Single Joist 'Sagging'

[charliegolf]

In a renovation at the moment, and I have noticed a single joist is lower than the rest causing a bow in the surface. The ceiling is in good condition generally, but is getting replastered due to elec and ch work needing the ceiling to be opened. Should I rectify this- it hasn't been noticeable till now; and only because I put a straight edge on it to draw a line. Can it be rectified even?

Thanks.

 

[Ivor Windybottom]

How much difference?

All ceilings have some variation. One of mine had sagged about 30mm, opened up a step in the ceiling, I replaced it. Think it was probably put in the wrong way up and/or the wood was wet when it was built. But it was also one of the reasons nobody else bid against us when we made a very cheeky offer for the place!

 

[blup]

If its not noticeable and not obviously structural leave as it is and re board it.

 

[Deluks]

The only way to be sure is to open it up and have a look, some people could live with it, some couldn't.

 

[charliegolf]

The only way to be sure is to open it up and have a look, some people could live with it, some couldn't.

That's actually the thing... I hadn't noticed it till I put a straight edge on it the other day. Plain white matt ceiling- not the easiest flaw to see. I will probably get on with it and see how it goes.

 

[stevie888]

My daughter moved into her first flat. Day 2 I get a call: "Dad the ceiling's fallen down." In the cold light of day the cold water tank was pretty much balanced mid span on 2x4 some 3.5 m long. Just a tad outside TRADA tables,, and the ceiling which had no sign of distress beforehad let go. (possibly provoked by dad having to go up a wiggle the inlet valve which had seized up on move in day!)

From underneath we were able to roll the tank a bit to fit a pair of 2x6s to spread the load over 8 joists without affecting the pipework. The culprit then sat bowed at least 50mm but a couple of hefty screws pulled it back to the new bearers and the room was re boarded and looked fine.

 

[big-all]

measure over a larger area and dont assume it lower it may be its the two to the side are higher or a mixture off both
also check the joists are identical as in 227mm for example

 

[cdbe]

I had one where it had been notched for a hearth upstairs and was quite low - I battened either side so the plasterboard finished flush with the bottom of the joist - I scrim taped over the joist. Plasterer said it might crack but it's fine 10 years later.

 

[noseall]

In a renovation at the moment, and I have noticed a single joist is lower than the rest causing a bow in the surface. The ceiling is in good condition generally, but is getting replastered due to elec and ch work needing the ceiling to be opened. Should I rectify this- it hasn't been noticeable till now; and only because I put a straight edge on it to draw a line. Can it be rectified even?

Thanks.

You may get some success with solid bridging (joist centre) and a couple of props.

 

[charliegolf]

You may get some success with solid bridging (joist centre) and a couple of props.

Sorry Noseall, for the dim... what would that entail?

 

[noseall]

Sorry Noseall, for the dim... what would that entail?

A solid (joist depth) run of noggins along the joist span centre and a prop under the sagger

 

[noseall]

Sorry Noseall, for the dim... what would that entail?

You'd need to get the noggs quite tight, to have an effect and the fixings would need to be big enough/long enough not to be bothered by the end-grain.