This is not an exhaustive or a complete subject. It is likely to change over time, with edits, additions and deletions, and is simply a collection of my thoughts based on many years of experience. You should follow your instincts, not rely at all on any of this and you must always seek your own professional advice.
Background
Buying a house which has origins of a historic timber-frame can be a high risk purchase. Doing a building survey of a historic timber-frame is not to be taken lightly and requires considerable experience, understanding of building pathology and an inquisitive point of view. The buyer needs to understand the risks. The surveyor has a fine line to work within owing to the physical limitations required for a non-invasive pre-purchase building survey. The outcome needs to be a balanced professional point of view that provides impartial information but without scaremongering or exaggeration. There needs to be a realistic awareness of what can be expected from the building and also from the surveyor.
It should be the clients decision whether to proceed with the purchase to not. That decision can be enhanced by the very best impartial building surveying advice. The advice should be based on a detailed assessment of the historic timber-frame and it should consider not simply the visual condition at the time of the inspection but it should try to anticipate the consequences of previous repairs and alterations that may have been done. This requires considerable care. It also requires considerable experience.
Limitations
There are practical, and physical, limitations of doing any building survey. A surveyor is given access to a house by agreement of the owner and there is an express understanding on both sides that care will be taken not to cause any damage to the building or anything within the building. The client who has booked the survey, in advance of a proposed purchase, has no input into how the survey is conducted. The limitations of what can reasonably be done, and what can be expected, are usually contained within the surveyors T&C’s and would also be explained within the written survey report. Pre-purchase surveys are visual only and there is not an opportunity for any ‘opening up’. Carpets are not taken up and furniture is not moved. Floorboards are not lifted. Holes are not made in floors, walls or ceilings. This is all considered as being standard professional practice. Even if the surveyor, and client, might want a more intrusive inspection to be done, there should be no expectation that it can actually be done. The property owner would need to agree to a more intrusive approach following a specific request to do so. This would probably require a conversation about costs, damage caused and repairs to make-good afterwards.
This scenario is not ideal but it is the conventional expectation and how pre-purchase surveys are conducted. The surveyor cannot be expected to see what cannot be seen and is not allowed to cause any physical damage to the property during the building survey. The client cannot expect the surveyor to exceed the professional responsibilities and liabilities – even if that would produce valuable information.
High-Risk Buildings
The following examples should all be considered as being high-risk for both the purchaser and the surveyor. Extreme caution is required. Inexperienced surveyors without specific training on historic timber-frames should not be doing building surveys on these buildings.
Any historic timber-framed property that is the classic ‘black and white’ format is likely to be high-risk.
The sole-plate (sometime called a sill beam) is an especially vulnerable location. Any sole plate that has been painted, has cement fillers, has been partly or fully covered by a cement render, has any other hard filler compound, has any contact with flexible silicone mastic, is located at ground level, is located on a plinth that has been rendered and any other comparable situation should all be considered as being high-risk.
Any use of an epoxy-resin filler anywhere at all on the historic timber-frame should be considered as being a high risk. I have previously commented about the use of epoxy-resins here.
Any infill panels that are rendered with a cement should be considered as being high-risk. These panels severely impact on the performance of the wall and can lead to hidden decay arising.
Brick infill panels can cause secondary problems, are thermally weak and can create a ledge which has other pathology impacts. These panels require careful review and would be considered as being a high-risk.
Any evidence of, or suspicion of, live death watch beetle should be considered as being a high-risk. This is a warning sign that there is a severe, and probably hidden, timber-decay in the building. It should be located as best as can be done during the survey and without the benefit of exposure. This will often be indicative of a localised problem rather than a more widespread problem.
Any proposal for ‘opening up’ should only be done after careful and considered assessment of the circumstances. Random exposure is usually pointless and will not lead to useful information.
A survey of a historic timber-frame by an experienced surveyor is a risk assessment but not any guarantee as to the condition of hidden and concealed parts. The surveyor should be able to make a reasonable risk assessment and advise on any future repairs based on what can be seen and assessed and based on professional judgement of what can’t be seen. However, no comments or guarantees can be made for those parts that are hidden.
Any property that has been recently ‘modernised’ or ‘lovingly restored’ is almost certainly going to be high-risk and not what it pretends it is.
Cement render and fillers, in any location, is incompatible with historic timber-frames and should be replaced with lime renders or traditional daub mix, as appropriate for the situation. The decision for when this repair would be needed is an element of professional judgement for the surveyor to make. It is entirely possible that this can be done slowly, on a phased approach, over several years. This allows for the client to finance and budget accordingly and avoids unnecessary stress on the building. It is unlikely, and generally not advisable, that a major project of cement render, or panel, replacement is done at any one time.
Any timber-frame that was originally clad, perhaps by weatherboard timber cladding or tile-hanging, and which is now exposed should be considered as being a high-risk. The externally exposed frame will now be weathering in a way that was never intended. These situations require careful professional assessment by the surveyor.
Notes for the buyer
If you are a buyer of a house which has a historic timber-frame, you need to immediately be aware that it is a high-risk purchase. Do not assume that it will be free of defect. It might well the case that there is not much wrong with it, but that would be a happy bonus result. Set aside a substantial budget for repairs to the historic timber-frame ‘just in case’. Make sure that you choose your surveyor with considerable care and do question the surveyor before the survey to make sure that you have made the right choice.
Notes for the surveyor
Do not accept the instruction for the survey unless you have considerable experience of comparable historic timber-frame properties and have been specifically trained to do this type of survey.
If you are an AssocRICS residential surveyor you should decline any surveys on historic timber-framed buildings unless you have additional specific training on this type of construction.
A report using the RICS Level 2 format will not be sufficient. The use of the colour-code ‘traffic lights’ format will be misleading and should not be used.
If you accept instructions for a building survey of a historic timber-framed house you put yourself at risk of professional negligence claims and your RICS Regulated Firm at risk of formal complaints and investigations if the consumer makes a complaint against you and the quality of your work.
The RICS Home Survey Standard 2019 must be followed at all times and it is a mandatory requirement that the surveyor has the required experience and competence to undertake the survey.
The surveyor should follow the advice contained with BS 7913 Conservation of Historic Buildings.
Disclaimer: Anything posted in this Blog is for general information only and it is not in any way intended to provide any advice, legal or otherwise, on any general or specific matter that you can rely on. You should always seek your own legal and surveying advice.