January 17, 2017

Make sure your roof can breathe

It’s winter.  It’s cold.  But at least you know your roof is cosy with all those inches of cushiony insulation keeping that expensive warm air from escaping into the wintery atmosphere, right?  Great!  Now how much outside air do you have coming in to the roof?  Yes, wherever there is insulation, there has to be ventilation.  Ventilation provides balance.  Ventilation prevents the insulation from suffocating the property, allowing it to breathe.  There are many signs around a home that it may be suffocating and in the roof space it’s damp caused by condensation.

In an unvented or under-ventilated roof space condensation will occur when the warm, moisture laden air meets the much colder surfaces of the roof such as felt and timbers.  At this point the warm air is cooled below the dew point temperature resulting in water drops (condensation).  Left untreated this water can start to rot timbers, and drip down saturating the insulation and your precious belongings.

Our tips for removing condensation from a roof space:

  • Check to see if the roof is ventilated.
    • Are the soffit boards/eaves ventilated at the front and the back of the property? If not don’t worry just yet.
    • Move everything out from between the rafters and check for daylight coming through roof vents at the bottom of the eaves in between each rafter. If you can see daylight –great.  If you can’t it may be that there isn’t a vent or the insulation was pushed too far down when laid and now blocks it.
    • Try to establish if the roof has a breathable membrane.
Condensation on roofing felt
Mould on roof timbers
  • If the roof doesn’t appear to have any ventilation at the soffit and/or eaves we highly recommend having some fitted. A roofing professional can advise you on exactly what ventilation will be required to bring your roof up to British Standard 5250.
  • If you think the insulation is blocking the vents it should be possible to create a new ventilation gap with the use of refurbishment ventilators such as our RV600, which are fitted from the inside.
  • If the roof appears to have breathable membrane, still consider introducing ventilation. Here we suggest asking a roofing professional for advice.
  • Don’t ram the items you are storing in the loft right down into the eaves. Leave plenty of room for the air to circulate around boxes to prevent patches of condensation.
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