Frequently Asked Questions


How well does the insulation control air leakage that can account for up to 50% of a home's energy loss?

Insulation is not designed to control air leakage. Improving air tightness should be achieved by other means such as seals around doors and openable parts of windows, draught stoppers, air tightness membranes, etc.

Can the insulation create an air barrier without the use of extra finishing materials (tape, gaskets, plastic wrap) and labor?


How quickly will the insulation pay for itself? Could the monthly savings outweigh the monthly cost of financing?

If you take into account health benefits and improvements in wellbeing (not just energy savings) the payback for good insulation is instant. In terms of energy savings, the payback for insulation depends on type of houses, number of occupants, heating patterns and many other factors. It is not unrealistic, however, to expect a good ceiling, floor and wall insulation to pay for itself in 4- 6 years.

How well does the high density insulation reduce air leakage heat losses in hard-to-insulate areas such as rim joists, cathedral ceilings, crawlspaces, garages, etc without extra materials?

High density (semi rigid) insulation is easy to fit snugly in difficult-to-access areas. Compression fitted between the structural elements the high density insulation eliminates gaps around the edges that low density insulation is often susceptible to. According to BRANZ such gaps can be responsible for substantial heat losses- up to 3% of reduction in R-value for 1 mm of a gap.

Can the insulation help reduce the size and cost of heating and cooling equipment?

Yes. Houses with good insulation have smaller heating loads than those with average or inadequate insulation.

Will the insulation minimize air infiltration to help keep out allergens, dust and other outdoor pollutants?


Will the insulation shift with the home as it settles and keep its R-value over time? (If gaps or seams exist in the material, R-value is sacrificed).

Well fitted good insulation should not move overtime. It should not reduce in thickness either.

How well will the insulation dry out, if it gets wet (i.e. through a roof leak)? Will it keep its insulating properties through the wetting and drying process? Is it a food source for mold?

Polyester insulation by InsulPro will dry out without any impact on thermal performance of the product.
Wet insulation (irrespective of its type) will have its thermal performance reduced. Wet fiberglass insulation will be permanently damaged by wetting.
If insulation gets wet in situ it is a sign of a weather tightness issue (such as a leaky roof). When wet for prolonged time, building materials are likely to become breading grounds for a fungal growth such as mold and mildew.

Does the insulation contribute to a "greener" home?

Yes. Insulation makes homes more sustainable.

Will it improve indoor air quality?

Not directly. But with higher temperature in the room the occupants are more likely to ventilate.

How much will it reduce energy consumption?

That depends on a wide range of factors such as the house typology, number of occupants and their behavior, heating patterns, climatic conditions, etc. Online software packages such as ALF by BRANZ and Design Navigator can help assess energy loads for particular house designs and levels of insulation.

Can the insulation help control sound (around plumbing, between rooms, street noise)? 

Absolutely. Especially well fitted semi rigid insulation that will eliminate sound transmission between insulation and framing.

What is a good insulation?

Insulation that can be easily fitted without undue compression, tucks and folds. Only then insulation will be it at its nominal thickness and deliver its nominal R-value.
For example, If your wall insulation is too soft it will be very hard to cut to size and fit well. Subsequently, its installed performance is likely to be compromised.
Insulation also must be durable. If affected by moisture, insulation’s performance can be greatly reduced.


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Earth Insulation is a proud member of the Insulation Association of New Zealand Inc.


All work carried out by Earth Insulation is done up to the EECA Standard and NZ Standard - NZS4246



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