Internal wall insulation: maintaining continuity of an aluminium-faced PIR layer

Inspect both sides before buying boards. Check gutters, sills, cracks and ground junctions. Damp plaster may result from a leak, poor ventilation or a cold corner; these call for different remedies.

Do not conceal a wet surface. Eliminate the cause and assess the substrate first. Internal insulation reduces heat reaching the masonry from the room, so its moisture conditions must be checked. A simple model does not include every process, such as airflow through gaps.

Gas-tight PIR facings are thin layers containing aluminium. One construction combines aluminium, paper and polyethylene; the exact composition depends on the product. This is not a structural steel facing. It limits gas exchange and vapour transmission through the board surface.

Simply placing such boards side by side is insufficient. Moisture can reach colder wall layers through joints and openings, so design a continuous airtight and vapour-control layer. Nor should shine be assigned an arbitrary “heat-reflecting” benefit: wall resistance follows from the actual assembly.

For a paintable interior, PIR factory-bonded to plasterboard is one option. The plasterboard may be 12.5 mm thick, which is added to the core. Confirm whether the quoted dimension means insulation alone or the complete composite. Similar-looking boards can have different constructions.

Allow for adhesive or a subframe, reveals, window sills and radiator position. A few centimetres on the main wall may make a larger difference at the window. In humid rooms use a version intended for those conditions, rather than choosing ordinary plasterboard solely on price.

Remove loose coatings, dust and wallpaper residues, and check plaster strength. Smooth or absorbent surfaces may need preparation compatible with the adhesive. Check required substrate and board temperatures; no single threshold covers every system. A cold wall can prevent installation even when the room air is warm.

Choose adhesive and fasteners for the system and substrate. Do not copy fixing spacing from another project. Uneven walls may need levelling or a subframe. Ceiling installation cannot simply copy wall bonding: the lining’s weight must be supported as specified.

Check where insulation meets the floor, ceiling and adjoining walls, including the window perimeter. Do not leave accidental gaps behind skirting. A skim coat cannot replace sealing of joints deeper in the assembly.

Plan insulation-gap filling and electrical-box sealing to suit the system. Arrange cables before bonding and do not cut improvised channels through the core. Adding a socket later can breach the completed sealed layer. Provide a defined detail for each service penetration.

Dry-fit a board at a window and corner before bonding the whole wall. Check reveal finishing, trims, handle and sash movement, and radiator-valve access. This inexpensive check reveals conflicts that become visible only with the complete lining thickness.

Do not shave away a large area of core to disguise a measurement error. Local thickness changes alter thermal performance. Decide the reveal detail beforehand; a thinner board or alternative arrangement should follow the design and system documentation.

Finishing too early can hinder drying. Set the waiting period for the adhesive, substrate and room conditions rather than assuming a universal time for PIR-plasterboard composites. High humidity and low temperature prolong drying. Check conditions before joint finishing.

After renovation, check ventilation and heating. Do not immediately place a large wardrobe against a previously damp area. Observe corners through the first season and keep photographs of hidden details with the product documents. They help investigate later stains or damage.

No. Performance also depends on joints, perimeter connections and service penetrations.

First identify and remove the cause of moisture. Covering the wall alone does not solve it.