Building up against a neighbours cavity block extension: fire proofing

antiskeptic

I'm looking at building a single storey, full house-width extension to the rear of a two storey terraced house.

The neighbour on one side already has such an extension, which sticks out further into his garden than I want to go. His extension's side wall is built on the party line: about 1/3 of the wall thickness over my side of the party line, 2/3rds over his side.

It makes sense for me to utilise this side wall as the side wall for that side of my extension. The neighbour is okay with the idea.

I gather cavity block isn't considered up to spec when it comes to fire separation. If that's the case, can I upgrade it with fireproofing material before doing my internal finishes?

Calahonda52

is the party line down the middle of his wall?

antiskeptic

Calahonda52 wrote: »

is the party line down the middle of his wall?

The wall is about 1/3 over my side of the party line and 2/3rds over his side.

I've edited the OP to clarify a straddling the party line

Calahonda52

Thanks, and what are you going to do at the other side, if its full width?

This
http://www.irishstatutebook.ie/eli/2009/act/27/enacted/en/print#part8-chap3

springs to mind, may not be relevant: I have invoked it on jobs... as you will see, consent is not required but there are procedures

Victorian House

How were you going to insulate on your side if it is a cavity block construction? The insulation would be on your neighbours house keeping him warm - presumably you will want to add your own insulation?

Take a look at isover products which may be of help: https://www.isover.ie/applications/separating-party-walls

antiskeptic

Calahonda52 wrote: »

Thanks, and what are you going to do at the other side, if its full width?

Block on flat 50/50 straddling the party line. Neighour on that side would aim to use that wall for his own extension(the boom is back!)

This
http://www.irishstatutebook.ie/eli/2009/act/27/enacted/en/print#part8-chap3

springs to mind, may not be relevant: I have invoked it on jobs... as you will see, consent is not required but there are procedures

Not required for..?

The neighbours are pretty okay with plans and we'd have a written agreement in place covering the fact of use of party walls.

But I'd like to ensure I'm doing it right by fire regs on the cavity block wall side of the extension.

Is it a case of adding fire resistant plasterboard to the wall?

antiskeptic

Victorian House wrote: »

How were you going to insulate on your side if it is a cavity block construction? The insulation would be on your neighbours house keeping him warm - presumably you will want to add your own insulation?

Insulated plasterboard (more to prevent losses to ground and through top of wall.

I was wondering whether adding firegrade plasterboard to the walls (whatever thickness required). Then services down on the face of that, then insulated plasterboard on top of that.

It's suitable fireproofing I'm keen on getting insight on.

Gumbo

Cavity blocks don’t pass Part E (Sound) either as far as I’m aware. So on top of the fire issues, you also have the sound transmission issue.

antiskeptic

kceire wrote: »

Cavity blocks don’t pass Part E (Sound) either as far as I’m aware. So on top of the fire issues, you also have the sound transmission issue.

Fair point. I had a look at part E and tripped across what get's done in timber framed construction. Which leads me to suppose that

a) sound proofing can be carried out (copying timber framed solutions)

b) fireproofing can be carried out (as it appears plasterboard is the barrier in that case)

What do you think?

Gumbo

antiskeptic wrote: »

Fair point. I had a look at part E and tripped across what get's done in timber framed construction. Which leads me to suppose that

a) sound proofing can be carried out (copying timber framed solutions)

b) fireproofing can be carried out (as it appears plasterboard is the barrier in that case)

What do you think?

If the Plasterboard manufacturer has a cert outlining that it can be achieved using cavity blocks then you are covered as long as its fitted as per their diagrams and DoP/Agreement Cert.