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Cavity Wall

What different types of Cavity Wall are there?

There are two types of cavity wall ; Full-fill & Partial-fill.

Full-Fill Cavity Wall

Full-fill cavity walls are the most popular method of insulation. Roughly 55% of all newbuild cavity walls are fully filled. If you include refurbishments, it takes the total to 85% of all residential cavity walls. The reason is simple: filling a cavity with mineral wool offers substantial savings compared to partial-fill solutions – sometimes as much 50%. You’ll be able to achieve the thermal performance required by the Building Regulations while saving anything up to £500 a plot. There are other reasons to fully fill a cavity. There’s less chance that performance will be impaired by air flows within the cavity. The products we would recommend using for this particular application would be:

                 •  Mineral Fibreglass Insulation Slabs - Enables complete filling of masonry cavity walls to give                                   outstanding thermal performance. Knauf's Dritherm slabs knit together to eliminate all                                               air gaps


Partial-Fill Cavity Wall

The efficiency of partial-fill cavity walls relies on the superior thermal performance of polyurethane (PUR), polyisocyanurate (PIR), and phenolic insulation products. A thin layer of these materials is enough to achieve the thermal values you require. The closed-cell structure of PIR, PUR, and phenolic products makes them resistant to moisture. The products we would recommend using for this particular application would be:

                  •   PIR / Phenolic Rigid Foam Cavity Wall Boards - Simple insulation for partial-fill cavity wall                                       applications which are conveniently sized to fit between cavity wall ties.Celotex                                                                          CW4000 range offer outstanding thermal conductivity & ease of installation.

Do I need anything else?

As with any project, there are accessory products that are intended to be used in conjunction, this helps the products efficiency and ensures it performs as it should. Some of the products we would recommend using for partial and full fill cavity wall projects are:

                   •  Masonry Cavity Wall Ties - These clips help connect the inner and outer leaves of a masonry                                   wall cavity to enabling moisture to cross the cavity from the inner and outer.

                   •  Insulation retaining discs - These are designed for Rigid insulation boards (PIR) these discs                                     are used in conjunction with wall ties and hold the rigid boards in place against the                                                   inner leaf of the cavity

                   •  Foil Tape - Bostik's foil tape maintains insulation efficiency creating an air tight seal between                                    boards and protecting against the effects of moisture and fire. They are reliable,                                                      strong and durable

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For instructional videos on some of the products you can use to install cavity wall insulation, visit our Video Library 

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