It’s fair to say that flat roof gullies do more work than the rest of the roof. Like gutters, a gully is where water goes to drain away. It is also a place that can get blocked with ice, snow, autumn leaves, and other debris. 

Being an element of the roof that has to work so hard, this can make it more prone to wear and tear, which, if left unchecked, can lead to leaks that you often won’t spot until the water is coming into your home. We take a look at the potential issues with flat roof gullies and why it is so important to get them checked. 


The underlayment of the valley will take some weathering and sometimes is not designed to last as long as the flat roof material itself. In older roofs, where materials other than EPDM have been used, you may find that the underlayment is in need of replacement. This will be a problem for those that have attempted DIY solutions, or had the job done ‘cheap’.

It is essential to get this checked out, especially on older roofs, or those that have not had the work carried out by professionals. If the work was done before you lived in the property, it’s always a good idea to have the whole roof checked out for any signs of potential damage.


In warmer weather, this underlayment may expand and wrinkle. This can lead to cracks and tears in the material. This isn’t just the case with the underlayment. Where materials like felt have been used, the entire roof can be vulnerable to the extremes in temperature of the weather. Replacing flat roofs with a material like EPDM means that your roof is far less likely to experience shrinking or expansion in hot/cold weather.

Cross Wash

You may also get ‘cross wash’, especially in heavy winds and rains. This is when the water is too much for the valley and ends up washing up and under the roofing material. Add to that debris that may be sat in the gulley and you have yourself a recipe for disaster. In periods of heavy, relentless rain, you need to be super confident that the elements of your flat roof are in good working order without any blockages or tears.

Flat Roof Gully Inspection 

Out of sight, out of mind is the issue when it comes to flat-roof gullies. If you can’t see it, often you don’t think about it. The problem is, the first thing you do see could be more costly than the preventative measure of getting up on the roof to check for any potential issues. 

Even if you aren’t experiencing any issues currently, it’s good to have an inspection to avoid future problems. If your flat roof is older, you weren’t the property owner when it was installed, or you are concerned about any aspect of it, give us a call on 01934 824005 and we will be only too happy to advise.