Auckland Suburbs developed with Internal Gutters

What Homeowners Need to Know

There were thousands of homes, in fact entire suburbs, built around the 1970s–2000s in Auckland with an internal gutter system (sometimes called a box or hidden gutter) behind the fascia rather than a standard external rain-water gutter (see list below). These systems, while once popular, are increasingly being converted to external spouting and fascia systems. This is a 6 Part blog designed to walk you  through…

(1) what an internal gutter conversion is

(2) why many Kiwi homes are doing it

(3) how the conversion works

(4) costs and timing

(5) things to watch out for, and how to decide if you should act now

(6) how to select the correct contractor

Part 1 - What is an internal gutter system?

An internal gutter is a rain-water trough built within the roof edge or behind the fascia, rather than the more familiar external gutter fixed to the front edge of the roof. These were often paired with fascia systems which were designed to hide the spouting within a clean fascia line. 

From a design standpoint they gave a neat modern edge-look, but from a practical perspective they also introduced potential failure points: because the gutter is hidden, access is harder for cleaning and inspection; overflow or blockage often causes the water to end up inside structural cavities rather than being safely shed. 

The governing standard for roof drainage in New Zealand sets out minimum requirements for internal gutters (for example minimum width/depth, freeboard, etc) and the design risks.

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Why convert internal gutters to external gutters?

There are several strong reasons why many homeowners in NZ are choosing to convert internal gutters:

1. Reduce risk of hidden leaks & structural damage Internal gutters often fail in ways that are hard to see: corrosion within the box, blockages, inadequate overflow capacity, hidden water ingress into walls, roofs, insulation. When internal gutters fail… water can go into walls, ceilings and insulation causing thousands of dollars of damage.

2. Easier maintenance and inspection External gutters are easier to see, clean and maintain. Internal gutters are hidden behind the fascia, harder to inspect, and blockages can go unnoticed until extensive damage has occurred.

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3. Modern building standards and architecture shifts As building codes and rainfall intensities change, and as more emphasis is placed on robust drainage systems, external systems are often better suited to cope. For example, internal gutters must meet specific design depth and width for cross-sectional area, or they may be undersized.

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4. Increase in property value and buyer confidence Because internal gutter systems carry a known risk in NZ (especially with older homes), converting to external spouting is seen by some as an upgrade that improves the home’s health, reduces future maintenance/repair risk, and may appeal to future buyers.

5. Long-term durability External gutters made from modern materials and properly installed tend to require fewer hidden repairs and can be easier to replace or maintain down the line compared to internal ones locked into the structure.

The Suburbs where Internal Gutter systems were installed:

Suburbs with Internal Gutters
Area	Suburb
Whangaparāoa	Gulf Harbour
	Army Bay
	Manly
	Stanmore Bay
	Arkels Bay
	Red Beach
Hibiscus Coast	Silverdale
	Millwater
	Orewa
	Unsworth Heights
Albany	Rosedale
	Oteha
Pakuranga	Dannemora
	Golflands
	Highland Park
	Botany Downs
Howick	North Park
	Farm Cove
	Cockle Bay
	Half Moon Bay
	Bucklands Beach
	Mellons Bay
Manurewa	Wattle Downs
	Conifer Grove
	The Gardens
	Totara Park
Papakura	Pahurehure
West Auckland	West Harbour
	Te Atatua Peninsula