Roofing Ventilation

Danelaw® offers a wide range of roofing ventilation products covering a wide range of tile types and construction details, from new build developments to refurbishment.

Hambleside Danelaw’s range of tile and slate vents provide ventilation into the roof void, and can also be used with mechanical extraction in bathrooms or kitchens or used for soil ventilation. All of these functions are achieved by the use of an additional flexi-pipe adapter kit which connects the required service to the vent terminal, thereby removing unsightly penetrations through the roof.

Alongside the tile and slate vents, Danelaw offers a range of eaves and soffit vents, CON6+ and CLAY6+; the ventilated dry fix ridge and hip systems.

For refurbishment options, Danelaw® manufacture products such as the Universal Refurbishment Tray Vent which is installed into the eaves of a completed and traditionally constructed roof and prevents insulation from blocking the airflow for roofing ventilation.

When upgrading roof space insulation, it is important to consider the effect on the roof and ensure that adequate levels of roofing ventilation is provided or maintained to avoid damage and the decay caused by the increased risk of condensation.  Hambleside Danelaw have produced a short article about the ventilation requirements for cold and warm pitched roofs which is featured on Roofing Today.  Ensuring familiarity with the roofing ventilation requirements will assist in constructing an appropriately ventilated roof.

Our ventilation products have been used in a wide range of developments across the UK.  To find out about where our products are stocked, take a look at Hambleside Danelaw’s stockist page.  Hambleside Danelaw also have demo days, so check out our events page for the next opportunity to talk about all things Danelaw®.

To learn more about Hambleside Danelaw’s roofing ventilation range, have a look at our downloads section, or get in touch with us at

Ventilation FAQs

Can I use one of your tile vents for a cooker hood extractor terminal?

Technically yes, however because it is not usually possible to access, dismantle and clean a roof ventilation terminal of any build-up of grease etc, we would not recommend it.

Can I use you plain tile vents for mechanical extraction in a vertical application?

We would not recommend this as it is likely that high levels of moisture in the form of vapour would flow under the tiles in the courses above and condense on the underside of the tiles, battens and wall facing material.

How many tile or slate vents will I need per metre to ventilate a roof space?

This will depend on the opening area equivalent. At the eaves, it will be either 10,000mm² per metre or 25,000mm² per metre of eaves and 5,000mm² at the ridge or on both sides of the ridge depending upon the situation.

The calculation is:            area opening requirement (mm²/m)  x  length of eaves (or ridge) in metres.

vent airflow area opening (mm²)

How do I ventilate a warm roof?

Warm roofs generally do not require ventilation as there should be an Air & Vapour Control Layer (AVCL) or vapour barrier on the warm side of the insulation to prevent the passage of warm moisture laden air to the colder uninsulated parts of the roof.

Where the insulation follows the line of the rafters, often referred to as a ‘hybrid’ roof, this may or may not require ventilation depending upon the design detail and the roof covering type.

How do I ventilate a cold roof?

Ventilation openings can be provided at the eaves over a fascia, through a soffit or at a brick corbel, at low or high level through the roof surface using slate or tile ventilators, or high level using a mechanically fixed dry ridge system.

The actual requirements will depend on the pitch of the roof and the span of the roof.

Why is my vent leaking?

No good quality roof vents leak when installed correctly. If a slate or tile vent is suspected of leaking, the circumstances should be considered.

It is possible for rainwater and condensation to run down the roofing underlay and drip though the opening cut into the underlay. This will usually be apparent on the outside of the vent, or on the underlay. To prevent this, the underlay should be cut and dressed around the opening to divert any rainwater or condensation around the opening in the roof.

If water is draining through a ceiling extractor fan, it is most likely that it is condensation forming in the ducting and draining back to the fan. To minimise this, the ducting should be as short as possible and lagged with insulation where it passes through a cold roof space. If this is not possible, or the problem persists and a condensation trap has not been fitted above the extractor fan, then this should be done.

In very extreme conditions, such as experienced during the ‘Beast from the East’ in 2018, extremely low temperatures combined with fine dry powdery show can create a situation where small amounts may enter through the ventilator. It is not possible to produce a ventilator cost effectively that will allow the free flow of ventilating air and not the very fine snowflakes.

In these situations, in-line or flush fitting ventilators often perform better due to an internal rainwater trap rather than those that rely on a covering hood or cowl.

What is the minimum roof pitch for your slate and tile vents?

This depends on the individual product. All of our slate and tile roof vents are designed to suit the minimum pitch of the slates or tiles that they are intended to be used with.

My roof is covered with hand-made clay tiles therefore I need a tile ventilator that doesn’t show when installed. What can I use?

The Danelaw HD 10/10 plain tile ventilator is designed to carry small cuts of the same tile that is being used on the roof, and therefore is not visible on the completed roof except for the small black ventilation slot that must remain exposed.

What is the airflow of your tile vents when used for extraction terminals?

Generally, the airflow is restricted by the length, size and straightness of the ducting being used, and the adaptor that connects the pipework.

We can only quote the pressure resistance created by the baffles and louvres in vent design. The extractor fan should be selected to suit the variables found in each different application, and as advised by the extractor fan manufacturer.

When installing tile vents in a roof with sark boarding, does the board need to be cut?

Yes, a hole that corresponds with the rear spigot or aperture of any vent should be cut in the sarking board when the vent is being used to deliver ventilating air into the roof void.

The underlay should be cut and dressed around the opening to divert any rainwater or condensate around the opening in the roof.

Do you offer a universal tile vent?

No. This is something that we have considered, however all universal designs are a compromise and usually considered quite unsightly when installed.

We do offer a wide range of discreet flush fitting tile ventilators to suit most applications.