How To Insulate your Motorhome, Campervan or Caravan Using Armaflex

There are a number of European manufacturers who sell caravans and motorhomes that are designed and built to survive the worst winter conditions, but the majority of vans will need upgrading if you are considering taking your van to the Alps in winter. In this case, improving the insulation should be the number one priority on your ‘to do’ list.

In this article our winter caravanning expert John has created a step by step guide to upgrading your motorhome, caravan or campervan plumbing insulation using Armaflex.

What Needs To Be Insulated on Your Motorhome, Caravan or Campervan?

Protecting internal and external water pipes, tanks, and on some vans, heating ducts, is essential to avoid the damage and inconvenience of freezing up whilst on a motorhome or caravan ski holiday. Damage caused by freezing water can impact the entire ecosystem of your van and can be extremely costly.

Even though your van may have been built to DIN 1645-1 level 3 standard (winterised), this may not be enough to prevent freezing, especially if your van was built in the UK where manufacturers are predominately building for a three-season market and may not design their van with your ski holiday in mind. 

Your van may be certified to DIN 1645-1, but will still probably have un-insulated water pipes running around the outside wall of the van and un-insulated internal and external water tanks.

If you’re unsure as to what a ‘winterised’ van is, we wrote an article that covers everything you need to know when assessing just how ‘winter-ready’ your van is. Check it out here.

DIY Insulation

DIY upgrades aren’t just for self-build conversions but there are many things that we don’t recommend tackling yourself when it comes to upgrading your motorhome to a winter-ready specification. Items such as gas and electrical appliances, and adapting pipework and wiring is best left to a professional unless you are very competent.

It is also important to note that many alterations you might be considering may invalidate any existing warrantee remaining on your vehicle and so it is very important that you check the fine detail of your paperwork before you consider doing anything to your van. 

Where Can I Find The Right Materials for Insulating My Motorhome or Caravan?

Step 1!

First port of call in your hunt for insulation is most likely to be your local DIY store for a supply of the grey pipe insulation that we are used to buying for home insulation. Don’t make this mistake.

Whilst this type of insulation can work for internal use in a domestic situation it is comparatively bulky, made of polyethylene, and has limited resistance to water ingress. It isn’t suitable for outdoor use and whenever we consider any upgrades to a motorhome, caravan or campervan intended for winter use, we opt for an alternative product, designed specifically to withstand freezing conditions. This is why we chose Armaflex.

Armaflex Insulation for Campervan, Motorhome and Caravan Plumbing

Armaflex (Class O) is a much more efficient product than grey lagging which is manufactured from a CFC free, closed cell, nitrile rubber foam, has much higher insulation values and particularly good resistance qualities for water ingress making it ideal for internal and external use. It is available in both pipe wrap and sheeting.

Armaflex Class O is available in 2m tubes from 6mm up to 114mm diameter and 6, 9, 13, 19, 25 and 32mm wall thickness. 15m tube coils are also available in addition to flat sheets of 1m wide rolls for insulating larger pipes and tanks. Tubes and sheet are available with a self-seal backing to simplify and speed up installation times. 

For exposed external use and areas where insulation could be vulnerable to impact, Armaflex is also available with a polymeric covering called ‘Tuffcoat’ which is fully waterproof and often used in industrial applications underground. Choosing which thickness of Armaflex to use is often governed by the amount of available space you have to work with in the area of your van you are trying to access. For 12mm semi rigid plastic van pipe, or on older vans 15mm flexible pipe, try to use 9mm or greater thickness, and for sheeting 10mm or greater.

You’ll find a list of suppliers at the bottom of this article. 

Water Tank Insulation

Our most recent project with Armaflex has been to repair and upgrade an under-slung fresh water tank on our caravan. The unit is a 40-litre Whale tank suspended under the van harnessed by two steel straps just behind the axles.        

40-litre Whale ‘underslung’ tank

These tanks are sold within the trade to manufacturers and are claimed to be tri-walled and frost proof. Unfortunately there is no data available from Whale as to their actual performance, so it must be assumed that they cannot cope with alpine conditions. 

This particular tank has been previously insulated with a 12v tank heater and foil covered bubble wrap, but due to a design flaw is prone to grounding on rough terrain such as a snowbound campsite. Inevitably the insulation wrap has been damaged beyond repair and needs upgrading.

Materials used In a winterised tank upgrade:

  • Armacell Armaflex 10mm AF Class O sheeting 
  • Armacell Armaflex 3mm self adhesive tape
  • Armacell Armaflex 520 Adhesive
  • Armacell Armaflex Class O self seal pipe insulation

As we intend to fit an aluminium cover on the tank, we have used the standard Armaflex O class 10mm sheet which is not self-adhesive and is the cheapest way to complete the job.

The sheet comes in 2m x 0.5m pieces, is easily cut and shaped with scissors or a sharp Stanley knife, and requires Armaflex 520 contact adhesive to stick to your tank. The adhesive will stick to almost any surface and is impressively efficient, but check your tank material against the checklist on the Armaflex website to be sure.

How To Insulate Your Water Tank With Armaflex

  1. Start by ensuring that you tank is clean, dry and free of any residual road grime and dust. Use Isopropyl for the best cleaning and to make sure you get the best adhesion between the Armaflex and the surface. Isopropyl is available as disposable wipes which are convenient but can dry out if not stored properly or used once the packaging is open. There is a list of products at the end of the article that are recommended for this job.
  2. Decide on the shape and number of pieces of sheeting you need to use and cut them out. If you’re worried, make cardboard templates first before making any cuts to the Armaflex sheeting.
  3. Armaflex will mould itself to undulations in the shape of the tank, but you may need to allow a little bit extra for rounded corners and indentations.
Armaflex will mould itself to the shape of the tank
  1. Allow for joints to butt together and not to be stretched into place when gluing.
  2. The 520 adhesive can give off a slightly nauseating vapour when used in an enclosed space such as the cramped conditions when working underneath a van. Try to enable as much ventilation as possible, take your time and take breaks if required, and if necessary, wear a mask.
  3. Working one piece at a time, apply a thin layer of 520 adhesive to both surfaces and the edges for jointing and wait for it to almost dry. It should not be tacky when touched with your finger but just malleable enough to take pressure from your finger nail. There are a number of You Tube videos to help with this at
  4. Getting edges aligned and neatly jointed can be a little tricky when working on a tank under your caravan or motorhome, but joints can be reinforced with Armaflex Class O 3mm self adhesive tape. Whilst not sold by Armaflex for this purpose, it does help with reinforcing and repair particularly well.

Insultating Your Caravan, Campervan or Motorhome Pipes with Armaflex Lagging

Armaflex pipe insulation comes in a variety of diameters and thicknesses and should be available to meet the needs of all van pipework and tubing you wish to insulate. 

The ‘Tuffcoat’ variety is especially useful for external pipework such as grey water and heater hose, with the standard self-seal version being ideal for internal pipe.

The pipe wrap is easy to slide onto pipework and close by pulling the protective tape away from the edges and gently squeezing the cut edges to create a seal. It can be cut with scissors to create 90-degree bends and joints, which can be sealed with 520 adhesive or with the self-adhesive tape. It can be secured to fixtures and fittings in the van using pipe clips or cable ties and if reinforcing is required to support the fixing, the self adhesive tape will come in handy again.

If you are refurbishing an older van and re-plumbing using 12mm semi rigid pipe, this is an ideal opportunity to re-route pipes away from external walls where possible and insulate with armaflex as you work.

Armaflex lagging is easy to install

Other Things You Can Insulate In Your Van With Armaflex

We recommend you keep any surplus Armaflex you have left over as it can be used for a variety of jobs in the motorhome – here are some examples of where else we have used Armaflex in a motorhome:

  • Wheel Arches – a sometimes overlooked area of the van when insulating
  • Bodywork Air Gaps – depending on the quality of your van, these may or may not be intentional! There are a number of ‘gas drops’ which provide ventilation for safety reasons and these should not be covered but some vans come with their own unique holes! Armaflex is excellent for all those drafts that you only discover once you’re on the road!
  • Garages – insulating your garage is something you should consider where you do not have heating routed through the area. Inevitably, this area gets wet on a motorhome ski holiday and frozen ski bindings can be a hazard to your fingers!
  • And lastly – surplus Armaflex is our favourite ‘anti-rattle’ solution and can be used to prevent all sorts of irritating noises during transit!

Products Recommended For Insulating Motorhome and Caravan Plumbing


Amazon – You can get almost everything you need from Amazon and whilst these suppliers are not always the cheapest, if you have Amazon Prime (and therefore free shipping) or are in a hurry to get hold of anything, Amazon can be your best bet. Here’s a link to Armaflex Products on Amazon

JTM Plumbing – These guys are dedicated plumbing merchants and have a full range of Armaflex products. They are very competitive on price but charge for shipping and remember to check as all products are quoted ex VAT.

Isopropyl WipesAmazon

Isopropyl Alcohol Amazon

If you’re new to motorhome, campervan and caravan skiing, check the ‘Beginners Info’ section here which will take you through a number of how-to guides as well as answer some questions you didn’t even know you had!

Disclaimer: All articles posted on are designed to provide information and advice on how to identify what you might need when you take your caravan or motorhome skiing in Europe. They are not intended to be definitive reviews, but a guide to help you with further research to choose what is right for you. As with many caravan and motorhome projects upgrading insulation on water tanks and pipework is a straightforward job. However if you are not confident that you can safely undertake the work you should consider using an NCC accredited engineer to do the work for you.

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