Concrete porches

Porches concentrate several problems in a small area. They are attached to the house at exactly the point water is least welcome, they sit over backfill that settles, and they meet a door threshold whose height cannot easily change.

That combination is why porch work is often more fiddly than its size suggests, and why the two details that matter most are the isolation joint and the fall.

What it is

A porch slab typically bears on foundation walls or piers at the house side and on fill elsewhere, which is why differential settlement so often shows as a slab tilting back towards the building.

It meets the house at a threshold with limited tolerance. A porch that has settled leaves a step down at the door; one lifted too far fouls the door or the sill.

Because it is small and adjacent to the entrance, appearance and safety both weigh more heavily than on a utility slab.

What seeing this cannot establish

• A gap at the house does not establish which element moved. The porch may have settled or the wall may not have.
• Whether a porch is supported on walls, piers or fill is often not visible and materially affects the options.
• The threshold height constrains how much lift is achievable regardless of method.
• Nothing visible tells you whether water has been running down behind the slab into the backfill.

What you can safely check yourself

• Level across the porch from the house outward and photograph. Establishing whether it falls away from the door is the single most useful observation.
• Measure the step at the threshold and note whether it has changed.
• Photograph the joint between the porch and the house, and note whether it is open enough to admit water.
• Tap the slab and compare the sound near the house with the outer edge.
• Note where roof water lands — porches are frequently right beneath a valley or a downspout.
• Note whether handrails or posts bear on the slab, since their fixings constrain lifting.

When professional evaluation matters more

• The porch now falls towards the house, or water ponds at the threshold
• The step at the door has become a trip risk, particularly at an entrance
• The joint at the house is open and taking water into the backfill
• Handrails or posts have become loose as the slab moved
• The porch is supported on walls or piers and those show cracking, which is an engineer question

When replacement enters the conversation

• The slab has broken up rather than moved as a unit
• Required lift would conflict with the threshold
• Supporting walls or piers need work that cannot be done with the slab in place

Evidence worth having before you ask for estimates

Every item here is something you can produce without tools or risk, and every one of them makes an estimate more accurate.

• Level readings from the house outward, photographed
• Threshold step measurement
• Photographs of the porch-to-house joint
• Roof water discharge points
• Photographs of any handrail or post fixings

Questions to ask whoever comes out

• Is this porch bearing on walls, piers or fill, and how do you know?
• What fall are you restoring and how does that interact with the threshold?
• How will the joint at the house be detailed to shed water?
• What happens to the handrail and posts during the work?
• If lifting, how much is achievable before the threshold becomes a problem?

Where estimates for this commonly differ in scope

These are the places two prices for apparently the same work stop being comparable.

• The joint at the house is the water detail that matters most and is frequently excluded.
• Handrail and post removal and reinstatement is often assumed to be someone else's work.
• Threshold adjustment is rarely priced and sometimes necessary.
• Whether the porch is structurally supported changes the trade required, and estimates rarely state an assumption.

Who tends to do this work

• A concrete leveling specialist
• A residential flatwork concrete contractor
• A drainage contractor or landscaper who does grading

ConcreteOwner does not inspect, certify or approve contractors. This describes which trade usually holds this work, not a recommendation of anybody in particular.