Park Home floor insulation – facts and fallacies.

Tingdene Homes have a lovely square chassis, always a pleasure to work below their homes!

You may have insulated your walls and roof, but your feet still feel cold. It’s time to think of the amazing benefits of Park Home floor insulation. Choosing the right materials and the right Company to fit it is a minefield, so here’s some information to help you make that choice.

Many refurbishers refer vaguely to ‘new systems’, wonderful new lightweight technology and the ubiquitous ‘Superfoil’ or ‘Double Bubble’ quilt type insulation.

Back to school

Going back to school – I know, I know, for the vast majority of us, a long time ago – but you may remember the following facts from the Physics teacher about heat transfer:

Three types: Radiant, Conduction and Convection. The full info here from the good old Beeb if you are of a scientific bent:

In layman’s terms, Radiant means reflection (eg light/heat bouncing off shiny surfaces), Conduction means similar material up against similar material (eg metal to metal) and Convection means cold air replacing hot.

Which insulation keeps you warmer?

‘Superfoil’ and other double-bubble insulation is only good at combatting Radiant heat loss. It does not combat Conductive nor Convective heat loss effectively. The material is too thin. The material usually poorly fitted by cowboy installers (ie edges not sealed and run over pipes and wiring and sometimes even the chassis!)

Typical cowboy fitting of ‘Superfoil’ or ‘double-bubble’ under a home.
No sealed edges, gaping holes, poor fitting, no care taken.

Loft Roll (eg glass fibre, rockwool, sheep’s wool etc) is only good at combatting Conductive heat loss. It does not combat Radiant nor Convective heat loss effectively unless combined with a reflective layer. Insulation must be sealed tight and be fitted at an even depth below the home. This is rarely possible due to it being slung between the floor bearers (joists) and held up by netting or a moisture barrier.

The only completely effective Park Home underfloor insulation is PIR Board. It combats Radiant heat loss due to the foil backing on both sides, it combats Conductive heat loss due to the non-conducting foam construction and is gas-tight due to the closed-cell construction (ie it won’t let air through.)

PIR Board makes are those such as Recticel, Celotex, Xtratherm, Ecotherm, Kingspan, Quinntherm etc.

The right materials still need fitting correctly

Now, though PIR Board is the best material for below Park Homes, full effectiveness relies on the following:

1. The thickness of the board.
2. The quality/method of the fitting.
3. The type (manufacturer) of board.
4. The measures taken to combat ‘Thermal Bridging’ or ‘Cold Bridging’.
5. Gas Safety and the importance of ventilation.
6. The importance of the moisture barrier.

1. Board Thickness.

There are calculations and all sorts of scientific equations (eg ‘U’ value and ‘R’ value) made to specify what thickness of board is most effective and there are strict rules governing depth/thickness of board required in New Build Bricks and Mortar regulations.

Thankfully, we don’t have to stick to those when fitting aftermarket insulation below Park Homes otherwise it would take an age to fit and cost you the earth!

Suffice to say the thicker the better and more effective – ie you will feel warmer and be turning down your thermostat several degrees. Conversely, in Summer, you will feel cooler because the heat below your home will be kept out of the House by the ‘thicker’ insulation.

The vast majority of Park Home underfloor insulation contractors that use PIR Board use 25mm (1″ in old money) board. Some claim to use 30mm – and indeed charge for it – but they don’t, reckoning that you won’t be out there with a tape measure checking for the 5mm difference!

We use 40mm (1 1/2″) Board as standard, but will fit 50mm (2″ in old money) if you wish. Like any insulation though, the effectiveness is in the fitting. You can fit 100mm (4″) but if it’s fitted badly it’s no better than 40mm fitted well!

2. Quality/Method of Fitting

Proper care when fitting brings the best results. Park Homes are a unique challenge to the installer due to the steel chassis, the pipework and the wiring that run below and above an insulation fitment.

This means that cut-outs have to be made around these obstructions. All gaps must be filled and all joints must be sealed in order to make the fitment as air tight as possible. This combats Convective heat loss – that is the ‘sucking-out’ of the warm air and replacement with cold air.

Our attention to detail saves you money.

We use foil tape to seal the joints and cut outs. Some contractors use Expanding Foam to seal the joints/cut outs. It’s quick for their fitters, but will lead to expensive repairs should you need plumbing or electrical work under your home in the future. Many fall for it and regret it later.

Look at the mess. Try removing and replacing that if you’ve a problem below your floor.

3.  Type/Manufacturer of Board

We’ve tried and tested all the major manufacturers. In spite of the manufacturer’s claims, we have found only two makes of boards that are suitable below a Park Home. Every other type of board has split or curled away from the fixings.

The two types of Board that we use are Recticel and Ecotherm because of their rigidity, resistance to curling/splitting and their durability.

Many other boards degrade quickly as well. Take a stroll down the insulation aisle of a B & Q or a Wickes and have a look at the state of the boards in those aisles. Yellow/orange sides and lumps missing.  Do you really want that board under your Home?

4.  Combatting ‘Thermal’ or ‘Cold Bridging’

The unique challenges of insulating a Park Home are legion! It’s not easy to get a good fit at the sides above tight brick skirting. The steel chassis is an excellent conductor of heat and cold, so I describe it loosely to clients as a ‘dagger of cold into your warm space’.

100mm (4 inch) wool lining the steel chassis to combat thermal bridging.

We get around this by isolating the chassis with 100mm recycled wool or Rockwool Flexi. The material also acts as a barrier, so that if the insulation is breached or damaged subsequently, there will only be one cold spot. No thermal bridging material fitted halves the effectiveness of insulation.

5. Gas Safety and the importance of ventilation.

Mains gas is lighter than air, so therefore will rise. As long as you have plenty of ventilation in your walls and windows,  you won’t have a problem should a gas leak occur. LPG (Liquid Petroleum Gas) is heavier than air and will collect at the lowest point.

Residential Park Homes with a LPG supply, whether through Gas Bottles or piped from a tank MUST have Gas Safety drop-down holes fitted in the floor at every pipe entry point.

This means that if there’s a gas leak in the Home, the gas will drop through these holes into your crawl space and disperse safely through airbricks.

We fit LPG gas drop-down holes as a matter of course during an Insulation fitment. We know that other underfloor insulation firms don’t because we’ve seen their work. and had to insert drop-down holes for worried customers.

Drop-down LPG gas escape below a refurbished Donnington Castle single unit.

Ventilation below the Home is crucial. Airbricks must be fitted on the bottom or first course of any brick skirting for LPG gas dispersal. Many bricklayers are ignorant of this fact and place the airbricks halfway up the skirting or at the top, even on new Homes. We fit correctly positioned airbricks where the ventilation is poor or the bricks have been fitted incorrectly.

6. The importance of the Moisture Barrier

Some Park Homes have a Vapour Barrier, some have a Moisture Barrier fitted below the floor.  Some older Park Homes have no barrier at all. Those early homes were not intended to last as long as this.

A Vapour Barrier is to stop low concentrations of damp rising up through your floor. A Moisture Barrier is to stop heavy concentrations of damp rising up through your floor.

A repaired moisture barrier before insulating.

Left unchecked, rising damp from below the Home (eg flooded base, leaking pipes, overflowing rainwater barrels, undiverted rainwater) can destroy your flooring and lead to mould and fungus on your lower walls. This is a definite health hazard along with causing spongy floors and ill-fitting laminate flooring.

We repair torn/missing portions of moisture barrier and fit entirely new where none exists. Anyone insulating below a floor with no moisture barrier is asking for future trouble, and possible extensive floor repairs in the future.

In conclusion, there is definitely a right and a wrong way to insulate a Park Home floor. The trouble is, you won’t find out that you’ve chosen wrongly until some years later.

This isn’t a scientific article. Hopefully you can now make an informed choice for a major upgrade of your insulation. Don’t waste money on poor materials and poor workmanship. Don’t take the Salesperson’s word for it, do your research.

If you’ve enjoyed reading this and would like a quote for your floor to be insulated properly, email us on

Leave a Reply