25 degree rule

[Deejay]

I've very roughly worked out how the 25 degree rule will work with our planning application for a replacement dwelling.  The dwelling is L shaped with the gable end of the garage with granny flat over being nearest to the boundary wall at the bottom of our neighbour's garden.  The garage width is 6 m with an apex roof.  Clearly this is not as wide as the house (which is not affected by the 25 degree rule) - does the fact that the garage is only 6 m wide affect how this rule is worked out ie 25 degrees from middle of ground floor window of neighbour's house, measured upwards.  I'm assuming with a narrower obstruction ie garage gable end, there will be less loss of sunshine/light - or have I got that wrong.   I want to do right by my neighbours and would not want to obstruct their light but am trying to work out what height we are allowed.  I should be very grateful if someone could explain this to me.  

[DevilDamo]

Any plans to see/review?

[Deejay]

I'll try and upload the location plan but this will depend on whether my scanner is working so may be some time.  I wish I was more proficient with technology!  Anyway, thank you for your interest. 

 

[bassanclan]

Do you mean the 45 degree rule?

[DevilDamo]

1 hour ago, bassanclan said:

Do you mean the 45 degree rule?

The 25 degree rule is a ‘thing’…

 

https://www.firstinarchitecture.co.uk/designing-for-daylight-45-and-25-degree-test/

Edited May 22, 2021 by DevilDamo

[Deejay]

The Planning Officer for the pre-planning application said we had to comply with the 25 degree rule and there is a way of measuring this, which I have roughly done.   This will restrict our garage height considerably and we have to accept this.  However, say one was only building a 2m x 2m square tower for example then the same 25 degree rule would apply but there is nothing to take into account that the "obstruction" causing the light reduction is only 2 m wide.  In our case the garage gable end is 6 m wide with an apex roof, and I wondered if anyone knows whether it says anywhere whether this is taken into account.  

 

I believe the 45 degree rule is for extensions but I'm not sure whether this, or something similar, would be allowed to be used if the obstruction is of a smaller width.