Underfloor Insulation Sydney
Underfloor insulation in Sydney stops cold air and lost heat coming through suspended timber floors, one of the most common complaints in older homes across the city. Insulation Extract installs Knauf Earthwool® underfloor batts and closed-cell spray foam wherever there is safe crawl-space access.
Extraction & Batts
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Why timber floors feel cold in Sydney homes
A large share of Sydney's older housing sits on piers or brick footings with an open space underneath. Federation and interwar homes, weatherboard cottages, fibro homes and many houses on sloping blocks were built this way. Air moves freely under the floor, so in winter the boards stay cold and draughts come up through gaps between them, around skirting boards and through old floor vents.
This matters more in western Sydney's climate zone 6, where winter mornings in suburbs such as Penrith, Richmond and Campbelltown can be frosty. But even in coastal climate zone 5, homes on the North Shore, Northern Beaches and in the Sutherland Shire often sit high off the ground on sloping blocks, which leaves a lot of floor exposed to cool, damp air.
Underfloor insulation adds a thermal layer between the subfloor space and the room above. It makes floors noticeably warmer underfoot, reduces draughts and means heating does not have to work as hard.
Sydney homes that suit underfloor insulation
- Federation and interwar homes with suspended timber floors
- Weatherboard and fibro cottages across the south west, Central Coast and Illawarra
- Homes on sloping blocks with a tall subfloor at the downhill end
- Raised homes and extensions built on piers or posts
- Any home with timber floors and a crawl space we can safely access
Mixed homes are common too. Many Sydney houses have an original timber-floored section at the front and a newer slab extension at the back. We insulate the suspended part and leave the slab section as it is.
Homes built on a concrete slab do not have a subfloor to insulate in this way. We check access height, ground conditions and ventilation during the assessment and tell you if the space is not workable.
Underfloor insulation options
We use two main products under Sydney floors. Each suits different homes and budgets.
Knauf Earthwool® underfloor batts
Earthwool FloorShield batts are made from silicone-treated glasswool with an ECOSE® glass veil facing that helps protect against wind-wash from air moving under the house. They are fitted snugly between the floor joists and held in place so they do not drop over time.
- Good thermal performance at a lower cost than spray foam
- Absorbs sound for a quieter floor
- Made with recycled glass, with no added formaldehyde
- Non-combustible to AS1530.1
Closed-cell spray foam
Closed-cell polyurethane foam is sprayed directly onto the underside of the floorboards and joists, where it expands and bonds to the timber. It seals gaps between boards as well as insulating, which makes it very effective against draughts.
Because spray foam bonds to the boards, any floorboard repairs or replacements should be done before it is applied.
- Air-seals the floor as well as insulating it
- Resists moisture, which suits damp subfloors near the coast and harbour
- Helps block gaps that pests use
- Costs more than batts and must be installed by trained applicators
Heritage and character homes
Federation and interwar homes in conservation areas often have original floorboards worth keeping. Underfloor insulation is installed from below, so it does not change the look of the floor or the house, which makes it a practical upgrade for character homes in suburbs such as Haberfield, Hunters Hill, Annandale and Ashfield.
Moisture and ventilation under Sydney homes
Sydney subfloors can be damp, especially in low-lying areas, near creeks and on the shady side of sloping blocks. Good subfloor ventilation is important, and insulation should never block vents. If we see pooling water, rot or blocked vents, we point it out so it can be fixed before insulation goes in.
Pests in the subfloor
Rats and mice like the shelter of a subfloor, and old insulation that has fallen down can become nesting material. We remove damaged material, and closed-cell foam in particular closes off many of the small gaps pests use. Termite inspections and barriers should still be kept up to date, and insulation is installed so inspection access is not blocked.
Combining underfloor and ceiling insulation
A home loses and gains heat through every surface, so underfloor insulation works best alongside a properly insulated ceiling. If your roof space still has old or patchy insulation, we can assess both at the same visit and plan the work so the house is improved from top to bottom.
How underfloor insulation is installed
- Free on-site assessment of access, clearance and floor structure
- Removal of any old, fallen or damaged underfloor material
- Batts fitted between joists and secured, or spray foam applied to an even depth
- Clearances kept around wiring, plumbing and floor vents
- A final check of coverage and a clean-up of the crawl space
Underfloor insulation across Greater Sydney
From our depot at Unit 4/1 Powdrill Rd, Prestons, we install underfloor insulation across the Inner West, Eastern Suburbs, North Shore, Northern Beaches, Hills District, Western Sydney, South West Sydney including Liverpool and Campbelltown, the Sutherland Shire, the Central Coast and Wollongong.
Insulation Extract has been operating since 2014, is part of the Energy Efficiency Group (EEG) and has retrofitted more than 45,000 Australian homes. To book a free assessment, use the quote form or call (02) 7233 1266.