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Frost protection for domestic pipes

With the cold weather approaching we thought it would be a good idea to touch on how best to protect your pipes from frost this winter.

When dealing with frost protection on pipes inside a building your aim with insulating them is to delay the onset of freezing for as long as possible; it is not possible to guarantee a pipe will not freeze by insulation alone. The better the insulation, and the thicker the insulation, the longer you will give yourself. Under normal circumstances you aim to give yourself about 8-10 hours protection against sub zero temperatures. With pipes inside a home this is usually long enough to be sure the pipes will not freeze.

Ice formation inside the pipes will lead to an increase in pressure. As the water tries to flow this pressure will increase, and eventually will lead to the pipes bursting. A burst pipe can cause a lot of problems, not least of which is a lot of damage to your property and a lot of expense incurred.

Water regulations state that all water pipes (excluding warning or overflow pipes),  taps and fittings should be protected against frost wherever it is practical to do so. Where this protection takes the form of pipe insulation, the below table gives a guide to what thickness of insulation ought to be used. This is worked out in accordance with the values given in water Bylaw 49 and intended for internal pipes.

Pipe Size
Thermal Conductivity of Pipe Insulation (W/m.K)
30 (30)
25 (62)
15 (12)
19 (20)
15 (8)
19 (12)
15 (6)
9 (9)
15 (5)
9 (7)
Note: Figures shown in brackets are calculated values shown in BS 6700

Most flexible foam pipes insulation such as EurobatexClimaflex or Armaflex would be classed as 0.035W/m.K materials, having thermal conductivities of 0.033, 0.034 and 0.034 respectively. This means 15mm pipes need 25mm insulation 22mm & 28mm pipes need 19mm insulation and 35mm & 42mm need 9mm insulation to protect against frost damage.

 Places that would be particularly at risk of frost bursts are pipes installed near windows, air bricks, external doors, insulated roof spaces (where they are above the insulation and deprived of heat from the house), unheated cellars, unheated garages or outhouses; essentially anywhere where draughts are likely to cause heat to be taken away from the pipes.

In areas where damp is a risk it is best to use a closed cell product that will not absorb water, such as Eurobatex, Climaflex or Armaflex Self-Seal. Wet insulation is worse than having no insulation at all, as water fills all the air gaps and insulation works on the premise of trapping air which is really where your insulation value comes from. Also, as you increase the surface area by putting insulation on it will cool more quickly so freezing becomes more likely when then product is wet.

For more information on the different products available, refer to our product specific blog entries or visit our website for the full product ranges:

Blog Page on Eurobatex

Blog Page on Climaflex

Blog page on Armaflex Self Seal

Web Store Page of Pipe Insulation Products


  1. Can Climaflex be painted? If so, can you recommend a paint?

    Bernard Hardy

  2. Hello Bernard. Polyethylene has what is called a "release surface" which essentially means that liquids cannot bond to it, so the paint will not stick to it properly. Are you looking to paint for UV resistance or aesthetic reasons please?

  3. Hi. Is Climaflex suitable for outdoor use as lagging to water mains supply pipe and does it require a water vapour barrier to minimise water permeation? Thanks

  4. Climaflex can be used outdoors, although it will degrade faster than internally; it would most likely require replacing after 3-5 years.

    Climaflex has very, very low water absorption characteristics; it would need to be submerged for about a month to absorb as much as 3% by volume - in other words, you need not worry about water ingress.

  5. Hi. Many thanks for the advice. Which other product would you recommend as having a longer lifespan. Would something like Armaflex do the job? And do you know if it complies with the Water Regulations (inferred by BS 6700 and BS 5422)


  6. It does depend on the size of your pipe, but I would assume 32mm? If so, I believe the best product currently available on the market is Thermsmart Pro which we have just introduced. It has a superior (lower) thermal conductivity to Climaflex and Armaflex and is UV stable so will last a long time outside. 13mm would be enough to comply with regulations, though of course insulation alone cannot guarantee a pipe will not freeze, it ought to be sufficient to provide you with at least 12 hours frost protection down to about -6C.

    The product can be found here:

  7. Thank you very much. Most appreciated.

  8. This comment has been removed by a blog administrator.

  9. there are specialized engineers who work hard to do regular checks on various pipelines - Hot tapping services and keep them healthy through timely checks from time to time

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  19. Our condensing boiler is situated in a ventilated loft. And the pipework is above the loft insulation. I have a couple of questions regarding pipe protection against frost.
    1. The smaller gauge pipes are fixed to the wall and the gap between the wall and back of the pipes is tight, only about 12mm. How do I protect in this situation?

    2. The larger 22mm pipes that have long runs across the loft are easily accessible except for the point where the joists have been notched out to carry them. How would I provide insulation at these points, as the bottom of the pipes are resting on the joists and the two sides are enclosed where the joists are notched out?


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