Stud wall to roof truss fixing options.

[epsilonGreedy]

During the past few days different experts have recommended two ways of fixing the top of a stud wall to roof truss joists and neither of these methods matched my default assumption on how best to do it.

• Expert A: A carpenter who is quoting for the stud work has recommended fixing the ceiling plasterboard across the whole first floor before he builds the stud walls. He wants to include fixing the ceiling plasterboard in the scope of the job.
• Expert B: Suggested building the stud wall up to a few mm below either the truss joists or the in-place ceiling plasterboard and then using expanding foam to anchor the stud wall to the roof.
• Me: I was expecting the stud wall to be nailed or screwed firmly to the roof truss joists but I have been advised this might lead to creaking sounds.

 

Merging these opinions together I am now swaying towards this revised plan:

1. Build the stud wall frame to say 8mm below roof joists.
2. Squirt in a low expanding foam glue for an squeak free adhesive bond.
3. Plasterboard each room ceiling by cutting the sheets to the studwall frame.

 

Is there a BuildHub best-practice consensus on this subject? 

Edited June 13, 2020 by epsilonGreedy

[Russell griffiths]

Method A is faster for sheeting, less cuts and less wastage. 

Sheet the whole of  the ceiling in probably half the time it would take to cut it to fit between the walls. 

[Hobbiniho]

Yeh option A is the fastest way to do it, you would be mental to fit all the internal partitions first then try to cut all the plasterboard to fit around them, as you will need a massive amount more dwangs in the celing to catch the ends of the boards you are  making a massive amount of work for yourself, obviously load bearing walls will need to be built first.

 

I have never seen nor heard of fixing stud walls in with expanding foam that to me sounds lik a commpete bodge to me

[tonyshouse]

+1 ceiling first, some noggins where Walls parallel to trusses 

 

nails for to fix everything 

[nod]

I worked for a house builder that would ask us to nip in each plot for an hour at the end of the day and board the ceiling's ready for studs 
Grate for plasterers not so for electricians and anything that has to go up there 

 

I never board onto trusses Often up and down and running out 

Not much of a target for the boarders to hit as you point out a pain to stud 

What I do each week is counter Barton with 75 x 25 timber or or metal top hat 

 

[ProDave]

I will counter this.

 

There are in fact only a few non load bearing internal walls.  I built all of them myself first, before the floor went down or the ceiling went up.  so yes a lot more cutting of floor boards and plasterboard and more dwangs to catch the edges.  But nothing creaks or groans.

 

As an electrician I HATE it when the joiner wants the ceiling up before the internal walls go in.  It usually ends up asking them to mark where the wall will be so I can leave cables hanging out of the ceiling. Then the wall arrives and it is not where marked, so you have to cut holes in the ceiling to thread the cables out where they really should be.  It always ends up as a dogs breakfast for everyone, all for the sake of not cutting the plasterboard edges.

[epsilonGreedy]

[Edit: There was ] A clear consensus plus pro+ tips from @nod

 

I forgot to say:

• I have an L-shaped hipped roof design and had a hunch there might be some sag with such a roof hence I liked the idea of a stud wall transferring some of that sag load down to the ground floor block walls. My thinking was that it would be best to transfer that force direct from rafter to studwall wood rather than through in intermediate 15mm shim of crumbly plasterboard. The roof cover is slate so maybe I am overthinking roof loads.
• Expanding on point-1, I am considering ordering attic trusses for the central 4m ridge of the main hipped roof, this will create a useful attic storage area 4m x 3m however with a ridge height of 1.7m this 4m x 3m area will never be converted to a room. Given a possible cumulative attic storage load of say 200kg I thought it best to fix the stud wall direct to rafters. 

Does this additional info change the advice?

Edited June 13, 2020 by epsilonGreedy

[PeterW]

Stud walls up tight  to the ceiling trusses and the headers sprag nailed through both sides of each side of the ceiling joist.
 

50x25 counter battens to suit your boards then first fix electrics.  
 

Then board the ceilings then the walls. 
 

Only time I’ve seen foam used was when the there were top hats fitted and they wanted an additional stud wall and it was used to fill the void. 

[nod]

41 minutes ago, epsilonGreedy said:

[Edit: There was ] A clear consensus plus pro+ tips from @nod

 

I forgot to say:

• I have an L-shaped hipped roof design and had a hunch there might be some sag with such a roof hence I liked the idea of a stud wall transferring some of that sag load down to the ground floor block walls. My thinking was that it would be best to transfer that force direct from rafter to studwall wood rather than through in intermediate 15mm shim of crumbly plasterboard. The roof cover is slate so maybe I am overthinking roof loads.
• Expanding on point-1, I am considering ordering attic trusses for the central 4m ridge of the main hipped roof, this will create a useful attic storage area 4m x 3m however with a ridge height of 1.7m this 4m x 3m area will never be converted to a room. Given a possible cumulative attic storage load of say 200kg I thought it best to fix the stud wall direct to rafters. 

Does this additional info change the advice?

Try using I stud It’s load baring 

Stronger and 100% true 

[tonyshouse]

Insulation above is poor! 
 

When I build roofs I go roof structure, fascias, tack, lighting wiring, insulate, (dead easy to perfectly at this stage including over the wall plate area), felt, batten and tile 
 

?

[Oz07]

I've never seen ceilings done first. Round here the boarders get paid low 3 quid per m2 whether it's one massive area or small rooms. Not saying it can't or isn't done but I always fix top plate to the underside trusses

[Russell griffiths]

What I put as a comment about boarding the whole roof, was not really what I would do personally 

personally I would build all stud walls, fixed securely to underside of trusses

then cross batten underside of trusses and fit electrical then board. 

 

But you asked for an opinion on your carpenters ideas. 

[tonyshouse]

In airtightness terms I like to have a full air barrier above the plasterboard, so poly sheet first then plasterboard etc 

 

cant see how air tightness could possibly work with plates first? 

[Russell griffiths]

19 minutes ago, tonyshouse said:

In airtightness terms I like to have a full air barrier above the plasterboard, so poly sheet first then plasterboard etc 

 

cant see how air tightness could possibly work with plates first? 

That’s a good point. 

[Oz07]

Here's my hybrid. After much procrastination I went with the membrane as opposed to OSB. created a void below trusses for services.

[tonyshouse]

How will you ensure no draughts from outside get into the void? 

[Oz07]

Membrane is taped and linked down to parge coated blockwork. Only 3 penetrations in membrane all taped around 

[WWilts]

On 14/06/2020 at 13:10, tonyshouse said:

I like to have a full air barrier above the plasterboard, so poly sheet first then plasterboard etc

What poly sheet would you use, to allow plasterer to see where roof trusses are? (avoiding battens under roof trusses if possible, to preserve limited floor to ceiling height)

When stud wall top plates are attached to roof trusses, could the poly sheet still go on after stud walls put up? (stud walls not yet begun)

If so, how to get airtight seal above stud wall?