Investigating, Reporting & Resolving Roof Issues in Weybridge, Surrey

Wyatt Carruthers Jebb were engaged to investigate and report on water penetration via the flat roofs and parapets and defects to the external cladding system which was cracking in several locations.

// Project Overview

This property comprises three blocks of flats varying between five and six storeys in height.

Construction

The blocks are of concrete frame construction with brick and block outer skin with flat roofs and felt roof coverings and PVC windows.  The blocks were constructed circa 1960 and have been over-clad with an insulated render system which is approximately 20 -25 years old.  The properties had a mixed tenure of both tenants and leaseholders.  The properties had a history of leaks from the roof.

Background

Tenants and leaseholders had reported dampness within the blocks.  Wyatt Carruthers Jebb were initially engaged to investigate and report on water penetration via the flat roofs and parapets which was affecting the residents’ enjoyment of the property.  Wyatt Carruthers Jebb were later instructed to inspect defects to the external cladding system which was cracking in several locations.  The Client had engaged separate consultants to undertake a Fire Risk Assessment of the blocks and intended to incorporate any recommendations within the remedial works package.

Initial inspection

The Client instructed Wyatt Carruthers Jebb Ltd to undertake an initial inspection of the roofs and external cladding and provided asbestos survey reports of the property and copies of the fire risk assessment.  Wyatt Carruthers Jebb Ltd attended site and undertook a visual inspection of the roof.  Areas of the roof and parapet were opened up and the form of construction and defects noted.  Wyatt Carruthers Jebb also inspected areas of the cracked external render. Again, areas were opened up to confirm the form of construction and cause of the cracking.  Reports were prepared confirming the form of construction and defects found with the roof covering, parapets and external cladding together with recommendations for remedial measures.

Design and Specification

Specialist reports were sought from a roofing materials manufacture together with recommendations for appropriate products for the properties to meet with the Clients requirements.

All matters were combined into an external refurbishment and part internal refurbishment project comprising replacement of roof coverings, external elevational repairs, window repairs, external decoration, upgrade of fire doors to flats and lobby areas and repairs to garage blocks including garage roofs, elevations and doors and localised ground works.

Owing to the height of the buildings, provisional sums were incorporated into the specification for elevational repairs subject to remeasure following erection of scaffolding.

Wyatt Carruthers Jebb Ltd were instructed to prepare a specification of works, tender documentation and subsequent Contract Administration of the remediation works through to completion.  The Client arranged for a separate consultant to take on the role as Principal Designer.  Wyatt Carruthers Jebb therefore maintained in communication with the Principal Designer as the design evolved.

Statutory Approvals and Party Wall Matters

The roof works were controlled under the Building Regulations.  This was managed and self-certified by the Contractor via the government approved NFRC Competent Roofer scheme.

The repairs did not alter the pre-existing external appearance of the property; therefore, Town and Country Planning Approval was not required. 

None of the work was notifiable under the Party Wall etc Act 1996.

CDM Regulations

The Client arranged for another consultant to take the role of Principal Designer.  Wyatt Carruthers Jebb maintained communication with the Client and the Principal Designer throughout, providing updates of any risks identified.  The Principal Designer also attended monthly project meetings and any concerns were recorded and acted upon.  The client appointed Principal Designer undertook regular site visits and provided health and safety inspection reports.

Contract Administration and Inspection of the Works in Progress

Works were procured under a JCT minor works building contract with an initial project duration of 19 weeks.  The works were split into three phases (Block1, block 2 and block 3).

During the works Wyatt Carruthers Jebb undertook regular inspections of the site to schedule the works to the external elevations and to assess the progress of the works. 

Problems were encountered with third party telecommunication masts and equipment on the third roof which obstructed the roof repairs and could potentially cause a hazard to health.  Whilst this had been envisaged at the start and plans put in place for the relocation of the masts and equipment, it was found that co-ordination with the operators was difficult, particularly as the relocation required a shutdown of services and complicated engineering by the third party which they had not anticipated.

Tests were undertaken to check safe working zones and the third party operators undertook and engineered design to lift and relocate the equipment.  Further problems were encountered as liquid roofing that had been laid started to fail.  The manufacturers were invited to take samples and offer their advice on remedial measures which were it in action, however, further failures occurred and it was determined by Wyatt Carruthers Jebb that the liquid system recommended by the manufacturers was not appropriate.  Wyatt Carruthers Jebb was instrumental in the replacement of the roof covering having negotiated with the manufacturer and installer and the covering was replaced for a more conventional 3 layer felt covering with walk on mat supplement to two of the blocks without impact on the contract sum.

The effect of the delays was assessed and part of this was covered with and extension of time extending the contract to 35 weeks. 

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