How do I bathroom / kitchen / extension? etc.

We have laminate with a bonded underlay backer on each piece. The underlay is only maybe 2.5 mm thick.
I have not seen any sign of it compacting under load.
Much better than the roll form of foam underlay.

I thought that normally you join them up ? That's what we did at the last house. I haven't looked for the one I've just done.

Yeah, and there’s prob a couple of ways, but they want us to build right up to theirs rather then the usual gap and infill, and they are asking for plans to be updated to show.
The plans by the “architect” are pretty wrong in every possible way but Alex insists they are fine for submitting (which they prob are), no chance of updating either way.
Hopefully it’s just them being nervous/not understanding, they are a nice elderly couple who we’ve had great relationships with so far.

Unless there’s a fire wall between them that ain’t gonna happen

Ohhhhhhhhhhh interesting! That’s a very good point come to think of it (or makes sense).
Do you have any further details?

Won't that change the planning approval? I'm pretty sure that doesn't conform to PD rules. Does get you more space though....

Yeah thats possibility too, he's using his son who has had work done before as an oracle, but in reality neither him nor I know the real details around this and tbh I'd rather have half a foot less space than any dependence on a neighbour.

Get them to pay for the required firewall. Job done.

And the level of service they are asking for (proper architect).
Lovely couple, extremely tight, doubt they will contribute.

I think PD only refers to the requirement for a set back from the eaves of 200mm. So you can build up to the centre line of party wall. Ironically you can't typically get planning permission for this kind of 'full width' dormer - because it looks shit and is much better architecturally to be set in from either side a decent amount. But PD is PD.

If your neighbour's have built up to centre line or close to it they have forced your hand to either - connect your dormer (with adequate waterproofing detail + fire resistance for the new 'party wall' - could be brick but not necessarily) or. set your dormer cheek in far enough for it to be constructed properly and maintained. - so at least 50cm between the tiled dormer cheeks - or thereabouts. This one obviously seriously limits your internal space.

You do see dormers built right up to each other but the construction, waterproofing and maintenance issues are best avoided.

On the other party wall where there is no neighbour's dormer you need to consider if you will a. raise a party wall in brick - allowing them to build a dormer up to it in future, or b. have the cheek finish on the centre line, which will lead to the same negotiation later when someone wants to do a dormer that side.

Dodgy gap you don't really want

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brick wall - proper job - be a nice neighbour

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Join em up

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I wonder how you can adequately fireproof that to the required standard.

But yes, I always wonder how folks would accept putting themselves in to the world of hurt they are going to find themselves in by having dormers butting up to each other but not actually joined.

There seems to be a first mover advantage here - at our old place, the neighbours went into the loft and their dormer goes to the center line.

At one stage we wanted to go into the loft too, and would have needed to either build up the whatever-the-upstand-bit-is-called, or have some awful bodge with flashing over the top to stop crap getting into the gap.

My wife, who was the owner of the property, naively signed the party wall agreement. What she should absolutely have done was to have insisted on her own surveyor. Nothing but aggro because of not doing so.

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this is the way. accept no substitutes

Fireline board and plaster

Solid info as ever.
The builder has only cost up joining with a set back spacer thing, would love a brick wall but defo don’t have the money. Will make sure we don’t go up to the wall either!

Annoyingly this was a solved problem hundreds of years ago with regular mansard roof construction. One house would build up with a party wall, and the rest of the terrace would follow suit, until it was banned at some point.

Don't know why we've collectively decided to rule against simpler party wall agreements and construction, and only allow weird boxes on the the back of the house with current permitted development rights.

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Mansards are so much better than slopy lofts, particularly non-full width slopy lofts. One of the ironies of conservation areas is that they incentivise you to go for a mansard, as you're going in for planning whatever you do.

Presumably in the roof void as well?

Some folks around our way have these, but rear facing only. They look much, much better than the standard box dormer.

There seems to be a first mover advantage here

Well, it means that if you do the same, and have the horrible flashing bodge, then both you and the neighbour put themselves in to a world of hurt later down the line.

I wonder if you could actually prevent them from doing this, even with a surveyor acting in your interests. The best you could hope for might have been to go halves on extending the party wall up.

Friends of ours down the street agreed with their neighbour to split the costs of having it re-done properly when they converted theirs, so that now they have a brick firewall between them.

Oh definitely! I’ll take a bit of irony over bad aesthetics/construction any day.

This is worth a read on policy suggestions (despite its oddly traditionalist and narrow framing), if you haven’t seen it already (which is where I nicked the image from):

https://www.createstreets.com/wp-content/uploads/2021/08/Living-Tradition.pdf

Would be nice to see more like this applied to all buildings, rather than just flat-roof pre-1920s middle class lifestyle statements.