Asbestos Roof Overcladding
If you cannot afford to replace your asbestos roof, or if coating isn’t viable or not preferred, the next most cost effective solution is to over-clad the existing asbestos roof with a modern metal profile.
Depending on budget, it is often desirable to also consider over-cladding asbestos wall profiles to give a complete face-lift and add value to an older property.
Usual health and safety practices apply and regulation scaffolding adds a considerable amount to the cost of the job. It’s therefore often more cost effective to over clad an entire roof than it is to replace blocks of failed sheets and sky lights.
Some roofing contractors will prefer to conduct patch repairs to cracked and damaged asbestos roof sheets, but this is usually a false economy, because once problems begin to occur, they tend to recur on a regular basis, which is good for them, but not for you.
With an over-cladding system, the original asbestos cement roof sheets remain in place and new skylights are usually installed to replace the old ones which are usually delaminated and discoloured.
The addition of new roof lights can make a significant difference to the amount of light that enters the building and will often result in decreased energy usage.
To fix the new over-cladding, a grid is usually placed over the existing roof and new metal roof sheets are fixed to it, along with new roof lights, fixed down with self drilling fixings, which are fitted with sealing washers and protective caps. Insulation is laid between the old and the new roof to prevent condensation build-up and of course, to provide additional thermal insulation.
There are several things to consider about over-cladding;
- The original asbestos cement roof remains in-situ therefore, you will always have an asbestos issue, though this shouldn’t be a problem.
- You may require planning permission from your local authority, since the roof will be higher than originally intended.
- The local authority might specify a higher level of insulation than normal to meet emission targets – other building regulations might apply.
- The existing structure might not support the increased weight of an over-cladding system, so structural calculations will be required.
- Provision might need to be made to increase drainage capacity since water runs off a metal roof much quicker than an asbestos roof.
- Building Regulations & Planning Permission adds to the cost.
Costs of Overcladding Asbestos Roofs
The “headline” price for over cladding asbestos roofs is generally in the region of £40 per square metre.
However, this rarely takes into account the additional cost of roof lights, the actual fixing system, health and safety considerations and insulation.
The “per metre” budget cost is actually nearer to £60, but this could increase depending on the need for roof lights, since these usually have to be replaced in the original asbestos cement roof as well as incorporated into the metal profile.
More complex roofs could easily reach £70 – £75 per square metre for overcladding.
In addition, the gutters may also require upgrading with a lined system to account for increased water flow from the metal profile cladding, which is considerably faster than off a fibre cement alternative.
In terms of health and safety, we recommend that perimeter edge scaffold is employed, along with walking boards with handrails where applicable and the use of a satisfactory fall arrest system, usually internal netting, safety harnessing or other recognised safety devices.
We will be pleased to discuss your requirements and provide you with options for over-cladding depending on your own circumstances. A price estimate can even be provided over the telephone with no obligation whatsoever. Once you have an initial indication of budget price, we can arrange for a contractor to visit site and provide a more accurate price quotation.
If you would like to discuss your options, please call us on 0121 709 5352 (Mon-Fri 8:30am to 5:30pm only please).