You don’t need to remove linings to install existing wall insulation. These can be insulated by drilling and filling holes through the external or internal lining and installing an existing wall insulation system. With these types of existing wall insulation systems there are usually three to four 15-25mm holes drilled in the wall, about every 500mm around the building.
Dry Fibre Existing Wall Insulation Systems
Total R-value of R2.2 -R2.9 is achieved in a typical 90-100mm wall cavity with a high density dry fibre system (if installed correctly).
Dry fibre, water-resistant CosyWall insulation has been installed into New Zealand homes since 2002. CosyWall is installed at an optimum design density to prevent future settlement and ensure that the Total R-value is achieved and maintained. With the CosyWall system holes are plugged with filler immediately after the existing wall insulation is installed, then the external cladding is sanded, primed and finish coated.
Tests on the CosyWall existing wall insulation system indicate no moisutre wicking after 30 days and no settlement after twelve months (at the design density). CosyWall insulation also prevents potential fire spread in the cavity and reduces noise transmission through walls.
Wet Foam Existing Wall Insulation Systems
Dry fibre systems should not be confused with wet foam products, which are usually manufactured on site from urea formaldehyde chemicals and water (or occasionally urethane foams). Installation of Wet systems is more complex, which often means long-term that the Total R-values (installed) are considerably less than that stated by suppliers.
If you decide to use a wet foam existing wall insulation remember the following:
The wet foam process requires 25-30 days full home ventilation to aid curing and reduce formaldehyde levels.
Ideally, the home should not be occupied during this period.
External wall hole plugging should not be completed until full curing is complete and internal wall moisture content is less than 24%.
Serious concerns about the suitability of wet foam for existing wall cavities have been raised by Department of Building & Housing (Determination report 2008/35) and which are available on their respective websites.
There are also conserns around the thermal performance of such systems, and Branz report SR233 states 6% perimeter and thickness shrinkage from framing timber as the foam cures – which reduces the manufacturers claimed R2.9 to a Total R-value (installed) of R1.0 – R1.6
When making a decision on your exisitng wall insulation system get advice from the experts.
Contact your local CosyWall distributor at www.cosywall.co.nz or call 0800 267 992