How to run pipes through insulation


When insulating a property one of the key things is to ensure a continual layer of insulation around the building envelope, however this is not always possible.

Occasionally it may be necessary to run services through the insulation such as pipework or electric cables. We’ve looked at putting electrical sockets and light fittings into insulation previously but in this post we will discuss the best methods of running pipework through insulation.

Our recommended solution would be that, wherever possible, don’t run your pipework through your insulation or at least try and minimise the penetrations through the insulation, to limit the damage to the insulation layer and vapour check. The insulation is there for a good reason and it is best to avoid cutting it. Absolute best practice would be to move services to an area that will not have insulation fitted.

If this is not practical or possible then there are best practice details available which can be followed to ensure the system remains effective and therefore limits the risk of condensation, additional heat losses via air leakage and thermal bridging.

There are a number of different types of pipes that you may need to run through the insulation, from water pipes to flues and the requirements may be slightly different for each.

Gas or oil pipe
When you have to run a gas or oil pipe, for example, through a wall, you should use a pad saw or core drill (a circular disc drill bit) to cut through the insulation to provide a snug fit and reduce the oversize to a bare minimum. Any damage to the insulation should be made good by filling any large gaps (10mm +) with expanding foam insulation and the pipe perimeter should be sealed with flexible sealant.

Flue pipe
For flue pipes there may be a requirement to create a separation layer between the insulation and the flue pipe. This will vary depending on the operating temperature of the flue and the flue specification itself. This needs to be checked before installation.

In all cases, the installation of gas, oil pipes, flues, electrics and telecoms should only be done by a competent person such as a qualified electrician, Gas Safe, OFTEC, HETAS or BT certified engineer. It is also vital that ventilation requirements for certain combustion appliances are not removed, blocked or reduced in size. All works involving appliances, fittings or flues should be carried out in accordance with Approved Document J for England & Wales, or Section 3.17 – 3.24 of the Scottish Technical Standards and / or manufacturer’s guidance.


For more information please contact our technical department.

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Kingspan Insulation is a market leading manufacturer of optimum, premium and high performance rigid insulation products and insulated systems for building fabric and building services applications.

0 comments on “How to run pipes through insulation
  1. Flue liners can be placed inside chimneys for use with a wood burning stove. These should be capable of withstanding the high temperatures that are produced by wood burners. They should also be flexible enough to be pulled through a chimney and should cope with any damp conditions inside the chimney. For these reasons, flue liners for use in a domestic dwelling are usually made from stainless steel that is a minimum of 316 grade. It is also possible to buy flue liners that are made from higher grade stainless steel or liners that are made from concrete. However, concrete liners are a more permanent solution, and are more expensive to fit due to the labour involved.

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