1890's joist concerns

[bigdrew]

This thread is probably fairly useless without pictures so I will update it as soon as I can. but any immediate help would be appreciated

My partner has just brought a 1890's built cottage and I am fairly concerned a supporting wall has been removed without any additional support. The joists are about 1" wide by 6" deep and seem to be spanning around 5m and are pretty bouncy and sagged. (the lounge ceiling is (was) artex so it hasn't happened in the past 40 years but I suspect it has happened!)

I need to lift some of the floor in the adjacent bedroom to check they do run the full distance

was it usual for them to construct with such small beams and long spans way back? (they are about every 30cm)

Not really sure what to do!?

Lounge ceiling is very low so a beam in under isn't really an option, hiding it in the void is way more disruption then I would like to cause. (and the ceiling has just been plastered!)

sistering the joists with either steel or timber?

Leave it as it is?

There was a fairly detailed survey done but nothing picked up...

 

[bernardgreen]

was it usual for them to construct with such small beams and long spans way back?

Not uncommon....the timber used in those days was often better quality and smaller joists could carry more weight than a modern joist of the same dimensions.

Low ceilings can be an indication that the first floor was added at some time to make what was a single storey building into a two storey building. The extra rooms would be bedrooms or similar with light loading so small joists woere seen as OK.

The joists of my loft floor are not much more than an inch by five and span about 3 metres. That said I would not be happy to put much weight on them.

 

[oldbutnotdead]

If you cut any timber of that age you'll notice the growth rings are very close together (a millimetre or so)- do the same with modern fast-grown timber & its more like 5mm. And you'll get a lovely smell when you cut the old stuff as well .

How low is low (ceiling height)? And how is the headroom in the rooms above? You could try sistering 6 x 2s to the existing (which will reduce the bounce but maybe not the sag), or rip some 25mm ply into 6" strips and sister with that (common in the US, again it'll stiffen the joists but probably not do much about the sag). Current span tables say 50 x 220 C24 for that span......and unless the sag is blatant (like 50mm + drop in the middle with visible cracks) you can forget chasing the surveyor

EDIT The old ceiling timber here at the House of Pain were 1" x 4" and supported me and a gable end wall's worth of bricks without going anywhere. Soon as I dropped the attached lath and plaster ceiling they went very wobbly in both planes......

 

[tony1851]

That sounds more like a trampoline than a floor.
You will never get rid of the sag - timber under load undergoes long-term creep and will stay in its deflected state whatever you try and do with it.
As above, the timber is probably of good quality when compared with todays' rubbish, but it's not going anywhere and won't collapse.
If its' and old cottage, why not just try and live with it? But keep any heavy items upstairs near the perimeter of the room.

 

[bernardgreen]

Soon as I dropped the attached lath and plaster ceiling

Assassin.......

 

[wessex101]

I cannot believe that the original builders intended a skinny 6 inch joist to try and span 5 metres, even allowing for the quality of the timber (That is almost a floor board laid on edge). In fact 5 metres seems a rather large room for an old cottage so it would appear quite likely that someone has removed an old supporting wall.

Other than reinstating the wall, with a low ceiling height the only way I can see you could strengthen the floor is to insert a steel beam within the thickness of the floor and even then you might still have a small downstand.

 

[bigdrew]

I don't particularly want to get rid of the sag. It doesn't detract from the house. Everything it pretty wonkey!. It's only downstairs the ceilings are low. Upstairs rooms are 2.8m.

My only concern is long term damage. I'm perfectly happy to leave it as is (probably add some noggins and maybe ply as suggested). IlI update with pictures this afternoon.

I do think a wall has been removed at some point in history. I've no experience with old houses but two windows in the livliv room and small plasterboarded section of ceiling splitting up the lath and plaster all point towards it.

Unfortunately the lounge ceiling has just been over boarded and skimmed. Putting a beam in the void would not go down well. And I would like to avoid if absolutely necessary.

 

[wessex101]

If you decide to keep the floor with the sag I would suggest you check the bearings where the joists go into the main walls. You might be surprised how much the sag pulls the joists out of their pocket. Which in turn of course calls into question the lateral support to the external walls.

I'm still really struggling with the concept of 6x1 floors joists let alone spanning 5 metres. There is something very odd going on here.

 

[bigdrew]

Thanks illI check for that. One side is fine ill pull the boards up at the other. More for the sake of the joists.
They are the shared walls so pretty well supported.

Maybe I just get on with it and put a beam in. It feels like the right thing to do.. after getting someone that knows what they are on about to have a look.

Wessex, I think the joists are struggling with the concept of spanning 5m...

 

[bigdrew]

Thin joist are actually 1.5" with a couple of 2.5"

There has definitely been a wall removed at some point. Just visible in the picture the lath and plaster finishes and there is 150mm of plasterboard the lath and plaster starts again..

Old wall would have been ,1.8m into the 5m span..

 

[bobasd]

yeah, that photo is a different story to your first post.
the wall looks like a stud partition but it still carrys weight.

if it comes to it you can slide in rippings of 3/4" ply an sister them with lots of screws.
the ply doesnt have to be the full length of the span or the full depth of the section - it can be short of the bearin walls.
any sisterin has to take account of insitu cables an pipe

 

[bigdrew]

Would ply be better than c16 timber. Is that a suitable alternative to splitting the span with a beam?.

I did consider 3mm steel plate. Not sure how that would compare to ply.

 

[bobasd]

ply will work fine

 

[Keithmac]

Just be careful your Artex isn't riddled with asbestos..

 

[bigdrew]

Thanks Keith, all work was finished 8 months ago. There is now a ub in there and it's nice and solid!