Sagging ceiling joists

[Whatwhy]

Hi all,

I am hoping to get some advice/thoughts on how to best tacking an issue with our ceiling.
Our bedroom ceiling in our Victorian house needed replacement as the old plaster was damp and falling down. I have removed the old plaster and some of the old lathe, but have noticed that the existing joists are bowed/sagging in the middle of the room. The span is a relatively long at 5300mm with old 40x95mm joists at 400 centres.
My initial though was to add a suspended ceiling like gypline and fix to the existing joists.
https://www.british-gypsum.com/Spec...ector/ceilings/gypceiling-lining/c106020-b-en
But if anyone has other thoughts, I would be glad to hear them.

Regards,
Sam

 

[foxhole]

You could cross batten and level to put up a new ceiling .

 

[IJWS15]

Previous owner may have had too much stored in the loft.

having stripped it back that far I would replace the joists with something thicker to give a flat ceiling.

 

[Whatwhy]

Previous owner may have had too much stored in the loft.

having stripped it back that far I would replace the joists with something thicker to give a flat ceiling.

Thanks, I had considered that, but from what I have been able to find online, with a span as big as mine BS recommends a joist size of 47x220 for spans up to 5400 which would add a lot more weight than I currently have. Also one side of the current joists rests on an internal stone wall that has a large roof truss in front of it, I don't think I would not be able to get a bigger joist past that truss to rest on the wall again, but I will take an other look.

 

[martygturner]

Thanks, I had considered that, but from what I have been able to find online, with a span as big as mine BS recommends a joist size of 47x220 for spans up to 5400 which would add a lot more weight than I currently have. Also one side of the current joists rests on an internal stone wall that has a large roof truss in front of it, I don't think I would not be able to get a bigger joist past that truss to rest on the wall again, but I will take an other look.

It all depends on the use of the loft space. If you want to use it and keep the original timbers you will need to shorten the span. Add a purlin at the half way mark, engineered timber beam would do. Some bravery is needed to cut the joists, but you can then jack them back up to level.

Or just take it down and do the same...shorten the span, put two cross beams in and you are down to 38x100. 2 off 6x2 glued and screwed off a joist hanger would be overkill.

If you don't want the loft space for anything other than the crimbo decorations and and just wanted it done I would do construct a flitch beam at 90's to the original joists above the centre point the height required for the top of the joist to be returned to level ( well level ish) and jack the originals back up with a an acro prop, and block and screw them to the beam above. 2 of 6x2 containing 3x4x2 on edge supports a hell of a load.And are easy enough to drag up and in by taking a couple of tiles off if you are stuck for access.


If cash is tight. ....some firings glued and screwed to the indeside to the joists is all that is needed..You just need a skill saw for that.

If you don't have a skill saw, just run some batten down the sides....its only plasterboard.

Or take it all down insulate that roof and have a marvelous vaulted ceiling.

 

[cdbe]

If you don't mind losing a bit of ceiling height, you could install a separate ceiling spanning across the (hopefully shorter) other direction on hangers. The span tables include a load allowance that considerably exceeds the weight of skimmed plasterboard so you could chance something less. It's not structural so your only issues is slightly more deflection and resulting possible cracking of the skim, generally on the joins, this can largely be avoided if you position the plasterboard lengthways centrally across the span.

Your original ceiling would have likely hung from timber hangers off the purlins so worth checking they're still there

 

[Whatwhy]

It all depends on the use of the loft space. If you want to use it and keep the original timbers you will need to shorten the span. Add a purlin at the half way mark, engineered timber beam would do. Some bravery is needed to cut the joists, but you can then jack them back up to level.

Or just take it down and do the same...shorten the span, put two cross beams in and you are down to 38x100. 2 off 6x2 glued and screwed off a joist hanger would be overkill.

If you don't want the loft space for anything other than the crimbo decorations and and just wanted it done I would do construct a flitch beam at 90's to the original joists above the centre point the height required for the top of the joist to be returned to level ( well level ish) and jack the originals back up with a an acro prop, and block and screw them to the beam above. 2 of 6x2 containing 3x4x2 on edge supports a hell of a load.And are easy enough to drag up and in by taking a couple of tiles off if you are stuck for access.


If cash is tight. ....some firings glued and screwed to the indeside to the joists is all that is needed..You just need a skill saw for that.

If you don't have a skill saw, just run some batten down the sides....its only plasterboard.

Or take it all down insulate that roof and have a marvelous vaulted ceiling.

Hi Marty, thanks for the suggestions.

The loft space above that particular room will be used for storage mainly. Nothing too heavy. I am trying to get hold of a structural engineer to try and find a way past the tie in the attic truss I mentioned, that would give me the option of adding a bathroom, but that is an other project..

For your first option, can you clarify where the purlin would go? Would it be a cross beam running the across the shorter span? or would it be fixed to the roof rafters?

I'm tempted to go with taking it down and adding cross beams. My walls are all solid (no cavity) stone construction, what's the best way to fix the new spans and beams to the walls?

Could I not add a couple of cross beams instead of a fitch and do the same as you suggested? Still not sure how to support/hang the beams though.

Everything comes down to money these days, so firring strips is an option, but it means clearing the old lath nails from the existing joists...i feel replacing them might be easier and less messy.

Thanks again for the options

 

[Whatwhy]

If you don't mind losing a bit of ceiling height, you could install a separate ceiling spanning across the (hopefully shorter) other direction on hangers. The span tables include a load allowance that considerably exceeds the weight of skimmed plasterboard so you could chance something less. It's not structural so your only issues is slightly more deflection and resulting possible cracking of the skim, generally on the joins, this can largely be avoided if you position the plasterboard lengthways centrally across the span.

Your original ceiling would have likely hung from timber hangers off the purlins so worth checking they're still there

Thanks cdbe,
The original ceiling joists run into the external stone (Stone exterior and brick interior, no cavity) on one side, and onto an internal stone wall on the other, no hangers used.
I don't really mind losing a bit of height, just not entirely sure how to fix the new ceiling joists to the stone walls.

 

[martygturner]

A filch beam can be assembled above the existing joists as they are made up of smaller items ie a two off 6x2 sandwiching 3 off 4x2 to give 6x8 beam. its just a case of access and weight ...trying to lift and manage a heavy beam through the existing joist would be a pain.....and it goes across the joists...as does all other beams they are there to shorten the span of the joists. A solid 5m 6x8 beam weighs in at 65kg a 6x8 plank is 14kg...which one is easier to navigate through the existing joists.

So you could cut you joist in the middle and put a cross beam up and then join you existing to the cross beam with joist hangers. The cross beam is fixed to the side wall with joist hanger.

If you shorten the span then you can use a smaller joist ...have a look at robbins price guide https://www.robbins.co.uk/wp-content/uploads/2023/03/Retail-Price-Guide.pdf

So with one cross beam you would need 2x 2.48m long 47x120 for a 25n loading @ a cost of 3.16 per m or £15.67 per run

With it direct end to end you will need 75x220 x 5m which is £8.06pm or £40.03 per run both at 400mm spacing.

You really need to plan if the ceiling will be a floor or just a support for insulation and plasterboard...making firrings is not difficult or being really cheap plastic packers and batten.

Fixing anything to a stone wall is just a question of which anchor to use...joist hangers are made to do that job of supporting beams.

 

[cdbe]

just not entirely sure how to fix the new ceiling joists to the stone walls.

Masonry Joist hangers into the wall or a ledger board fixed to the surface of the wall and joists fixed with timber to timber hangers.