Buying a thatched house and what to check first

A thatched roof changes three things about a purchase, which are who will insure it, who will lend on it, and what the survey needs to cover. The thatch is a material that is renewed on a cycle, and the serious fire risk sits in the chimney rather than in the thatch. This is general information rather than advice on a particular property.

The fire risk is a chimney problem

Historic England’s research programme, which included full-scale fire tests, disproved the theory that heat passing through the chimney wall sets thatch alight. Fires start from high-energy sparks and embers thrown out of the chimney, for example when a bird’s nest in the flue catches alight, and from hot flue gases leaking through defects in the stack.

The fundamental recommendation is that wood burning and multi-fuel stoves should not be used in thatch roofed buildings. If the house you are viewing has a stove, treat it as an issue to resolve rather than a feature.

What to check before you offer

Several points in Historic England’s guidance can be answered before exchange. A CCTV inspection of the flue finds defects, and lining the flue is the fix, ideally with a rigid twin-walled insulated stainless steel liner, or a twin-walled flexible one where access or the shape of the chimney prevents it. A mesh-topped bird guard helps too, because sweeping alone does not deal with nesting when the heating and nest-building seasons overlap.

Check the distance from the top of the chimney pot to the thatch against the minimum guidance in Approved Document J of the Building Regulations. Where the distance is not enough and cannot be increased, stove use is not advisable.

On sweeping, a chimney serving a stove that burns wood every day through the heating season might need sweeping four times a year. Ask the seller for the sweep certificates, not just an assurance.

Re-ridging and re-thatching

A thatched roof is renewed in two separate cycles, and mixing them up leads to bad budgeting. The ridge wears first and needs renewing several times between re-thatching, typically every 10 to 15 years according to the Society for the Protection of Ancient Buildings, although an experienced thatcher should advise. Straw and water reed roofs may perform well for at least 30 years before they need re-thatching.

Get written quotes from two master thatchers on the specific roof before you commit to a price, and ask the seller when the ridge was last renewed and when the coat was last stripped back.

Listed building consent

If the house is listed, you need listed building consent for work that alters its character, and the roof covering is a large part of that. Historic England says to check with your local planning authority before any repair to a thatched roof, and to use the material and methods typical for your region.

Changing the type of thatch, for example from long straw to water reed, will need consent where the existing type is the traditional one for the area, and consent should not normally be granted for a change of material. The oldest layer, the basecoat, can also carry heritage value, and you may need permission to remove it completely, especially if the house is listed. Our guide to buying a listed building explains how consent differs from planning permission and why enforcement risk stays with the property.

Insurance and the conflict to be ready for

Thatch is a specialist insurance market rather than a comparison-site one, so get a quote in principle before you exchange rather than assuming cover. Read any conditions about sweeping and stove use before you commit.

Be ready for one direct conflict between what your insurer asks for and what the research found. SPAB advises owners to resist pressure from insurance companies to fit spark arrestors, which clog up. Historic England's fire tests found that flue-top devices described as spark arrestors appeared to have little or no impact on spark mitigation and might even keep emitted sparks close to the thatch. If an insurer makes one a condition, get the condition in writing and price the extra sweeping, because you would be accepting a maintenance burden for a device the testing did not support.

Lenders and surveys

Lender appetite for thatch varies, so ask a broker before you offer. SPAB says its helpline may be able to suggest insurers and mortgage companies who understand the needs of thatched buildings, and a broker who has placed a thatch case recently is worth more here than a rate table.

Consider a Level 3 building survey, the level recommended for older or unusual homes, and our guide to structural surveys for older homes covers what it includes. Add a separate condition report from a master thatcher, because a general surveyor may not be able to say whether the thatch needs a new ridge or a full recoat. The difference between those two answers is the difference between a maintenance item and something to negotiate on.

Line up a conveyancer who has handled a listed building purchase, since listed building consent history is a matter for the title and enquiries. You can compare conveyancing quotes and compare survey quotes in one place.