Norwich Roofers helps homeowners in Brundall choose the right flat roofing material for their extension, garage, or outbuilding with honest advice before any work begins.
The material your flat roof is made from will determine how long it lasts, how much maintenance it needs, and what it costs when it eventually needs replacing. Get that decision right and you could have a roof that outlasts the extension beneath it. Get it wrong - or let a roofer choose on your behalf without explanation - and you may be back in the same position in ten years.
We install flat roofs in Brundall and across the Norwich area. Before we quote, we survey the roof and give you a written specification. Part of that conversation is always about which material is right for your particular roof, your budget, and your priorities.
Most garage and extension roofs built before the early 2000s were laid with mineral-faced bitumen felt, typically in three overlapping layers. It is the material most people picture when they think of a flat roof, and it has a long track record. However, that track record includes a realistic service life of only 10 to 15 years under typical conditions.
Felt becomes brittle as it ages. Thermal movement - the roof expanding in summer heat and contracting in winter cold - causes it to crack, particularly at edges and upstands where movement is greatest. Once a felt roof starts to crack, water finds its way in quickly. Felt is also relatively lightweight and can be lifted at edges by wind if edge details are not properly secured.
The main reason felt still gets fitted is cost. It is the cheapest option per square metre to install. But when you factor in a lifespan of a decade or so before the whole surface needs stripping and replacing, the long-term cost is not always as attractive as the upfront price suggests.
EPDM stands for ethylene propylene diene monomer. It is a single-ply rubber membrane that has been used in flat roofing for decades and has a well-established record in the UK and Europe. A correctly installed EPDM membrane can be expected to remain serviceable for 30 years or more, and manufacturers supply long product warranties to support that.
The key advantages over felt are flexibility and longevity. EPDM stays pliable at very low temperatures, so it can accommodate the thermal movement that cracks felt without splitting. It is also highly resistant to UV degradation, which is one of the main reasons felt surfaces deteriorate. Because it comes in large sheets - rolls wide enough to cover many small roofs in a single piece with no seams - there are fewer joints for water to find. Where joins are necessary, purpose-made EPDM tape and bonding agents are used.
EPDM is bonded to the roof deck using a contact adhesive. Edges are dressed over a timber fascia and secured with aluminium or EPDM edging trim. Upstands are taken up the vertical face and tucked under flashing or sealed against the wall with purpose-made adhesive strips. The finished surface has a smooth, dark grey appearance.
Torch-on felt - a thicker, polymer-modified bitumen sheet bonded to the deck using a gas torch - sits between standard felt and EPDM in both cost and performance. It is more durable than traditional three-layer felt, with a realistic lifespan of 15 to 20 years, and it bonds more firmly to the deck. However, it is still a bitumen product and still susceptible to UV cracking over time, particularly on south-facing roofs that receive full sun.
For a homeowner in Brundall who wants a significant step up from old felt but is working to a tighter budget, torch-on is a reasonable mid-point. It is worth discussing with your roofer which system makes sense given the age of the building, the deck condition, and how long you plan to stay in the property.
Whatever membrane goes on top, the structural deck beneath it must be sound. The deck on most domestic extensions and garages is 18mm or 22mm tongue-and-groove OSB or plywood. If the existing deck has taken on moisture from a previous leak - and on older roofs this is not unusual - it will need to be replaced before a new membrane is laid. A new membrane on a soft or delaminating deck will not perform as the manufacturer intends, and the deck will continue to deteriorate underneath.
Ask your roofer to inspect the deck before committing to a surface price. If they are not willing to give you a clear view of what the deck looks like before and after stripping, that is worth noting.
No membrane - however good - will perform well if water cannot drain off the roof. Building regulations require a minimum fall of 1:80 across the roof surface. On a roof that has settled or was originally built without adequate falls, the solution may involve installing tapered insulation boards to recreate the correct gradient before the new surface goes on. This adds cost but is the proper solution. Simply laying a new membrane over a roof that ponds water will shorten the life of the new surface significantly.
Outlets and downpipes should be checked and cleared as part of any flat roofing job. A blocked outlet on a flat roof can back water up across the whole surface within a single heavy shower.
We survey flat roofs in Brundall and nearby before quoting, and we will tell you plainly which material we recommend and why. If you are weighing up your options or have had quotes for different systems and want a straight explanation of what you would be getting for your money, call us to arrange a survey.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
