Far from being outdated, flat roofs are
enjoying a resurgence in popularity. Here’s all you need to know
about why flat is fabulous.
is a flat roof a good option?
If you’re a first-time home-buyer or
cost conscious, a flat roof is the most inexpensive way to go. This
does not mean that your home won’t be aesthetically pleasing from
the inside or outside. As with all design choices, it comes down to
what you make of this roof-top style, whether renovating, buying or
your dream home.
The appeal of the flat roof goes far
beyond saving roofing costs. Thanks to your perfectly horizontal
interior ceiling, how you utilise and design your internal space is
limited by your imagination only. Gone are the restrictions of having
to adhere to the architectural challenges that come with a pitched
roof, slants and angles: you can map out your internal walls – and
indeed your internal vertical areas – with precision.
Perfectly straight ceilings also
generally mean more comfy, even internal temperatures, especially
when various insulation options are taken into account. Ever feel
that chill in a house with a pitched roof thanks to an attic-like
space created to meet the upward slant of a ceiling? That’s one
problem you’re unlikely to have.
It is not necessarily true that a flat
roof equals less interior space. The impression of roominess when you
look at a pitched-roof structure from the outside is just that: an
impression. You still have the option of raising your ceiling fairly
high, or creating interior design illusions of space with mirrors and
other features that draw the gaze upwards, such as a chandelier or
other striking lighting option.
It goes without saying that with a
little bit of love and effort, your horizontal roof makes for
incredibly inventive outdoor roof-top living or home features. Some creative advantages are:
solar panels, air conditioning units and
satellite dishes are easier to install
a living garden could be an attractive roof-top
reality with a little love
an envy inducing roof-top patio is much more of
a reality on a horizontal surface.
A flat roof lasts an average of 20
years, provided it is installed properly by a professional roofer, although there are some exceptional options
that come with a lifetime guarantee.
Types of flat roofs
Built-up roof (BUR)
Typically, a built-up roof is made up
of layers of durable, leak-proof materials such as tar and gravel.
BUR is the most tried and tested method, thanks to its relative
strength, durability and aesthetically pleasing finish. It can
accommodate roof-top living better than most other options and is a
good insulator of heat. A BUR does tend to be more weighty than other
options, so make sure it is supported well.
This is involved when you go the
‘single ply membrane’ route. A variety of roofing materials can
be used, but PVC remains the most common choice, of which Sarnafil
remains the most superior brand. Make sure to have it professionally
installed and use the flat roof materials suggested by your
You could also use a rubberised
This involves putting down just a
single layer and most homeowners can do this themselves. It is
generally a peel back-and-stick down job, with the roofing material
comprising some sort of mineral-based adhesive that is resistant to
wear and tear. Do not confuse this with the older felt-tip roofs.
This modern take on felt uses superior, reinforced materials and
modernised methods of application, such as via a big blow torch, are
types of flat roof material
For each of the various
types of horizontal outer ceiling housing covers discussed above, a
variety of materials can be used.
While PVC is a popular
single ply membrane material option, another one is TPO
Polyolefin), especially if you
object to the use of PVC on environmental grounds. PIB
is another option here.
When it comes to
rubberised roofing options – a highly popular alternative to the
PVC roof – EPDM is the leading material used. Not surprising, as it
is manufactured by leading tyre-maker Firestone. It is mechanically
glued to the sub-surface layer and has a lifespan of 30 years if
Spray-on coatings are one
of the more recently developed roofing materials. The material is
sprayed on with a pump, and should be done so meticulously. You can
apply it directly to the material below without first using a primer,
to form a bonded, waterproof membrane. The ease of installation and
reflective surface of the spray has seen this roof solution increase
The average cost of
installing a flat roof
The following approximate prices are
applicable per square metre. Expect to pay more if your roof is
higher up than most, your home is in a major city or in a remote
area, and if you want to use more expensive materials or need to
replace other substrate layers as well. Added insulation, ventilation
requirements and improved internal drainage could also see you pay
Naturally, the bigger the surface area,
or the more complex the job or required installation method, the more
Compare quotes as well as the
Modified bitumen or felt roof:
£50 to £60, assuming the boards below are in good shape. It costs
about £40 for every new board you need to replace.
EDPM rubberised roof, e.g.
Firestone: €85, assuming no damaged boards below. The price
includes a quality permaroof finish, and new overboarding to bond
with the rubber.
Fibreglass and PVC: £90, if
there are no boards underneath requiring replacing. The price
includes the necessary new overboarding as well as professional
The installation process
The basic design involves a substrate
layer of timber or board, held up by joists. The internal ceiling is
fixed to the underside of the joists.
Next, you should add a layer of
waterproofing and insulation, as required by building regulations. A
cap sheet or top layer of protection may be required, especially
against fire hazards. You may or may not need to lay down this cap
sheet, depending on the materials used for your flat roof.
Remember that a flat
roof is even, but not literally ‘flat’ – it
should slope at a slight angle or angles to allow for water drainage.
Now place your chosen flat roof
material or membrane (see Types of flat roof).
Finally, trim uneven pieces or any
joists or timber sticking out to give you a neat appearance. It’s
best to use machine trimmers.
Finding a trusted roofing company
A good place to start is the National
Federation of Roofing Contractors (NFRC). Alternatively, look for a
Competent Roofer as certified by the government’s Competent Person
Scheme. They should be in possession of a Building Compliance
Certificate, valid for 10 years. Membrane manufacturers will also
have a list of approved contractors that can professionally use their
materials and build your roof.
The best recommendations though remain
via word of mouth, so ask around. Then see if you can get reviews for
any of these contractors and be sure to check the comments. It is
always a good idea to search for reviews on any contractor. Search
the Yellow Pages for competent tradespeople or use one of our