Installing fire break walls in loft

Hi, I'm about to embark on boarding out my loft for light storage, and felt that it would be a good time to also remedy the lack of fire breaks in my mid terrace house. I cant seem to find any advice about firebreak specifications or building regs so would be grateful if I could be shown in the correct direction. I cannot decide whether to build up the tops of the dividing walls (visible) with block and mortar (if so is there a specific specification? I was thinking fixing firfix to the dividing chimneys for e.g.) or with stud and plasterboard (again what is the spec). I feel the latter would be easier but the former may be more sturdy/soundproof. Any advice on which to choose and how to go about it would be gratefully received. How do you fix to the roof if the rafters dont line with the wall - can you use noggins in wood? Many Thanks, Richard.
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On Sun, 30 Dec 2007 15:12:50 -0800 (PST), a particular chimpanzee,
produced:

Are you doing this in conjunction with your neighbours? If not it's at least best to warn them what you're doing. Strange knocking noises directly above their bedroom ceilings may get you complaints via Environmental Health and Building Control. It's also going to be a lot easier and more effective if you can get to both sides of your new party wall.
So long as you're not making the situation any worse in terms of structure or fire safety than before, the work is not subject to Building Regulations. The Party Wall Act may have a bearing on what you're doing, but this is a civil matter between you and your neighbour(s).
Masonry is obviously easier to do from one side, is more robust, and will resist sound transmission better. Lay your blocks flat rather than trying to lay two leaves, make sure that they are well mortared to avoid air paths, and fill the space between the wall and the felt/covering in Rockwool.
If you want a party wall in studwork that will form an effective sound barrier, it needs to be done as two separate stud walls, each independent of the other, lined with 2 layers of 12mm plasterboard on each side. A single stud could be used, but it wouldn't form any serious impediment to noise. It would also not help you very much if there was a fire in your neighbours unless you could plasterboard their side of the stud wall (if they have a fire, the timber on their side is unprotected and would burn through, collapsing the stud wall). As you say, you can noggin between the rafters, but fill the space over the top with Rockwool.
If it's just life safety you're worried about, a third option could be a 'cavity barrier' such as Rockwool Fire Blanket (http://www.rockwool.co.uk/sw55784.asp ).
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Many thanks for your helpful reply - heres the answers inline..

Yes
The party wall is likely 4in single skin brick (possibly 9in although unlikely), so I'd be building ontop of this if that changes opinion. I would therefore imagine blocking on edge as per usual, but with single skin? Would you fix to the chimneys with wall ties to increase strength?
Is there a more effective way to seal to the slopes of the roof than rockwool - would you bother cutting angled blocks to fit the spaces, or is this overkill?

As someone else pointed out, I dont really need soundproofing come to think of it - just the physical barrier for security and the fireproofing, so I guess fireproof plasterboard on both sides of a single skin stud would be effective. Would you bother installing anything into the stud cavity??
What would your personal choice be in this situation - stud or block? Which spec blocks would you use btw.
Are there any alternatives to heavy chipboard panels for the floor - stronger but lighter would be the ideal (whilst still reasonably priced of course!)
Many thanks for all your help..
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Richard wrote:

I wouldn't... you say security is a concern: if you consider that there's a risk of a scrote breaking into your neighbour's house and climbing up into his roofspace in order to enter your house, do you think a couple of sheets of plasterboard will impede his progress for more than a few seconds?!
Also, I don't know how big your loft hatch is but that might well be an issue when it comes to taking sheets of plasterboard up there; at least you're going to be restricted to using small bits only.
David
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Yes.
Good point. Probaly best to use blocks if they can be eaily taken up.
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Doctor Drivel wrote:

I remember enlisting the help of one of my sons with a renovation project a few years ago, and set him on to demolishing a stud partition. He was able to climb through it in a matter of minutes - mind you, he was only 9 at the time.
David
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To climb into a loft then through a stud wall and then down into the house below you must have something worth getting. If it is that valuable then it shouldn't be in the house.
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Really more a privacy than full on security issue then I guess.

Hatch is about 2.5ft square so pretty big by all accounts I guess. Thanks.
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Do you mean there is no wall in the loft between each terraced house?
First fill the gaps between the joists with insulation. On top of the joist install slabs of thick ridgid foam. On top of that the boards. The secews go through both and into the joists. This elimintes cold bridging through the joists and increases the insulation thickness without using extra joists.
It is best to lay a vapour barrier on the loft floor above the plasterboard. This is poly sheet. This will prevent water vapour entering and condensing in the loft. Also seal up any pipe and wire holes in the loft.
Two ways to do the walls:
1. Extending the wall up into the roof space is best using lightweight blocks. On the top of the existing walls use a course of highly insulated blocks to reduce heat loss through the wall into the cold roofspace.
2. Use wooden or metal studding and Fermacell boards. These boards only need one layer and will conform to fire regulations. <http://www.fermacell.co.uk/
You may want to insulate the sloping roof having gone this far. Make sure any air gaps are clear.
You mention soundproofing. Why? These walls are in the loft. Soundproofing will be on the loft floor via the insulation and boarding.
Also fit a sealed and insulated loft hatch.
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Thanks for our advice - a few Q and A's on what you said..

Yes
I like this idea, but...bearing in mind that I will be walking on this to a computer that I intend to permanently site up there, will the foam compress under the boards or spread the load effectively enough? I imagine the foam would take up some uneveness in the joists?? - this would be good, as being an 1863 house, the joists are a bit up and down. I guess the noise will be reducred too? And the foam weight is negligible as I want to minimise the extra weight involved when boarding out to maximise what I can safely put up there?? What foam do you recommend and what thickness - is there a good value brand available (do you mean Kingspan type stuff?) as I'm on a bit of a budget for this?
I intend to remove the filthy old existing insulation and replace with new. This process will involve vacuuming out the years (inches!) of accumalated dirt before I start. Does anyone see and problem with this approach?
Also how do you approach insulating deep into the eaves - I thought there was plastic moulded formers available to finish the insulation into the eaves (triangle-shaped which the ends of the insulation run into), but cant find them anywhere on the web.

Any ideas for board material, stronger and lighter than chipboard (to reduce the stress on the joists/roof?). FYI the ceiling joists are not resting on the wall plates, but are constructed so that they are fixed to the (substantial) rafters which sit on wall plates. This means there are sloping edges to the ceiling that I havent yet worked out how to insulate behind the lathe and plaster, due to lack of access - any ideas how to finish these?

Do you mean so it goes up and down over the joists, or just strips between the joists? (presume the former)

Any brand recommendations?

Any thoughts for v. lightweight boards to go over the rafters insulation - hardboard possibly??

Totally agree!
Many thanks for your ueful post!
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some wrote:

but shouldnt the vapuor barrier be at the warm side, which is underneath the insulation?
or am i wrong again...
and why are you insulating the floor if the loft is to be used for computering, shouldnt the insulation go above the room?
v ery interesting, i should put fire walls into this old house/..
george
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Yep.
Yep. Insulate the roof. Have Rockwool insulation in the floor to reduce sound.
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Thanks. The loft isnt going to be used as a room as such - floor isnt up to that, I just want to put a noisy PC server up there with wireless anda small LCD for occassional access, scanning etc., as we dont have room in the house proper any longer. TIA.
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Watch the temperature if you do that. The ambient can easily reach 40+ degrees in the summer, and the internals of the PC up to the 50s.
Ideally, some external ventilation would be good - e.g. add a means of ducting and fan blowing cooler air from the house to the intakes of the PC.
As a minimum, make sure that the disk drives are well spaced out and that there is a fan in the case explicitly blowing air over them. Lifetime of hard drives is significantly reduced with increasing temperature and ideally you want to keep them below 50 degrees on the cover side of the drive.
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Richard wrote:

[...]
I'm puzzled by the construction here... how come there's no wall between you and the neighbours up there, but apparently there *is* a finished lath and plaster ceiling over the rafters?! Or am I missing something?
David
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That used to be a common method of construction in terraced houses - a cost saving measure.
Originally, many didn't have loft hatches because there was no plumbing up there - remember that cold water was a tap in the kitchen and hot water was a copper followed by filling the bath from that.
Hatches were added when roof tanks were installed, but often people didn't bother to brick up the partitions - I suppose because they trusted their neighbours.
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Sorry if I misled you - it is an unusual construction I think. For clarification - the roof rafters are not covered at all. About 4 ft from the end of each rafter ( poking into the outside, the ceiling joists are attached. This gives nice high ceilings with sloped egdes towards the walls. It is only this (approx 2-3ft) of the rafter that is lath and plaster (on the slope) then it flattens to the ceiling proper, formed by the lath and plaster on the joist. The remainder of the rafter goes into the loft, uncovered, as a continuation of the rof. Hope this helps!
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Richard wrote:

Ah, OK - got you now! Yes, sounds quite similar to my own home actually, except that in mine the slopey bits are more like 6-8 ft rather than 2-3 ft!
There was a thread a few weeks ago by someone who wanted to insulate a sloping kitchen ceiling where this was discussed at some length - can't find it now I'm afraid but maybe you or someone else can?
David
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Richard wrote:

Remember Richard,
If you are working on a party wall(s) to build them up to roof level as a fire break, then you need to comply with the Party Wall Act with regards to legal notices, supervision etc and to also inform your local building control department.
Also, to give even a semblance of fire protection, a stud partition will have to be plasterboarded on both sides to at least an 1" thick along with a fire resistant sheet material under that - otherwise it is next to useless, other than to stop the neighbours wandering around in your attic.
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will do many thanks. Anyone have suggestions to alternatives to chipboard for the floor and hardboard for the rafters btw??
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