Should I Consent to ‘Special Foundations’?

by The Party Wall Surveyor

Question

My neighbour is planning to build a basement, I have been asked to sign a notice of consent for special foundations.  I asked my surveyor the difference between foundations, he stated the only difference is special are stronger and I am at no disadvantage by approving this is my neighbours build.  Is this correct ?  If so why would I have to consent?

Answer

‘Special’ under the party Wall Act means reinforced – normally with steel bars. The reason that they require written consent from an adjoining owner is because they are more difficult to alter should you ever need to. This dates back to a time when some foundations were considerably wider (known as ‘grillage foundations’) and really would hinder an adjoining owner’s future plans due to the distance they projected. 

In basement conversions, the underpinning is reinforced to allow it to be slimmed down and take up less space so your main concern would be whether the toe of the foundation will project on to your side of the boundary at a position which may hinder you adding a similar, or deeper, basement in the future.

Your surveyor should have reviewed the foundation design and be able to advise you on this.