How to replace your roof

Julian Davies is the Managing Director of Earl Kendrick Associates, a multi award winning chartered surveyors with offices in London, Brighton and Manchester.

How to replace your roof

There are times when, despite the best maintenance plan, you will need to invest in a new roof. Here are Earl Kendrick’s seven steps to making the right decisions along the way

Step one: Is it really necessary?

Replacing a roof is not a quick or easy business. It will cause disruption to the residents and any other occupiers of the building.  So don’t act in haste.

For a start, consider whether your roofing project could (safely) wait until your next cycle of external repair and maintenance?  If so, you’ll only require a single use of scaffolding and all the disruption can be contained in a single period of external maintenance.  This is the ideal scenario, and is worth considering if you are making a decision on economic rather than safety grounds.

If the decision is out of your control and the roof is either dangerous or irreparable, then you will need to move fast.  This scenario is likely to be caused by:

  • Ongoing water ingress that has created significant/structural damage with the threat of more; or
  • A series of widespread and ongoing repairs that would be more expensive to repair than the cost of a new roof.

Step two: Appoint an impartial, qualified building surveyor

Roofs are, by definition, complicated elements of a building.  They are awkward, require high levels of workmanship and must be watertight.  Once constructed, they will rarely be inspected and may be inaccessible.  Future repairs will inevitably be costly and you don’t want to leave anything to chance.

The best way to ensure long-term peace of mind, is to commission a comprehensive, independent report on the condition of the roof; the requirements for maintenance and associated costs, and to ensure that a strategy for eventual replacement is in place.

A surveyor will be able to do all this, and, assuming a replacement is necessary, will offer impartial advice on the suitability of all available roofing types and materials.  The advantage of using a qualified professional is that they will:

  • have in-depth knowledge of the life expectancy of the existing roof,
  • can predict the necessary frequency of and costs for ongoing maintenance,
  • can explain all the suitable replacement options, and;
  • provide an objective view on architectural, legal, statutory and structural limitations.

Whether the surveyor’s view is repair or replace, he or she will provide detailed recommendations that will need to include:

  • Investigating hidden defects (particularly where new roofs are being laid on top of old roofs that may contain rot)
  • Obtaining planning approval and listed building consent where required for new materials
  • Preparing applications for Building Regulations (where a new roof is being installed)
  • Preparing the specification of works and managing the tender process
  • Assessing tenders
  • Advising on the appropriate choice of formal Building Contract for the works
  • Managing the works on site and administering the building contract
  • Checking quality of works, progress and financial management, ensuring that payments are made only for works that have been completed.

Step three: assess your options

A new roof is not a new carpet or a lick of paint - you can’t go back and change it next year.  So it’s vital that you investigate your options, which are vast.  The alternatives will depend on the shape and size of your roof, but materials come in many forms. One type doesn’t fit all and roofs and roofing materials are constantly changing.  The well-known materials such as slate and tiles on pitched roofs and asphalt and felt on flat roofs are now being used far less frequently, due to advancements in architectural design and materials (where planning regulations allow).  More traditional materials have recently given way to plastic liquids (or polymers) that are often used for flat roof surfaces.  The liquid systems are applied in layers and often have the benefit of a guarantee period of between 15-25 years, depending on the number and thickness of the layers.  The liquid systems are favourable to insurance companies as they reduce the amount of “hot works” and thus the risk of fire during the works.  Maintaining and repairing this type of roof is also relatively easy and as the roof deteriorates it can be re-coated in the future to provide a brand new guarantee.

It may be worth replacing your existing materials to bring your roof into line with the more modern approaches that you will take for granted elsewhere in your life.  In other cases though, due to the cost of removing the old roof coverings, if the existing coverings are in good condition it can be worth leaving an old roof in place and applying the new liquid on top of it. A particular advantage of liquid systems is where there is plant and machinery on the roof as the liquid systems can often work around the plant, minimising the cost and disruption involved in temporarily removing it.

Step four: consult with residents from the start

Replacing a roof will constitute “Qualifying Works” under Section 20 of the Landlord and Tenant Act 1985 and the cost of replacing a new roof will almost inevitably breach the cost threshold of the Section 20 consultation procedure, requiring Notices to be served.

Consultation is vital both from a statutory legal and a management perspective.  If your block is managed by a professional block manager, you have a legal right to be consulted. If you self-manage then your management company is also obliged to keep residents informed. When planning a major project, good communication is vital, especially when it is the residents who will be paying for it. Involved leaseholders will be more sympathetic towards the project and this will help minimise delays further down the line. By holding an AGM to discuss your project right from the start it will be easier to get buy-in from all flat owners in the block. If you have a Residents’ Association make sure progress is reported in the newsletter or emails sent out to members.

When appointing surveyors and contractors, ask them to come along and meet the residents before you decide which one to use. If they are not keen to do this – they are not the best firm for the job. The secret to a successful project is to get buy-in from those involved but to delegate liaison with the project team to one or two members of the Residents’ Association or RMC and task them with reporting progress back to the block as a whole. Allowing too many people to get involved is almost as bad as having too few and will slow progress, as everyone is likely to have a different view. Keep it simple but keep talking and your project should run smoothly.

Step five: get the tender right

A detailed survey with a comprehensive specification will minimise the risk of costs rising during the works on site.

It is good practice for between three and five contractors to be invited to tender.  This should be a sealed tender in accordance with the National Joint Consultative Committee (NJCC) Code of Procedure for Single Stage Selective Tendering. The entire tender should be based on the surveyor’s specification of works, any specific requirement for guarantee periods, programming constraints and any supplementary information, such as information provided in accordance with the Construction Design and Management Regulations (CDM).

A surveyor will assess the tenders to ensure that the specification has been priced properly and that the contractors have included for use of the same materials to ensure like-for-like comparisons.

Step six: be realistic about timings

New roofs don’t appear overnight.  The length of the project will depend on:

  • The size and type of roof and the condition of the existing coverings/structure;
  • Whether the old roof is being removed or will remain under the new one; and
  • The weather: during wet periods a temporary scaffolding roof will avoid delays and minimise the risk of damage.  

But temporary roofs come at a price!  Liquid applied roofing materials cannot be used when the temperature is below 5 degrees, asphalt and felt roofing cannot be laid in damp conditions.

Step seven: avoid the obvious pitfalls

There are a number of issues that can delay and complicate roofing projects.  To avoid them you should ensure that the:

  • System selected is robust and facilitates future repairs. Liquid applied roofing materials are relatively adaptable.
  • Future of the roof is considered. Don’t leave the installation of mechanical plant for next time.  Integrate it in the initial build where future roof alterations may need to be undertaken, 
  • Materials are suitable.  Single ply membrane, for example, is susceptible to damage in a heavy trafficked areas.
  • Guarantees offered by roofing manufacturers and installers are robust.  Read the small print to ensure that any requirements of period inspections and maintenance are adhered to once the new roof has been installed.  Consider taking out a separate bond or insurance for the roofing guarantee.
  • Contractors price the job on a like-for-like basis, using the same specification and manufacturer for materials. Alternatives may look similar, without offering the same quality and guarantee.
  • Schedule of Condition is prepared for the top floor areas/flats beneath the new roof, to help apportion liability for any damage as a result of the project (which may be caused by vibration, water ingress etc).

It is important to remember that a new roof won’t be the easiest job you and your fellow residents have undertaken, but with careful management, consultation and planning, it should not cause undue nightmares.