Approved Document M specifically acknowledges the interaction between accessibility and damp protection: when providing level or ramped access and a level threshold, the design of the dwelling still needs to meet the moisture-resistance requirements associated with Part C. (GOV.UK)
In simpler terms:
Part M doesn't cancel Part C.
The builder cannot simply raise paving against the house and ignore the effect on the wall because an accessible entrance is required.
Instead, the entrance and external levels should be designed to achieve both objectives.
What should happen when the path rises above the normal DPC level?
There isn't one detail that is correct for every home.
The solution depends on the wall construction, location of the DPC, threshold arrangement, drainage and the design of the access route.
However, the important principle is that a raised path should not simply bridge the moisture protection or trap water against the wall.
Depending on the design, you might see:
a separation between the raised path and the wall;
a gravel or drained strip;
a channel drain;
the paving falling away from the property;
locally altered or stepped DPC detailing;
additional waterproofing or cavity-tray detailing;
or a combination of these.
At the threshold itself, good drainage becomes particularly important.
LABC guidance for level thresholds recommends that the external landing falls away from the door and that drainage channels are provided where necessary to prevent surface water reaching the threshold. (LABC)
So a path rising towards your front door is not in itself a snag.
What would be worth questioning is a raised path that simply appears to have been built hard against the wall above the normal DPC level without any obvious consideration for separation, drainage or alternative damp-proof detailing.
Should there be a gap between the path and the house?
Where a path has to rise alongside the property above the normal external ground level, some form of separation or designed drainage detail may be appropriate rather than simply building the paving straight against the masonry.
That might take the form of a:
drained gap;
gravel strip;
linear drainage channel;
or another designed detail appropriate to the construction.
It is important not to turn this into a new homeowner rule that says “every Part M path must have a 100mm gravel gap”, because the correct detail varies.
Instead, ask a more useful question:
If this path is above the normal DPC level, how has the wall been protected from moisture and surface water?
If that isn't obvious, ask the developer to explain the detail.
It can also be useful to look at the area after heavy rain. If water flows towards the wall, ponds against the brickwork or runs directly towards the threshold, that provides useful additional evidence.
What is an air brick?
An air brick is a ventilation opening built into the external wall.
On a home with a ventilated void beneath a suspended floor, air bricks allow outside air to circulate through that void.
This airflow helps manage moisture. On some developments the ventilated void can also form part of a ground-gas protection design, so blocking vents without understanding their purpose can have consequences beyond simple ventilation. Approved Document C sets out ventilation requirements for suspended timber floors, including ventilation openings in opposing external walls. (GOV.UK)
The simple homeowner rule is:
Air bricks should remain clear.
Soil, paving, plants, bark, gravel or stored items should not obstruct them.
How high should an air brick be above the ground?
This is where DPC and air-brick guidance are sometimes confused.
The 150mm DPC figure does not mean every air brick must also be 150mm above the ground.
NHBC technical guidance says air bricks serving an underfloor void should ideally be at least 75mm above hard or soft landscaped areas to reduce the risk of blockage or flooding. (NHBC)
It also recognises that an air brick can sometimes be closer to ground level where:
the surrounding surface is suitably hard landscaped;
the ground falls away from the building;
and drainage is provided where required.
So seeing an air brick less than 150mm above paving is not automatically wrong.
The questions are different:
Is the vent unobstructed? Can air flow through it? Is it protected from water entering it?
Can an air brick be below the general ground level?
Potentially — but the surrounding ground needs proper consideration.
NHBC guidance illustrates situations where an air brick can sit below the general ground level if a larger area immediately in front has been deliberately lowered and adequately drained.
Its example shows the reduced ground extending at least 600mm out from the air brick, with the vent at least 75mm above that reduced level. (NHBC)
What should raise more concern is an air brick sitting in a small recessed pocket surrounded by higher soil or paving.
Those pockets can quickly collect:
leaves;
loose soil;
gravel;
vegetation;
and rainwater.
The vent might technically still be visible, but its ability to perform properly can gradually disappear.
Don't confuse air bricks with other wall vents
Not every small opening in your brickwork is an air brick.
New-build homes can also have weep vents or perpend vents.
You may see narrow vertical openings within mortar joints, often above windows and doors or at other locations where cavity drainage or ventilation is required.
These openings may look insignificant, but they have a purpose.
NHBC's homeowner guidance advises that air bricks, permanent ventilators and perpend vents should not be blocked or covered by soil or paving. (NHBC)
Unless you know exactly what an opening does, don't fill it because you think somebody forgot the mortar.
What should I check around my new-build?
You don't need specialist equipment to make a useful first check.
1. Identify the DPC
Walk around the external walls and identify the damp-proof course.
If you're unsure, ask the developer rather than guessing.
2. Look at the general ground clearance
Away from the accessible entrance, look for roughly 150mm — about two brick courses — between the DPC and soil or paving.
If something looks significantly different, photograph it.
3. Check where water goes
Look at the falls on paths and patios.
Does water appear to run away from the house, or towards it?
Checking during or shortly after heavy rain can reveal far more than looking at completely dry paving.
4. Treat the front entrance separately
If the path ramps up towards the door, don't automatically call it defective because it passes the normal DPC level.
Look for how the higher path has been dealt with.
Is there separation from the wall? Is drainage provided? Does the path shed water safely?Is the doorway protected from water?
5. Check the air bricks
Look for soil, paving, plants or debris restricting them.
Pay particular attention to vents close to driveways and garden areas where finished levels may have been altered.
What if I have added a patio or changed the garden?
This is particularly important with new-builds.
Your house may originally have been handed over with the correct relationship between the DPC, ventilation and external levels.
If you later:
install a patio;
raise a driveway;
add significant amounts of topsoil;
install artificial grass;
create raised beds;
or change the levels around the house,
you can potentially alter that relationship.
For example, bringing a new patio up to internal floor level without considering the DPC and threshold detail could create a problem that wasn't present when the property was built.
Before changing levels close to the house, identify the DPC, vents and drainage arrangements first.
And if you're employing a landscaper, don't assume they will automatically consider the building's original damp-proofing and ventilation design.
What should I do if the ground looks too high?
Don't immediately start digging.
First, record what is there.
Take:
a wider photograph showing the wall and surrounding area;
a close-up showing the DPC;
a photograph with a tape measure showing the approximate clearance;
photographs of any affected air bricks;
and, if relevant, photographs showing ponding or water flow after rain.
Then report the concern through your developer's normal aftercare process.
If it is around the front entrance, explain that you understand the path may form part of the accessible approach but would like confirmation of how the DPC, drainage and raised path have been detailed.
That is a much more useful question than simply stating “the path is less than 150mm below the DPC”.
Record it clearly with The SnagClear App
Ground-level issues are a good example of why snagging photographs need context.
A close-up measurement is useful, but someone reviewing the issue also needs to understand where it is on the house and what is happening around it.
With The SnagClear App, you can record the issue, add photographs and notes, keep it with the rest of your snagging record and create a clear PDF report for your developer.
For a concern involving the DPC or an air brick, try to capture:
the whole section of wall;
the DPC and surrounding ground;
the measurement;
any affected vent;
and any relevant drainage or ponding.
You don't need to diagnose the cause yourself.
The aim is to give the developer a clear, well-recorded issue that they can inspect and respond to.
So, how far below the DPC should your ground level be?
For most external walls, around 150mm is the useful starting point.
That is why approximately two visible brick courses between the DPC and the surrounding ground is commonly expected.
But don't apply that number blindly to every part of a modern new-build.
A path designed to provide accessible entry under Part M may rise much higher as it approaches the front door. What matters is that the change in level has been properly designed so accessibility, damp protection and drainage continue to work together.
Air bricks are another separate consideration. They do not simply follow the DPC's 150mm rule, but they do need to remain open, ventilated and protected from obstruction or water entry.
When checking your home, ask:
Where is the DPC?
Are the general ground and paving levels suitably below it?
Is a higher front path clearly part of the accessible entrance design?
How is that raised path separated or drained?
Does water run away from the house?
Are all air bricks and wall vents clear?
Those questions give you a much better picture than simply walking around the house counting brick courses.
Publishing note: Because Building Regulations differ across the UK, the specific Approved Document C and Part M references above relate to England, and that requirements and terminology can differ in Wales, Scotland and Northern Ireland. If you are outside of England please check your local regulations on the applicable goerment website.
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