Keeping in the Warmth

A well-insulated loft hatch and ladder is more important now than ever before. Premier Loft Ladders explains what to look for.

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An uninsulated home loses considerable heat through the roof. Insulating the loft or attic could therefore save hundreds of pounds in energy costs while also improving comfort for the property’s occupants. However, the cooler air in an insulated loft can result in draughts through gaps in the insulation, such as an ill-fitting and poorly insulated loft hatch. It is therefore important to fit an insulated loft hatch with draught-excluding seals. Furthermore, choosing a loft hatch with an integrated ladder offers safe and convenient access into the loft space.


Passive House Institute certified component, the Designo loft ladder from Premier Loft Ladders

When choosing an insulated loft hatch and ladder there are three important factors to consider:

1 The amount of thermal insulation provided by the loft hatch.

Thermal insulation is the reduction of heat transfer through objects of differing temperature. A well-insulated loft hatch therefore reduces the heat loss from the warm room into the cooler loft space above.

Pay attention to the U-value. This is a measure of how much heat is lost through the loft hatch by conduction, convection and radiation. A high U-value indicates high heat loss. A low U-value indicates low heat loss. As a benchmark, a solid wall has a U-Value of approximately 2W/m2K.

For a well-insulated loft hatch, you should really be looking for a product offering a U-value of less than 1W/m2K. Be particularly cautious of loft ladders claiming to be ‘highly-insulated’ if they are not supported by a U-value. Also, don’t be afraid to ask where that U-value came from.


2 Air permeability through the loft hatch box.

This relates to the amount of air that will travel through the hatch while in its closed position (eg through gaps around the trapdoor).

The first thing to look for is whether the loft hatch is certified with a Class 4 air permeability rating. Class 4 is the highest rating, so anything certified to this standard is recommended.

The other thing to consider is the construction of the trapdoor. A strong, rigid trapdoor, made from durable materials, should last the test-of-time and provide a tight seal for many years of use. Also consider the number of locking-points on the trapdoor. Modern windows feature multiple locking-points to help ensure a tight and even seal around all its edges. The same applies to an insulated loft hatch with ladder. Consider loft hatches that have multiple locking points. For example, our Designo wooden loft ladder features a high quality six-point locking mechanism for a window-tight seal.


Multi-point locking system provides airtight seal

3 Air permeability around the outside of the hatch box.

Now you have a well-insulated and sealed loft ladder hatch. The final challenge is to minimise the amount of air that escapes around the outside of the hatch box. It is therefore important to make sure that you choose a hatch box that fits the size of your ceiling opening. Where possible, choose a made-to-measure loft ladder to ensure a good fit and one that leaves a sufficient gap between the hatchbox and the structural opening. The small gaps around the edges are required to allow for installation tolerances as well as to minimise heat transfer through thermal bridging.

Finally, it is important to seal and insulate the gaps around the edge of the hatch box. To ensure the best possible seal, you can order your loft ladder from Premier Loft Ladders with WDL sealing tape. The patented WDL tape is pre-assembled to the hatch box and offers an airtight seal with the building. Made of tear-resistant material, it also provides thermal and acoustic insulation. Alternatively, a suitable insulating material can be applied between the gaps after installation.


Patented sealing and insulation tape prevents heat loss and draughts around the outside of the loft hatch

Achieving Passive House standards

The factors considered above are essential for projects aiming to achieve Passive House standards. Premier Loft Ladders offer a version of the Designo loft ladder certified by the Passivhaus institute. Also available are a couple of specialist loft ladders offering U-values as low as 0.28 W/m2K, featuring either folding wooden loft ladders or retractable aluminium stairs. They feature a secondary upper cover that can be closed immediately after entering the loft. This not only helps to lock the warmth in the home or building, but also prevents moist air from flowing into the loft and condensing in the cold areas.


Designo with additional upper hatch for enhanced thermal insulation

For further details, please visit our web site:
Alternately if you would like to discuss your project, please call us on 01394 214413 or send an email to


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