With over 30 years' experience working in the building products' sector, our Technical Manager, Dave Osborne is a reliable authority with a wealth of practical advice geared at achieving the best results. This time, Dave turns his attention to effective guttering system installation, with some expert advice on achieving the best results regarding both new and replacement projects.

As heavy downpours now occur with increasing regularity, it's wise to never underestimate the importance of installing a well-fitted guttering system on domestic properties and buildings. Correctly fitted around the roof perimeter and securely fastened to the fascias, good quality guttering can be a first line of property defence during rainy periods, guarding against leaks and standing water issues.

By understanding how to choose a system with the appropriate flowrate, and fitting both the guttering and downpipe so the system works cohesively, you'll be rewarded with an installation that will serve to prevent building damage and last for many years to come.

New Projects

First and foremost - for all installations, preparation is key! Select a gutter system that meets the design flowrate or area of your particular roof. As well as normal levels of rainfall, a domestic or light commercial eaves gutter system must be able to cope with an intense rainfall event, lasting at least two minutes. Visit British Standard BS12056 and you'll see how to work out the amount of rainwater (in litres per second) that could run off your roof.

Replacement projects

Again, consider the preparation and remember to plan your installation using specific component diagrams to assist in selecting the correct materials from the start. When it comes to replacing guttering, it's only natural to consider "like for like" as the most sensible option. However, you should consider the greater frequency of storms and increased rainfall we now experience and modify your system's capacity as a positive precautionary measure.

Follow the guidelines and help your project to run smoothly

The below step-by-step guide has been designed to help you understand installation process and get the best results.

Gutter installation guidelines

• Position the running outlet accurately by holding a plumb line against the fascia directly over the drain. Mark the position on the fascia with a pencil. Fit the outlet no more than 50mm below the level of the roof tiles, then fix with 2 x 25mm x 5mm round-head stainless steel screws (don't use countersunk screws as these can be over torqued with cordless drivers, consequently damaging mouldings).
• Fit a fascia bracket just below the top of the fascia board at one end of the run of guttering (opposite end of the outlet).
• Tie a plumb line (string) around the base of the bracket and stretch from the bracket along the fascia board before tying it to the outlet.
• Check that there is a fall towards the outlet (1:350 is recommended) to encourage water to drain efficiently.
• Mark the position of the fascia brackets, spacing them according to the gutter system chosen (see table below) but no more than 150mm from any corner, union, running outlet or stopend.
• In locations where heavy snowfall is prevalent, we recommend that fixing centres for fascia brackets be reduced to 600mm.
• Fix the fascia brackets with 25mm x 5mm stainless steel screws – we would recommend using all available fixing holes.
• Starting at the outlet, fit the first length of gutter by tilting the gutter to fit under the back clip, and clip in at the front edge.
• Fit a union bracket at the other end of the first length and screw it into the fascia using all available fixing holes - then fit the next length of gutter into it. Continue joining lengths ensuring all joints line up with the "fit to here" depth marked in the fittings.
• Cut the last section of gutter to fit using a hacksaw and fit a stopend.
• RECOMMENDED: Use lubricant/silicone spray on all gutter seals for ease of fitting and for improved in-service performance.

The fascia bracket spacing guide below also provides some helpful information:

Once the guttering is in place, you’re ready to add the downpipe.

Hopefully, these technical pointers will enable you to better understand the guttering system installation process and help you to get the job done right, first time.

Until next time, Dave.