Building a Second Storey: What It Means for Your Existing Foundation
Adding a second storey means genuinely more load on your existing foundation — worth understanding what that assessment process actually involves.
Why Existing Foundations Need Reassessment
A second storey adds genuinely significant additional load to your existing foundation, which was originally designed for a single-storey structure’s loads — this makes proper reassessment a necessary step, not an optional formality.
What an Assessment Involves
An engineer assesses your existing foundation’s condition, original design capacity (from any available documentation), and the additional loads the second storey will introduce, to determine whether it can support the addition as-is or needs modification.
Possible Outcomes
Outcomes range from the existing foundation being assessed as adequate, through to requiring localised strengthening, or in some cases needing more substantial foundation work — the specific outcome depends entirely on your existing structure’s actual condition and the addition’s design.
Strengthening Existing Foundations
Where strengthening is required, this might involve additional footings, underpinning, or other engineered solutions specific to what the assessment identifies — a genuine, sometimes significant scope of work worth understanding early in project planning.
Planning Around This Early
Because foundation assessment outcomes can meaningfully affect project scope and cost, this assessment should happen early in second storey planning — before design and budget are locked in around an assumption the existing foundation simply doesn’t need attention.
Recently Completed Projects
We complete residential and commercial concrete, excavation and foundation projects across Melbourne every week. Explore our project gallery to see the range of work we deliver.
Frequently Asked Questions
Does adding a second storey always require foundation work?
Not always, but it always requires a proper assessment — the existing foundation was designed for single-storey loads and needs to be checked against the new loads.
What does a second storey foundation assessment involve?
An engineer assessing your existing foundation’s condition, original design capacity, and the additional loads the second storey will introduce.
Can existing foundations always be strengthened rather than replaced?
Often yes, through additional footings, underpinning or other engineered solutions, though the specific approach depends on the assessment findings.
When should I get a foundation assessment for a second storey?
Early in project planning, before design and budget are locked in around an assumption about the existing foundation.
Who assesses an existing foundation for a second storey addition?
A structural engineer, based on the existing structure’s condition and the new loads the addition will introduce.
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