Heel Height & the Baffle. How to offset your specified ventilation.
The quality of New Zealand homes is becoming more considered – with more care taken to create healthy, energy efficient homes. One major building block of a healthy home that is sometimes forgotten is passive roof space ventilation.
Evidence has shown that without adding ventilation to our builds, condensation and mould build up is becoming a secondary concern and causing irreparable structural damage to new homes, just one to three years down the track.
Roof ventilation is standard in building codes in Europe and recently introduced to Australia to remedy this problem. While we have E2 (E2 3.5/3.6) which tells us what risks to protect against, the E2 clause does not specify how to be compliant with New Zealand building standards for mould and moisture mitigation. For architects and builders, specifying and installing roof ventilation alleviates potential liability for structural mould issues down the track.
You can mitigate your liability, and offset your costs.
Vent systems have a bespoke solution that reduces your build’s heel height while achieving compliance with NZS 4246:2016, offsetting the cost of adding ventilation and protecting your liability against potential mould damage. By installing a Vent baffle you can offset the cost of your ventilation system by reducing your cladding costs.
How?
Current insulation requirements include an added heel height in order to create enough space for thicker insulation. Added heel height means extra cladding costs.
The Baffle is a custom designed Vent product that allows you to build to the previous standard heel height and still be building code compliant, saving you cladding costs and creating a more insulated home.
The baffle slightly compresses insulation allowing you to fill to the very edge of the roof ridge and across the top plate, reducing thermal bridging and creating a more robustly insulated home.
Does compression reduce insulation to less than the minimum standard?
Yes it can. If you install a R3.6 (180mm) with a standard heel height (110mm), the compression of insulation at the perimeter causes the R3.6 insulation to reduce down below the R.3.3 construction value required at the eaves.
However, If you use the G502 eaves baffle with insulation greater than R4.0. Even with compression of insulation, you exceed R3.3 R-value. Using the G502 you can also benefit from only needing to use R7 insulation across the whole roof cavity instead of reducing the insulation from R7 to R3.6 in the last 500mm of the roof, the baffle’s compression still exceeds R.3.3, you will still meet code as well as creating a more insulated home. Combining a baffle with an insulation thickness of R7 across the entire roof cavity, not just the central area, means you can insulate fully over the top plate whereas it normally stops half way and you will still maintain the required 25mm gap between the trusses and insulation.
How do I install it?
The baffle is easy to install, roll it out over your trusses then cut it and nail it down. There is no labour intensive install.
Can I install a baffle without a ventilation system?
This is an option but we don’t recommend it. Our ventilation systems are so cost effective, it makes sense to install at a minimum an over-fascia vent with your baffle, but we recommend a complete Vent system to ensure air flows through your tightly insulated build, minimising condensation at dew point.
The money you’ve saved in heel height costs can be reinvested into ventilation.
Will installing an eaves baffle affect the recession plane?
We understand in suburban developments and high density areas that every millimetre matters. Installing an eaves baffle (on a truss roof) allows you to reduce your heel height, and in turn reduce your height to boundary needs.
Create a moisture free, hassle free build at little to no extra cost with Vent. Talk to us today to find out more about tailored, cost effective ventilation systems that protect your build and reputation.