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How to Insulate A Loft?

We apply Lapolla Spray Foam to the underside of the roofing felt or membrane and then spray down to the eaves. This will completely seal…

We apply Lapolla Spray Foam to the underside of the roofing felt or membrane and then spray down to the eaves. This will completely seal the area leaving no air gaps. By doing this we prevent air infiltration and prevent heat from the property escaping through the roof.

Insulation Types

There are varying products that can be used to insulate your Roof.  These can be used with varying degrees of efficiency, cost and ease of installation.

Mineral Wool and Fibreglass

Mineral Wool Insulation and Fibre Glass insulation are the most commonly found insulants in existing domestic buildings.  Fibreglass insulation was first introduced into domestic buildings in the 1930’s.  It was primarily used as a replacement for asbestos based insulants that were developed to retain temperatures in dwellings in their lofts, walls and floors.  Made from pure asbestos, this is the most hazardous material found in roofs (rarely) and with the identification of asbestos related hazards, the installation of this type of insulation was quickly ceased. 

Mineral wool Insulation is formed using a mix of products (including molten glass) that are spun into a wool like material and that is subsequently formed into rolls and used both for sound and heat loss insulation in buildings. The products ability to restrict and partition air flow does give it some heat retention qualities but it is far better when used for sound proofing in partitions etc.  The fibres of the wool conduct heat very well and limit the products ability to effectively prevent heat loss.

Fibreglass Insulation is produced in much the same way as Mineral Wool Insulation and it is the products ability to partition and trap air within the product that gives it some thermal properties.  Again, this is a product that we consider to be better suited to sound insulation.

Both Mineral Wool and Fibreglass both break down over time and there is much speculation about health issues related to their use.  Primarily these relate mainly to the installation and working practices that should be adopted during installation.  It is often the case that these working practices are not followed and the products are left exposed in lofts and below floors. 

Both products are known to trap moisture that we find in an airborne state in most properties.  Over time, this moisture build up will increase and high levels of moisture are regularly found as being trapped within the products.

Rigid Polyisocyanurate (PIR) Insulation

This type of insulation has been developed for a range of insulating applications including walls, floors and roofs.

Most commonly found in New Build properties, these products were developed as a roof insulation to aid the need to use as much of internal building space for habitation.  Many new build properties now include an additional floor within what would normally be the roof void.  The use of this type of insulant to insulate the sloping sections of the roof aids and facilitates this requirement with a certain degree of ease.  Insulant qualities are relatively good although sound insulation properties are relatively low.

These are products that are often used by DIY enthusiasts and contractors as a means to improve the thermal performance of dwellings although without specific skills the effective use of these insulants can be limited and a little hit and miss. The insulation requires a perfect fit to be completely effective and in practice, installing to this perfect fit requirement is difficult.

Lapolla Spray Foam Insulation

Spray Foam Insulation (Lapolla) is by far the most advanced Insulation available on the market. Available as both Open Cell and Closed Cell products this type of insulation is widely used for insulating floors, walls and roofs.

This product was originally developed in the USA but soon became one of the most widely used insulants in the UK today.  Lapolla has the benefit of BBA Certification for all of its products and is fast becoming the No 1 insulation chosen by homeowners in the UK.  This type if Insulant is spray applied to the underside of the roof and comes with a host of benefits and applications. It has superior thermal properties to all other products and is widely used to remedy many other problems that are resultant from the previous use of other types of insulant.

Installation is fast and efficient and significant savings can be made on installation cost as well as creating minimal disruption for the homeowners.

Thermal Performance

Disadvantages of Rigid Polyisocyanurate (PIR) Insulation

  • Acceptable Thermal Performance but only when perfectly fitted.  Not really suited to retrofit installations as the slightest imperfection fitting will have a significant overall impact on the overall performance.

Disadvantages of Mineral Wool and Fibreglass

  • Fibreglass is generally found beneath Mineral Wool even though the products are similar.  Both products will be found loosely laid between ceiling joists, often with a second layer laid transversely across the joists as a top-up.  Often found laid over rafters and bonded to roofing underlay. Where both products are laid, fibreglass will be the lower layer because of its age.
  • Generally found in thicknesses of 100 mm & 15 mm with more recently insulated properties having insulation thicknesses of 225 mm – 300 mm.
  • Laid by hand and often found to be poorly laid which limits the overall thermal performance.  Known to be one of the most significant causes of condensation on roof voids after eaves ventilation becomes inadvertently blocked.

Disadvantages of Rigid Polyisocyanurate (PIR) Insulation

  • When installed as a remedial measure in RetroFit installations the products must be painstakingly cut to size for tight fitting between the rafters. 

The installation of these products is immensely time consuming and the degree of product wastage is significant.  Installation can typically take up to one week for a larger property leading to higher labour costs and ultimately significantly higher overall installation costs. They are extremely messy and untidy installation procedure and not really suited as a Retrofit product for existing residential dwellings.

Advantages of Lapolla Spray Foam Insulation

  • Quick, clean and efficient Installation.  Can usually completed within 1 day dependant of the size of the property.
  • Spray applied between the existing rafters or trusses within the roof void.
  • Perfect air tight fit on every installation with very little disruption or mess.
  • Most efficient and cost effective solution to Retrofit and New Installations.

Request a free loft survey

Spray foam insulation can make a huge difference to your home with energy savings and comfort. Our surveyors are trained to identify existing damp in your loft space and demonstrate the benefits of the spray foam insulation to leave you in no doubt about it’s attributes. It costs nothing for us to provide a loft survey so you have nothing to lose by getting in touch.

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