Insulated Garage Doors, U-values and energy bills
In the past insulation was never really considered a big factor for a garage door. Doors were constructed from timber or single sheets of steel and they were designed to primarily fill a hole. Having gaps around a door was part of the design and not particularly unusual. Technology, construction methods and consumers needs have changed quite a bit since the early days of garage doors however, and there are now a large number of insulated and sealed garage door products on the market. So let’s take a look at what constitutes an insulated garage door and exactly what it has to offer.
What is an insulated garage door?
An insulated product typically consists of two ‘skins’ filled with an insulating material. This is usually reinforced steel or aluminium skins filled with polyurethane or ‘PU’ foam. The type of foam, construction of the product and the thickness of the panel all have a bearing on the insulating properties of the door.
The image below shows a cross section of a Hörmann LPU40 sectional door panel. Hörmann’s panels are 42mm thick and feature a rubber seal that protects and insulates each panel.
How does that affect my garage?
The insulating properties of a product are only one area that can affect the ability of a door to provide insulation. The seal between the door and the frame along with the seal between the frame and the garage construction have an impact on how well a door will insulate the property. Some manufacturers and products offer options for a more substantial seal between the door and the frame providing even higher levels of insulation. The manufacturer, Hörmann, have a ‘Thermo Frame’ additional option that is available on their sectional doors. If insulation is an important factor in your choice of garage door it is worth asking if there are options for different frame seals. It is also worth bearing in mind that these seals will be bigger and have an effect on the overall appearance of the installation.
The method of installation will also have an effect on the levels of insulation as this usually determines how the door and frame are sealed against the garage. A sectional type door installed fully behind the opening usually offers the highest levels of insulation as the door and frame will be sealed fully against any brickwork. If a smaller height door needs to be installed then it is worth thinking about how any gaps are finished. Matching PVC or steel will deliver an aesthetically suitable and cost effective solution but it will not offer very high levels of insulation and can undermine the thermal qualities of a door. Some manufactures offer matching insulated fascia panels though these will obviously add to the cost.
The floor level will also have an impact on how well the bottom seal of a door can provide insulation. Any uneven or sloping garage floors can present gaps in the bottom edge or seal of a door and have an impact on the levels of insulation.
U-values and energy bills
There are a number of ways to calculate and present the insulating properties of a product but the most common method that is relevant to the construction industry is a U-value. The U-value is a measurement that shows how much heat is lost through a particular material or product. It takes the three main methods of heat loss into consideration – conduction, convection and radiation and it is measured in watts per metres squared kelvin, or W/m²K.
Whilst this may sound complicated the main thing to note is that lower values indicate better insulation and the nearer to zero the better.
To give you some idea of how U-values relate to real life situations here are some examples;
A typical hardwood external entrance door = 3 W/m²K
A typical composite entrance door = 1.8 W/m²K
A typical single glazed window = 4.8 W/m²K
A typical modern double glazed window = 1.6 W/m2k
Do bear in mind that U-values are really only a guide and there are other factors, as we have mentioned previously, that will affect that the final insulating values that a particular door installation will provide. But ultimately the lower the U-Value, the less you are going to pay in energy bills if the garage is attached to your home.
Types of insulated garage doors
There are a number of different types of garage door that offer insulation so let’s have a look at them in more detail…
Sectional garage doors
Most modern sectional garage doors will be available as an insulated product usually around 40mm in thickness. These doors are usually constructed from steel with PU foam insulation. Generally these will offer the highest levels of insulation when installed fully behind a garages structural opening and will usually provide a U-value of between 1.4 and 2 W/m²K when fitted. A good sectional door will also have rubber seals in-between each panel and feature a compression seal at the bottom of the door to provide insulation when the door is closed.
Insulated roller garage doors
Aluminium roller doors are usually constructed with insulated aluminium ‘laths’ or slats that are hinged together. The laths are usually around 20mm thick so whilst they do offer some level of insulation they are never going to be the same as a 40mm sectional door. It is also hard to determine an exact U-value for a roller door as the hinges between the laths are not insulated and there can be quite a big difference in the number of laths used depending on the height of the door. Generally speaking a good insulated roller door fitted fully behind the structural opening will provide reasonably high levels of insulation, particularly if the door roll is covered with a ‘full box’ hood.
There are a number of factors that vary between manufacturers that will have an impact on the thermal performance of the door and generally speaking, the old adage ‘you get what you pay for’ is particularly relevant here. Features such as the webbing, brush strip, the type of tracks and guides used and the depth that the door sits in the tracks will all have an effect on the overall performance.
Side hinged doors
Traditional timber side hinged doors have always offered reasonable levels of insulation. Timber is pretty good as far as insulating materials go and if the doors do not feature any glazing and are fitted properly they can provide good levels of thermal performance. Recently, insulated side hinged doors have started to appear on the market. Constructed in a similar way to sectional doors with PU foam insulation and factory fitted frames they can offer levels of insulation similar to a sectional door. Again, there are varying qualities of product available and price will often dictate the levels of thermal performance a product provides.
Side sliding doors
Timber side sliding doors were popular for a while but eventually fell out of fashion. The steel channel fitted into the concrete would invariably collect debris and eventually it would be difficult to open and close the door. There are now modern variations of this type of product that are effectively sectional type doors turned on their side. They no longer feature sunken channels in the floor and with typical sectional door panel construction they can provide U-values similar to a standard sectional door of around 2 W/m²K. The nature of these doors means that they always need to be installed in the same manner, behind an opening, so the insulating values are fairly consistent across different installations and properties.
Up and over doors
We like up and over doors here at ABi. They have been around a long time and for good reason. They look good and they work. They are not, however, particularly good at providing insulation. By their very nature they need a gap between the door leaf and the frame. Their design has been refined over the years and weather strips and floor seals provide some degree of insulation but ultimately if insulating properties are a factor then an up and over door is not really the best choice.
For more information on insulated garage doors and U-values why not drop into our showroom or contact a member of our dedicated sales team.
ABi garage doors specialise in the suppy, installation and repair of garage doors, entrance doors and remote controls covering the entire Yorkshire region including Leeds, Bradford, Wakefield, York and Huddersfield.