Now that we have had a chance to get used to and work with the Part L change that came into effect from June 2022, and as construction completes we’ve started to receive requests for as built calculations on those Regs, it’s a good time to bring a few things to your attention.
As Built calcs are the most important of the calcs we undertake as they are representative of the actual constructed building, and the basis for the Building Control submission and EPC.
During the design work a lot of time is taken to establish a spec that initially passes so that its known what to build.
The as built calc should therefore be an update of that design calc and also take into account some information that wasn’t known at the time, ie a confirmed air test result.
The as built calc and EPC are legal documents, so they must be as accurate to reflect the as built building, as such here is some guidance I hope you final helpful:
Every single piece of input into the SAP calc must be verified at completion. To enable this I have produced a detailed As Built checklist that contains directions and guidance for all the information that is required.
Some of this, if provided at design stage, for example, wall, roof and floor builds ups, if unchanged and I have already calculated their u values then all that is required is confirmation that nothing has changed.
If however, some of those construction details were not provided and we used target u values, or a construction has changed during the build, ie a different insulation produce was used, then the construction build up must to be provided at the as built stage so I can calculate their u values. If I can’t calculate it, a default must be used.
Other than construction details, all other information must be supported by some third party documentation.
Windows and doors will need a certificate or other proving their u value and solar g value
Thermal Bridging – no doubt you are aware of this part of the input, probably the most confusing or it all. In a nutshell – thermal bridging must be input into SAP. We measure the various junction lengths, ie wall to ground floor, and input the length, together with the psi value for that junction. The psi value is the heat loss through that junction as must be verified for the type of junction from a known source. So for example, thermal bridging details are provided by some insulation manufacturers, or we can compile one from approved sites like Recognised Construction Details, or they must be bespoke calculated. We can use a few default psi values, but in no way can we use all default psi values, to do so would result in a fail overall. These psi values are usually supported by on site checklists, or a calculation report. At As Built we must have either a copy of those calculation report, or signed on site checklist, supported by you inputting the info on the as built checklist.
Commissioning documents, MCS certs etc are all required for the heating, hot water, renewables and mechanical ventilation.
Other items like the lighting and showers also need written confirmation.
A lot of the input into the as built calc requires commissioning certificate numbers, and details of the who the installer is.
I can’t accept the boxes on the checklist stating refer too… The boxes must be completed so I can make a detailed check accurately and efficiently.
If a heating or mechanical ventilation product is not listed in the Product Characteristics Database, a database maintained by the BRE that includes 1000’s of products that have been tested by them and the performance values confirmed, then it cannot be input into the SAP calc and the only option is to input the SAP default for the particular product.
Invariably this will result in a fail overall or as a minimum a fail for the particular system performance.
Under no circumstances can a substitute product, no matter what the supplier or manufacturer states about its performance, be used in place of the actual installed product. Its important to therefore to check with us at the earliest opportunity that the system you are proposing to install is in that database.
There is also now a photographic evidence file required of various elements taken throughout and at completion of the build. This file is an important part of the as built checks and is required by Building Control. Guidance for the details required and the format is on the attached. There are also on line resources where you can download an app to collate this info, see below.
So far the photographic files I have received have been variable in their quality to say the least. Following feedback from audits, from here onwards, unless a file in in the format as detailed in the attached I cannot accept them unless I have written confirmation from Building Control that what has been submitted is acceptable.
https://www.mysitewitness.com/
Incidentally – I get loads of Electrical completion certs, but I’ve never asked for one and its not listed on the as built checklist. Please, don’t sent me what you think I might need, but send me what is listed on the checklist.
Without the above documentation I can’t complete the as built calcs. The As Built checklist if completed fully and the additional documents are provided it makes the as built checks straightforward and ensures nothing is missed. If boxes are just ignored or the required documentation not supplied I can’t do my job and there will be a delay in getting the final certificates.
Due to their importance and legal status as built certification is the most important part of the SAP process, and as such I will only complete the checks once I have received all the information required – the As Built Checklist completed fully, the photographic evidence file, and all the documents noted as required on the As Built Checklist. This ensures I can access the SAP file and work systematically checking all the information off in one session, meaning that its far more likely to be as accurate as possible.
