Cavity slabs are a type of insulation used to insulate cavity walls. Cavity slabs come in a variety of sizes, styles, and thicknesses. For example, Dritherm cavity slabs by Knauf are a mineral wool slab, which are manufactured with a water repellent additive. They are also rot-proof, which deters the growth of mold, fungi, or bacteria. Cavity slab insulation is popular as it is easy to install and provides excellent thermal performance.
Cavity slabs work by filling the air space of a cavity wall with material that inhibits heat transfer, cavity wall insulation is used to reduce heat loss through that wall.
Cavity walls have a hollow center. As a result, they are composed of two “skins” separated by a hollow chamber (cavity). Skins are usually masonry, such as bricks or cinder blocks. The masonry material absorbs rainwater and humidity, making it an extremely absorbent material.
Building cavity walls became prevalent in the United Kingdom during the 1920s. As early as the 4th century, stone ties were used to connect the two skins. During the 20th century, metal ties were used. Early cavity widths were narrow so that moisture could be reduced from getting into the interior of buildings. In the 1970s, cavity insulation became standard, and it became mandatory in the 1990s.
By insulating cavity walls, a house is also less likely to lose heat through its walls and therefore be kept warm more efficiently. Cavity wall insulation can also prevent convection as well as make a house warmer by preventing heat from escaping. About a third of the heat lost by an uninsulated home escapes through its walls.
Cavity slab insulation provides excellent thermal performance within the cavity wall. This can help reduce energy bills by providing a building with better insulation properties. Cavity slabs such as the Dritherm range are water repellent and will not encourage the growth of mold, fungi, or bacteria. In addition to this, they will not attract the likes of vermin and therefore improve the health and safety of the occupants of a building.
They are easy to install and very cost-effective. In the winter months, cavity slab insulation can reduce heat loss due to convection. This is similar to putting a hot drink in a flask. The heat is retained and therefore the need for heating is reduced. This reduction is excellent for the environment.
The water repellent properties of a cavity wall slab can prevent condensation. Moisture from condensation can cause mold to grow. The insulation itself restricts moisture from passing through the walls. Water can pass through the outer wall because it is porous. Cavity slabs will trap the water and allow it to run down to the ground rather than through the inner wall. By using a water repellent cavity slab, we essentially remove the environment for mold to form.
Cavity slabs can be easily installed. Below is a guide that we wrote for installing Isover, however, most cavity slabs can be installed using the same process. Before you begin, you will need wall ties. These are vital for securing the structural integrity of a wall. It is vital that wall ties are correctly installed to prevent damp issues, cracking, or in severe cases, wall collapsing.
When installing cavity slabs, build up the first section of the leading leaf to include the first row of wall ties. Ideally, the insulation needs to start a minimum of 150mm below DPC level to provide effective edge insulation as well as reducing thermal bridging at the junction.
It is important to clean off any mortar snot protruding into the cavity from either cavity trays or wall ties.
The cavity insulation slab should then be positioned against the masonry (between the wall ties). Make sure the drips are halfway across the top of the insulation. If the insulation needs cutting then use a sharp knife and a straight edge for an even fit.
Once you have done these steps, you then need to build up the second leaf. This should be built to the top of the insulation. The wall ties need to slightly slope away from the internal to the external leaf. Any excess mortar needs to be removed from the cavity face to prevent mortar droppings on the top of the insulation. The butt joints need to be tightly butted and the vertical joints need to be staggered from course to course.
If you are looking for cheap cavity slabs, we sell top brands at trade prices. Why pay more for your cavity slabs when you could use Trade Insulations? You don't need an account to place an order with us and we keep our trade prices open to everybody. The Dritherm range from Knauf Insulation is a top seller and is available in a whole host of variations.
If you need any help or advice regarding insulation simply get in touch with us. Our friendly team is always happy to help!
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