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Property Surveying Blog
Written by Bradley Mackenzie

Party Wall FoundationsThis week we had an enquiry from a building owner in North London who had decided to build a 6 metre rear extension to his property. The proposed extension was going to be located alongside his neighbours’ extension and the building owner wasn’t sure if the Party Wall etc Act 1996 would apply.

We therefore reviewed the proposed work plans on behalf of the building owner and informed him of the necessary Party Wall requirements.

We thought it would be helpful to look at some of those requirements, as in many circumstances they will apply to most proposed rear extensions in built up areas.

When a building owner decides to build their extension up to the boundary line (which is common in most circumstances, as the aim is to maximise the added space), they will be required to serve a Section 1(5) Party Wall Notice upon the adjoining owner.

A Section 1(5) Party Wall Notice deals with a new wall built up to the line of junction, but wholly on the building owner’s land.

In layman’s terms this effectively means the flank wall of the proposed extension will be built up to the boundary line, with all parts of it including; the foundations, the wall, any fascia, gutters and ledges all being entirely on the building owner’s land.

Given the specifics of the building owner’s proposed works, a Section 1 Party Wall Notice will usually be accompanied by a Section 6 Party Wall Notice.

A Section 6 Party Wall Notice deals with the proposed excavations which are required in order to accommodate the proposed foundations… After all you cannot have foundations without excavating for them!

In this case the building owner also needed to serve a Section 2(2) Party Wall Notice upon the adjoining owner, as the proposed construction works would mean the building owner would have to insert a flashing into the adjoining owner’s flank wall to weatherproof the junction of the new wall and the existing wall.

One of the most common sights we see as Party Wall Surveyors is a Section 1(5) Party Wall Notice being served with a concentrically loaded foundation. While this is fine for building control or planning application, it will almost always be flagged up by an experienced Party Wall Surveyor.

Party Wall FoundationsHere at Berry Lodge Surveyors we will usually always ask that the Section 1(5) Party Wall Notice is served with an eccentrically loaded foundation, as we find that by using an eccentrically loaded foundation you can avoid future issues which include

• A future trespass claim from the adjoining owner

• Potentially having to pay the future costs for having the projecting part of the foundation cut back

• Intrusive excavations on the adjoining owner’s property

Although you will most likely find that it is the engineer who designs the proposed foundations, there are a number of key points to bear in mind:

• Make sure the soil has a good bearing capacity

• The width of the proposed foundation should generally be three times the width of the wall it is supporting

• The depth of the proposed foundation should generally be equal to or greater than the overall width of the supported wall

There are many different types of foundations that a building owner or their contractor can use when undertaking the proposed works.   With the foundations supporting the structure above them, it is key to ensure that the right foundation is always used, it is for that reason that we always recommend the foundation is carefully designed to take into account the ‘lay of the land’.

If you have any questions regarding foundations or are perhaps about to undertake construction work and would like to see if the Party Wall etc Act 1996 applies, feel free to give one of our Chartered Surveyors a call, we are always on hand and happy to assist!