What is a Subfloor?
- Latisha Coloma
- Feb 5
- 7 min read
I'm sure you know that dark, damp space beneath your home. Remember you left those surfboards you bought back in 2004 down there, never to be seen again...
Well that's your Subfloor and, without proper Mechanical Ventilation, it can be the cause of mould growth or musty smells in your home.
Because it isn't a liveable element of your home, this space can easily be neglected. However this space may have some of the biggest impact on the indoor air quality of your home, unknowingly affecting the health of you and your family. If that doesn't seem bad enough; lack of subfloor ventilation can also lead to significant & costly structural damage to your home.
This is because, being it is so dark and damp down there, mould and moisture get trapped inviting pests, risking wood rot of timber flooring and/or supports and allowing contaminants & musty odours to creep into your home.
Unfortunately, because of the fantastic job your builder probably completed to achieve an airtight, well insulated & sealed home (great for energy efficiency), your home cannot breathe and methods of natural ventilation probably aren't cutting it.
So, what's the solution? How do we treat poor ventilation of the Subfloor?
Firstly, it's important to understand the "mathematics" to achieve proper ventilation. But don't worry, when it comes to your project, we will take care of the numbers.
There are two vital elements to effective ventilation of a Subfloor. In order to achieve the suggested 4-5 air changes per hour (in a standard subfloor*), methods of exhausting and supplying air must be utilised to achieve proper ventilation.
*where a subfloor is experiencing significant dampness, holds excess moisture or other special conditions - up to double the suggested air changes may be required
Exhaust Air
For example: let's say your home's floor plan was a perfect square
Step One: Calculate Square Meterage
In this case 10m x 10m = 100m^2
Now let's imagine your Subfloor was at a perfect height of 2m all the way across - this is the ultimate dream for our 6ft2 sparky
Step Two: Calculate Volume
In this case 100m^2 x 2m = 200m^3
Let's find a fan which will achieve 5 air changes of this complete volume.
Step Three: Calculate Required Capacity
In this case 200m^3 x 5 air changes = 1000m^3 OR 278 L/s
Therefore, this subfloor would require1 of our BLAUTURBO200 in-line fan capable of 1080m^3 per hour.
See our product page here for more fans
Now that we've chosen our fan, Comfort Zone will develop a customised Ducted System Design to target troubled zones/rooms and extract from multiple strategic points, to draw air OUT of the Subfloor to atmosphere.
Supply Air
Passive methods of ventilation are most common and ideal for most Sydney homes. Those Terracotta Louvre or Square Vents you might've painted over during your last home 'spritz' did have a purpose.
If functional, these vents allowed fresh flowing air into the Subfloor. However, they aren't the best available & they are easily obstructed and/or damaged.
To supplement your Mechanical Subfloor Exhaust Air System, we replace all existing vents and strategically install new Mesh Vents (as seen below) to introduce this fresh air to your Subfloor once more.
As the air is exhausted out of your Subfloor, via the fan, pressure decreases to allow fresh air to be pulled through these vents creating that cyclic pattern which achieves... light bulb moment incoming... AIR CHANGES!
Okay, information overload over. Let's summarise.
What is a Subfloor?
Your Subfloor is the supporting structure of your home. It is the open space beneath the floor of your home where all the foundational walls & structures live to evenly distribute weight across your home. It is grounded on a raw environment of soil, sandstone, rock & more.
Why is it important to be treated and looked after?
This space is almost always neglected by the home builder & owner due to lack of education on its impacts and needs. Being it is such a dark damp space, mould and moisture get trapped inside inviting pest, risking wood rot or timber floors/joists/supports and allowing contaminants & odours to creep into your home. This unknowingly affects the health of you and your family but can also lead to significant & costly structural damage to your home.
Why does it require mechanical ventilation?
Though you may not utilise your Subfloor, your builder definitely did when they built your foundations and put in your ducted Air-Con or In-Floor Heating System. This means there are a multitude of obstacles for air to get trapped during attempts to flow through any relief vents or weep holes present.
How do we ventilate it?
At Comfort Zone we Supply & Install complex custom ducted Subfloor Systems like below.
The benefits to a ducted subfloor system are:
It can be targeted to reach the depths of your subfloor or more troublesome zones
Provides the opportunity to extract air from multiple points - up to 6 with our single fan systems & 12 with our dual fan
Equipped with volume controlling dampers which mean custom settings to suit the needs of your subfloor space
This system is 'Set & Forget' where we electrically connect it to mains power, programmed by a local or remote 24-hour control timer. We will set it to your best suited 12-hours of the day typically 7am-7pm - as running the fan during the day has the advantage of drawing in daytime air which is typically warmer with better drying qualities. Also, during this time, occupants are usually out of the home which means noise will not be heard or will be drowned out by general ambience.
What are the Signs & Symptoms of a poorly ventilated Subfloor?
Damp/musty smells in your home
Mould growth on walls and/or furniture against walls
Mould growth on cupboard contents
Recurrent cold, allergy or asthmatic symptoms
Your Pest or Building Inspector suggests more ventilation (no they aren't just trying to spend your money)
Wood decay, rotting bearers/joists, floor cupping and/or bending
The Mechanical Subfloor Ventilation System we've presented to you throughout this read is typical to most Australian homes and other buildings (such as shopfronts, restaurants, offices, schools & chapels) which have a suspended timber floor.
Contact our office or Submit An Enquiry to speak to a member of our staff and arrange a quote, inspection or find out more about what Comfort Zone has to offer.
FAQ
How much will it cost?
At Comfort Zone we've designed a costing catalogue for all our standard Systems & Services. For a Comfort Zone Quality Subfloor Ventilation System we offer the following standard "packages":
Single Fan System with 6 extract points (suited to most average Australian homes) - priced at $3,900 (including GST and labour)
Dual Fan System with 12 extract points - priced at $7,000 (including GST and labour)
Supply Air Mesh Vents can be replaced or installed from $138-$185 per vent (including GST and labour)
Although all prices listed here are subject to complete site inspection with all necessary trades.
How loud are the fans?
Can I get a fan which pushes air into my Subfloor to force the air out instead?
What if we just replace the existing vents to introduce cross-flow ventilation?
You installed my system yesterday and I can smell mustiness more than before.
Why choose Comfort Zone?
Comments