Possible floor joist problem - what to do?

Olga_da_Polga

Hi all, long time lurker hoping for some advice and hopefully some reassurance too.


We've got a patch of floorboards outside our kitchen which have steadily become wonkier and more uneven over time. It's a high traffic area and the carpet is pretty worn but it seemed odd, and our neighbours downstairs mentioned their light fitting moves when we walk in that area, so we've just taken the carpet and a couple of floorboards up to have a look and now I'm worried.


The background is the house was built around 1905 and was split in the 1950s into two flats, and we're in the upper part. There's a shared hall on the ground floor and we have our own entrance from that up a flight of stairs to our part on the 1st and 2nd floors. The kitchen is on the 1st floor off an L-shaped landing which runs between the main stairs and the staircase up to the 2nd floor. There will have been lots of work done under the floorboards at different times - separating out the gas/water/electricity when the house was split, central heating going in later, you get the idea.



It looks like there are 3 joists running along the length of that bit of the landing, and the floorboards have all been cut at the middle joist line. Under the floorboards we lifted we could see the joists have been notched to allow pipes to be fitted - approx. 2cm notches in joists which are about 8cm deep which from online research I think is deeper than is safe?



The question is, what do we do about it and who should we approach? - a builder, a joiner...? I don't want us to suddenly fall through the floor into the downstairs neighbours' house but I'm a bit scared by the thought of needing to have structural work done.



Any suggestions very gratefully welcomed!

tacpot12

The existing joists sound very shallow if they are only 8cm deep. They should only be unsupported over a short length. Have a look at this document from Haringey to see what is safe.

https://www.haringey.gov.uk/sites/haringeygovuk/files/note07_-_domestic_timber_floors.pdf

If the joists are suppported adequately, they you just need to double up the joists by bolting another joist along side the existing joists over the longest possible length.
Either a builder or a joiner should be able to do the work so go with the best quote/tradesperson.

FreeBear

Sounds like something the freeholder should be sorting out. Check your lease agreement to see who is responsible for this type of work.

Olga_da_Polga

No freeholder to pass this on to unfortunately, we're in Scotland.

TeamPlum

Without pictures, it's difficult to say.

I'd be tempted to get a joiner, who might try a technique called 'sistering' which is attaching supporting timber to the side.

First I'd be temptd to replaced the damaged boards, and ensure they ran the length and we're adequately tightened down.

maisie_cat

Without pictures it's hard to tell, but it was common to notch joists to allow copper pipe to pass through, and if the remainder is 8cm it sounds like the joists were originally standard 4". You could sister underneath where the pipes go through with something like 3x2.
Although that treatment of pipework through joists is not best practice now, it was probably done years ago and you just need to not make it worse.

Olga_da_Polga

Thanks for all the input so far! I do have pictures - not sure how to upload them but I'll try to do it tonight if I can get the time.

Ectophile

It may be that the joists are still reasonably sound, just too springy because someone has cut out too much material. You can get metal joist repair plates. Screwing those across the cut should stiffen the joists.

Olga_da_Polga

Here are the pictures, I hope - I am a techno numpty usually.



http://s32.photobucket.com/user/jennydiver/media/038_zpszrirlhbq.jpg.html?sort=3&o=0


http://s32.photobucket.com/user/jennydiver/media/036_zpsgidev0dk.jpg.html?sort=3&o=1


http://s32.photobucket.com/user/jennydiver/media/035_zpsbsutiw1l.jpg.html?sort=3&o=2