Do you install rooflights on thatched roofs?

Why it is different

Thatch is not a covering laid over a waterproof membrane. The thatch itself is the weathering layer, working by depth and by the angle water takes through the material rather than by lapping discrete units.

Introducing anything into it means understanding how water moves through the coat and how the material will behave around a rigid frame over decades. That is a thatcher’s knowledge, not a glazier’s.

The specific problems

Depth. A thatched coat can be 300mm or more. A rooflight has to sit above that, on a substantial upstand, which is visually prominent on exactly the kind of building where prominence is unwelcome.

Fire. Thatch fire risk is taken very seriously, and anything introduced into a coat is considered in that context.

Movement and settlement. Thatch settles over its life. A rigid frame within a settling coat is a detail that needs real expertise.

Re-thatching. A roof is re-coated periodically, and any fixed element has to be dealt with each time.

Who to approach

A master thatcher. Some fit specialist glazed panels designed for thatch, and the sensible route is to start with the person who will maintain the roof rather than with a glazing company.

Where the property is also listed, which many thatched buildings are, consent comes into it as well.

What we can help with

Any part of the property that is not thatched: a tiled or slated rear extension, an outbuilding, a garage. Those are ordinary work and we are glad to do them.

No, and it is worth explaining why

Thatch is a specialist trade with its own skills, materials and safety considerations, and it is not one we work in. Fitting glazing into thatch is done by thatchers working with specialist rooflight makers, not by a rooflight installer working around a thatcher.

We would rather say so plainly than take the job and subcontract the part that actually matters.

Why thatch is different

Depth. A thatched roof is several hundred millimetres thick. A rooflight has to sit in a purpose built framed opening that projects through that depth, and the detail is nothing like flashing into a tile.

Weathering. Water in thatch runs within the material rather than over a surface, so the detail has to shed water into the thatch below the opening without letting it track back. That is a thatcher’s knowledge.

Fire. Thatched roofs have particular fire risk considerations, and anything introduced into the roof, including a glazed opening and any wiring near it, is assessed in that context.

Movement and maintenance. Thatch is re ridged and re coated periodically, and anything fitted into it has to accommodate that cycle.

Consent

Most thatched properties are listed, and many are in conservation areas as well. Listed building consent is required for any rooflight, on any slope, visible or not, and on a thatched roof the case is a harder one to make than on tile or slate, because the roof itself is frequently a large part of what is significant.

That is a conversation to have with the conservation officer at an early stage, and before any product is chosen.

What we would suggest instead

Where a thatched property has a later extension, an outbuilding or a section of tiled roof, that is frequently where daylight can be added without touching the thatch at all. We are happy to look at that.

Where the only option is the thatch itself, we will point you toward a master thatcher rather than attempting it, and we would rather do that than be the reason a good roof is spoiled.

What we do work on

Slate, plain clay tile, concrete and clay interlocking tile, pantile, and flat roofs in felt, single ply and other membranes. That covers the overwhelming majority of buildings in this part of the country, including most listed and conservation area property.

If you are not sure which category your roof falls into, send a photograph and we will tell you honestly whether it is a job for us.

Why thatch is treated differently

Thatch is not a covering that can be cut into and made good the way tile or slate can. It is a continuous water shedding layer built up in courses, and its performance depends on that continuity and on the depth of the coat.

Cutting an opening interrupts the run of the thatch and creates a junction where water has to be managed by a detail rather than by the natural shedding of the material. Get that wrong and the thatch around the opening stays wet, and wet thatch rots.

There is also fire. Thatch fire risk is taken very seriously, and anything that introduces a penetration, a metal component or a potential heat path is scrutinised.

What is possible

Traditional thatched buildings do have openings in their roofs, in the form of eyebrow dormers, and that is the historically correct way to get light into a thatched roof. It is thatching work rather than rooflight work.

Where a rooflight is genuinely wanted, it has to be designed with the master thatcher, detailed for that specific coat and pitch, and agreed with the conservation officer and the insurer. It is not a product decision.

Our position

We do not fit rooflights into thatch. It is specialist work belonging to the thatching trade, and the right first call is a master thatcher who knows the building.

Where a thatched property has a tiled or slated rear addition, which many do, that part of the roof is ordinary work and we are happy to look at it.