Five flat-roof defects to look out for< Back to Blog

Modern flat-roofing systems are strong, long-lasting and quick to install. They provide a building with a high standard of insulation and represent great value for money. What’s not to like?

Well, like many construction products, flat-roofing will only offer these advantages if the system is correctly installed and properly maintained. Anything else could mean you’re going about your daily life with a problem literally hanging over your head!

Most of the systems installed by Sheriff Construction require minimal routine maintenance checks and a few simple preventative measures.

Take a look at our previously published article ‘How to care for a flat-roof’ for more detailed guidelines.

Meanwhile, if you’re ready to carry out your summer maintenance check on a flat-roof, here’s five of the most common defects to look out for:

#1. Standing water

Despite their name and appearance, most flat roofs have a small slope which helps with drainage. If, however, the roof is ‘too flat’ this can result in standing (or ponding) water which causes damage and sometimes leakages. Standing water can also be the result of blockages or other issues with drains or gutters. Look for pools of water and/or concave areas with watermarks.

#2. Blistering

A common problem, blistering occurs when air or moisture gets trapped between the different built-up layers that make up the flat-roof structure. The heat of the day causes that air/ moisture to expand and ‘blister’ so watch out for bubbles and tears.

#3. Thermal movement

Repeated cycles of heating and cooling cause flat roofing materials to expand and contract. Many of the materials used in today’s flat-roofing systems have been engineered to deal with these movements but older roofs will inevitably crack under the pressure! Look out for cracking.

#4. Exposed layers

Exposed to the elements and being more prone to footfall (due to better access than pitched roofing) means flat roofing is probably going to have a bit of wear and tear over time. Look out for signs of decline or patchiness in those protective layers.

#5. Poor quality flashing

Flashing is used to stop water from penetrating a junction but problems can occur if they’ve been installed incorrectly, if they’ve somehow been bent or damaged, or if there are issues like fungus growth. Carry out regular inspections to assess the condition of the flashing.


Sheriff Construction installs a range of flat-roofing systems that are among the best for strength and durability – products that offer exceptional resistance to these kind of defects as well as those which are equipped with self-healing qualities. Many of our systems come with a life expectancy of 30-40 years!

We also offer a leak-testing service for flat-roofing and we’re currently working with two of our valued clients (L&Q and Fairview) to fulfil roofing repair contracts.*

Find out more about our expertise in flat-roofing here.


*Sheriff is unable to take roofing or maintenance work for clients other than those who have previously used our installation services.