Categorized | Construction

How over insulating your home can lead to issues

Posted on 08 December 2020 by editor

This time of year we desperately want to keep our homes warm and cosy. One way homeowners have been encouraged to do this is by having full fill cavity wall insulation installed. This is where they drill through the our skin of your home and blow new insulation into the cavity.

This definately imporves the thermal connectivity of your home, the problem is however, the more we try to improve the thermal insulation, remove drafts etc, the less likely the house can breathe and this then leads to condensation. One local builder this week was called to a home in Northfield to examine water in the loft space. This was being caused by condesation forming on the under-side of the roof felt and was slowly dripping on the loft insulation.

As soon as they opened the loft trap and entered the roof space, they could tell immediately what the problem was. The roof space was warm.

There were three primary reasons why this was happening. a) Poor roof insulation was allowing heat from the home to move into the roof space. b) Insulation has been packed into the roof space and was pressing on the roof felt. c) Too much insulation had been packed in at the eaves and blocking airflow.

It is very important that a roof space can breathe and has airflow. Insulation must not block vital air flow from the eaves into the loftspace and it must never touch the underside of the roof felt.

The builder had to remove some of the loft insulation, because it had been pushed too far in towards the fascia boards and soffits, that this was blocking any airflow. Ideally, you should be able to see the fascia board when you look down the length of the roof trusses, if not, chances are sufficient airflow is being blocked. Modern houses to to have eaves protection kits installed, this contains corrugated plastic that prevents roof felt from touching the underside of the roof felt, but also allows sufficient airlflow to enter the loftspace.

In the winter, if you go into your loft and you find it is warm, this will lead to increased condensation. Hot air will hit the cool underside of the roof felt and water will condense. This will then drop onto the roof felt.

This article was contributed by Sure Seal Solihull. Suppliers of UPVC Windows, Doors, Conservatories, Orangeries & Bi-Folds in Solihull

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