Older buildings often have damaged, corroded, unsealed joints and are often of single skin construction. The building envelope will have very poor insulation properties and typical air leakage rates three times higher than today’s worst acceptable performance.

One way to reduce the energy consumption and CO₂ emissions is to refurbish the building envelope to increase the thermal efficiency of the building. Refurbishment could be either through a metal based re-sheet or overclad. It is possible to dramatically increase the thermal efficiency of a building and so reduce energy consumption by up to 60%.

Installing high quality products, and ensuring correct practices to effectively seal the building and meet the current insulation performance requirements, will enable the building performance to approach that of a complete new build.

By working closely with supply chain partners, leading manufactures are able to create building envelopes which can meet and exceed demands of Building Regulations and legislation.

For more information on this topic, visit our website.

By Ian Clarke, Applications Development Manager at Corus Colors

Therefore, it is evident that more thought needs to be put into the decision to install a flat roof system at the initial stages of a project and there are a number of questions that should be answered:

Is a flat roof a long-term solution for a new build situation?

Compared with alternative solutions, multi-layer felt and modern single ply products have a limited life expectancy, with flat roofing material suppliers generally offering guarantees on their products of between 10 to 15 years. Some come with guarantees of 20 years, but these have a hefty price tag. In either case, the long-term suitability of these materials is highly dependent on onsite workmanship and the detailing of the interfaces and junctions.

I would suggest an alternative solution is the specification of a metal low-pitched roof, such as a standing seam or concealed fix system. These systems work down to a pitch as low as 1° and the jointing and connection details have been tried and tested. This system approach which utilises high performance pre-finished steel products, provides a durable, maintenance free result, for up to twice as long as many membrane solutions.

I have a flat roof installed which has failed, what are my options?

If your roof is repaired with the same or a similar system, this could result in a comparable failure in the future. The problem of permanently ponding water will also not be resolved. Therefore, I would suggest that a more appropriate solution would be to convert the current flat roof to a pitched roof using a lightweight steel structure.

The lightweight steel structure supports a profiled pre-finished steel roofing sheet, which provides weatherproof covering. This approach offers additional choices in profile shape and colour to change and improve the aesthetics of the building.

This also provides the opportunity to easily incorporate additional thermal insulation, which will in turn increase the energy efficiency of the building. As such, the flat to pitch option offers much more than just a simple replacement, it provides a complete solution with additional functionality and performance.

What are the key design issues when considering a flat to pitch conversion?

The most important factor to consider is the structural capability of the existing roof. This must be checked by a qualified person who can assess the existing structure and best advise on a suitable method of attaching the new roof.

Lightweight steel pitch conversion kits are available for attachment directly to the existing flat roof structure and some systems can span over the roof and transfer the loads down into the main structural frame or wall.

Our website discusses this in more detail.

By David Taylor – Refurbishment consultant at Corus Colorcoat^®

However, with steel building envelope refurbishment projects the impact on occupancy of the building ultimately comes down to the type of refurbishment chosen – a complete strip and re-sheet or an over clad system.

The most thorough refurbishment is a re-sheet which involves the compete removal of the existing building envelope down to the steel structure. This is most suitable when the existing cladding, which is often fibre reinforced cement, is in very poor condition. A thorough asbestos survey needs to be undertaken before any cladding can be disturbed or removed.

Any modifications and/or repairs to the structure are carried out and the cladding is then completely replaced with the new system. This method of refurbishment has a considerable effect on the occupants of the building and can only be completed if the area being refurbished can be completely closed down. In some cases, areas of a building can be fully resheeted without closing the building, provided adequate safety measures such as fully boarding out the roof truss area have been carried out, however this has very high associated costs and is usually not practicable.

Although this level of refurbishment carries the disadvantage of having to effectively close the building down, it can however pay dividends in other areas. It can improve aesthetics both internally and externally, and increase the thermal efficiency of the building up to that of a new building, significantly reducing heating and lighting bills.

Another option available to building owners and the one probably most preferred by those looking to keep their building occupied during a refurb project, is to over clad the existing building envelope

This method is completed by using a single-skin sheeting system. The existing sheet is used as a ‘liner’ and an insulation quilt is normally incorporated between the two skins. It is possible to over sheet a roof using a composite panel, but this isn’t the ideal solution, as unnecessary and excessive additional loads are imposed upon the existing structure and it can become more costly.

An over clad refurbishment ensures minimum disruption to the building occupants as the existing building envelope is kept intact and it can be completed a lot quicker than a re-sheet.

It does require a structural check before commencing to ensure the existing structure can take the additional loads. The existing cladding, which is often fibre reinforced cement also needs to be in good condition and a thorough asbestos survey needs to be undertaken.

Although both methods have their benefits, for a building owner looking to keep his property occupied during a refurbishment, over cladding is usually the preferred option.

The refurbishment priorities section of our web site discusses these options in more detail.

By David Taylor – Refurbishment consultant at Corus Colorcoat^®

Whatever the reasons for refurbishment there are a number key things to consider, from the type of refurbishment project undertaken, to the materials used on the building.

In relation to metal building envelope refurbishment projects, it is important to determine the most appropriate level of refurbishment, based on the condition of the existing building and the condition of the structural frame and then consider the most suitable pre-finished steel cladding product.

Cutting costs at this stage, using cheaper, lower quality cladding products may risk premature coating failure and the associated rectification costs as well as higher ongoing maintenance costs which were one of the driving forces for the original refurbishment.

It is essential to ensure that the pre-finished profiled steel cladding specified can meet the structural requirements of building location, design and the existing purlin spacings. The cladding manufacturer must be able to provide load span tables and evidence that the material supplied meets the gauge requirements of EN 10143:2006 for the gauge of material used to calculate the original tables. Failure to do this could result in structural failure of the cladding.

A refurbishment that appears to be initially low cost can actually end up being far more expensive in the near future. This is because the building envelope requires ongoing inspection, maintenance on an annual basis and serious rectification throughout its life with numerous repaints or further refurbishment.

The future re-sale value of the building is determined by the state of the building and any repair works that are required once ownership changes. In which case, it is important to point out that a quality refurbishment can ensure that the re-sale value of a building is maintained for the duration of its life.

For more information on this subject and property refurbishment, visit www.beatthewolf.co.uk

Ian Clarke, Sustainability Consultant, Corus Colorcoat^®

1) The occupiers of the building
The workforce and the general public need to be protected, particularly in the case of re-sheeting. With this type of project there is a risk that building users will be exposed to hazardous or falling material, so it is important that protection measures are put in place, such as close-boarded internal protection scaffolding and/or the work area being flagged off.

 2) The contractors
When working on fragile roof surfaces, such as asbestos cement, measures should be taken to protect the contractors from falls through or off the roof. For a re-sheet project, close-boarded internal protection scaffolding is necessary, but in the case of an over cladding project, safety netting is usually required. Access boarding will be required, when working on a fragile roof.

3) Removal of hazardous waste
An asbestos survey should be carried out prior to any work commencing. It is essential to ascertain the nature of the asbestos and determine a safe method of removal and disposal. If it is deemed safer to leave the asbestos containing material in place, then an over cladding solution may be a better option. Where asbestos containing material is left in situ, it must be clearly identified and recorded in the building log book.

4) Protection of building operations
It is important to make sure that machinery, equipment etc is protected or relocated temporarily until the work is completed.

5) Protection of finished goods
Whether a manufacturing facility or a warehouse, steps must be taken to ensure finished goods are protected or relocated temporarily until the work is completed.

 6) Prevention of water ingress
If the premises are occupied, then a ‘strip and cover’ policy should be adopted by the contractors, particularly where a re-sheeting method is used. This means that no more material should be stripped in one day than can actually be replaced during the same day. This way, no openings are left in the roof/cladding overnight and the risk of rain entering the building is minimised.

7) Allow a Contingency Sum in the contract
This is sensible for most refurbishment work. It can be extremely difficult to ascertain the condition of the existing structural members, such as purlins or sheeting rails (whether steel or timber) before stripping of the existing cladding begins. A sensible sum should be put aside for possible expenditure on the replacement of defective structural members, should they be needed.

In order to ensure these issues are carefully considered, it’s important to appoint building surveyors and a CDM co-ordinator, who can put a health and safety plan in place and carry out a full risk assessment before the work commences.

David Taylor – Refurbishment consultant at Corus Colorcoat^®

As it currently stands in the UK, not all asbestos containing material has to be removed by law, it all depends on the condition of the asbestos found in the building as to whether it must be removed. However, this is an area that the government is continuously monitoring and beginning to get stricter on. 5-10 years down the line, once your refurbishment project has been completed, it may become compulsory to refurbish any building found to be containing any form of asbestos – this is worth bearing in mind.

If poor quality asbestos has been found in your property, then there is really only one solution and that’s complete removal and replacement of the substance and a full re-sheeting operation.

This is a more involved refurbishment which usually requires the building to be completely vacated and closed down.

However, the installation of a new thermally upgraded building envelope does offer a number of benefits, such as vastly increased air-tightness, improved aesthetics both internally and externally, and increased thermal efficiency, which significantly reduces heating bills.

If the asbestos containing material found in your building is in good condition, it can actually be left in place and an over cladding solution can be used instead.

This is a much faster refurbishment method – it can be completed within a matter of weeks, depending on the size of the building, and if it is planned properly, it will cause minimum disruption to building occupants and internal processes. The new building envelope (sheeting, insulation and air-tightness membrane) is simply installed and fastened through the existing envelope into the sheeting rails. It is important, however, to carry out a full structural survey before commencing work to ensure the existing structure can take the additional weight.

If you do find that you have to refurbish your building due to asbestos, you may be able to claim tax relief on your project through the ‘Land Remediation Tax Relief’ scheme. This will allow you to recover some of the costs associated with the refurbishment and the removal of the material.

David Taylor – Refurbishment consultant at Corus Colorcoat^®

DON’T underestimate the importance of obtaining a thorough structural survey on your building before commencing any refurbishment project. For example, before an over cladding project, which involves a new building envelope being built around and secured to the existing building envelope, a structural survey is essential to ensure that the existing building structure can withstand the additional weight being placed on it.

DO futureproof your building. The refurbishment of a building is a process that involves a lot of up front planning. Current and future changes to Building Regulations, such as Part L 2B, need to have a bearing on refurbishment decisions. When undertaking a project you need to ensure that your building will stand the test of time and meet the regulations of today and tomorrow.

DON’T cut corners. Using low quality products with minimum standard guarantees and not employing a reputable company to undertake the work, can lead to serious issues in the future. Expert consultation and surveys should always be obtained before the start of any refurbishment.

DO remove any asbestos containing materials, which is showing signs of deterioration, from your building and undertake a complete re-sheet. If the asbestos containing material is in good condition, it can be left in place and an over cladding solution can be used instead. However, it is important to remember that the asbestos containing material must be clearly identified on the building and recorded in the building log book to prevent risk of accidental exposure on future building work.

David Taylor – Refurbishment consultant at Corus Colorcoat^®

There are a number of considerations to take into account before deciding on whether to undertake a refurbishment. But if you answer ‘yes’ to any of the following questions, then refurbishment is the answer you have been looking for…

Do you want to reduce your energy bills?

The largest ongoing costs of a building are the operational costs of heating, lighting and cooling. By refurbishing your building, either through a re-sheet or over cladding, you can considerably increase the thermal efficiency of your property and reduce ongoing expenditure.

By rectifying factors such as poor detailing and design, which causes significant air-leakage and poor thermal performance, your building can increase energy performance by up to 75%.

Do you want to improve the value of your property?

Not only can refurbishment considerably reduce the ongoing costs of a building, the re-sale value can also see a significant increase. The introduction of Energy Performance Certificates (EPC’s) has seen a real change in attitude towards building performance – a recent McGraw-Hill study found that thermally efficient buildings command 3% higher rental rates, an average increase of 7.5% in building value, deliver 3.5% higher occupancy rates and ultimately improve return on investment by an average of 6.6%.

Has an asbestos survey found crumbing asbestos containing materials or asbestos in your roof?

This can be a serious health and safety issue, if deteriorating asbestos has been found then there is only one solution, removal and a re-sheet. If the asbestos containing material is in good condition, it can actually be left in place, and in this case an over cladding solution can be used. However, it is important to remember that the asbestos containing material must be clearly identified on the building and recorded in the building log book to prevent risk of accidental exposure on future building work.

David Taylor – Refurbishment consultant at Corus Colorcoat^®

The introduction of Energy Performance Certificates (EPC’s) has seen a real change in attitude towards building performance and they should be recalculated after any major refurbishment project. If the refurbishment includes a building fabric upgrade which has been undertaken correctly, an EPC should show a vastly improved energy rating, making the building much more appealing to potential buyers.

A recent McGraw-Hill study found that thermally efficient buildings command 3% higher rental rates, an average increase of 7.5% in building value, deliver 3.5% higher occupancy rates and ultimately improve return on investment by an average of 6.6%.

In addition to this, the government has announced legally binding carbon targets as part of the 2009 budget. As a result, building owners, property managers, building contractors and architects will have to ensure that their projects are meeting these targets. This will focus the interest of potential buyers or tenants, who will be looking to ensure that your building meets both current and future regulation.

A refurbishment that includes a building fabric upgrade can increase the energy performance of a building by up to 75%, therefore reducing the ongoing operational costs that heating, lighting and cooling create. Any tenant or buyer looking to rent or purchase your building will take energy bills into consideration, so the lower you can make these costs, the more appealing your property becomes.