Boarding a Ceiling & joist hangers etc

[Spinny]

Will need to board the ceiling in the new extension soon. Some ceiling joists sit in joist hangars which therefore protrude down below the general level of the bottom of the ceiling joists. Also one or two joists not perfectly level in places with the rest of the timbers.

 

When it is boarded is this likely to be a problem ?

What can I do about it ?

[SBMS]

1 hour ago, Spinny said:

Will need to board the ceiling in the new extension soon. Some ceiling joists sit in joist hangars which therefore protrude down below the general level of the bottom of the ceiling joists. Also one or two joists not perfectly level in places with the rest of the timbers.

 

When it is boarded is this likely to be a problem ?

What can I do about it ?

Counterbattening your ceiling is what we are doing. Solves this problem, strengthens the floor above and mitigates any potential issues with plaster skim cracking as the floors settle. 
 

 

you can also shim under your counterbattens if not perfectly level. 

Edited yesterday at 08:14 by SBMS

[nod]

1 hour ago, Spinny said:

Will need to board the ceiling in the new extension soon. Some ceiling joists sit in joist hangars which therefore protrude down below the general level of the bottom of the ceiling joists. Also one or two joists not perfectly level in places with the rest of the timbers.

 

When it is boarded is this likely to be a problem ?

What can I do about it ?

[Spinny]

Have heard of counter battening but was never specified or part of our plan.  We wanted the ceiling height to match the main house. We don't have any floor above, it is a single storey extension. Seems like quite significant extra work, cost, and time.

 

Is there another way ?

bash them up as tight as possible with a hammer ? and/or score out a bit of plasterboard behind them ? 

some judicious use of a multitool ?

 

See photos

[Galileo]

That dwang could be removed easily enough and put level, but by the time you've messed about doing that, hacking the back of the plasterboard to get it level, you might as well have just nailed up some simple cheap battens and be done. If you're going to get it plastered, that would cover a few sins, or maybe use insulation backed plasterboard which will conform better, but of course cost more.

[SBMS]

5 hours ago, Spinny said:

Seems like quite significant extra work, cost, and time

Hardly… a few 25mm tile battens, nail gun could have it done in a day? Much easier than faffing around compromising your hangers in my mind. Apparently it’s better for plastering - less likely to crack so I’ve been told. Is that true @nod?

[nod]

6 minutes ago, SBMS said:

Hardly… a few 25mm tile battens, nail gun could have it done in a day? Much easier than faffing around compromising your hangers in my mind. Apparently it’s better for plastering - less likely to crack so I’ve been told. Is that true @nod?

I used 3-1 on both ours It is better for plastering Gets over the hangers But also stops the floor above creeping 

 

The one I pictured today Is one we where asked to do to give a bit more depth 

[Mike]

6 hours ago, Spinny said:

Is there another way ?

There was (notching the timbers so that the hangers are flush) but, from where you are now, counter-battening is your best option.

[JamesP]

I fitted resilient bars, separates the plasterboard from the floor joists and supposedly helps with reducing noise. @nod will confirm?

Noise not an issue if single storey but would get you under the hangers.

 

Edited yesterday at 20:55 by JamesP

[Eric]

I had multiple brackets on JJI joists so I made cut outs in the plasterboard with the multi tool.

[Spinny]

How about if I use acoustic isolation strip across the underside of all the joists and then cut it out where the hangers are ?

 

(Might give me some slight sound benefit at the same time.)

 

https://www.insulationuk.co.uk/products/50mm-tekfon-acoustic-isolation-strip-50mm-x-10m?currency=GBP&gad_campaignid=17325772288&gad_source=1&gbraid=0AAAAAoNNCLS46l0Skr_o4MTjiC7gA41RT&gclid=EAIaIQobChMIg-Gws-TsjQMVJJdQBh0YBiM8EAQYCCABEgIoRvD_BwE&utm_campaign=&utm_medium=cpc&utm_source=google&variant=54935887774075

[SBMS]

6 minutes ago, Spinny said:

How about if I use acoustic isolation strip across the underside of all the joists and then cut it out where the hangers are ?

 

(Might give me some slight sound benefit at the same time.)

 

https://www.insulationuk.co.uk/products/50mm-tekfon-acoustic-isolation-strip-50mm-x-10m?currency=GBP&gad_campaignid=17325772288&gad_source=1&gbraid=0AAAAAoNNCLS46l0Skr_o4MTjiC7gA41RT&gclid=EAIaIQobChMIg-Gws-TsjQMVJJdQBh0YBiM8EAQYCCABEgIoRvD_BwE&utm_campaign=&utm_medium=cpc&utm_source=google&variant=54935887774075

10m of acoustic tape.. £8

10m of treated battens… £5.40

[Spinny]

27 minutes ago, Mike said:

There was (notching the timbers so that the hangers are flush) but, from where you are now, counter-battening is your best option.

The Builders Prj Manager took great care to ensure the joists could be notched over the steels to avoid the steels being proud of the joists. Strange to then completely ignore the hanger issue.

(I suppose they are there because of the rooflights. I guess he had never done a build with rooflights before. (He was a former chef))

[Spinny]

14 minutes ago, SBMS said:

10m of acoustic tape.. £8

10m of treated battens… £5.40

Acoustic strip is just self adhesive straight onto the existing joists though - no layout time trying to avoid all the lighting positions - no cutting time - less reduction in ceiling height.

Edited yesterday at 21:31 by Spinny

[SBMS]

20 minutes ago, Spinny said:

Acoustic strip is just self adhesive straight onto the existing joists though - no layout time trying to avoid all the lighting positions - no cutting time - less reduction in ceiling height.

Fair enough. Am no expert so perhaps someone will be along here to agree with acoustic strips! We designed in counter battening from the start for our ceilings but agree if you haven’t got the height that would put me off 

[Spinny]

3 minutes ago, SBMS said:

Fair enough. Am no expert so perhaps someone will be along here to agree with acoustic strips! We designed in counter battening from the start for our ceilings but agree if you haven’t got the height that would put me off 

We have the ceiling height but it might make a tight fit with the top of the kitchen units. It will also deepen the depth of the rooflight 'wells' - something that hadn't occurred to me before the build and for a warm roof they get quite deep.

Would indeed be nice if someone can comment on actual experience of using acoustic strip. I have one roll in my hands, seems quite sticky, and seems quite stiff to squeezing, so presumably doesn't give you a bouncy ceiling. We are going to have some ceiling speakers though, not sure of any implications there.