From buying a property ‘blind’ to poor cost control, there are many traps for the renovator.

Turning a tired, run-down property into something fresh and desirable can be a hugely rewarding experience. But negotiating the complexities inherent in renovation projects is generally a lot more challenging than new construction, where you have the luxury of starting with a blank sheet of paper.

In reality, it’s all too easy to make innocent mistakes and find yourself lumbered with a bottomless money-pit, bogged down in stressful disputes, or living in a half finished bomb site. Here we’ve listed 14 common pitfalls so that you can avoid them.

Whether you are refurbishing a home for yourself, or for profit, aim to pick properties that aren’t in too hopeless a condition. You want to renovate, not rebuild. At auction, novice investors sometimes ‘buy blind’. But more experienced and savvy builders will often commission a preliminary survey to flag up hidden dangers, defects and structural botches, works where consent should have been obtained (but may not have been), as well as location risks such as obscure rights of way, flooding and radon.

If you’re buying an old building, check whether it’s listed, as this will severely limit the changes you can make, plus as a new owner you’re legally liable for rectifying any past illegal works, often at huge expense. Generally, unless you have a bottomless budget, avoid:

• properties built to a substandard quality, such as some cheaper Victorian terraces built without firebreak party walls in lofts and with worryingly thin single brick rear additions (which cause problems with mortgage lenders)
• those that have suffered botched alterations such as chimney breasts and internal walls illegally removed without Building Regulations’ consent.

Anything likely to need expensive structural work is best avoided, or your budget will vanish surprisingly fast on hidden defects to drains and roof structures rather than fittings and finishes. Instead, try to find houses in shabby decorative condition which look ‘worse than they are’, just needing a decorative makeover and some updating to kitchens and bathrooms.

‘Wouldn’t that look nice?’ Last-minute impulse purchases, plus design changes once a quote has been accepted and work is underway on site, can play havoc with costings.

• Keep a generous contingency sum, say 10 to 20 per cent of the overall build budget
• Try not to lavish money on expensive frivolous fittings such as designer ‘tree stump’ radiators
• Don’t waste money on unnecessary works, such as ineffective damp treatments
• Make do and mend — in older properties repair can often be a better option than replacement and is normally a lot cheaper
• Keep the design simple, eschewing complex custom-designed vaulted zinc roofs and suchlike.

Keeping a lid on costs also depends on good communication, so it’s worth scheduling regular builder-client site meetings. This should prevent misunderstandings over small details which otherwise have a nasty habit of growing into expensive disputes.

Before the build starts, it’s important to think about the details — light switches, sockets, radiators, taps, basins and so on, so the builders know exactly what’s required.

Logic dictates that you shouldn’t waste money buying more stuff than you actually need. But it’s a false economy to order too few materials and risk work being held up because you’re a few tiles short. Most materials come in standard pack sizes, so quantities of things like insulation, bricks and blocks need to be rounded up. Contractors know that an allowance needs to be made for breakage, both in delivery and on site.

Reclaimed materials for renovation projects have an even higher wastage factor. You may need to over-order by up to 20 per cent on second-hand bricks, slates and tiles compared to around five per cent for new. Better order too much than not enough. Any surplus can usually be sold or returned.

Optimists have a tendency to forge ahead, believing that everything will work out fine. Being keen to ‘just get on with the job’ means there’s a temptation to rush the budgeting stage, perhaps making the sums add up by writing down the lowest possible prices.

Renovation is less predictable than new build, so you need to factor in the risk of unwelcome surprises, such as dry rot under the kitchen units or having to unexpectedly upgrade the existing services, by setting aside a fairly healthy contingency sum. There are also a lot of ‘hidden’ costs that people sometimes forget to include, which often isn’t included in quotes, including:

• professional fees for surveyors, architects and engineers
• fees for planning and Building Control
• fees for arranging funding
• VAT

A lot of homeowners only discover halfway through the works that their plans are completely unachievable on their budget. So it’s essential to research prices in advance. Drawings need to be translated into a list of materials and labour.

Materials are fairly easy to check online but labour rates are harder to predict, varying considerably depending on market forces – how busy builders are – and the geographical area (prices tend to be higher in posh postcode areas!). Obtaining competitive quotes based on clear drawings and specifications should help pin costs down in advance.

Aspiring renovators sometimes get so focused on getting the desired ‘visual result’ with fabulous kitchens, décor and so on, that they risk running out of money for works to the building envelope — sometimes referred to as the ‘unseens’. If you don’t prioritise key works, such as leaking roofs, timber decay and structural movement, it won’t be long before deterioration of the fabric takes hold, at which point it might be a matter of some regret that so much of the budget was showered on top-of-the-range designer appliances.

Many renovators also have a tendency to underestimate the level of work required to upgrade existing services such as electrics and heating systems to make them fit for purpose.

A lot of unnecessary work can be prevented in period properties (1930s and older) by adopting a ‘repair not replace’ approach. Overhauling original doors and windows and retaining period features is often cheaper than replacement, adding value in the process by enhancing period character. In many cases, the original door and window timbers and joinery were of far better quality than today’s equivalents.

Fitting secondary glazing to original windows is often a good ‘best of both worlds’ solution. If modern double-glazed units have misted, you can save a lot of work by replacing just the glazing panels, rather than the whole window.

With roofs, localised repair may be all that’s needed in most cases. Surveyors can sometimes pass premature death sentences when there may be another 10 or 20 years’ lifespan left.

When the housing market is buoyant there’s usually a high demand for building services, making it hard to find good builders at a reasonable price. It can be tempting to pick the cheapest builder who can start next week, but if a quote price is super-cheap there’s normally a good reason: perhaps they forgot to include something, or simply just got their sums wrong.

Either way, the builder will realise they’re working at a loss. And if they walk off the job, it will cost you dearly to get someone else to finish it, with all the hassle that goes with that. It may be cheaper in the long run to go for a medium-range price rather than risk work being skimped to recoup losses, leaving you with a badly done job.

If your project is not time critical, employing ‘friends of friends’ or friends on ‘mates’ rates’ may work. But more often than not something else will come up on the day when they promised to finish your job, which could then hold up the following trades.

The golden rule when refurbishing older buildings with solid walls is to use traditional materials that are compatible with the way they were originally built, i.e. lime-based mortars, renders and plasters, rather than anything containing modern cement. Old buildings with shallow foundations are affected by seasonal ground movement and because cement is very brittle it tends to develop small cracks. This allows rain to penetrate, which then can’t escape.

Modern paints applied to walls can also cause trouble by blocking natural evaporation. Trapped damp can then precipitate serious frost damage in masonry walls. However, not all builders are familiar with lime, often preferring to stick with mainstream products. So you need to be clear that the trades you employ have the necessary skills.

When renovating a property it can sometimes be tempting to give heavily advertised ‘miracle cure’ treatments a try, lured by extraordinary claims such as ‘never paint again’, ‘seal leaks for good — instantly’ or ‘the ultimate solution to all roofing problems’. But some of these products can actually be very damaging when applied to older buildings.

Spray-on renders and polyurethane foams can block crucial ventilation paths in walls and roofs, and despite claims to the contrary offer virtually zero insulation benefits. Instant damp sealants are rarely effective and can trap damp in walls. Basically, if something sounds too good to be true, it probably is.

You may be a genius renovator but you could still come a cropper. Every street has an invisible ceiling that dictates how much buyers are prepared to pay, no matter how many tennis courts and basement gyms you add. The quality of fittings needs to be closely geared to the expectations and demands of the market sector the property is likely to appeal to.

At one extreme, it would obviously be a false economy to deck out an historic Georgian townhouse in the opulent end of town with cheap MDF joinery and foam ceiling tiles. Conversely ‘the best house in the worst street’ syndrome is a recipe for disappointment. It sounds obvious, but this is a surprisingly common lapse of judgement.

It’s sometimes thought that the first job in a renovation project is to hack off all the plasterwork or tear down old ceilings. Of course, the right approach will depend on the age and type of property.

With anything post-war you’ve got more of a free hand; no one’s going to accuse you of vandalism for ripping out an original avocado bathroom suite. But with older properties it makes sense where possible to retain or reinstate original features, which not only saves a lot of work and expense but should also add to the value. So think twice before sacrificing old fireplaces, cornicing, floor tiles and internal walls.

Builders are sometimes very quick to advise taking down historic lath and plaster walls and ceilings when they can be repaired. It’s just that small fiddly jobs aren’t always popular with contractors, but specialists can work wonders.

Buying materials that are incredibly cheap is usually a false economy. For a start, anything obviously ‘cheap and nasty’ is likely to detract from the value of the finished property. To comply with Building Regulations, the drawings will specify the correct strength class of timber, and concrete blocks of the required density and thermal efficiency to ensure they can support loadings and meet energy targets. So you can’t just use any old stuff.

Quality can be difficult to determine from blurry online product photos. It’s also not unknown for stolen goods to be flogged off cheap via internet auction sites, and if you innocently buy something that turns out to be stolen, legally they can be reclaimed by the original owner at your expense. Sourcing cheap materials from overseas can also be a minefield and specifying Canada compliant materials with appropriate K-values and so on can be fraught with linguistic problems.

Avoid spending large amounts of money on misguided works that actually reduce the property’s value. Kerb appeal is obviously fundamental when it comes to attracting buyers, so doing anything that messes up an older building’s appearance, no matter how well-intentioned, can be counter-productive.

The prime example of this is artificial stone cladding glued to the walls, which apart from looking dire has a tendency over time to start cracking with bits dropping off, blocking windows and air vents. Widening and enlarging window openings can create an instant ‘character transplant’, and putting plastic fascias and windows into period buildings is one of the quickest ways of losing money by slashing their market value.

Overconfident DIY enthusiasts sometimes overestimate their abilities. It can take at least twice as long to complete the build doing a lot of work yourself, especially if you’re learning new skills in the process. And slow DIYers cause delays to following trades, throwing a spanner into the overall programme.

Before committing to the DIY-intensive route, it can be worth asking yourself:

• How time critical is the project? If you’re relaxed about deadlines there’ll be greater freedom to plough your own furrow.
• Are you tough enough? Sitting at a desk all day doesn’t build physical strength, so you’ll struggle to work anywhere near as fast as the professionals.
• How much time can you commit? DIY generally takes longer than you imagine.
• What are your skills? Perhaps consider doing the decoration towards the end when there’s less time pressure or focus on the project management role.
• In the cold light of day, it often makes more sense to earn more money in your job so you can employ professionals on site, rather than taking on time-consuming DIY tasks yourself.

There’s a certain amount of paranoia among the public when it comes to dealing with builders. The fact is, most builders try to do a decent job, often despite late payment and awkward clients giving them a lot of grief. Individual tradespeople can actually be a mine of valuable experience.

Of course, sometimes there’s an ulterior motive to drum up business. But it’s often the case that the person tasked with doing the job will know a better, less expensive or simpler solution in a specific area than designers focused on the bigger picture. Trades also tend to have a useful knowledge of materials and local suppliers, potentially helping you save time and money. So don’t automatically disregard advice from the person doing the job.