Orlit Houses on Hatfield Close in Mitcham Surrey 2015

Orlit House structural report gives all clear – received from Circle Housing

Circle Housing’s regen team have finally released the structural engineer’s report into the Orlit Houses. The conclusion is below:

“8.6 Based on the observations and concrete testing carried out to date, the Orlit houses appear to be consistent in much of their construction with that described in the BRE Reports from the early 1980’s. There have been no structural engineering concerns identified however and the concrete frames, where investigated, are in a reasonable structural condition. The main concerns highlighted with the BRE research related to concrete beams on flat roofs. The roofs of the Orlit houses at Ravensbury Estate are pitched. It should be recognised however that this conclusion is based on only a limited amount of investigations within a small proportion of all the Orlit houses.”

“To extend the useful life of such buildings it is therefore important to have an effective maintenance regime in place to keep external finishes in good order and to limit potential for water ingress.
8.9 It is therefore important to keep gutters and downpipes clear for debris so they can work effectively.”

Suffice to say that the conclusion of this report illustrates what residents have said all along, that there is nothing wrong with the structure of the Orlit Houses.

Circle’s regen team will have priced the remedial works however, and will use this in their pursuit for demolition.

The Circle Housing regen team probably consider the structural condition of the houses as secondary to the residents survey which they have spun to suggest people are in favour anyway. Having received their board’s permission to move ahead, they probably consider this much of a muchness.

It should be noted that the main report is dated March 2015.
The full conclusion is at the bottom of this article.

Ravensbury Residents Association

Orlit House structural engineering report page 1
Orlit House structural engineering report page 1
Orlit House structural engineering report page 2
Orlit House structural engineering report page 2

Conclusion in full:

8.0 Concluding Remarks on Condition of Orlit Houses and Extending Their useful Life
8.1 The usual approach of dealing with existing buildings is to assess them and to address issues (by way of repairs) which are highlighted as a result of that assessment. Such an assessment considers the quality of the original design and construction, how the structure as been altered, if at all, and the condition of the building fabric. The strategy for repairs needs a discussion with the building owner as there is often a balance to be made between the costs of repairs and the building owner’s expectations of how they want the building to perform.
8.2 The Orlit houses need to be considered slightly differently in that this type of proprietary construction has already been subject to concerns and thorough investigation by the BRE elsewhere in the UK. They have also been identified as defective.
8.3 However, if the reported defects from the BRE report can be proved to not be prevalent in the houses specifically being assessed, the historic concerns should not affect the approach to how the useful life of the building is extended.
8.4 The crucial point here though is how much investigation and appraisal is required to demonstrate this. Whilst the requirements of potential mortgage lenders and warranty providers such as NHBC cannot be commented on at this time, it is likely they would require a very thorough structural appraisal of the majority – or even all – of the Orlit houses to be carried out before the buildings can be accepted by them as having a ‘clean bill of health’. Such an approach however would be very costly and disruptive, not only as it would have to consider most (or all) of the houses, but also because the investigations within each house would probably need to be far more extensive than has been possible to date. There is also a risk that some houses may be shown to have unacceptable defects and so do not ‘pass’ the test.
8.5 If the houses were to be retained for rent only, and a NHBC warranty was not necessary, then the extent of further structural assessments required may differ from what potential mortgage lenders and the NHBC require. This point needs further discussion with the interested parties however to understand their expectations.
8.6 Based on the observations and concrete testing carried out to date, the Orlit houses appear to be consistent in much of their construction with that described in the BRE Reports from the early 1980’s. There have been no structural engineering concerns identified however and the concrete frames, where investigated, are in a reasonable structural condition. The main concerns highlighted with the BRE research related to concrete beams on flat roofs. The roofs of the Orlit houses at Ravensbury Estate are pitched. It should be recognised however that this conclusion is based on only a limited amount of investigations within a small proportion of all the Orlit houses.
8.7 If the conclusions reached from the assessment of the 4 Orlit houses were to be reflected in the other 68 properties, then the main issues to consider are linked with the effects of water ingress and the cladding panels.
8.8 Water ingress can affect the condition of the roof timbers through beetle infestation or decay. As has been seen with the entrance canopies, water ingress can also cause deterioration of concrete elements, especially where reinforcement is allowed to corrode. To extend the useful life of such buildings it is therefore important to have an effective maintenance regime in place to keep external finishes in good order and to limit potential for water ingress.
8.9 It is therefore important to keep gutters and downpipes clear for debris so they can work effectively.
8.10 The cladding panels need to be made good where the joints in the cladding panels have opened up. This will reduce the potential for water ingress. The spalled and cracked corner panels also need
replacing and will require additional restraint to tie them back to the structure behind. This will take the form of remedial wall ties and these may also need to be introduced around window and door
openings where there are currently a lack of ties. Such an approach will require both a visual and a radar survey of every elevation to be carried out.
8.11 The strategy for repairs to the cladding panels needs to be coordinated with non-structural matters to improve the insulation to the elevations. The cavities which are currently filled with insulation are potential encouraging water to become trapped in the building. Options here include removing the cladding panels so that the insulation can be removed or over-cladding the building with a new rainscreen
8.12 Similarly the cracking to the window frames should also be made good.
8.13 Although not significant structurally the concrete entrance canopies and support where deteriorated should also be made good and/or removed and replaced with new canopies. The junction of the canopy with the elevations needs to prevent water draining back on to the elevation.

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