Party wall options for a terraced house full-width dormer

1 Jul 2020
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United Kingdom
We are planning a loft conversion with a full width rear dormer, which is very common in our area. We've had mixed views about how to deal with the party wall and so I'm seeking some wisdom.

The first option is to build inside the boundary with a typical dormer with a timber frame. All the loft conversion companies we've spoken to have advocated for this option.

The second option which a neighbour advocates is that we extend the existing party wall up between the houses. He is also planning a loft extension where his next-door neighbour has an existing full width dormer that was built in their boundary, and it has caused them some issues considering how to join onto that. The loft conversion specialists assure us this should be easy, but my neighbours is experience is that it isn't at all.

Our next-door neighbours are also considering loft extensions in the next few years, so we want to take an option that will make it easy for them too and leave us with a high quality build and avoid any maintenance issues. We're leaning towards the second option, but that is also more expensive.

Any input appreciated!
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I suspect your neighbour advocates the second option because when they build theirs it makes it much cheaper for them because you're paying to extend the party wall!

You need to do what works best for you and is within your budget , not spend more money on yours to make it cheaper for your neighbours
@sircerebus666 thanks for the reply. The neighbour advocating it is actually due to complete their loft conversion before us. They have had a lot of difficulty figuring out a design with their neighbour on the other side (who build a loft extension right up to, but not using, the party wall). We're actually trying to decide for the neighbour on the other side of us, and trying to make a decision that doesn't mess up their conversion in the future.

In terms of cost, the one silver lining is that if we do build up the party wall, then when our neighbours make use of it in the future they'll need to pay us 50% of the build cost to make use of it, so at least we won't bear the full cost.

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