RE: Self Build and BNG Exemption: How to secure self build permissions - Public forum - Planning Advisory Service (PAS)

I am a policy planner in an LPA. We are currently considering how best to secure planning permissions for self build in light of the fact that self build homes are exempt from Biodiversity Net Gain requirements.

When an applicant submits an application for a self build home, they are exempt from BNG and therefore do not need to submit the survey information required to set the BNG baseline. If planning permission is granted, there appears to be a risk that the permission could be sold on and not built out as self build, or that it could be built out as a self build home but then immediately sold on. Without some way to secure the permission as being solely for self build, this appears to be a 'loophole' for getting out of delivering the BNG that would otherwise have been sought. Furthermore, there would then be no way of retrospectively asking for the BNG, and no way of knowing what the BNG baseline would have been as the applicant was not required to provide survey information.

I am interested in knowing how other LPAs are considering dealing with this issue of how to secure a self build permission?

Our current thinking is that it appears to give rise to a need for a s106 agreement (or a UU?) for every self build permission, with the s106 requiring that the home be delivered as self build, and either not sold or rented out for a period of time (probably 3 years to align with the requirements for CIL exemption), or that a financial amount equivalent to an average figure for off-site BNG for a single dwelling be paid in the event that it is sold or rented out before the end of that time period.

Some further thoughts/reservations about this approach:
- The financial amount would probably need to be based on quite a high average so as to discourage this as a strategic route particularly for sites with a high BNG baseline.
- This would create quite a burden for the LPA in terms of monitoring and enforcement. (Would it be excessive to require applicants to pay the average off-site BNG amount up front and then for it to be paid back to the applicant after the home has been built out and retained as self build for 3 years?)
- It feels quite onerous to have to do a s106/UU for every single self build permission. Could this be mitigated by having a standard pro-forma UU that the applicant could simply complete and submit? Does anyone have an example of one?

Apologies for a somewhat rambling question, but grateful for any views or examples of how best to secure self build permissions in light of self build being exempt from BNG, and any thoughts on the possible approach outlined above.