We hired a construction engineer to inspect the slab before the concrete is poured. Here is his report:
The site inspection was carried out on Wednesday 9 December 2020.
During the site inspection the proposed waffle slab layout was inspected. As part of the site inspection a number of photos were taken. The aim of the site inspection was to identify any areas that need to be addressed prior to the pouring of the concrete.
The following observations were made that need to be addressed prior to the placing of the concrete.
1. In relation to the 800mm deep bore piles that are specified locations details on Drawing S05/28 were not inspected as access to them was impossible. It is assumed that the depth and founding material of the bored piles had been inspected prior to the placement of the concrete and were found to be in compliance with the design.
2. The 2.0m long 3-L11TM located front right hand side corner of the garage was measured and was found to be 1.8m instead of the 2.0m specified on the design drawing. At other locations the length was measured to be 2m as specified on the drawings.
3. Concrete cover at numerous locations of the slab would need to be addressed as the specified concrete will not be achieved. The main reasons for this is due to the undulating pods, reinforcement touching the foam pods, inadequate placement of bar chairs to support the reinforcement above the foam pods to ensure reinforcement encapsulation by the concrete. At the rear left hand side that is inadequate concrete cover provisions for the top mesh adjacent to the formwork. Ie the reinforcement is too close to the formwork.
4. The are numerous foam pods that have been placed at and angle and accordingly the steel reinforcement is not adequately supported. It is expected that if this matter is not addressed there will be greater variability in the location of tile reinforcement within the concrete slab and will
result in non-compliance.
5. It was identified that the formwork at the rear left hand side appears to be incomplete. It is expected that given the height of the edge beam and the lack of lateral support at the bottom of the edge beam, when the concrete is poured and vibrated the concrete will escape into the surrounding area. It is recommended that the concreter review the formwork at this location to confirm that there will be no issues with the placement of the concrete.
6. The sewer pipes were identified as not being lagged by the plumber. These would need to be addressed.
7. In general the a number of foam pods appear to be inadequately supported and it is expected that these will move with the placement of the concrete.
It should be noted that levels were not checked and it is expected that the builder has undertaken it level checks to ensure that the final levels of the slab will he within the required tolerance limits.
It is also noted that the relevant Building Surveyor is required to undertake his own site inspection and sign off the pre-work as being in compliance with current regulations prior to the placement of the concrete.
It is recommended that the above items be attended to prior to the placement of the concrete.
We asked the builder to address these issues.