Did you know that too much insulation can cause condensation?
Eaves ventilation is important as it creates an airflow through the lower section of the loft and can help prevent condensation. Some homeowners block this airflow with excess loft insulation.
Thus, it is important to insulate a loft correctly but also to add vents in the right places. This allows the loft to breath but keeps the home warm.
For an Existing Roofline
If the fascia and soffit boards are not being replaced then the easiest way to vent the loft via the eaves is to use soffit board vents. A hole is cut into the existing boards and the vent simply slots into place. The vents can be either circular or rectangular as shown in the image below.
It is however very important that these vents are not used on asbestos soffit boards as cutting or drilling these boards will produce harmful asbestos dust. Asbestos boards look similar to cement so if the soffit boards are made of a non timber, cement type board then it is highly likely that they contain harmful asbestos particles.
Soffit vents are unattractive and visually obtrusive, they also become full of dirt, grime and cobwebs. As an alternative, it is possible to install
over fascia ventilation strips which are fixed directly to the top edge of the fascia boards and are almost invisible when viewed from ground level as they are located above and behind the guttering.
To install these strips of vents, the first row of tiles must first be removed. If you are considering installing new fascia and soffits soon then do give some thought to using the over fascia vent.
There are two sizes of over fascia eave vents – 10mm or 25mm. Both are 1 metre in length.
The 10mm is the preferred size as it meets British Building Regulations and is almost invisible from ground level view. The vent strip is very easy to install once the first row of tiles have been removed. It is simply nailed to the top edge of the fascia board with 40mm fixings spaced 300mm apart.
This product has become very popular and is now used by most professional Upvc roofline installers. It can also be used with the rigid eaves felt system and products such as the bird entry prevention comb.
Pre-Molded Soffit Vents
If a new roofline is being installed then pre-vented Upvc soffit boards can be used. These were very popular in the late 1990’s and are still used today. They are however less appealing than a smooth non vented board. So it may be best to use the over fascia vents – at least from a visual perspective.
Both the pre molded soffit boards and the over fascia vents offer the same level of ventilation and both meet current regulations (in the U.K).