When it comes to renovating old buildings, knowledge is king. Knowing that the cracks in the walls that have put most other buyers off can be fixed easily may mean you get hold of a money-spinning bargain. Knowing when it is best to walk away because the cracks mean that the wall has to be entirely rebuilt can save you sinking your last penny into a money pit.

Good Buy or Bad?

Assessing the structural condition of a house in need of renovation is critical in discovering what that building is worth in the current market. Knowing what is wrong with a building is important but you also need to know how much fixing any problems is going to cost. Deciding whether the property is a good buy or bad involves weighing up those costs, together with the purchase price, against the likely end value. A house that is a total wreck can still be a good buy at the right price, whilst a gem of a place, in need of only minor repairs, can be a bad buy if it is already overvalued.

Download your renovator’s checklist to avoid buying the wrong home


Assessing Structural Condition

You can learn to spot many structural defects yourself through research and it is well worthwhile. However, anyone thinking of buying an old house, other than an experienced renovator, should always commission a building report by a chartered building surveyor. Unless you have real knowledge it is a false economy to save on the few hundred pounds that it costs for an experts opinion.

Whilst being able to spot major problems yourself is no substitute for a survey, it can help you decide whether or not it is worth forking out for one (£500-£1,500). Sometimes the cost of renovating a building, relative to its likely end value, is clearly so high that it is not even worth commissioning a survey.

If you do commission a building report, be aware of its limitations. A surveyor can only make a visual inspection of a building and so cannot discover or reveal hidden problems. The report is unlikely to include a valuation unless you specifically request one and whilst the report should include a schedule of any remedial work required, sometimes listing repairs in order of priority, it is unlikely to give a written indication of the cost of those works. Although some surveyors may be willing to indicate likely repair costs, this part is usually down to you to find out.


Will it need rewiring?

If a property has not already been rewired within the last 25-30 years the chances are it will need upgrading, at least in part. A full rewire will cost around £2,000 for a three bedroom terraced house and considerably more for a larger property, not including the cost of making good the decoration.

Often a full rewire can be avoided: providing the existing cabling is sound and able to carry any additional loads, it may be possible to upgrade it by adding a modern consumer unit, proper earthing arrangements and cross bonding. An electrician will typically charge £100-150 for a survey with a verbal report. This isn’t a wasted expense if it helps you decide whether the project will be financially viable.

You should be able to tell if a house has been rewired or not yourself by inspecting exposed parts of the wiring and by inspecting the electricity meter and fuse box (known as the consumer unit). Tell-tale signs are:

  • an old-style fuse box with no circuit breakers;
  • a mixture of switch and socket styles, especially old round pin sockets or dolly switches;
  • any cabling other than modern PVC-insulated cable, coloured grey or white.

Are there signs of damp?

You can invariably smell damp before you see it, as mould and fungi are usually present, rapidly creating a musty or mushroom smell. You can also spot damp because of either the presence of water, damp patches, mould, wet or dry rot, white salt deposits on brick or stonework, and/or failing plasterwork on walls and ceilings. The key to understanding damp and its implications is to identify the source and then come to an appropriate solution.

Once a damp problem is resolved, any damage will have to be repaired, starting with the structure. Check all timber elements that have been exposed to damp, and get a specialist to look for signs of wet or dry rot or wood-boring insects. If evidence is found, lenders are likely to require chemical treatment and this will cost £800-1,500 depending on the extent of infestation.


Are there signs of structural movement?

Are the walls and floors square and true? If not, the building may have suffered structural movement. Look for signs of cracks in the walls, especially around windows and doorways. The building may have moved because of the failure of structural elements which have led to the building bowing, twisting or spreading, or due to movement in the ground, know as subsidence (collapsing ground) and heave (rising ground). Buildings that have moved can be repaired and it is typical for a period house to have experienced some movement in its lifetime.

The important thing is to find out whether the movement is historical, dormant or active. Historical movement may have long since ceased and been corrected with metal ties, underpinning, piers, metal staples and stitching and buttresses, all of which can add to the character of an old house and need be nothing to worry about. Some older buildings are prone to some movement over the course of the seasons. This may not pose a structural threat, providing the building is repaired appropriately with flexible materials like lime mortar.

Active movement is the one to be most concerned about, where there are visible cracks and failed structural elements, with signs of fresh dust and debris. Arches and lintels may be collapsing and windows and doorways out of square. The floors and roof may be damaged if the walls that support them have moved.

The building will have to be stabilised, possibly by underpinning or soil grouting, and then repaired. The work involved can be extensive and you should not proceed without specialist advice and detailed estimates for remedial work, which should be reflected in the purchase price.


How is it constructed?

The materials and methods used in the construction of the original house will influence the type of materials used for its repair and renovation, and this will influence costs. Houses built post-WWI may have cavities and these can often be insulated for very little cost. Older houses are likely to have solid walls, built using lime mortar rather than cement, and so any repairs need to be on a like-for-like basis. Insulation will have to be added on the internal face of the walls, and it is important that the walls remain breathable to prevent damp problems.

Older houses may have little or no foundations and this will have to be taken into account when designing any extensions to prevent differential movement (to stop the extension from damaging the original house), and may limit the scope for alterations or building up additional storeys which will alter the loading on the building.


Do the windows and doors need replacing?

Replacing external windows and doors will cost at least £2,500-3,000 for a typical three bedroom semi-detached house and a great deal more for a larger property or where period-style windows are required. Check the condition of the windows: is the paintwork intact and the timber sound? If you can restore original timber windows, it is worth doing so and this is likely to be more cost-effective than replacement.


Are the walls in good condition?

Look for signs of wear on brick or stonework. Inspect the mortar joints to see whether or not they are worn and need repointing. Look at any architectural details like stone quoins and check their condition. Take a good look at the chimney to see if it is square and stable, and whether or not it needs repointing.

If the building is rendered, make sure the render is solid and not coming away from the wall. Examine all external decorative timbers such as bargeboards, finials, dormer window cheeks and soffits to see whether they need painting or replacing.


Does the plumbing need replacing?

If you are altering, relocating or adding bathrooms it is worth considering whether you should replace the plumbing system. If you are going to be lifting floorboards anyway in order to rewire, or making other alterations, adding new plumbing, waste and soil pipes will be worthwhile. It is also a good idea to check that all of the drains are working. You can do this by lifting the inspection chamber and getting someone to pour food dye down each WC.


Are the flues working and intact?

These are quickly and easily checked with a smoke pellet — but do get the vendor’s permission before potentially smoking out the whole of the house. Repairing a chimney flue by relining it will cost from £600-800.


What’s the heating system like?

If there is a central heating system, find out what fuel it uses and the age of the boiler. Replacing a gas-fired radiator central heating system will cost around £2,000- 2,500. A modern condensing boiler will be more energy efficient than an old model — replacing just the boiler will cost £900-1,400.

If the radiators are in good condition but there are cold spots, you may be able to powerflush (pflush.com) the system and avoid replacement (desirable if there are old column radiators).

Interpreting Your Findings

Whether you have discovered a building’s problems by inspecting it yourself, with the help of a builder or architect, or following the findings of a building report, the next stage is to interpret the implications of those findings. You need to know how serious the problems are; whether they can be fixed; how long it will take and, most importantly, how much it will cost to put right. Here is a list of some of the most common problems found in old buildings and their likely implications.

Wiring Requires Updating: Rewiring a typical three bedroom terraced house (90-100m²) will cost from £2,500-£3,000, including removing the old wiring, lifting and replacing the floorboards, and installing a new consumer unit, but excluding making good the plaster and decoration. The job should take a pair of electricians five to seven days.

The tell tale signs that a house is in need of rewiring are easy to spot. Look for an old fashioned fuse box instead of a modern consumer unit, old fashioned round light switches, round pin plugs or old wires.

No Central Heating: Adding a wet radiator, gas central heating system to a typical three bedroom terraced house will cost £2,500-£5,000 and will take a plumber eight to ten days. Adding central heating is easily one of the most cost effective improvements you can make to a house and will always add more to the value of a property than it costs to install.

Rainwater System in need of Repair: A replacement PVCu rainwater system will cost around £400-£800 for a typical three bedroom terraced house however, the gutters and downpipes on an old property rarely need replacing entirely and wherever possible, original cast iron rainwater systems should be retained.

Cracks: Are They Structural or Cosmetic? Cracks in plaster walls and masonry can look extremely worrying, but are frequently only cosmetic. Being able to tell them apart from the symptoms of more serious structural problems can be very useful in making your initial verdict on a renovation project and in the decision over whether to commission a survey or walk away.

Cracks to materials that are isolated, for instance a crack in a single brick, or a stress crack in a plaster wall adjacent to a window or doorway, are unlikely to be structural. Where the cracking is more extensive and follows a pattern, i.e. a crack running through a series of bricks, there is likely to be a more serious cause. Look for signs of movement in the building. Typical causes are subsidence or heave in the ground which may necessitate underpinning beneath the walls, or the failure of the floor or roof structure. In a very old building, however, the structure may be perfectly stable despite twists, bows and warps, and attempts at repairs may do far more harm than good.

No Upstairs Bathroom: Many old houses were built either without bathroom facilities or have since had them added on the ground floor. Installing a new bathroom at first floor level is likely to cost around £800-£1,000, with a basic white bathroom set from one of the DIY stores costing around £250-£350. Creating the stud walling for a new bathroom out of an upstairs bedroom is likely to cost £1,500-£2,500 including finishing and tiling, but consider the implications of possibly losing a bedroom to make space for a new bathroom.

Dry Rot: A fungus that will destroy timber very quickly. It even penetrates brick walls to get to more timber. Dry rot loves moist, poorly ventilated conditions and is usually found in the roofspace or under wooden floorboards.

Dry rot is easy to identify the spores send out fungal strands along the timber and through/along any wall. These strands can become quite dense to form a mass like cotton wool, penetrating and destroying the timber. The first sign of dry rot is often its distinctive musty smell when you lift a floorboard or even just the carpet.

Getting rid of dry rot will cost around £1,000 for treatment by a specialist firm. Repair costs for replacing any damage are in addition to this, and can be extensive. Some recommend the removal of all infected materials. The best way to prevent a recurrence is to improve ventilation and eradicate any damp.

Wet Rot: Hardly a problem compared to dry rot. It is basically the timber decaying naturally in the presence of high levels of moisture. Timber suffering from wet rot will feel spongy (even through a coat of paint) and look darker than the surrounding timber. When dry, the timber will easily crack and crumble into fine particles.

The cost of solving wet rot will depend on the damage it has caused to timber in the house. Repairs should be treated. The problem will not return if you solve damp problems in the house and improve ventilation.

Cracked or Blown Render: Minor cracks in cement render are rarely more than cosmetic and are inexpensive to fill and repair. If cracks are more severe, however, check that they are not a sign of structural movement by inspecting the blocks or bricks beneath. If the render has started to come away from the wall typically due to prolonged frost damage it will need to be removed and replaced. Render is a two coat process and will cost around 14-18/m² supply and fix.

New Kitchen Required: Assuming modest tastes, a basic contract quality kitchen from a builders merchant or popular DIY store can be fully installed for £3,500-£4,500, including all white goods, oven and laminate worktops (assuming an area of around 10m²). DIY installation would reduce these costs.

Remedial Roof Repairs: Roof damage will usually manifest itself in leaks inside the house. Typical problems will be broken or slipped roof tiles, missing or damaged flashings, damaged or missing underfelt, and worn pointing on verges. Providing the problem has been spotted early enough, the roof structure should not have been exposed to sufficient damp for it to require total replacement. Where timbers have been damaged due to exposure to the elements, they will need replacing.

Replacing or refixing a few roof tiles or slates, and repointing the verges, is not a major task and will cost £100-£200. If the damage is extensive, then it may be cheaper to remove the old roof covering and lay a new roof. The advantage of this is that the roof can be felted and battened to make it weathertight. Replacing the entire roof over a typical three bedroom terraced house will cost from £2,000-£3,000 including scaffold hire.

Collapsing Ceilings: A collapsed ceiling is usually a sign that damp has got into the structure or that there has been a flood of some sort. Old lathe and plaster ceilings can be incredibly messy to remove as they produce a vast amount of rubbish. In most instances the ceiling will need to be replaced using plasterboard, fixed onto new, level ceiling joists, and finished with a skim coat. Costs are likely to be £400-£500 per room, including removal of waste. If the ceiling has not collapsed too far, you may be able to plasterboard over the original lathe and plaster ceiling instead, at a cost of £100-£200.

Woodworm: A common pest in damp timber and can cause major problems if the damage is extensive. However, in most situations the damage is superficial (providing the holes are 2mm or less) and the problem can be eradicated using pesticides. The problem can be more serious if the woodworm has managed to get into less accessible areas of the structure that cannot easily be treated. Before paying for any treatment, make sure the woodworm is still active and has not already been eradicated look for signs of sawdust around the holes. Pesticide treatment will cost from £600-£1,000 for an average house.

Signs of Damp in Walls or Floors: Old buildings without damp are the exception, so do not be too concerned about signs of damp as they can always be solved. First you need to identify the source of the damp and, once discovered, solving it involves simple and inexpensive repair or replacement. In an old brick building a damp proof course can be created by injecting silicone into the bricks both inside and outside the building. For the average three bedroom terraced house this is likely to cost around £3-400 plus the cost of redecorating, (total cost £1,200-£1,800) as it usually involves replacing the damaged plaster from all ground floor walls up to a height above the level of the rising damp.

Windows Require Replacing: PVCu double glazed windows will cost from £100-£200 each and the same again for fitting. A new door will cost £100-£500 plus £100-£200 for installation.

Replace your original windows with caution, however, as they can be an inherent part of a buildings character and therefore its value. Original windows can often be repaired and this may cost less than replacing them with new windows in a sympathetic style. In many areas, however, replacement windows are a must for all buyers and will add considerably more to the value of a property than they cost. Even so, it is worth paying considerable attention to the style and proportions, and which lights should be opening or fixed.

Evidence of Subsidence or Heave: Where the ground has either expanded or shrunk due to a change in moisture content, it can have a dramatic effect on the foundations and walls of a building or its ground floor oversite slab if supported directly on the ground.

Subsidence is where the ground level drops, and heave where it lifts. Both problems will manifest themselves in undulating and or cracked walls or floors. Ground movement typically occurs after a period of extreme rainfall or drought, where trees have recently been planted or removed close to the building, or where there has been localised flooding. Houses built in clay soils with shallow or no foundations are the most prone to this kind of problem.

The consequences of movement on the structure of a house can be dramatic and so this is an area where extreme caution and independent expert advice are required. A building can almost always be stabilised and repaired, but the issue is one of cost. Sometimes it can be cheaper and easier to demolish a property and treat the site as a plot, than it is to repair the problem by underpinning the walls with concrete.

In addition, the end value of a building once it has been underpinned can be severely compromised because buyers are likely to be wary of any continued risk, and because insurers may be reluctant to provide cover.

Before proceeding with any underpinning work, check for the proximity of drains, as a collapsed drain can cause ground movement resulting in cracks in walls that can be mistaken for subsidence.

Poor Decorative Order: A term that is likely to be applied to most buildings in need of renovation. It sounds benign and therefore inexpensive to put right, but can be a catch-all term for problems ranging from the need for a bit of clearing and redecorating, to a total replaster throughout. Replastering the walls and ceilings of a three bedroom terraced house will cost from £2,000-£3,000 and will take a gang of two plasterers 8-10 days.

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