Gutters are troughs installed along the eaves of a roof, designed to collect rainwater flowing off the roof and channel it through downspouts away from the building's foundations. Without functioning gutters, rainwater would pour directly onto the facade and beside the plinth, causing moisture problems and foundation deterioration. In Finland, gutters are a mandatory part of a building's stormwater system. The Ministry of the Environment decree on the moisture performance of buildings (782/2017) requires that rainwater be directed away from buildings in a controlled manner. In practice, this means a functioning gutter system on all residential buildings. Gutter design and dimensioning are based on the roof area, roof pitch and local rainfall amounts. In Finland, the typical design rainfall intensity is 0.015 l/(s·m²), but heavy downpours can exceed this many times over. A properly dimensioned gutter system ensures that water does not overflow even during the heaviest rainfall.
Gutter materials and dimensions
The most common gutter materials in Finland are galvanised steel, painted steel, copper and plastic. Galvanised steel gutters are the most affordable option — durability approximately 15–25 years. Painted steel (polyester coating) is the most popular choice and lasts 25–40 years. Copper gutters are the longest-lasting (over 50 years) but cost 3–4 times as much as steel. Plastic gutters are mainly used on summer cottages and lightweight structures.
Standard gutter sizes in Finland are 100 mm, 125 mm and 150 mm (trough width). In single-family houses, 125 mm gutters are most commonly used. For buildings with large roof areas and in regions with heavy rainfall, 150 mm gutters are recommended. The gutter cross-section is typically semi-circular or box-profile.
The gutter slope towards the downspout should be 3–5 mm per metre. Adequate slope is important so that water does not stand in the trough — standing water accelerates corrosion and in winter, freezing can break the gutter brackets. Brackets are installed at a maximum spacing of 600 mm.
Gutter installation and fixing
Gutters are installed using brackets fixed to the eaves boarding or fascia board. The bracket type is selected according to the roof structure: hook brackets are installed under the battens and used in new construction, while fascia brackets (so-called quick hooks) are used in renovations because they attach to the fascia board without removing the roofing material.
A critical step in installation is determining the gutter's height position relative to the lower edge of the roof covering. The front edge of the gutter is installed approximately 10 mm below the front edge of the roof covering. If the gutter is too high, a snow guard will press it down; too low and water will not be directed into the trough correctly. A gable roof typically requires two separate gutter lines that slope towards downspouts at the building's corners.
Gutter joints are sealed either by soldering (copper and galvanised steel) or with elastic seals (painted steel, plastic). Soldered joints are more durable but require professional skills. Current practice favours so-called snap-fit joints, where an EPDM rubber seal ensures easy installation of watertight connections.
Gutter maintenance and cleaning
Gutter cleaning is the most common roof maintenance task and should be done at least twice a year: in spring after the snow has melted and in autumn after the leaves have fallen. A blocked gutter causes water to overflow, leading to facade and plinth moisture damage. Standing water in blocked gutters also freezes the entire system in winter.
Cleaning is done by hand or with pressure flushing. Work safety requires proper scaffolding or a personnel lift — ladders are not recommended. During cleaning, the condition of brackets, tightness of joints and gutter slope are checked. Maintenance cost is typically 3–8 €/running metre; for a single-family house done by a professional, gutter cleaning costs approximately 150–400 € per session.
Gutter leaf guards can significantly reduce the need for cleaning. The guard grilles prevent leaves and debris from entering the trough while allowing water through. The cost is approximately 5–15 €/m, but it pays for itself through reduced maintenance costs within a few years, especially on buildings surrounded by trees.
Gutter problems in the Finnish climate
Finnish winter conditions are the greatest challenge for gutters. Freezing water expands by approximately 9 percent, which can break gutters, brackets and joints. Particularly problematic are ice dams that form at the eaves and prevent meltwater from reaching the gutter. Ice dams can weigh several hundred kilograms and tear the entire gutter system loose.
Heating cables are the most effective solution for preventing freezing problems. A self-regulating heating cable is installed on the gutter bottom and in the downspout, keeping the path open even in freezing conditions. The typical power requirement is 30–40 W/m for gutters and 40–50 W/m for downspouts. Energy consumption is moderate because the self-regulating cable automatically reduces power as the temperature rises.
Corrosion is another significant problem, especially in maritime climates and industrial areas. The zinc coating of galvanised steel wears over time, and once the steel is exposed, rusting progresses rapidly. The coating of painted gutters can be mechanically damaged — ladders leaning against them, ice dams or tools used during cleaning can break the paint surface. Damage should be repaired immediately to prevent corrosion.
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Updated: April 2026
