What it is
In a timber-framed house, a frame of timber posts, studs and beams carries the floors and roof. The walls you see may be the frame itself, or an outer skin of brick, render, tiles or boarding built around it. Timber frame falls into three broad groups.
Historic timber frame
Timber framing was once used in all parts of the country, and some timber-framed houses and cottages in our area are several centuries old. Historic England describes box framing, in which horizontal and vertical timbers form panels filled with wattle and daub or, later, brick, as the most widespread form. Cruck frames use pairs of large, usually curved timbers to carry the roof down to the ground. Many timber houses were later encased or re-fronted in brick or stone, or hidden behind render, tile-hanging or weatherboarding.
These buildings were made with materials such as timber, lime mortar and lime render, which absorb moisture and let it evaporate. Historic England advises against replacing them with modern impermeable materials, such as cement mortars and renders, which can trap moisture and lead to decay.
Many historic timber-framed houses are listed. Altering or extending a listed building in a way that affects its character needs listed building consent from the council, and carrying out unauthorised works is a criminal offence.
Post-war timber frame
From the 1960s to the early 1980s, builders used factory-made timber wall panels in a range of proprietary systems, often with a brick outer skin, tile-hanging or boarding. In 1983 a television documentary raised concerns about the quality of timber-frame house building, and confidence in the method fell for some years. The standard of design and workmanship varies from house to house, and the original paperwork may not survive.
Modern timber frame
Timber frame is now widely used for new homes. A typical modern wall has a timber stud frame with insulation between the studs, a vapour control layer on the warm inner side, and sheathing boards with a breathable membrane on the outer side. Outside that is a cavity and an outer leaf of brick, block or rendered cladding, tied to the frame with flexible metal ties. The cavity lets any water that gets past the outer leaf drain away.
How to recognise it
- Historic: exposed or partly exposed timbers, jettied (overhanging) upper floors and irregular walls. Many are hidden behind later finishes, and many are listed.
- Post-war and modern: from outside, often indistinguishable from brick. Inside, the external walls may sound hollow when tapped. Look for gaps left under window sills and below the eaves to allow the frame to shrink and settle.
- Documents: the EPC wall description, a new-home warranty, building control records or the developer's specification.
Common problems
- Moisture in the frame. This is the main risk. Leaks from roofs, gutters, windows, showers and plumbing, or damp from outside ground that is too high, can go unnoticed inside a wall until the timber decays.
- Vapour control. The vapour control layer behind the plasterboard stops warm, moist indoor air getting into the frame and condensing. Holes for sockets, pipes and fixings, especially during alterations, can weaken it.
- Fire in concealed cavities. Hidden cavities can let fire and smoke spread unseen. Building Regulations fire safety guidance deals with this through cavity barriers and fire stopping at key points, such as where the wall between two homes meets the external wall and the roof. These are hidden, and they can be missing or disturbed by later work.
- Wall ties and movement. The outer leaf is tied to the frame with flexible ties. Timber shrinks slightly as it dries, so gaps are left at window sills, eaves and where services pass through. If the gaps are filled, or ties are missing or corroded, the brickwork can crack or bulge.
- Alterations. Cutting studs, removing walls or making openings without proper design can weaken the frame. Retro-fitted cavity wall insulation is generally unsuitable, because the cavity needs to drain and ventilate.
- Historic frames. Decay at the base of posts and in sole plates, beetle attack, distortion, and damage caused by cement repairs or impermeable paints.
Mortgages and insurance
Many lenders treat modern timber frame with a brick or block outer leaf as standard construction, although they may ask about its age, warranty and condition. Post-war system-built timber frame and some historic timber-framed homes may be treated as non-standard, and some lenders ask for more information or a specialist report. Listed status and thatched roofs can also affect lending and insurance. Check with your lender or broker, and describe the construction accurately to your insurer.
What we check
In a Level 3 Building Survey of a timber-framed house we:
- identify the type and likely age of the frame
- look closely for signs of moisture around roofs, gutters, windows and bathrooms, check outside ground levels, and use a moisture meter where suitable
- check movement gaps, sealants and the outer leaf for cracking or bulging
- look in the roof space at the walls between homes, where fire stopping can sometimes be seen
- note alterations and ask for approvals
- on historic frames, assess the visible timbers, infill panels and finishes, and note unsuitable modern materials
- use a drone to look at the roof and high-level details, where flight is permitted
A Level 3 survey is a visual inspection. We cannot see inside the walls, so where there are signs of moisture or movement we may recommend opening up or a specialist inspection.
What we have found locally
Timber frame appears in our reports more often than any other non-standard type.
Reports that recorded timber frame construction:
43 DBISS survey reports since 2022
They include historic timber-framed homes around Aylesbury, Buckingham, Bedford, Ware and Stotfold; homes built between 1900 and the mid-1980s in places such as Hemel Hempstead, Berkhamsted, St Albans, Bletchley, Hitchin and Marlow; and modern timber frame in places including Leighton Buzzard, Didcot, Wantage, Stevenage and Watford. We also record timber frame in parts of buildings, such as extensions, dormers and garages.
Sources
- Historic England: Listing Selection Guide, Domestic 1: Vernacular Houses
- Historic England: Energy Efficiency and Historic Buildings: Application of Part L
- Historic England: Listed Building Consent
- GOV.UK: Fire safety: Approved Document B
- BRE: SAP 10 and RdSAP 10 specifications, which include timber frame as an EPC wall type