Roof access hatches – what you need to know

Share page here

Roof access hatches are an important installation on commercial buildings where safe access to the roof is required. When looking to specify an access hatch, consideration should be given to how the hatch will integrate into the roof structure without compromising the building envelope performance. The hatch must be fully weatherproofed, and the installation carried out in a safe manner while ensuring compliance with regulations covering working at height.

Commercial building flat roofs frequently support services for the building including heating, ventilation and air conditioning (HVAC) as well as water cisterns and associated piping. Installing one or more roof access hatches provides a safe and easy way to reach these services to perform checks and any required maintenance. An access hatch may also be used if any works on the roof are being carried out.

Roof access hatches for commercial roofs

A roof access hatch is usually a fabricated metal enclosure, made from insulated panels. The lid can be either a solid, insulated panel or alternatively can be finished with a clear panel, enabling the space below to benefit from natural daylight whilst maintaining the functionality of the hatch. Where required, for example if a roof access is needed above a plant room, a hatch with fire rated properties can be specified.

The size of the hatch can vary from a small square, wide enough for a person to pass through, to a larger hatch allowing room for the movement of tools and equipment onto the roof.

When specifying a roof access hatch, consideration must be given to whether access to the roof is required only to perform occasional maintenance or more frequently for other reasons. The hatch must be large enough to allow tools and equipment to be carried onto the roof if required and be located where it is most needed. An important requirement of an access hatch is that it should be capable of being safely opened and closed by one person.

Olympic stadium Waterproofing and access hatch installation
Bilco access hatch with a white walkway on a weatherproofed roof
weathertight roof upstands and access hatches shown on top of a building
weathertight Roof ventilation
Access hatch commercial roof

Small access hatches are usually installed with a fixed vertical ladder to allow the user to reach them. The ladder must be constructed in line with BS 4211:2005 and installed opposite the hinge of the hatch to ensure access is not obstructed. Larger access hatches installed to allow tools and equipment to be carried onto the roof may require a fixed staircase to ensure ease and safety of use.

Finally, a roof access hatch must be installed to work holistically with the desired performance of the rest of the roof. A lot of time and effort goes into the calculations of a commercial flat roof to ensure relevant U-values, as well as other metrics, are accurate and adhere to relevant building regulations and standards. An access hatch effectively becomes a potential thermal bridge and if not correctly installed and weatherproofed can detrimentally affect the performance of a roof, and so should be considered at the early stages of design where possible.

If an access hatch is specified later in the building’s construction, then an installer should be employed that understands the needs of the commercial flat roof and how to install a roof access hatch without compromising the build envelope’s overall performance.

Jones and Woolman UK – Roof access hatches

Jones and Woolman UK is a leading installer of roof access hatches for all roof types, and when installed, are sealed to the upstand to form an effective barrier against water ingress and the elements. Our access hatches also contain a layer of high-performance thermal insulation so as not to compromise the thermal performance of the roof.

We supply and fit a wide range of roof access units. Our standard product range includes Bilco hatches, as well as a range of aluminium hatches that can be supplied with your choice of polycarbonate domes or pyramids. The hatch is finished with a flat, thermally insulated, aluminium lid. In addition to this, we can provide bespoke large plant access panels, as well as weathering systems and covers for service risers.

Jones and Woolman are a UK company based in the West Midlands, since 1979, they have been providing roof penetrations, weathering and GRP Mouldings solutions. As approved expert installers of cold-applied liquid fibreglass roofs, Jones and Woolman UK can provide a complete roofing service from initial site surveys through to the design and installation of the roofing system.

To discuss using a fibreglass roof on your next project or any of our other solutions please get in touch here.

Fibreglass roof vs Felt roof – which is best?

Share page here

When looking to specify a weatherproofing system on your commercial flat roof project to protect it from the elements, there are several different membrane types available. Here we look at two popular choices – a more traditional felt based system, or a more durable fibreglass roof solution. It is worth noting that a fibreglass roof is more commonly known as a glass-reinforced plastic (GRP) roof and for the purposes of this blog we will refer to this type of roof this way.

Each of these has their own benefits and ultimately the system selected will be determined by the specific needs of the project. Installing a glass-reinforced plastic roof, however, generally offers more design freedom, is safer to install, with no requirements for hot works, and is more durable, offering increased longevity. Fibreglass also has increased resistance to fire spread which is an important consideration in any flat roof specification.

Felt covered commercial flat roofs

A traditional felt covered commercial roof uses a bituminous felt membrane which is hot applied using a flame – more commonly referred to as a torch-on application. The weatherproofing membrane is usually made up of three layers of material – one or two layers of bitumen felt – and a finishing layer of mineral felt.

A gas torch is passed over the underside of the bitumen layer, causing it to become an adhesive. A roller is then used to apply pressure to the layer so that it bonds to the roof surface. The felt is applied in sections leaving a seam where the sections meet. The seam is the weak point of the roof’s weatherproofing layer and tends to be where failure may occur first.

For many project types, particularly domestic and smaller commercial roofs, a traditional felt weatherproofing membrane is a popular choice and offers several benefits including:

  • Cost – Compared to a GRP roof, a felt weatherproofing membrane is usually cheaper, although in the long term, the increased lifespan of fibreglass can more than make up for this.
  • Lifespan – A properly installed felt roof covering can typically be expected to last for eight to ten years.
  • Ease of transport – Felt used for roofing is supplied as a roll which is compact and reasonably lightweight, allowing easy transport to site.
  • Flexibility – Roofing felt is a very flexible material and can be easily moulded and shaped to fit the roof structure it is being applied to.
Fibreglass Flat Roofs With Roof Light
GRP Fibreglass Flat Roof
Fibre-Glass-Flat-Roof install
GRP fibreglass architectural mouldings commercial clients
flat roof repair and replace

Glass-reinforced plastic (GRP) covered commercial flat roofs

Glass-reinforced plastic makes a great choice for use as a weatherproofing layer. The membrane is applied to the roof using a resin adhesive and bonded to the roof surface giving it a strong, protective layer with no seams which tends to be the first point of failure in more traditional weatherproofing membranes, including felt.

To install a GRP weatherproofing membrane, a layer of resin that has been mixed with a catalyst is applied to the roof deck, a sheet of fibreglass mat is then laid onto the resin followed by a finishing layer of resin. This forms a tight, weatherproof seal with high UV light resistance. A glass-reinforced plastic roof also has excellent resistance to fire, making it a safer alternative to traditional felt based systems. Pigment can be added to the final coat of resin meaning the roof can be finished in a colour to match any design requirements.

When considering GRP as the weatherproofing membrane for your roofing project, it can be useful to learn the benefits that this system can provide.

  • Safer to install – A glass-reinforced plastic roof is cold applied; therefore, no flame (hot works) is required for installation.
  • Longevity – Research shows that a properly maintained roof of this type can last for 30 years or more.
  • Maintenance – GRP roofs are easily maintained. Occasionally, leaves and debris should be removed, and the surface given a wash with a mop.
  • Visual appeal – The top layer of a GRP roof can be coloured to match any aesthetic requirements.
  • Durability – This type of roof has no seams which tend to be the weak points of a traditional felt based covering.
  • Fire resistance – Fire safety is of paramount importance in all construction and GRP benefits from increased resistance to fire spread.
  • Strength – A glass-reinforced plastic roof offers excellent resistance to the effects of foot traffic and impact from debris including tree branches, hail and dislodged masonry. Additionally, this type of roof is more tolerant to the effects of UV light.
  • Seamless finish – The surface of a GRP roof is a continuous layer with no seams or joints, this makes the roof much less susceptible to damage from water ingress and gives a more visually pleasing finish.

Is GRP the most suited weatherproof layer for commercial flat roofs?

Commercial building flat roofs tend to be large areas which, if finished using a traditional felt weatherproof membrane, will have multiple seams or joints where the layers meet, increasing the potential for water ingress and failure. GRP roofs are applied with no seams making them a much more durable solution.

Glass-reinforced plastic can be easily moulded to form complex shapes and the final layer of resin can have pigment added to create a coloured finish.

A traditional felt roof contains bitumen which is flammable whereas GRP has an increased resistance to fire making it a much safer product for use in roof weatherproofing. The installation process for a felt roof requires the use of a flame torch, some projects – notably schools and hospitals – may have restrictions on the use of torch-on systems and a cold-applied finish such as glass-reinforced plastic is usually the preferred solution.

Jones and Woolman are a UK company based in the West Midlands, since 1979, they have been providing roof penetrations, weathering and GRP Mouldings solutions. As approved expert installers of cold-applied liquid GRP roofs, Jones and Woolman UK can provide a complete roofing service from initial site surveys through to the design and installation of the roofing system.

To discuss using a GRP roof on your next project or any of our other solutions please get in touch here.